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Khan J, Rydèn T, Van Essen M, Svensson J, Grudzinski J, Bernhardt P. Dosimetric implications of kidney anatomical volume changes in 177Lu-DOTATATE therapy. EJNMMI Phys 2024; 11:71. [PMID: 39090481 PMCID: PMC11294297 DOI: 10.1186/s40658-024-00672-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 07/12/2024] [Indexed: 08/04/2024] Open
Abstract
INTRODUCTION This study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in 177Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes-whether caused by radiation or amino acid infusion-by comparing them with spleen volume changes as a marker for radiation-induced alterations. METHODS SPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of 177Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated. RESULTS Whole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. BL), 10.77% (D1 vs. BL), 1.10% (D2 vs. BL), and 1.10% (D7 vs. BL), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes. CONCLUSIONS Kidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to an overestimation of the absorbed dose. The fluctuations in kidney volume are most likely attributable to amino acid infusion.
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Affiliation(s)
- Jehangir Khan
- Department of Medical Physics and Biomedical Engineering (MFT), Sahlgrenska University Hospital, Gothenburg, SE-41345, Sweden.
- Department of Medical Physics, Faculty of Medicine and Health, Örebro University Hospital, Örebro, Sweden.
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, USA.
| | - Tobias Rydèn
- Department of Medical Physics and Biomedical Engineering (MFT), Sahlgrenska University Hospital, Gothenburg, SE-41345, Sweden
| | - Martijn Van Essen
- Department of Clinical Physiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Johanna Svensson
- Department of Oncology, Institution of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Joseph Grudzinski
- Department of Radiology, University of Wisconsin - Madison, Madison, USA
| | - Peter Bernhardt
- Department of Medical Physics and Biomedical Engineering (MFT), Sahlgrenska University Hospital, Gothenburg, SE-41345, Sweden
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, USA
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Stokke C, Gnesin S, Tran-Gia J, Cicone F, Holm S, Cremonesi M, Blakkisrud J, Wendler T, Gillings N, Herrmann K, Mottaghy FM, Gear J. EANM guidance document: dosimetry for first-in-human studies and early phase clinical trials. Eur J Nucl Med Mol Imaging 2024; 51:1268-1286. [PMID: 38366197 PMCID: PMC10957710 DOI: 10.1007/s00259-024-06640-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/04/2024] [Indexed: 02/18/2024]
Abstract
The numbers of diagnostic and therapeutic nuclear medicine agents under investigation are rapidly increasing. Both novel emitters and novel carrier molecules require careful selection of measurement procedures. This document provides guidance relevant to dosimetry for first-in human and early phase clinical trials of such novel agents. The guideline includes a short introduction to different emitters and carrier molecules, followed by recommendations on the methods for activity measurement, pharmacokinetic analyses, as well as absorbed dose calculations and uncertainty analyses. The optimal use of preclinical information and studies involving diagnostic analogues is discussed. Good practice reporting is emphasised, and relevant dosimetry parameters and method descriptions to be included are listed. Three examples of first-in-human dosimetry studies, both for diagnostic tracers and radionuclide therapies, are given.
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Affiliation(s)
- Caroline Stokke
- Department of Diagnostic Physics and Computational Radiology, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.
- Department of Physics, University of Oslo, Oslo, Norway.
| | - Silvano Gnesin
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Johannes Tran-Gia
- Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany
| | - Francesco Cicone
- Nuclear Medicine Unit, Department of Experimental and Clinical Medicine, "Magna Graecia" University of Catanzaro, Catanzaro, Italy
| | - Søren Holm
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Marta Cremonesi
- Department of Medical Imaging and Radiation Sciences, European Institute of Oncology, IRCCS, Milan, Italy
| | - Johan Blakkisrud
- Department of Diagnostic Physics and Computational Radiology, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway
| | - Thomas Wendler
- Computer-Aided Medical Procedures and Augmented Reality, Technische Universität München, Munich, Germany
- Clinical Computational Medical Imaging Research, Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Nic Gillings
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Ken Herrmann
- Department of Nuclear Medicine, University of Duisburg-Essen, and German Cancer Consortium (DKTK)-University Hospital Essen, Essen, Germany
- National Center for Tumor Diseases (NCT), NCT West, Heidelberg, Germany
| | - Felix M Mottaghy
- Department of Radiology and Nuclear Medicine, GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
- Department of Nuclear Medicine, University Hospital RWTH Aachen, Aachen, Germany
| | - Jonathan Gear
- Joint Department of Physics, Royal Marsden NHSFT & Institute of Cancer Research, Sutton, UK
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Brosch-Lenz J, Ke S, Wang H, Frey E, Dewaraja YK, Sunderland J, Uribe C. An International Study of Factors Affecting Variability of Dosimetry Calculations, Part 2: Overall Variabilities in Absorbed Dose. J Nucl Med 2023; 64:1109-1116. [PMID: 37024302 PMCID: PMC10315703 DOI: 10.2967/jnumed.122.265094] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/07/2023] [Accepted: 02/07/2023] [Indexed: 04/08/2023] Open
Abstract
Dosimetry for personalized radiopharmaceutical therapy has gained considerable attention. Many methods, tools, and workflows have been developed to estimate absorbed dose (AD). However, standardization is still required to reduce variability of AD estimates across centers. One effort for standardization is the Society of Nuclear Medicine and Molecular Imaging 177Lu Dosimetry Challenge, which comprised 5 tasks (T1-T5) designed to assess dose estimate variability associated with the imaging protocol (T1 vs. T2 vs. T3), segmentation (T1 vs. T4), time integration (T4 vs. T5), and dose calculation (T5) steps of the dosimetry workflow. The aim of this work was to assess the overall variability in AD calculations for the different tasks. Methods: Anonymized datasets consisting of serial planar and quantitative SPECT/CT scans, organ and lesion contours, and time-integrated activity maps of 2 patients treated with 177Lu-DOTATATE were made available globally for participants to perform dosimetry calculations and submit their results in standardized submission spreadsheets. The data were carefully curated for formal mistakes and methodologic errors. General descriptive statistics for ADs were calculated, and statistical analysis was performed to compare the results of different tasks. Variability in ADs was measured using the quartile coefficient of dispersion. Results: ADs to organs estimated from planar imaging protocols (T2) were lower by about 60% than those from pure SPECT/CT (T1), and the differences were statistically significant. Importantly, the average differences in dose estimates when at least 1 SPECT/CT acquisition was available (T1, T3, T4, T5) were within ±10%, and the differences with respect to T1 were not statistically significant for most organs and lesions. When serial SPECT/CT images were used, the quartile coefficients of dispersion of ADs for organs and lesions were on average less than 20% and 26%, respectively, for T1; 20% and 18%, respectively, for T4 (segmentations provided); and 10% and 5%, respectively, for T5 (segmentation and time-integrated activity images provided). Conclusion: Variability in ADs was reduced as segmentation and time-integration data were provided to participants. Our results suggest that SPECT/CT-based imaging protocols generate more consistent and less variable results than planar imaging methods. Effort at standardizing segmentation and fitting should be made, as this may substantially reduce variability in ADs.
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Affiliation(s)
- Julia Brosch-Lenz
- Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, British Columbia, Canada
| | - Suqi Ke
- Division of Quantitative Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hao Wang
- Division of Quantitative Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eric Frey
- Rapid, LLC, Baltimore, Maryland
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Yuni K Dewaraja
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - John Sunderland
- Department of Radiology, University of Iowa, Iowa City, Iowa
| | - Carlos Uribe
- Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, British Columbia, Canada;
- Department of Functional Imaging, BC Cancer, Vancouver, British Columbia, Canada; and
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
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Lyu Y, Chen G, Lu Z, Chen Y, Mok GSP. The effects of mismatch between SPECT and CT images on quantitative activity estimation - A simulation study. Z Med Phys 2023; 33:54-69. [PMID: 35644776 PMCID: PMC10082378 DOI: 10.1016/j.zemedi.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 03/19/2022] [Accepted: 03/25/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND Quantitative activity estimation is essential in nuclear medicine imaging. Mismatch between SPECT and CT images at the same imaging time point due to patient movement degrades accuracy in both diagnostic studies and target radionuclide therapy dosimetry. This work aims to study the mismatch effects between CT and SPECT data on attenuation correction (AC), volume-of-interest (VOI) delineation, and registration for activity estimation. METHODS Nine 4D XCAT phantoms were generated at 1, 24, and 144 h post In-111 Zevalin injection, varying in activity distributions, body sizes, and organ sizes. Realistic noisy SPECT projections were generated by an analytical projector and reconstructed with a quantitative OS-EM method. CT images were shifted, corresponding to SPECT images at each imaging time point, from -5 to 5 voxels and also according to a clinical reference. The effect of mismatched AC maps was evaluated using mismatched CT images for AC in SPECT reconstruction while VOIs were mapped out from matched CTs. The effect of mismatched VOI drawings was evaluated using mismatched CTs to map out target organs while using matched CTs for AC. The effect of mismatched CT images for registration was evaluated by registering sequential mismatched CTs to align corresponding SPECT images, with no AC and VOI mismatch. Bi-exponential curve fitting was performed to obtain time-integrated activity (TIA). Organ activity errors (%OAE) and TIA errors (%TIAE) were calculated. RESULTS According to the clinical reference, %OAE was larger for organs near ribs for AC effect. For VOI effect, %OAE was larger for small and low uptake organs. For registration effect, %TIAE were larger when mismatch existed in more numbers of SPECT/CT images, while no substantial difference was observed when using mismatched CT at different imaging time points as registration reference. %TIAE was highest for VOI, followed by registration and AC, e.g., 20.62%±8.61%, 9.33%±4.66% and 1.13%±0.90% respectively for kidneys. CONCLUSIONS The mismatch between CT and SPECT images poses a significant impact on the accuracy of quantitative activity estimation, attributed particularly from VOI delineation errors. It is recommended to perform registration between emission and transmission images at the same time point to ensure diagnostic and dosimetric accuracy.
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Affiliation(s)
- Yingqing Lyu
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China
| | - Gefei Chen
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China
| | - Zhonglin Lu
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China
| | - Yue Chen
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St., Luzhou, Sichuan, China.
| | - Greta S P Mok
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Taipa, Macau SAR, China; Center for Cognitive and Brain Sciences, Institute of Collaborative Innovation, University of Macau, Taipa, Macau SAR, China; Ministry of Education Frontiers Science Center for Precision Oncology, Faculty of Health Science, University of Macau, Taipa, Macau SAR, China.
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Kiess AP, Hobbs RF, Bednarz B, Knox SJ, Meredith R, Escorcia FE. ASTRO's Framework for Radiopharmaceutical Therapy Curriculum Development for Trainees. Int J Radiat Oncol Biol Phys 2022; 113:719-726. [PMID: 35367328 DOI: 10.1016/j.ijrobp.2022.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/08/2022] [Accepted: 03/13/2022] [Indexed: 10/18/2022]
Abstract
In 2017, the American Society for Radiation Oncology (ASTRO) board of directors prioritized radiopharmaceutical therapy (RPT) as a leading area for new therapeutic development, and the ASTRO RPT workgroup was created. Herein, the workgroup has developed a framework for RPT curriculum development upon which education leaders can build to integrate this modality into radiation oncology resident education. Through this effort, the workgroup aims to provide a guide to ensure robust training in an emerging therapeutic area within the context of existing radiation oncology training in radiation biology, medical physics, and clinical radiation oncology. The framework first determines the core RPT knowledge required to select patients, prescribe, safely administer, and manage related adverse events. Then, it defines the most important topics for preparing residents for clinical RPT planning and delivery. This framework is designed as a tool to supplement the current training that exists for radiation oncology residents. The final document was approved by the ASTRO board of directors in the fall of 2021.
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Affiliation(s)
- Ana P Kiess
- Department of Radiation Oncology, Johns Hopkins University, Baltimore, Maryland.
| | - Robert F Hobbs
- Department of Radiation Oncology, Johns Hopkins University, Baltimore, Maryland
| | - Bryan Bednarz
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin
| | - Susan J Knox
- Department of Radiation Oncology, Stanford University Medical Center, Stanford, California
| | - Ruby Meredith
- Department of Radiation Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Freddy E Escorcia
- Molecular Imaging Branch, Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
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Liu Z, Li Z, Mhlanga JC, Siegel BA, Jha AK. No-gold-standard evaluation of quantitative imaging methods in the presence of correlated noise. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2022; 12035:120350M. [PMID: 36465994 PMCID: PMC9717481 DOI: 10.1117/12.2605762] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Objective evaluation of quantitative imaging (QI) methods with patient data is highly desirable, but is hindered by the lack or unreliability of an available gold standard. To address this issue, techniques that can evaluate QI methods without access to a gold standard are being actively developed. These techniques assume that the true and measured values are linearly related by a slope, bias, and Gaussian-distributed noise term, where the noise between measurements made by different methods is independent of each other. However, this noise arises in the process of measuring the same quantitative value, and thus can be correlated. To address this limitation, we propose a no-gold-standard evaluation (NGSE) technique that models this correlated noise by a multi-variate Gaussian distribution parameterized by a covariance matrix. We derive a maximum-likelihood-based approach to estimate the parameters that describe the relationship between the true and measured values, without any knowledge of the true values. We then use the estimated slopes and diagonal elements of the covariance matrix to compute the noise-to-slope ratio (NSR) to rank the QI methods on the basis of precision. The proposed NGSE technique was evaluated with multiple numerical experiments. Our results showed that the technique reliably estimated the NSR values and yielded accurate rankings of the considered methods for 83% of 160 trials. In particular, the technique correctly identified the most precise method for ∼ 97% of the trials. Overall, this study demonstrates the efficacy of the NGSE technique to accurately rank different QI methods when correlated noise is present, and without access to any knowledge of the ground truth. The results motivate further validation of this technique with realistic simulation studies and patient data.
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Affiliation(s)
- Ziping Liu
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
| | - Zekun Li
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
| | - Joyce C. Mhlanga
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Barry A. Siegel
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Abhinav K. Jha
- Department of Biomedical Engineering, Washington University, St. Louis, MO, USA
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
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Liu X, Liu H, Cheng L, Wu J, Bao T, Yao R, Liu Y. A 3-dimensional stationary cascade gamma-ray coincidence imager. Phys Med Biol 2021; 66. [PMID: 34666327 DOI: 10.1088/1361-6560/ac311b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 10/19/2021] [Indexed: 11/12/2022]
Abstract
Objective.For certain radionuclides that decay through emitting two or more gamma photons consecutively within a short time interval-called cascade gamma-rays, the location where a radiopharmaceutical molecule emits cascade gamma-rays can be identified through coincidence detection of the photons. If each cascade photon is detected through a collimation mechanism, the location of the molecule can be inferred from the intersection of the back-projections of the two photons.Approach.In this work, we report the design and evaluation of a three-dimensional stationary imager based on this concept for imaging distributions of cascade-emitting radionuclides in radiopharmaceutical therapy. The imager was composed of two gamma-ray cameras assembled in an L-shape. Both cameras were NaI(Tl) scintillator based, one with a multi-slit collimator, the other with a multi-pinhole collimator. The field of view (FOV) was 100 mm (∅) × 100 mm (L). Based on the unique characteristics of the cascade coincidence events, we used a direct back-projection algorithm to reconstruct point source images for assessing the imager's intrinsic spatial resolution and the standard maximum likelihood expectation maximization algorithm for reconstructing phantom images.Main results.We evaluated the performance of the imager in both simulated and prototype form with radionuclide177Lu (cascade photon emitter). On the simulated imager, the coincidence detection efficiency at the center of FOV was 3.85 × 10-6, the spatial resolution was 7.0 mm. On the prototype imager, the corresponding values were 3.20 × 10-6and 6.7 mm, respectively. Simulated hot-rod and experimental cardiac phantom studies demonstrate the first three-dimensional cascade gamma coincidence imager is fully functional.
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Affiliation(s)
- Xiao Liu
- Department of Engineering Physics, Tsinghua University, Beijing 100084, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Ministry of Education (Tsinghua University), Beijing 100084, People's Republic of China
| | - Hui Liu
- Department of Engineering Physics, Tsinghua University, Beijing 100084, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Ministry of Education (Tsinghua University), Beijing 100084, People's Republic of China
| | - Li Cheng
- Department of Engineering Physics, Tsinghua University, Beijing 100084, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Ministry of Education (Tsinghua University), Beijing 100084, People's Republic of China
| | - Jing Wu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Tianwei Bao
- Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Rutao Yao
- Department of Nuclear Medicine, University at Buffalo, State University of New York, NY 14214, United States of America
| | - Yaqiang Liu
- Department of Engineering Physics, Tsinghua University, Beijing 100084, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Ministry of Education (Tsinghua University), Beijing 100084, People's Republic of China
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Plyku D, Ghaly M, Li Y, Brown JL, O'Reilly S, Khamwan K, Goodkind AB, Sexton-Stallone B, Cao X, Zurakowski D, Fahey FH, Treves ST, Bolch WE, Frey EC, Sgouros G. Renal 99mTc-DMSA pharmacokinetics in pediatric patients. EJNMMI Phys 2021; 8:53. [PMID: 34283316 PMCID: PMC8292521 DOI: 10.1186/s40658-021-00401-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/05/2021] [Indexed: 11/10/2022] Open
Abstract
99mTc-DMSA is one of the most commonly used pediatric nuclear medicine imaging agents. Nevertheless, there are no pharmacokinetic (PK) models for 99mTc-DMSA in children, and currently available pediatric dose estimates for 99mTc-DMSA use pediatric S values with PK data derived from adults. Furthermore, the adult PK data were collected in the mid-70's using quantification techniques and instrumentation available at the time. Using pediatric imaging data for DMSA, we have obtained kinetic parameters for DMSA that differ from those applicable to adults. METHODS We obtained patient data from a retrospective re-evaluation of clinically collected pediatric SPECT images of 99mTc-DMSA in 54 pediatric patients from Boston's Children Hospital (BCH), ranging in age from 1 to 16 years old. These were supplemented by prospective data from twenty-three pediatric patients (age range: 4 months to 6 years old). RESULTS In pediatric patients, the plateau phase in fractional kidney uptake occurs at a fractional uptake value closer to 0.3 than the value of 0.5 reported by the International Commission on Radiological Protection (ICRP) for adult patients. This leads to a 27% lower time-integrated activity coefficient in pediatric patients than in adults. Over the age range examined, no age dependency in uptake fraction at the clinical imaging time was observed. Female pediatric patients had a 17% higher fractional kidney uptake at the clinical imaging time than males (P < 0.001). CONCLUSIONS Pediatric 99mTc-DMSA kinetics differ from those reported for adults and should be considered in pediatric patient dosimetry. Alternatively, the differences obtained in this study could reflect improved quantification methods and the need to re-examine DMSA kinetics in adults.
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Affiliation(s)
- Donika Plyku
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Michael Ghaly
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Ye Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Justin L Brown
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Shannon O'Reilly
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Kitiwat Khamwan
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
- Department of Radiology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand
| | - Alison B Goodkind
- Division of Nuclear Medicine and Molecular Imaging, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Briana Sexton-Stallone
- Division of Nuclear Medicine and Molecular Imaging, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Xinhua Cao
- Division of Nuclear Medicine and Molecular Imaging, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - David Zurakowski
- Departments of Anesthesiology and Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Frederic H Fahey
- Division of Nuclear Medicine and Molecular Imaging, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - S Ted Treves
- Division of Nuclear Medicine and Molecular imaging, Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Wesley E Bolch
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Eric C Frey
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - George Sgouros
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
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Chen J, Li Y, Luna LP, Chung HW, Rowe SP, Du Y, Solnes LB, Frey EC. Learning fuzzy clustering for SPECT/CT segmentation via convolutional neural networks. Med Phys 2021; 48:3860-3877. [PMID: 33905560 PMCID: PMC9973404 DOI: 10.1002/mp.14903] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/01/2021] [Accepted: 04/12/2021] [Indexed: 01/07/2023] Open
Abstract
PURPOSE Quantitative bone single-photon emission computed tomography (QBSPECT) has the potential to provide a better quantitative assessment of bone metastasis than planar bone scintigraphy due to its ability to better quantify activity in overlapping structures. An important element of assessing the response of bone metastasis is accurate image segmentation. However, limited by the properties of QBSPECT images, the segmentation of anatomical regions-of-interests (ROIs) still relies heavily on the manual delineation by experts. This work proposes a fast and robust automated segmentation method for partitioning a QBSPECT image into lesion, bone, and background. METHODS We present a new unsupervised segmentation loss function and its semi- and supervised variants for training a convolutional neural network (ConvNet). The loss functions were developed based on the objective function of the classical Fuzzy C-means (FCM) algorithm. The first proposed loss function can be computed within the input image itself without any ground truth labels, and is thus unsupervised; the proposed supervised loss function follows the traditional paradigm of the deep learning-based segmentation methods and leverages ground truth labels during training. The last loss function is a combination of the first and the second and includes a weighting parameter, which enables semi-supervised segmentation using deep learning neural network. EXPERIMENTS AND RESULTS We conducted a comprehensive study to compare our proposed methods with ConvNets trained using supervised, cross-entropy and Dice loss functions, and conventional clustering methods. The Dice similarity coefficient (DSC) and several other metrics were used as figures of merit as applied to the task of delineating lesion and bone in both simulated and clinical SPECT/CT images. We experimentally demonstrated that the proposed methods yielded good segmentation results on a clinical dataset even though the training was done using realistic simulated images. On simulated SPECT/CT, the proposed unsupervised model's accuracy was greater than the conventional clustering methods while reducing computation time by 200-fold. For the clinical QBSPECT/CT, the proposed semi-supervised ConvNet model, trained using simulated images, produced DSCs of 0.75 and 0.74 for lesion and bone segmentation in SPECT, and a DSC of 0.79 bone segmentation of CT images. These DSCs were larger than that for standard segmentation loss functions by > 0.4 for SPECT segmentation, and > 0.07 for CT segmentation with P-values < 0.001 from a paired t-test. CONCLUSIONS A ConvNet-based image segmentation method that uses novel loss functions was developed and evaluated. The method can operate in unsupervised, semi-supervised, or fully-supervised modes depending on the availability of annotated training data. The results demonstrated that the proposed method provides fast and robust lesion and bone segmentation for QBSPECT/CT. The method can potentially be applied to other medical image segmentation applications.
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Affiliation(s)
- Junyu Chen
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD,Corresponding author
| | - Ye Li
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
| | - Licia P. Luna
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
| | - Hyun Woo Chung
- Department of Nuclear Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, South Korea
| | - Steven P. Rowe
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
| | - Lilja B. Solnes
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
| | - Eric C. Frey
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD
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10
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Prospective SPECT-CT Organ Dosimetry-Driven Radiation-Absorbed Dose Escalation Using the In-111 ( 111In)/Yttrium 90 ( 90Y) Ibritumomab Tiuxetan (Zevalin ®) Theranostic Pair in Patients with Lymphoma at Myeloablative Dose Levels. Cancers (Basel) 2021; 13:cancers13112828. [PMID: 34204102 PMCID: PMC8201215 DOI: 10.3390/cancers13112828] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022] Open
Abstract
Simple Summary We prospectively evaluated the feasibility of SPECT-CT/planar organ dosimetry-based radiation dose escalation radioimmunotherapy in patients with recurrent non-Hodgkin’s lymphoma using the theranostic pair of 111In and 90Y anti-CD20 ibritumomab tiuxetan (Zevalin®) at myeloablative radiation-absorbed doses with autologous stem cell support. Unlike most routine dose escalation approaches, our approach used patient-individualized measurements of organ radiation absorbed dose from the tracer study, with patient-specific adjustments of the injected therapy dose to deliver a pre-specified radiation absorbed dose to the liver. Our approach was feasible, stem cell engraftment was swift, resulted in an 89% tumor response rate in treated patients, demonstrated over 3 fold variability in liver dosimetry/injected activity among patients, allowed us to exceed the FDA approved administered activity by over 5 fold and demonstrated the normal liver maximum tolerated dose to exceed 28 Gy. Dose escalation was not continued due to lack of drug availability. With modern dosimetry approaches, patient specific dosimetry-driven radiation dose escalation is feasible, allows adjustment of administered activity for heterogeneous pharmacokinetics and allows marked dose escalation vs. non-dosimetry driven approaches. Abstract Purpose: We prospectively evaluated the feasibility of SPECT-CT/planar organ dosimetry-based radiation dose escalation radioimmunotherapy in patients with recurrent non-Hodgkin’s lymphoma using the theranostic pair of 111In and 90Y anti-CD20 ibritumomab tiuxetan (Zevalin®) at myeloablative radiation-absorbed doses with autologous stem cell support. We also assessed acute non-hematopoietic toxicity and early tumor response in this two-center outpatient study. Methods: 24 patients with CD20-positive relapsed or refractory rituximab-sensitive, low-grade, mantle cell, or diffuse large-cell NHL, with normal organ function, platelet counts > 75,000/mm3, and <35% tumor involvement in the marrow were treated with Rituximab (375 mg/m2) weekly for 4 consecutive weeks, then one dose of cyclophosphamide 2.5 g/m2 with filgrastim 10 mcg/kg/day until stem cell collection. Of these, 18 patients with successful stem cell collection (at least 2 × 106 CD34 cells/kg) proceeded to RIT. A dosimetric administration of 111In ibritumomab tiuxetan (185 MBq) followed by five sequential quantitative planar and one SPECT/CT scan was used to determine predicted organ radiation-absorbed dose. Two weeks later, 90Y ibritumomab tiuxetan was administered in an outpatient setting at a cohort- and patient-specific predicted organ radiation-absorbed dose guided by a Continuous Response Assessment (CRM) methodology with the following cohorts for dose escalation: 14.8 MBq/kg, and targeted 18, 24, 28, and 30.5 Gy to the liver. Autologous stem cell infusion occurred when the estimated marrow radiation-absorbed dose rate was predicted to be <1 cGy/h. Feasibility, short-term toxicities, and tumor response were assessed. Results: Patient-specific hybrid SPECT/CT + planar organ dosimetry was feasible in all 18 cases and used to determine the patient-specific therapeutic dose and guide dose escalation (26.8 ± 7.3 MBq/kg (mean), 26.3 MBq/kg (median) of 90Y (range: 12.1–41.4 MBq/kg)) of ibritumomab tiuxetan that was required to deliver 10 Gy to the liver. Infused stem cells engrafted rapidly. The most common treatment-related toxicities were hematological and were reversible following stem cell infusion. No significant hepatotoxicity was seen. One patient died from probable treatment-related causes—pneumonia at day 27 post-transplant. One patient at dose level 18 Gy developed myelodysplastic syndrome (MDS), 4 patients required admission post-90Y RIT for febrile neutropenia, 16/18 patients receiving 90Y ibritumomab tiuxetan (89%) responded to the therapy, with 13 CR (72%) and 3/18 PR (17%), at 60 days post-treatment. Two patients had progressive disease at sixty days. One patient was lost to follow-up. Median time to progression was estimated to be at least 13 months. MTD to the liver is greater than 28 Gy, but the MTD was not reached as the study was terminated due to unexpected discontinuation of availability of the therapeutic agent. Conclusions: Patient-specific outpatient 90Y ibritumomab tiuxetan RIT with myeloablative doses of RIT up to a targeted 30.5 Gy to the liver is feasible, guided by prospective SPECT/CT + planar imaging with the theranostic pair of 111In and 90Y anti-CD20, with outpatient autologous stem cell transplant support. Administered activity over 5 times the standard FDA-approved activity was well-tolerated. The non-hematopoietic MTD in this study exceeds 28 Gy to the liver. Initial tumor responses were common at all dose levels. This study supports the feasibility of organ dosimetry-driven patient-specific dose escalation in the treatment of NHL with stem cell transplant and provides additional information on the radiation tolerance of the normal liver to radiopharmaceutical therapy.
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11
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Ramonaheng K, van Staden JA, du Raan H. The effect of calibration factors and recovery coefficients on 177Lu SPECT activity quantification accuracy: a Monte Carlo study. EJNMMI Phys 2021; 8:27. [PMID: 33738605 PMCID: PMC7973313 DOI: 10.1186/s40658-021-00365-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/08/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Different gamma camera calibration factor (CF) geometries have been proposed to convert SPECT data into units of activity concentration. However, no consensus has been reached on a standardised geometry. The CF is dependent on the selected geometry and is further affected by partial volume effects. This study investigated the effect of two CF geometries and their corresponding recovery coefficients (RCs) on the quantification accuracy of 177Lu SPECT images using Monte Carlo simulations. METHODS The CF geometries investigated were (i) a radioactive-sphere surrounded by non-radioactive water (sphere-CF) and (ii) a cylindrical phantom uniformly filled with radioactive water (cylinder-CF). Recovery coefficients were obtained using the sphere-CF and cylinder-CF, yielding the sphere-RC and cylinder-RC values, respectively, for partial volume correction (PVC). The quantification accuracy was evaluated using four different-sized spheres (15.6-65.4 ml) and a kidney model with known activity concentrations inside a cylindrical, torso and patient phantom. Images were reconstructed with the 3D OS-EM algorithm incorporating attenuation, scatter and detector-response corrections. Segmentation was performed using the physical size and a small cylindrical volume inside the cylinder for the sphere-CF and cylinder-CF, respectively. RESULTS The sphere quantification error (without PVC) was better for the sphere-CF (≤ - 5.54%) compared to the cylinder-CF (≤ - 20.90%), attributed to the similar geometry of the quantified and CF spheres. Partial volume correction yielded comparable results for the sphere-CF-RC (≤ 3.47%) and cylinder-CF-RC (≤ 3.53%). The accuracy of the kidney quantification was poorer (≤ 22.34%) for the sphere-CF without PVC compared to the cylinder-CF (≤ 2.44%). With PVC, the kidney quantification results improved and compared well for the sphere-CF-RC (≤ 3.50%) and the cylinder-CF-RC (≤ 3.45%). CONCLUSION The study demonstrated that upon careful selection of CF-RC combinations, comparable quantification errors (≤ 3.53%) were obtained between the sphere-CF-RC and cylinder-CF-RC, when all corrections were applied.
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Affiliation(s)
- Keamogetswe Ramonaheng
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - Johannes A van Staden
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - Hanlie du Raan
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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12
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Li Y, Chen J, Brown JL, Treves ST, Cao X, Fahey FH, Sgouros G, Bolch WE, Frey EC. DeepAMO: a multi-slice, multi-view anthropomorphic model observer for visual detection tasks performed on volume images. J Med Imaging (Bellingham) 2021; 8:041204. [PMID: 33521164 DOI: 10.1117/1.jmi.8.4.041204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 12/31/2020] [Indexed: 11/14/2022] Open
Abstract
Purpose: We propose a deep learning-based anthropomorphic model observer (DeepAMO) for image quality evaluation of multi-orientation, multi-slice image sets with respect to a clinically realistic 3D defect detection task. Approach: The DeepAMO is developed based on a hypothetical model of the decision process of a human reader performing a detection task using a 3D volume. The DeepAMO is comprised of three sequential stages: defect segmentation, defect confirmation (DC), and rating value inference. The input to the DeepAMO is a composite image, typical of that used to view 3D volumes in clinical practice. The output is a rating value designed to reproduce a human observer's defect detection performance. In stages 2 and 3, we propose: (1) a projection-based DC block that confirms defect presence in two 2D orthogonal orientations and (2) a calibration method that "learns" the mapping from the features of stage 2 to the distribution of observer ratings from the human observer rating data (thus modeling inter- or intraobserver variability) using a mixture density network. We implemented and evaluated the DeepAMO in the context of Tc 99 m -DMSA SPECT imaging. A human observer study was conducted, with two medical imaging physics graduate students serving as observers. A 5 × 2 -fold cross-validation experiment was conducted to test the statistical equivalence in defect detection performance between the DeepAMO and the human observer. We also compared the performance of the DeepAMO to an unoptimized implementation of a scanning linear discriminant observer (SLDO). Results: The results show that the DeepAMO's and human observer's performances on unseen images were statistically equivalent with a margin of difference ( Δ AUC ) of 0.0426 at p < 0.05 , using 288 training images. A limited implementation of an SLDO had a substantially higher AUC (0.99) compared to the DeepAMO and human observer. Conclusion: The results show that the DeepAMO has the potential to reproduce the absolute performance, and not just the relative ranking of human observers on a clinically realistic defect detection task, and that building conceptual components of the human reading process into deep learning-based models can allow training of these models in settings where limited training images are available.
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Affiliation(s)
- Ye Li
- Johns Hopkins University, Whiting School of Engineering, Department of Electrical and Computer Engineering, Baltimore, Maryland, United States.,Johns Hopkins University, School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
| | - Junyu Chen
- Johns Hopkins University, Whiting School of Engineering, Department of Electrical and Computer Engineering, Baltimore, Maryland, United States.,Johns Hopkins University, School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
| | - Justin L Brown
- University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering, Gainesville, Florida, United States
| | - S Ted Treves
- Brigham and Women's Hospital, Department of Radiology, Boston, Massachusetts, United States.,Harvard Medical School, Department of Radiology, Boston, Massachusetts, United States
| | - Xinhua Cao
- Harvard Medical School, Department of Radiology, Boston, Massachusetts, United States.,Boston Children's Hospital, Department of Radiology, Boston, Massachusetts, United States
| | - Frederic H Fahey
- Harvard Medical School, Department of Radiology, Boston, Massachusetts, United States.,Boston Children's Hospital, Department of Radiology, Boston, Massachusetts, United States
| | - George Sgouros
- Johns Hopkins University, School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
| | - Wesley E Bolch
- University of Florida, J. Crayton Pruitt Family Department of Biomedical Engineering, Gainesville, Florida, United States
| | - Eric C Frey
- Johns Hopkins University, Whiting School of Engineering, Department of Electrical and Computer Engineering, Baltimore, Maryland, United States.,Johns Hopkins University, School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
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13
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Mok GSP, Dewaraja YK. Recent advances in voxel-based targeted radionuclide therapy dosimetry. Quant Imaging Med Surg 2021; 11:483-489. [PMID: 33532249 PMCID: PMC7779928 DOI: 10.21037/qims-20-1006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 09/27/2020] [Indexed: 02/04/2023]
Affiliation(s)
- Greta S. P. Mok
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China
- Center for Cognitive and Brain Sciences, Institute of Collaborative Innovation, University of Macau, Macau, China
| | - Yuni K. Dewaraja
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
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14
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Chen J, Li Y, Du Y, Frey EC. Generating anthropomorphic phantoms using fully unsupervised deformable image registration with convolutional neural networks. Med Phys 2020; 47:6366-6380. [PMID: 33078422 PMCID: PMC10026844 DOI: 10.1002/mp.14545] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 08/28/2020] [Accepted: 10/09/2020] [Indexed: 01/07/2023] Open
Abstract
PURPOSE Computerized phantoms have been widely used in nuclear medicine imaging for imaging system optimization and validation. Although the existing computerized phantoms can model anatomical variations through organ and phantom scaling, they do not provide a way to fully reproduce the anatomical variations and details seen in humans. In this work, we present a novel registration-based method for creating highly anatomically detailed computerized phantoms. We experimentally show substantially improved image similarity of the generated phantom to a patient image. METHODS We propose a deep-learning-based unsupervised registration method to generate a highly anatomically detailed computerized phantom by warping an XCAT phantom to a patient computed tomography (CT) scan. We implemented and evaluated the proposed method using the NURBS-based XCAT phantom and a publicly available low-dose CT dataset from TCIA. A rigorous tradeoff analysis between image similarity and deformation regularization was conducted to select the loss function and regularization term for the proposed method. A novel SSIM-based unsupervised objective function was proposed. Finally, ablation studies were conducted to evaluate the performance of the proposed method (using the optimal regularization and loss function) and the current state-of-the-art unsupervised registration methods. RESULTS The proposed method outperformed the state-of-the-art registration methods, such as SyN and VoxelMorph, by more than 8%, measured by the SSIM and less than 30%, by the MSE. The phantom generated by the proposed method was highly detailed and was almost identical in appearance to a patient image. CONCLUSIONS A deep-learning-based unsupervised registration method was developed to create anthropomorphic phantoms with anatomies labels that can be used as the basis for modeling organ properties. Experimental results demonstrate the effectiveness of the proposed method. The resulting anthropomorphic phantom is highly realistic. Combined with realistic simulations of the image formation process, the generated phantoms could serve in many applications of medical imaging research.
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Affiliation(s)
- Junyu Chen
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, 21287, USA
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD, 21287, USA
| | - Ye Li
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, 21287, USA
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD, 21287, USA
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD, 21287, USA
| | - Eric C Frey
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, 21287, USA
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutes, Baltimore, MD, 21287, USA
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15
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Ramonaheng K, van Staden JA, du Raan H. Validation of a Monte Carlo modelled gamma camera for Lutetium-177 imaging. Appl Radiat Isot 2020; 163:109200. [PMID: 32561041 DOI: 10.1016/j.apradiso.2020.109200] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/11/2020] [Accepted: 04/08/2020] [Indexed: 10/24/2022]
Abstract
This study validated a model of the Siemens Symbia T16 dual-head SPECT/CT gamma camera created using the Monte Carlo program SIMIND for 177Lu. The validation was done by comparing experimental and simulated gamma camera performance criteria tests for the 177Lu 208 keV photopeak with a medium-energy collimator. Results showed good agreement between the experimental and simulated values. These results illustrated that SIMIND could emulate the Symbia T16 successfully and therefore, can be used with confidence to model 177Lu images.
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Affiliation(s)
- K Ramonaheng
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - J A van Staden
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
| | - H du Raan
- Department of Medical Physics, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa
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16
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Gustafsson J, Rodeño E, Mínguez P. Feasibility and limitations of quantitative SPECT for 223Ra. Phys Med Biol 2020; 65:085012. [PMID: 32092708 DOI: 10.1088/1361-6560/ab7971] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The aim of this paper is to investigate the feasibility and limitations of activity-concentration estimation for 223Ra using SPECT. Phantom measurements are performed using spheres (volumes 5.5 mL to 26.4 mL, concentrations 1.6 kBq mL-1 to 4.5 kBq mL-1). Furthermore, SPECT projections are simulated using the SIMIND Monte Carlo program for two geometries, one similar to the physical phantom and the other being an anthropomorphic phantom with added lesions (volumes 34 mL to 100 mL, concentrations 0.5 kBq mL-1 to 4 kBq mL-1). Medium-energy and high-energy collimators, 60 projections with 55 s per projection and a 20% energy window at 82 keV are employed. For the Monte Carlo simulated images, Poisson-distributed noise is added in ten noise realizations. Reconstruction is performed (OS-EM, 40 iterations, 6 subsets) employing compensation for attenuation, scatter, and collimator-detector response. The estimated concentrations in the anthropomorphic phantom are also corrected using recovery coefficients. Errors for the largest sphere in the physical phantom range from -25% to -34% for the medium-energy collimator and larger deviations for smaller spheres. Corresponding results for the high-energy collimator are -15% to -31%. The corresponding Monte Carlo simulations show standard deviations of a few percentage points. For the anthropomorphic phantom, before application of recovery coefficients the bias ranges from -16% to -46% (medium-energy collimator) and -10% to -28% (high-energy collimator), with standard deviations of 2% to 14% and 1% to 16%. After the application of recovery coefficients, the biases range from -3% to -35% (medium energy collimator) and from 0% to -18%. The errors decrease with increasing concentrations. Activity-concentration estimation of 223Ra with SPECT is feasible, but problems with repeatability need to be further studied.
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Affiliation(s)
- Johan Gustafsson
- Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden
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17
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Peters SMB, Meyer Viol SL, van der Werf NR, de Jong N, van Velden FHP, Meeuwis A, Konijnenberg MW, Gotthardt M, de Jong HWAM, Segbers M. Variability in lutetium-177 SPECT quantification between different state-of-the-art SPECT/CT systems. EJNMMI Phys 2020; 7:9. [PMID: 32048097 PMCID: PMC7013023 DOI: 10.1186/s40658-020-0278-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/27/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Quantitative SPECT imaging in targeted radionuclide therapy with lutetium-177 holds great potential for individualized treatment based on dose assessment. The establishment of dose-effect relations requires a standardized method for SPECT quantification. The purpose of this multi-center study is to evaluate quantitative accuracy and inter-system variations of different SPECT/CT systems with corresponding commercially available quantitative reconstruction algorithms. This is an important step towards a vendor-independent standard for quantitative lutetium-177 SPECT. METHODS Four state-of-the-art SPECT/CT systems were included: Discovery™ NM/CT 670Pro (GE Healthcare), Symbia Intevo™, and two Symbia™ T16 (Siemens Healthineers). Quantitative accuracy and inter-system variations were evaluated by repeatedly scanning a cylindrical phantom with 6 spherical inserts (0.5 - 113 ml). A sphere-to-background activity concentration ratio of 10:1 was used. Acquisition settings were standardized: medium energy collimator, body contour trajectory, photon energy window of 208 keV (± 10%), adjacent 20% lower scatter window, 2 × 64 projections, 128 × 128 matrix size, and 40 s projection time. Reconstructions were performed using GE Evolution with Q.Metrix™, Siemens xSPECT Quant™, Siemens Broad Quantification™ or Siemens Flash3D™ algorithms using vendor recommended settings. In addition, projection data were reconstructed using Hermes SUV SPECT™ with standardized reconstruction settings to obtain a vendor-neutral quantitative reconstruction for all systems. Volumes of interest (VOI) for the spheres were obtained by applying a 50% threshold of the sphere maximum voxel value corrected for background activity. For each sphere, the mean and maximum recovery coefficient (RCmean and RCmax) of three repeated measurements was calculated, defined as the imaged activity concentration divided by the actual activity concentration. Inter-system variations were defined as the range of RC over all systems. RESULTS RC decreased with decreasing sphere volume. Inter-system variations with vendor-specific reconstructions were between 0.06 and 0.41 for RCmean depending on sphere size (maximum 118% quantification difference), and improved to 0.02-0.19 with vendor-neutral reconstructions (maximum 38% quantification difference). CONCLUSION This study shows that eliminating sources of possible variation drastically reduces inter-system variation in quantification. This means that absolute SPECT quantification for 177Lu is feasible in a multi-center and multi-vendor setting; however, close agreement between vendors and sites is key for multi-center dosimetry and quantitative biomarker studies.
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Affiliation(s)
- Steffie M B Peters
- Department of Radiology and Nuclear Medicine, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500, HB, Nijmegen, The Netherlands.
| | - Sebastiaan L Meyer Viol
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Niels R van der Werf
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Nick de Jong
- Department of Radiology, Section of Medical Technology, Leiden University Medical Center, Leiden, The Netherlands
| | - Floris H P van Velden
- Department of Radiology, Section of Medical Technology, Leiden University Medical Center, Leiden, The Netherlands
| | - Antoi Meeuwis
- Department of Radiology and Nuclear Medicine, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500, HB, Nijmegen, The Netherlands
| | - Mark W Konijnenberg
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Martin Gotthardt
- Department of Radiology and Nuclear Medicine, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500, HB, Nijmegen, The Netherlands
| | - Hugo W A M de Jong
- Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marcel Segbers
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
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Brady SL, Shulkin BL. Analysis of quantitative [I-123] mIBG SPECT/CT in a phantom and in patients with neuroblastoma. EJNMMI Phys 2019; 6:31. [PMID: 31889238 PMCID: PMC6937351 DOI: 10.1186/s40658-019-0267-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 12/02/2019] [Indexed: 11/13/2022] Open
Abstract
Purpose To determine the accuracy of quantitative SPECT, intersystem and interpatient standardized uptake value (SUV) calculation consistency for a manufacturer-independent quantitative SPECT/CT reconstruction algorithm, and the range of SUVs of normal and neoplastic tissue. Methods A NEMA body phantom with 6 spheres (ranging 10–37 mm) was filled with a known activity-to-volume ratio and used to determine the contrast recovery coefficient (CRC) for each visible sphere, and the measured SUV accuracy of those spheres and background water solution. One hundred eleven 123I-metaiodobenzylguanidine ([I-123] mIBG) SPECT/CT examinations from 43 patients were reconstructed using SUV SPECT® (HERMES Medical Solutions Inc.); 42 examinations were acquired using a GE Infinia Hawkeye 4 SPECT/CT, and 69 were acquired on a Siemens Symbia Intevo SPECT/CT. Inter scanner SUV analysis of 9 regions of normal [I-123] mIBG tissue uptake was conducted. Intrapatient mean SUV variability was calculated by measuring normal liver uptake within patients scanned on both cameras. The intensity of uptake by neoplastic tissue in the images was quantified using maximum SUV and, if present, compared over time. Results The phantom results of the visible spheres and background resulted in accuracy calculations better than 5–10% with CRC correction. Interscanner SUV variability showed no statistical difference (average p value 0.559; range 0.066–1.0) among the 9 normal tissues analyzed. Intrapatient liver mean SUV varied ≤ 16% as calculated for 28 patients (87 examinations) studied on both scanners. In one patient, a thoracic tumor evaluated over 10 time points (18 months) underwent a 74% (3.1/12.0) reduction in maximum SUV with treatment. Conclusion The results demonstrate quantitative accuracy to better than 10%, and both consistent SUV calculation between 2 different SPECT/CT scanners for 9 tissues, and low intrapatient measurement variability for quantitative SPECT/CT analysis in a pediatric population with neuroblastoma. Quantitative SPECT/CT offers the opportunity for objective analysis of tumor response using [I-123] mIBG by normalizing the uptake to injected dose and patient weight, as is done for PET.
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Affiliation(s)
- Samuel L Brady
- Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Barry L Shulkin
- Department of Diagnostic Imaging MS 220, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA.
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Peters SMB, van der Werf NR, Segbers M, van Velden FHP, Wierts R, Blokland KJAK, Konijnenberg MW, Lazarenko SV, Visser EP, Gotthardt M. Towards standardization of absolute SPECT/CT quantification: a multi-center and multi-vendor phantom study. EJNMMI Phys 2019; 6:29. [PMID: 31879813 PMCID: PMC6933042 DOI: 10.1186/s40658-019-0268-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/05/2019] [Indexed: 11/29/2022] Open
Abstract
Abstract Absolute quantification of radiotracer distribution using SPECT/CT imaging is of great importance for dosimetry aimed at personalized radionuclide precision treatment. However, its accuracy depends on many factors. Using phantom measurements, this multi-vendor and multi-center study evaluates the quantitative accuracy and inter-system variability of various SPECT/CT systems as well as the effect of patient size, processing software and reconstruction algorithms on recovery coefficients (RC). Methods Five SPECT/CT systems were included: Discovery™ NM/CT 670 Pro (GE Healthcare), Precedence™ 6 (Philips Healthcare), Symbia Intevo™, and Symbia™ T16 (twice) (Siemens Healthineers). Three phantoms were used based on the NEMA IEC body phantom without lung insert simulating body mass indexes (BMI) of 25, 28, and 47 kg/m2. Six spheres (0.5–26.5 mL) and background were filled with 0.1 and 0.01 MBq/mL 99mTc-pertechnetate, respectively. Volumes of interest (VOI) of spheres were obtained by a region growing technique using a 50% threshold of the maximum voxel value corrected for background activity. RC, defined as imaged activity concentration divided by actual activity concentration, were determined for maximum (RCmax) and mean voxel value (RCmean) in the VOI for each sphere diameter. Inter-system variability was expressed as median absolute deviation (MAD) of RC. Acquisition settings were standardized. Images were reconstructed using vendor-specific 3D iterative reconstruction algorithms with institute-specific settings used in clinical practice and processed using a standardized, in-house developed processing tool based on the SimpleITK framework. Additionally, all data were reconstructed with a vendor-neutral reconstruction algorithm (Hybrid Recon™; Hermes Medical Solutions). Results RC decreased with decreasing sphere diameter for each system. Inter-system variability (MAD) was 16 and 17% for RCmean and RCmax, respectively. Standardized reconstruction decreased this variability to 4 and 5%. High BMI hampers quantification of small lesions (< 10 ml). Conclusion Absolute SPECT quantification in a multi-center and multi-vendor setting is feasible, especially when reconstruction protocols are standardized, paving the way for a standard for absolute quantitative SPECT.
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Affiliation(s)
- Steffie M B Peters
- Department of Radiology and Nuclear Medicine, Radboudumc, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Niels R van der Werf
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands.,Department of Medical Physics, Albert Schweitzer Hospital, Dordrecht, The Netherlands
| | - Marcel Segbers
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Floris H P van Velden
- Department of Radiology, Section of Medical Physics, Leiden University Medical Center, Leiden, The Netherlands
| | - Roel Wierts
- Department of Radiology and Nuclear Medicine, Maastricht UMC+, Maastricht, The Netherlands
| | - Koos J A K Blokland
- Department of Radiology, Section of Medical Physics, Leiden University Medical Center, Leiden, The Netherlands
| | - Mark W Konijnenberg
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Sergiy V Lazarenko
- Department of Nuclear Medicine, Noordwest Ziekenhuisgroep, Alkmaar, The Netherlands
| | - Eric P Visser
- Department of Radiology and Nuclear Medicine, Radboudumc, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Martin Gotthardt
- Department of Radiology and Nuclear Medicine, Radboudumc, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
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Li Y, O'Reilly S, Plyku D, Treves ST, Fahey F, Du Y, Cao X, Sexton-Stallone B, Brown J, Sgouros G, Bolch WE, Frey EC. Current pediatric administered activity guidelines for 99m Tc-DMSA SPECT based on patient weight do not provide the same task-based image quality. Med Phys 2019; 46:4847-4856. [PMID: 31448427 DOI: 10.1002/mp.13787] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE In the current clinical practice, administered activity (AA) for pediatric molecular imaging is often based on the North American expert consensus guidelines or the European Association of Nuclear Medicine dosage card, both of which were developed based on the best clinical practice. These guidelines were not formulated using a rigorous evaluation of diagnostic image quality (IQ) relative to AA. In the guidelines, AA is determined by a weight-based scaling of the adult AA, along with minimum and maximum AA constraints. In this study, we use task-based IQ assessment methods to rigorously evaluate the efficacy of weight-based scaling in equalizing IQ using a population of pediatric patients of different ages and body weights. METHODS A previously developed projection image database was used. We measured task-based IQ, with respect to the detection of a renal functional defect at six different AA levels (AA relative to the AA obtained from the guidelines). IQ was assessed using an anthropomorphic model observer. Receiver-operating characteristics (ROC) analysis was applied; the area under the ROC curve (AUC) served as a figure-of-merit for task performance. In addition, we investigated patient girth (circumference) as a potential improved predictor of the IQ. RESULTS The data demonstrate a monotonic and modestly saturating increase in AUC with increasing AA, indicating that defect detectability was limited by quantum noise and the effects of object variability were modest over the range of AA levels studied. The AA for a given value of the AUC increased with increasing age. The AUC vs AA plots for all the patient ages indicate that, for the current guidelines, the newborn and 10- and 15-yr phantoms had similar IQ for the same AA suggested by the North American expert consensus guidelines, but the 5- and 1-yr phantoms had lower IQ. The results also showed that girth has a stronger correlation with the needed AA to provide a constant AUC for 99m Tc-DMSA renal SPECT. CONCLUSIONS The results suggest that (a) weight-based scaling is not sufficient to equalize task-based IQ for patients of different weights in pediatric 99m Tc-DMSA renal SPECT; and (b) patient girth should be considered instead of weight in developing new administration guidelines for pediatric patients.
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Affiliation(s)
- Ye Li
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,The Russell H Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Shannon O'Reilly
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Donika Plyku
- The Russell H Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - S Ted Treves
- Department of Radiology, Brigham and Women's Hospital, Boston, MA, 02115, USA.,Department of Radiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Frederic Fahey
- Department of Radiology, Harvard Medical School, Boston, MA, 02115, USA.,Department of Radiology, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Yong Du
- The Russell H Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Xinhua Cao
- Department of Radiology, Harvard Medical School, Boston, MA, 02115, USA.,Department of Radiology, Boston Children's Hospital, Boston, MA, 02115, USA
| | | | - Justin Brown
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - George Sgouros
- The Russell H Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA.,School of Medicine, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Wesley E Bolch
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Eric C Frey
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,The Russell H Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, 21287, USA.,School of Medicine, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, 21287, USA
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Li T, Mok GSP. Technical Note: Virtual CT for reducing CT dose in targeted radionuclide therapy dosimetry. Med Phys 2018; 45:5138-5144. [PMID: 30229934 DOI: 10.1002/mp.13197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/27/2018] [Accepted: 09/04/2018] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Previously we have shown that using sequential CT images is superior to sequential SPECT for nonrigid registration in three-dimensional (3D) targeted radionuclide therapy (TRT) dosimetry. However, sequential CTs are often not available due to radiation concerns. In this paper, we propose a virtual CT (vCT) method for attenuation and scatter correction, image registration, and segmentation for improved dosimetric accuracy with single CT acquisition. METHODS We used a population of nine XCAT phantoms with different In-111 Zevalin biokinetics and anatomical variations for the simulations. An analytical projector was used to simulate sequential SPECT/CT acquisitions for a medium energy general purpose collimator at 1, 12, 24, 72, and 144 h postinjection, modeling attenuation, scatter, and geometric collimator-detector response. The corresponding sequential attenuation maps of the phantoms served as real CT (rCT) images. For vCT generation, we investigated three registration methods, that is, (a) SPECT to SPECT; (b) SPECT to CT, and (c) CT to SPECT, and the optimal time point for single CT acquisition. Difference images and average normalized mean square errors (NMSE) were calculated between different vCTs and their corresponding rCTs. Absorbed dose and dose-volume histograms (DVHs) for critical organs were computed for the rCT, optimized vCT, and conventional single CT (1CT) protocols, respectively, for dosimetric analyses. RESULTS For vCT generation, SPECT to SPECT registration with a single CT acquired at the first time point shows the smallest difference and NMSE. For organ absorbed doses, the results of vCT were similar to those of rCT and were superior to 1CT, that is, -0.24 ± 1.56% vs -0.49 ± 1.76% vs -6.37 ± 5.63% for the liver, -1.05 ± 2.89% vs -0.69 ± 2.74% vs -4.87 ± 4.35% for kidneys, respectively. The results of DVHs also showed improvement for all organs using vCTs as compared to the conventional 1CT protocol. CONCLUSION The optimized vCT method can effectively increase the TRT dosimetric results if there is only a single CT available in the sequential imaging protocol, reducing the substantial increase in radiation burden from repeated CT scans.
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Affiliation(s)
- Tiantian Li
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, SAR, China
| | - Greta S P Mok
- Biomedical Imaging Laboratory (BIG), Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, SAR, China.,Faculty of Health Sciences, University of Macau, Macau SAR, China
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22
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Determination of gamma camera calibration factors for quantitation of therapeutic radioisotopes. EJNMMI Phys 2018; 5:8. [PMID: 29717385 PMCID: PMC5930296 DOI: 10.1186/s40658-018-0208-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/23/2018] [Indexed: 01/23/2023] Open
Abstract
Background Camera calibration, which translates reconstructed count map into absolute activity map, is a prerequisite procedure for quantitative SPECT imaging. Both planar and tomographic scans using different phantom geometries have been proposed for the determination of the camera calibration factor (CF). However, there is no consensus on which approach is the best. The aim of this study is to evaluate all these calibration methods, compare their performance, and propose a practical and accurate calibration method for SPECT quantitation of therapeutic radioisotopes. Twenty-one phantom experiments (Siemens Symbia SPECT/CT) and 12 Monte Carlo simulations (GATE v6.1) using three therapy isotopes (131I, 177Lu, and 188Re) have been performed. The following phantom geometries were used: (1) planar scans of point source in air (PS), (2) tomographic scans of insert(s) filled with activity placed in non-radioactive water (HS + CB), (3) tomographic scans of hot insert(s) in radioactive water (HS + WB), and (4) tomographic scans of cylinders uniformly filled with activity (HC). Tomographic data were reconstructed using OSEM with CT-based attenuation correction and triple energy window (TEW) scatter correction, and CF was determined using total counts in the reconstructed image, while for planar scans, the photopeak counts, corrected for scatter and background with TEW, were used. Additionally, for simulated data, CF obtained from primary photons only was analyzed. Results For phantom experiments, CF obtained from PS and HS + WB agreed to within 6% (below 3% if experiments performed on the same day are considered). However, CF from HS + CB exceeded those from PS by 4–12%. Similar trend was found in simulation studies. Analysis of CFs from primary photons helped us to understand this discrepancy. It was due to underestimation of scatter by the TEW method, further enhanced by attenuation correction. This effect becomes less important when the source is distributed over the entire phantom volume (HS + WB and HC). Conclusions Camera CF could be determined using planar scans of a point source, provided that the scatter and background contributions are removed, for example using the clinically available TEW method. This approach is simple and yet provides CF with sufficient accuracy (~ 5%) to be used in clinics for radiotracer quantification.
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Li T, Wu NY, Song N, Mok GSP. Evaluation of sequential SPECT and CT for targeted radionuclide therapy dosimetry. Ann Nucl Med 2017; 32:34-43. [PMID: 29143283 DOI: 10.1007/s12149-017-1218-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/08/2017] [Indexed: 12/22/2022]
Abstract
PURPOSE In targeted radionuclide therapy (TRT), a prior knowledge of the absorbed dose biodistribution is essential for pre-therapy treatment planning. Previously, we showed that non-rigid organ-by-organ registration in sequential quantitative SPECT images improved dose estimation. This study aims to investigate if sequential CT can further improve TRT dosimetric accuracy. METHODS We simulated SPECT/CT acquisitions at 1, 12, 24, 72 and 144 h In-111 Zevalin post-injection using an analytical MEGP projector, modeling attenuation, scatter and collimator-detector response. We later recruited a patient injected with 222 MBq In-111 DTPAOC imaged at 3 SPECT/CT sessions for clinical evaluations. Four registration schemes were evaluated: whole-body-based registration performed on sequential (1) SPECT (WB-SPECT) or (2) CT (WB-CT) images; organ-based registration applied on organs individually segmented from sequential (3) SPECT (O-SPECT) or (4) CT (O-CT) images. Voxel-by-voxel integration was performed followed by Y-90 voxel-S-kernel convolution. Organ-absorbed doses, iso-dose curves, dose-volume histograms (DVHs) were generated for targeted organs for analysis. RESULTS In simulation study, organ-absorbed dose errors were (- 8.66 ± 2.83)%, (- 2.51 ± 3.69)%, (- 9.23 ± 3.28)%, (- 7.17 ± 2.53)% for liver, (- 14.81 ± 4.91)%, (- 3.60 ± 4.37)%, (- 18.13 ± 4.44)%, (- 11.34 ± 4.22)% for spleen, for O-SPECT, O-CT, WB-SPECT and WB-CT registrations, respectively. For all organs, O-CT showed superior results. Results of iso-dose contour, DVHs were in accordance with the organ-absorbed doses. In clinical studies, the results were also consistent which showed O-CT method deviated the most from the result with no registration. CONCLUSIONS We conclude that if both sequential SPECT/CT scans are available, CT organ-based registration method can more effectively improve the 3D dose estimation. Sequential low-dose CT scans might be considered to be included in the standard TRT protocol.
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Affiliation(s)
- Tiantian Li
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China
| | - Nien-Yun Wu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan, Republic of China.,Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China
| | - Na Song
- Department of Nuclear Medicine, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, 10461, USA
| | - Greta S P Mok
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China. .,Faculty of Health Sciences, University of Macau, Macau SAR, China.
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Li T, Ao ECI, Lambert B, Brans B, Vandenberghe S, Mok GSP. Quantitative Imaging for Targeted Radionuclide Therapy Dosimetry - Technical Review. Theranostics 2017; 7:4551-4565. [PMID: 29158844 PMCID: PMC5695148 DOI: 10.7150/thno.19782] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 07/25/2017] [Indexed: 01/06/2023] Open
Abstract
Targeted radionuclide therapy (TRT) is a promising technique for cancer therapy. However, in order to deliver the required dose to the tumor, minimize potential toxicity in normal organs, as well as monitor therapeutic effects, it is important to assess the individualized internal dosimetry based on patient-specific data. Advanced imaging techniques, especially radionuclide imaging, can be used to determine the spatial distribution of administered tracers for calculating the organ-absorbed dose. While planar scintigraphy is still the mainstream imaging method, SPECT, PET and bremsstrahlung imaging have promising properties to improve accuracy in quantification. This article reviews the basic principles of TRT and discusses the latest development in radionuclide imaging techniques for different theranostic agents, with emphasis on their potential to improve personalized TRT dosimetry.
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Affiliation(s)
- Tiantian Li
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China
| | - Edwin C. I. Ao
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China
| | - Bieke Lambert
- Dept of Radiology and Nuclear medicine, Ghent University, De Pintelaan 185 9000 Gent, Belgium
- AZ Maria Middelares, Buiten-Ring-Sint-Denijs 30, 9000 Gent, Belgium
| | - Boudewijn Brans
- Dept of Nuclear Medicine, UZ Ghent-Ghent University, St-Pietersnieuwstraat 41, 9000 Gent, Belgium
| | - Stefaan Vandenberghe
- MEDISIP-ELIS-IBITECH-IMEC, Ghent University, St-Pietersnieuwstraat 41, 9000 Gent, Belgium
| | - Greta S. P. Mok
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China
- Faculty of Health Sciences, University of Macau, Macau SAR, China
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Vicente EM, Lodge MA, Rowe SP, Wahl RL, Frey EC. Simplifying volumes-of-interest (VOIs) definition in quantitative SPECT: Beyond manual definition of 3D whole-organ VOIs. Med Phys 2017; 44:1707-1717. [PMID: 28207950 DOI: 10.1002/mp.12164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 01/23/2017] [Accepted: 02/02/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE We investigated the feasibility of using simpler methods than manual whole-organ volume-of-interest (VOI) definition to estimate the organ activity concentration in single photon emission computed tomography (SPECT) in cases where the activity in the organ can be assumed to be uniformly distributed on the scale of the voxel size. In particular, we investigated an anatomic region-of-interest (ROI) defined in a single transaxial slice, and a single sphere placed inside the organ boundaries. METHODS The evaluation was carried out using Monte Carlo simulations based on patient indium 111 In pentetreotide SPECT and computed tomography (CT) images. We modeled constant activity concentrations in each organ, validating this assumption by comparing the distribution of voxel values inside the organ VOIs of the simulated data with the patient data. We simulated projection data corresponding to 100, 50, and 25% of the clinical count level to study the effects of noise level due to shortened acquisition time. Images were reconstructed using a previously validated quantitative SPECT reconstruction method. The evaluation was performed in terms of the accuracy and precision of the activity concentration estimates. RESULTS The results demonstrated that the non-uniform image intensity observed in the reconstructed images in the organs with normal uptake was consistent with uniform activity concentration in the organs on the scale of the voxel size; observed non-uniformities in image intensity were due to a combination of partial-volume effects at the boundaries of the organ, artifacts in the reconstructed image due to collimator-detector response compensation, and noise. Using an ROI defined in a single transaxial slice produced similar biases compared to the three-dimensional (3D) whole-organ VOIs, provided that the transaxial slice was near the central plane of the organ and that the pixels from the organ boundaries were not included in the ROI. Although this slice method was sensitive to noise, biases were less than 10% for all the noise levels studied. The use of spherical VOIs was more sensitive to noise. The method was more accurate for larger spheres and larger organs such as the liver in comparison to the kidneys. Biases lower than 7% were found in the liver when using large enough spheres (radius ≥ 28 mm), regardless of the position, of the VOI inside the organ even with shortened acquisition times. The biases were more position-dependent for smaller organs. CONCLUSIONS Both of the simpler methods provided suitable surrogates in terms of accuracy and precision. The results suggested that a spherical VOI was more appropriate for estimating the activity concentration in larger organs such as the liver, regardless of the position of the sphere inside the organ. Larger spheres resulted in better estimates. A single-slice ROI was more suitable for activity estimation in smaller organs such as the kidneys, providing that the transaxial slice selected was near the central plane of the organ and that voxels from the organ boundaries were excluded. Under those conditions, activity concentrations with biases lower than 5% were observed for all the studied count levels and coefficients of variation were less than 9% and 5% for the 25% and 100% count levels, respectively.
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Affiliation(s)
- Esther M Vicente
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Martin A Lodge
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Steven P Rowe
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, 21287, USA
| | - Richard L Wahl
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Eric C Frey
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, 21287, USA
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Lysak Y, Dyomin V, Klimanov V, Narkevich B, Romodanov V. Approach to radionuclide therapy dosimetry planning. NUCLEAR ENERGY AND TECHNOLOGY 2016. [DOI: 10.1016/j.nucet.2016.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Gamma camera calibration and validation for quantitative SPECT imaging with 177Lu. Appl Radiat Isot 2016; 112:156-64. [DOI: 10.1016/j.apradiso.2016.03.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 02/09/2016] [Accepted: 03/07/2016] [Indexed: 11/21/2022]
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Jha AK, Caffo B, Frey EC. A no-gold-standard technique for objective assessment of quantitative nuclear-medicine imaging methods. Phys Med Biol 2016; 61:2780-800. [PMID: 26982626 DOI: 10.1088/0031-9155/61/7/2780] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective optimization and evaluation of nuclear-medicine quantitative imaging methods using patient data is highly desirable but often hindered by the lack of a gold standard. Previously, a regression-without-truth (RWT) approach has been proposed for evaluating quantitative imaging methods in the absence of a gold standard, but this approach implicitly assumes that bounds on the distribution of true values are known. Several quantitative imaging methods in nuclear-medicine imaging measure parameters where these bounds are not known, such as the activity concentration in an organ or the volume of a tumor. We extended upon the RWT approach to develop a no-gold-standard (NGS) technique for objectively evaluating such quantitative nuclear-medicine imaging methods with patient data in the absence of any ground truth. Using the parameters estimated with the NGS technique, a figure of merit, the noise-to-slope ratio (NSR), can be computed, which can rank the methods on the basis of precision. An issue with NGS evaluation techniques is the requirement of a large number of patient studies. To reduce this requirement, the proposed method explored the use of multiple quantitative measurements from the same patient, such as the activity concentration values from different organs in the same patient. The proposed technique was evaluated using rigorous numerical experiments and using data from realistic simulation studies. The numerical experiments demonstrated that the NSR was estimated accurately using the proposed NGS technique when the bounds on the distribution of true values were not precisely known, thus serving as a very reliable metric for ranking the methods on the basis of precision. In the realistic simulation study, the NGS technique was used to rank reconstruction methods for quantitative single-photon emission computed tomography (SPECT) based on their performance on the task of estimating the mean activity concentration within a known volume of interest. Results showed that the proposed technique provided accurate ranking of the reconstruction methods for 97.5% of the 50 noise realizations. Further, the technique was robust to the choice of evaluated reconstruction methods. The simulation study pointed to possible violations of the assumptions made in the NGS technique under clinical scenarios. However, numerical experiments indicated that the NGS technique was robust in ranking methods even when there was some degree of such violation.
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Affiliation(s)
- Abhinav K Jha
- Division of Medical Imaging Physics, Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
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Weng F, Bagchi S, Zan Y, Huang Q, Seo Y. An energy-optimized collimator design for a CZT-based SPECT camera. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT 2016; 806:330-339. [PMID: 26640308 PMCID: PMC4665111 DOI: 10.1016/j.nima.2015.09.115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In single photon emission computed tomography, it is a challenging task to maintain reasonable performance using only one specific collimator for radio-tracers over a broad spectrum of diagnostic photon energies, since photon scatter and penetration in a collimator differ with the photon energy. Frequent collimator exchanges are inevitable in daily clinical SPECT imaging, which hinders throughput while subjecting the camera to operational errors and damage. Our objective is to design a collimator, which independent of the photon energy performs reasonably well for commonly used radiotracers with low- to medium-energy levels of gamma emissions. Using the Geant4 simulation toolkit, we simulated and evaluated a parallel-hole collimator mounted to a CZT detector. With the pixel-geometry-matching collimation, the pitch of the collimator hole was fixed to match the pixel size of the CZT detector throughout this work. Four variables, hole shape, hole length, hole radius/width and the source-to-collimator distance were carefully studied. Scatter and penetration of the collimator, sensitivity and spatial resolution of the system were assessed for four radionuclides including 57Co, 99m Tc, 123I and 111In, with respect to the aforementioned four variables. An optimal collimator was then decided upon such that it maximized the total relative sensitivity (TRS) for the four considered radionuclides while other performance parameters, such as scatter, penetration and spatial resolution, were benchmarked to prevalent commercial scanners and collimators. Digital phantom studies were also performed to validate the system with the optimal square-hole collimator (23 mm hole length, 1.28 mm hole width, 0.32 mm septal thickness) in terms of contrast, contrast-to-noise ratio and recovery ratio. This study demonstrates promise of our proposed energy-optimized collimator to be used in a CZT-based gamma camera, with comparable or even better imaging performance versus commercial collimators such as low-energy high resolution (LEHR) and medium energy general purpose (MEGP) collimators.
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Affiliation(s)
- Fenghua Weng
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Srijeeta Bagchi
- Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Yunlong Zan
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Qiu Huang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Youngho Seo
- Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
- Department of Radiation Oncology, University of California, San Francisco, CA, USA
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Cheng L, Hobbs RF, Sgouros G, Frey EC. Development and evaluation of convergent and accelerated penalized SPECT image reconstruction methods for improved dose-volume histogram estimation in radiopharmaceutical therapy. Med Phys 2015; 41:112507. [PMID: 25370666 DOI: 10.1118/1.4897613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Three-dimensional (3D) dosimetry has the potential to provide better prediction of response of normal tissues and tumors and is based on 3D estimates of the activity distribution in the patient obtained from emission tomography. Dose-volume histograms (DVHs) are an important summary measure of 3D dosimetry and a widely used tool for treatment planning in radiation therapy. Accurate estimates of the radioactivity distribution in space and time are desirable for accurate 3D dosimetry. The purpose of this work was to develop and demonstrate the potential of penalized SPECT image reconstruction methods to improve DVHs estimates obtained from 3D dosimetry methods. METHODS The authors developed penalized image reconstruction methods, using maximum a posteriori (MAP) formalism, which intrinsically incorporate regularization in order to control noise and, unlike linear filters, are designed to retain sharp edges. Two priors were studied: one is a 3D hyperbolic prior, termed single-time MAP (STMAP), and the second is a 4D hyperbolic prior, termed cross-time MAP (CTMAP), using both the spatial and temporal information to control noise. The CTMAP method assumed perfect registration between the estimated activity distributions and projection datasets from the different time points. Accelerated and convergent algorithms were derived and implemented. A modified NURBS-based cardiac-torso phantom with a multicompartment kidney model and organ activities and parameters derived from clinical studies were used in a Monte Carlo simulation study to evaluate the methods. Cumulative dose-rate volume histograms (CDRVHs) and cumulative DVHs (CDVHs) obtained from the phantom and from SPECT images reconstructed with both the penalized algorithms and OS-EM were calculated and compared both qualitatively and quantitatively. The STMAP method was applied to patient data and CDRVHs obtained with STMAP and OS-EM were compared qualitatively. RESULTS The results showed that the penalized algorithms substantially improved the CDRVH and CDVH estimates for large organs such as the liver compared to optimally postfiltered OS-EM. For example, the mean squared errors (MSEs) of the CDRVHs for the liver at 5 h postinjection obtained with CTMAP and STMAP were about 15% and 17%, respectively, of the MSEs obtained with optimally filtered OS-EM. For the CDVH estimates, the MSEs obtained with CTMAP and STMAP were about 16% and 19%, respectively, of the MSEs from OS-EM. For the kidneys and renal cortices, larger residual errors were observed for all algorithms, likely due to partial volume effects. The STMAP method showed promising qualitative results when applied to patient data. CONCLUSIONS Penalized image reconstruction methods were developed and evaluated through a simulation study. The study showed that the MAP algorithms substantially improved CDVH estimates for large organs such as the liver compared to optimally postfiltered OS-EM reconstructions. For small organs with fine structural detail such as the kidneys, a large residual error was observed for both MAP algorithms and OS-EM. While CTMAP provided marginally better MSEs than STMAP, given the extra effort needed to handle misregistration of images at different time points in the algorithm and the potential impact of residual misregistration, 3D regularization methods, such as that used in STMAP, appear to be a more practical choice.
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Affiliation(s)
- Lishui Cheng
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287 and Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Robert F Hobbs
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - George Sgouros
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Eric C Frey
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
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Cederkrantz E, Andersson H, Bernhardt P, Bäck T, Hultborn R, Jacobsson L, Jensen H, Lindegren S, Ljungberg M, Magnander T, Palm S, Albertsson P. Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients. Int J Radiat Oncol Biol Phys 2015; 93:569-76. [PMID: 26460999 DOI: 10.1016/j.ijrobp.2015.07.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/22/2015] [Accepted: 07/06/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE Ovarian cancer is often diagnosed at an advanced stage with dissemination in the peritoneal cavity. Most patients achieve clinical remission after surgery and chemotherapy, but approximately 70% eventually experience recurrence, usually in the peritoneal cavity. To prevent recurrence, intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective dose associated with i.p. administration of (211)At-MX35 F(ab')2. METHODS AND MATERIALS Patients in clinical remission after salvage chemotherapy for peritoneal recurrence of ovarian cancer underwent i.p. infusion of (211)At-MX35 F(ab')2. Potassium perchlorate was given to block unwanted accumulation of (211)At in thyroid and other NIS-containing tissues. Mean absorbed doses to normal tissues were calculated from clinical data, including blood and i.p. fluid samples, urine, γ-camera images, and single-photon emission computed tomography/computed tomography images. Extrapolation of preclinical biodistribution data combined with clinical blood activity data allowed us to estimate absorbed doses in additional tissues. The equivalent dose was calculated using an RBE of 5 and the effective dose using the recommended weight factor of 20. All doses were normalized to the initial activity concentration of the infused therapy solution. RESULTS The urinary bladder, thyroid, and kidneys (1.9, 1.8, and 1.7 mGy per MBq/L) received the 3 highest estimated absorbed doses. When the tissue-weighting factors were applied, the largest contributors to the effective dose were the lungs, stomach, and urinary bladder. Using 100 MBq/L, organ equivalent doses were less than 10% of the estimated tolerance dose. CONCLUSION Intraperitoneal (211)At-MX35 F(ab')2 treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective dose potentially corresponds to a risk of treatment-induced carcinogenesis, optimization may still be valuable.
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Affiliation(s)
- Elin Cederkrantz
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Håkan Andersson
- Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Bernhardt
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Tom Bäck
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ragnar Hultborn
- Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Jacobsson
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Holger Jensen
- PET and Cyclotron Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sture Lindegren
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Michael Ljungberg
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund, Sweden
| | - Tobias Magnander
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Stig Palm
- Department of Radiation Physics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Per Albertsson
- Department of Oncology, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Rowe SP, Vicente E, Anizan N, Wang H, Leal JP, Lodge MA, Frey EC, Wahl RL. Repeatability of Radiotracer Uptake in Normal Abdominal Organs with ¹¹¹In-Pentetreotide Quantitative SPECT/CT. J Nucl Med 2015; 56:985-8. [PMID: 25977467 DOI: 10.2967/jnumed.115.155358] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/15/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED With an increasing emphasis on quantitation of SPECT imaging and its use in dosimetry to guide therapies, it is desirable to understand the repeatability in normal-organ SPECT uptake values (SPECT-UVs). We investigated the variability of normal abdominal organ uptake in repeated (111)In-pentetreotide SPECT studies. METHODS Nine patients with multiple (111)In-pentetreotide SPECT/CT studies for clinical purposes were evaluated. Volumes of interest were drawn for the abdominal organs and applied to SPECT-UVs. The variability of those values was assessed. RESULTS The average SPECT-UV for the liver (1.7 ± 0.6) was much lower than for the kidneys (right, 8.0 ± 2.4; left, 7.5 ± 1.7). Interpatient and intrapatient variability was similar (intraclass correlation coefficients, 0.40-0.59) for all organs. The average coefficients of variation for each organ for each patient were obtained and averaged across all patients (0.26 for liver, 0.22 for right kidney, and 0.20 for left kidney). The coefficients of variation for the organs across all scans were 0.33 (liver), 0.30 (right kidney), and 0.22 (left kidney). CONCLUSION Variability across all patients and all scans for the liver was higher than reported with (18)F-FDG PET, though left kidney variability was similar to PET liver variability and left kidney uptake may be able to serve as an internal metric for determining the quantifiability of an (111)In-pentetreotide SPECT study.
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Affiliation(s)
- Steven P Rowe
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Esther Vicente
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nadège Anizan
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hao Wang
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jeffrey P Leal
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Martin A Lodge
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eric C Frey
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Richard L Wahl
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Lee TS, Tsui BMW. The development and initial evaluation of a realistic simulated SPECT dataset with simultaneous respiratory and cardiac motion for gated myocardial perfusion SPECT. Phys Med Biol 2015; 60:1399-413. [PMID: 25612263 DOI: 10.1088/0031-9155/60/4/1399] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We developed a realistic simulation dataset for simultaneous respiratory and cardiac (R&C) gated SPECT/CT using the 4D NURBS-based Cardiac-Torso (NCAT) Phantom and Monte Carlo simulation methods, and evaluated it for a sample application study. The 4D NCAT phantom included realistic respiratory motion and beating heart motion based on respiratory gated CT and cardiac tagged MRI data of normal human subjects. To model the respiratory motion, a set of 24 separate 3D NCAT phantoms excluding the heart was generated over a respiratory cycle. The beating heart motion was modeled separately with 48 frames per cardiac cycle for each of the 24 respiratory phases. The resultant set of 24 × 48 3D NCAT phantoms provides a realistic model of a normal human subject at different phases of combined R&C motions. An almost noise-free SPECT projection dataset for each of the 1152 3D NCAT phantoms was generated using Monte Carlo simulation techniques and the radioactivity uptake distribution of (99m)Tc sestamibi in different organs. By grouping and summing the separate projection datasets, separate or simultaneous R&C gated acquired data with different gating schemes could be simulated. In the initial evaluation, we combined the projection datasets into ungated, 6 respiratory-gates only, 8 cardiac-gates only, and combined 6 respiratory-gates & 8 cardiac-gates projection datasets. Each dataset was reconstructed using 3D OS-EM without and with attenuation correction using the averaged and respiratory-gated attenuation maps, and the resulting reconstructed images were compared. These results were used to demonstrate the effects of R&C motions and the reduction of image artifact due to R&C motions by gating and attenuation corrections. We concluded that the realistic 4D NCAT phantom and Monte Carlo simulated SPECT projection datasets with R&C motions are powerful tools in the study of the effects of R&C motions, as well as in the development of R&C gating schemes and motion correction methods for improved SPECT/CT imaging.
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Affiliation(s)
- Taek-Soo Lee
- Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD 21287, USA
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Ao ECI, Wu NY, Wang SJ, Song N, Mok GSP. Improved dosimetry for targeted radionuclide therapy using nonrigid registration on sequential SPECT images. Med Phys 2015; 42:1060-70. [DOI: 10.1118/1.4906242] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Anizan N, Wang H, Zhou XC, Wahl RL, Frey EC. Factors affecting the repeatability of gamma camera calibration for quantitative imaging applications using a sealed source. Phys Med Biol 2015; 60:1325-37. [PMID: 25592130 DOI: 10.1088/0031-9155/60/3/1325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source activity using a radionuclide activity meter are potential sources of variability, this work investigated instrumentation and acquisition factors affecting repeatability using planar acquisition of sealed sources. The calibration factor was calculated for different acquisition and geometry conditions to evaluate the effect of the source size, lateral position of the source in the camera field-of-view (FOV), source-to-camera distance (SCD), and variability over time using sealed Ba-133 sources. A small region of interest (ROI) based on the source dimensions and collimator resolution was investigated to decrease the background effect. A statistical analysis with a mixed-effects model was used to evaluate quantitatively the effect of each variable on the global calibration factor variability. A variation of 1 cm in the measurement of the SCD from the assumed distance of 17 cm led to a variation of 1-2% in the calibration factor measurement using a small disc source (0.4 cm diameter) and less than 1% with a larger rod source (2.9 cm diameter). The lateral position of the source in the FOV and the variability over time had small impacts on calibration factor variability. The residual error component was well estimated by Poisson noise. Repeatability of better than 1% in a calibration factor measurement using a planar acquisition of a sealed source can be reasonably achieved. The best reproducibility was obtained with the largest source with a count rate much higher than the average background in the ROI, and when the SCD was positioned within 5 mm of the desired position. In this case, calibration source variability was limited by the quantum noise.
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Affiliation(s)
- N Anizan
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
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Ekjeen T, Tocharoenchai C, Pusuwan P, Fung GSK, Ghaly M, Du Y, Frey EC. Optimization and evaluation of reconstruction-based compensation methods and reconstruction parameters for Tc-99m MIBI parathyroid SPECT. Phys Med 2015; 31:159-66. [PMID: 25555904 DOI: 10.1016/j.ejmp.2014.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 11/26/2022] Open
Abstract
The value of Tc-99m MIBI parathyroid SPECT for localizing parathyroid hyperplasia in chronic renal failure patients remains inconclusive due to limited image quality. Advanced reconstruction methods to improve image quality have been developed but require optimization and evaluation. The goal of this study was to optimize and evaluate compensation methods and reconstruction parameters for Tc-99m MIBI parathyroid SPECT. A phantom population and projection data that modelled clinically realistic variations found in patients were simulated. The 3D OS-EM reconstruction with compensation for attenuation, detector response and scatter in various combinations were studied. For each compensation, the number of updates for OS-EM and the cutoff frequency of a 3D Butterworth filter were optimized and evaluated using anthropomorphic model observer. With optimal parameters, the method with compensation for attenuation and detector response, with or without the addition of scatter compensation, provided the highest lesion detectability for Tc-99m MIBI parathyroid SPECT.
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Affiliation(s)
- Tawatchai Ekjeen
- Department of Radiological Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand.
| | - Chiraporn Tocharoenchai
- Department of Radiological Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
| | - Pawana Pusuwan
- Department of Radiology, Siriraj Hospital, Bangkok, Thailand
| | - George S K Fung
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
| | - Michael Ghaly
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
| | - Yong Du
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
| | - Eric C Frey
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
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Abstract
Radiopharmaceutical therapy (RPT) involves the use of radionuclides that are either conjugated to tumor-targeting agents (e.g., nanoscale constructs, antibodies, peptides, and small molecules) or concentrated in tissue through natural physiological mechanisms that occur predominantly in neoplastic or otherwise targeted cells (e.g., Graves disease). The ability to collect pharmacokinetic data by imaging and use this to perform dosimetry calculations for treatment planning distinguishes RPT from other systemic treatment modalities such as chemotherapy, wherein imaging is not generally used. Treatment planning has not been widely adopted, in part, because early attempts to relate dosimetry to outcome were not successful. This was partially because a dosimetry methodology appropriate to risk evaluation rather than efficacy and toxicity was being applied to RPT. The weakest links in both diagnostic and therapeutic dosimetry are the accuracy of the input and the reliability of the radiobiological models used to convert dosimetric data to the relevant biologic end points. Dosimetry for RPT places a greater demand on both of these weak links. To date, most dosimetric studies have been retrospective, with a focus on tumor dose-response correlations rather than prospective treatment planning. In this regard, transarterial radioembolization also known as intra-arterial radiation therapy, which uses radiolabeled ((90)Y) microspheres of glass or resin to treat lesions in the liver holds much promise for more widespread dosimetric treatment planning. The recent interest in RPT with alpha-particle emitters has highlighted the need to adopt a dosimetry methodology that specifically accounts for the unique aspects of alpha particles. The short range of alpha-particle emitters means that in cases in which the distribution of activity is localized to specific functional components or cell types of an organ, the absorbed dose will be equally localized and dosimetric calculations on the scale of organs or even voxels (~5mm) are no longer sufficient. This limitation may be overcome by using preclinical models to implement macromodeling to micromodeling. In contrast to chemotherapy, RPT offers the possibility of evaluating radiopharmaceutical distributions, calculating tumor and normal tissue absorbed doses, and devising a treatment plan that is optimal for a specific patient or specific group of patients.
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Anizan N, Wang H, Zhou XC, Hobbs RF, Wahl RL, Frey EC. Factors affecting the stability and repeatability of gamma camera calibration for quantitative imaging applications based on a retrospective review of clinical data. EJNMMI Res 2014; 4:67. [PMID: 26116127 PMCID: PMC4452683 DOI: 10.1186/s13550-014-0067-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 11/21/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Absolute quantitative single-photon emission computed tomography (SPECT) has several important applications including monitoring tumor response after treatment and dose estimation for targeted radionuclide therapy treatment planning. Obtaining quantitative SPECT images in absolute activity units requires the use of a calibration factor, and the repeatability of this directly affects the repeatability of image quantification. This study focused on evaluating the factors affecting the repeatability of a calibration factor measured using a planar image of an in-air calibration source. METHODS The calibration factors calculated as part of (131)I-tositumomab patient dosimetry scans used in treatment planning performed over a 4-year period were retrospectively analyzed. Raw data included total counts in whole-body images of a radioactive calibration source, the activity of the source measured in a radionuclide activity meter (often referred to as a dose calibrator), and the background count rate obtained at three time points for each patient. The count rate from extrinsic flood source acquisitions and radionuclide activity meter constancy obtained on the same day as each image were also used. The data were analyzed statistically using a mixed-effects model to determine the factors affecting variations in the measured calibration factors. RESULTS The global variability in the calibration factor was equal to 2.3% and was decreased by 20% to 1.8%, when the decay-corrected measurements of calibration source activity were averaged over the three time points for each patient. Camera sensitivity variation measured using a (57)Co sheet source was small and had a weak relationship to calibration factor variations. When the averaged source activity was used, the main source of variance was related to preparation and measurement of the source (77%). Radionuclide activity meter constancy had a smaller but statistically significant impact on the calibration factor. CONCLUSIONS This study indicates that calibration factors based on planar measurements have good reproducibility. The findings of this study indicate (1) the importance of accurate and precise preparation and measurement of the calibration source activity, (2) the need to carefully control background activity during calibration factor assessment and patient data acquisition, and (3) that the calibration factor and camera sensitivity were stable over time, indicating that careful but less frequent calibration is needed.
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Affiliation(s)
- Nadège Anizan
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, 601 North Caroline Street/JHOC 4263, Baltimore, Maryland, 21287, USA,
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Lu Y, Chen L, Gindi G. Collimator performance evaluation for In-111 SPECT using a detection/localization task. Phys Med Biol 2014; 59:679-96. [PMID: 24442348 DOI: 10.1088/0031-9155/59/3/679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In SPECT, the collimator is a crucial element in controlling image quality. We take a task performance approach to collimator performance evaluation in which an ideal observer is applied to the raw camera data without regard to the subsequent reconstruction stage. The clinical context of our collimator study is one of searching for and detecting neuroendocrine tumor metastases in the liver as seen in In-111 Octreotide SPECT. Our task involves detection and localization of a signal and thus differs from the conventionally used detection-only task. The scalar task performance metric is ALROC, the area under the localization receiver operating characteristic curve. Since In-111 emits photons at both 171 and 245 keV, the higher energy emissions can contribute significant septal scatter and penetration. Our collimator evaluations address a question previously considered by Mähler et al (2012 IEEE Trans. Nucl. Sci. 59 47–53) who used a different methodology: does allowing a limited amount of septal scatter and penetration yield improved task performance? We used simulation methods to evaluate five parallel-hole collimators. The collimators had roughly equal geometric sensitivity and resolution but a range of contributions from septal effects leading to variations in total sensitivity and resolution. We found that the best performance was obtained with a collimator that allowed a moderate amount of septal scatter and penetration.
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Yip S, Chen AB, Aerts HJWL, Berbeco R. Sensitivity study of voxel-based PET image comparison to image registration algorithms. Med Phys 2014; 41:111714. [DOI: 10.1118/1.4898125] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Vandeghinste B, Van Holen R, Vanhove C, De Vos F, Vandenberghe S, Staelens S. Use of a Ray-Based Reconstruction Algorithm to Accurately Quantify Preclinical MicroSPECT Images. Mol Imaging 2014. [DOI: 10.2310/7290.2014.00007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Bert Vandeghinste
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Roel Van Holen
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Christian Vanhove
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Filip De Vos
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Stefaan Vandenberghe
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
| | - Steven Staelens
- From the Department of Electronics and Information Systems, Medical Image and Signal Processing (MEDISIP) Research Group, Ghent University-IBBT-IBiTech, Ghent, Belgium; Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium; and Molecular Imaging Center Antwerp (MICA), University of Antwerp, Wilrijk, Belgium
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42
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Ghaly M, Du Y, Fung GSK, Tsui BMW, Links JM, Frey E. Design of a digital phantom population for myocardial perfusion SPECT imaging research. Phys Med Biol 2014; 59:2935-53. [PMID: 24841729 DOI: 10.1088/0031-9155/59/12/2935] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48-184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as crosstalk in the context of single and dual isotope MPS.
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Affiliation(s)
- Michael Ghaly
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
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Rong X, Ghaly M, Frey EC. Optimization of energy window for 90Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch. Med Phys 2014; 40:062502. [PMID: 23718607 DOI: 10.1118/1.4805095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
PURPOSE In yttrium-90 ((90)Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy (90)Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of (90)Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for (90)Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for (90)Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. METHODS An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a Gaussian distribution; the signal was modeled as a tumor with a Gaussian-distributed activity parameter located randomly with equal probability at one of three positions. The IO test statistics (i.e., likelihood ratios) were estimated using Markov-chain Monte Carlo methods. The authors realistically modeled human anatomy using a digital phantom code, and realistically simulated (90)Y bremsstrahlung SPECT imaging with a clinical SPECT system and typical imaging parameters using a previously validated Monte Carlo bremsstrahlung simulation method. Model-mismatch was included by modeling image formation process in the calculation of IO test statistics using an analytic modeling method previously developed for quantitative (90)Y bremsstrahlung SPECT. To demonstrate the effects of the model-mismatch on the detection task, the authors optimized the energy window both with and without model-mismatch included in the IO. RESULTS For all the energy windows, the AUC values for the IO-MM were smaller than that for the IO. The optimal windows for the IO-MM and the IO were 80-180 and 60-400 keV, respectively. CONCLUSIONS The authors have demonstrated the degradation of the ideal performance due to model-mismatch and optimized the energy window for (90)Y bremsstrahlung SPECT for detection tasks by accounting for the effects of the model-mismatch. The obtained optimal window was much narrower when taking into account the model-mismatch and similar to that obtained previously for estimation tasks.
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Affiliation(s)
- Xing Rong
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21287-0859, USA.
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Shcherbinin S, Grimes J, Bator A, Cwikla JB, Celler A. Three-dimensional personalized dosimetry for 188Re liver selective internal radiation therapy based on quantitative post-treatment SPECT studies. Phys Med Biol 2013; 59:119-134. [PMID: 24334821 DOI: 10.1088/0031-9155/59/1/119] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We demonstrate that accurate patient-specific distributions of microspheres labeled with 188Re and resulting absorbed doses can be obtained from single-photon emission computed tomography (SPECT) studies performed after 188Re selective internal radiation therapy when accurate correction methods are employed in image reconstruction. Our quantitative image reconstruction algorithm includes corrections for attenuation, resolution degradations and scatter as well as a window-based compensation for contamination. The procedure has been validated using four phantom experiments containing an 18 ml cylindrical source (82-93 MBq of 188Re activity) simulating a liver tumor. In addition, we applied our approach to post-therapy SPECT studies of ten patients with progressive primary or metastatic liver carcinomas. Our quantitative algorithm accurately (within 9%) recovered 188Re activity from four phantom experiments. In addition, for two patients that received three scans, deviations remained consistent between the measured and the reconstructed activities that were determined from studies with differing severity of the dead-time effect. The analysis of absorbed doses for patient studies allowed us to hypothesize that D90 (the minimum dose received by 90% of the tumor volume) may be a reliable metric relating therapy outcomes to the calculated doses. Among several considered metrics, only D90 showed statistically significant correlation with the overall survival.
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Affiliation(s)
- S Shcherbinin
- Medical Imaging Research Group, University of British Columbia, 366-828 West 10th Avenue, Vancouver BC, V5Z 1M9, Canada
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45
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Personalized image-based radiation dosimetry for routine clinical use in peptide receptor radionuclide therapy: pretherapy experience. Recent Results Cancer Res 2013; 194:497-517. [PMID: 22918779 DOI: 10.1007/978-3-642-27994-2_29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
Abstract
Patient-specific dose calculations are not routinely performed for targeted radionuclide therapy procedures, partly because they are time consuming and challenging to perform. However, it is becoming widely recognized that a personalized dosimetry approach can help plan treatment and improve understanding of the dose-response relationship. In this chapter, we review the procedures and essential elements of an accurate internal dose calculation and propose a simplified approach that is aimed to be practical for use in a busy nuclear medicine department.
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Cheng L, Hobbs RF, Segars PW, Sgouros G, Frey EC. Improved dose-volume histogram estimates for radiopharmaceutical therapy by optimizing quantitative SPECT reconstruction parameters. Phys Med Biol 2013; 58:3631-47. [PMID: 23648371 DOI: 10.1088/0031-9155/58/11/3631] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In radiopharmaceutical therapy, an understanding of the dose distribution in normal and target tissues is important for optimizing treatment. Three-dimensional (3D) dosimetry takes into account patient anatomy and the nonuniform uptake of radiopharmaceuticals in tissues. Dose-volume histograms (DVHs) provide a useful summary representation of the 3D dose distribution and have been widely used for external beam treatment planning. Reliable 3D dosimetry requires an accurate 3D radioactivity distribution as the input. However, activity distribution estimates from SPECT are corrupted by noise and partial volume effects (PVEs). In this work, we systematically investigated OS-EM based quantitative SPECT (QSPECT) image reconstruction in terms of its effect on DVHs estimates. A modified 3D NURBS-based Cardiac-Torso (NCAT) phantom that incorporated a non-uniform kidney model and clinically realistic organ activities and biokinetics was used. Projections were generated using a Monte Carlo (MC) simulation; noise effects were studied using 50 noise realizations with clinical count levels. Activity images were reconstructed using QSPECT with compensation for attenuation, scatter and collimator-detector response (CDR). Dose rate distributions were estimated by convolution of the activity image with a voxel S kernel. Cumulative DVHs were calculated from the phantom and QSPECT images and compared both qualitatively and quantitatively. We found that noise, PVEs, and ringing artifacts due to CDR compensation all degraded histogram estimates. Low-pass filtering and early termination of the iterative process were needed to reduce the effects of noise and ringing artifacts on DVHs, but resulted in increased degradations due to PVEs. Large objects with few features, such as the liver, had more accurate histogram estimates and required fewer iterations and more smoothing for optimal results. Smaller objects with fine details, such as the kidneys, required more iterations and less smoothing at early time points post-radiopharmaceutical administration but more smoothing and fewer iterations at later time points when the total organ activity was lower. The results of this study demonstrate the importance of using optimal reconstruction and regularization parameters. Optimal results were obtained with different parameters at each time point, but using a single set of parameters for all time points produced near-optimal dose-volume histograms.
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Affiliation(s)
- Lishui Cheng
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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Shcherbinin S, Chamoiseau S, Celler A. Simulation-based reconstruction of absolute activities from the99mTc/111In dual-isotope SPECT/CT: phantom experiments and imaging of neuroendocrine tumors. Phys Med Biol 2013; 58:3339-57. [DOI: 10.1088/0031-9155/58/10/3339] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bailey DL, Willowson KP. An evidence-based review of quantitative SPECT imaging and potential clinical applications. J Nucl Med 2013; 54:83-9. [PMID: 23283563 DOI: 10.2967/jnumed.112.111476] [Citation(s) in RCA: 242] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
SPECT has traditionally been regarded as nonquantitative. Advances in multimodality γ-cameras (SPECT/CT), algorithms for image reconstruction, and sophisticated compensation techniques to correct for photon attenuation and scattering have, however, now made quantitative SPECT viable in a manner similar to quantitative PET (i.e., kBq cm(-3), standardized uptake value). This review examines the evidence for quantitative SPECT and demonstrates clinical studies in which the accuracy of the reconstructed SPECT data has been assessed in vivo. SPECT reconstructions using CT-based compensation corrections readily achieve accuracy for (99m)Tc to within ± 10% of the known concentration of the radiotracer in vivo. Quantification with other radionuclides is also being introduced. SPECT continues to suffer from poorer photon detection efficiency (sensitivity) and spatial resolution than PET; however, it has the benefit in some situations of longer radionuclide half-lives, which may better suit the biologic process under examination, as well as the ability to perform multitracer studies using pulse height spectroscopy to separate different radiolabels.
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Affiliation(s)
- Dale L Bailey
- Department of Nuclear Medicine, Royal North Shore Hospital, St. Leonards, Australia.
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Chun SY, Fessler JA, Dewaraja YK. Correction for collimator-detector response in SPECT using point spread function template. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:295-305. [PMID: 23086521 PMCID: PMC3619230 DOI: 10.1109/tmi.2012.2225441] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Compensating for the collimator-detector response (CDR) in SPECT is important for accurate quantification. The CDR consists of both a geometric response and a septal penetration and collimator scatter response. The geometric response can be modeled analytically and is often used for modeling the whole CDR if the geometric response dominates. However, for radionuclides that emit medium or high-energy photons such as I-131, the septal penetration and collimator scatter response is significant and its modeling in the CDR correction is important for accurate quantification. There are two main methods for modeling the depth-dependent CDR so as to include both the geometric response and the septal penetration and collimator scatter response. One is to fit a Gaussian plus exponential function that is rotationally invariant to the measured point source response at several source-detector distances. However, a rotationally-invariant exponential function cannot represent the star-shaped septal penetration tails in detail. Another is to perform Monte-Carlo (MC) simulations to generate the depth-dependent point spread functions (PSFs) for all necessary distances. However, MC simulations, which require careful modeling of the SPECT detector components, can be challenging and accurate results may not be available for all of the different SPECT scanners in clinics. In this paper, we propose an alternative approach to CDR modeling. We use a Gaussian function plus a 2-D B-spline PSF template and fit the model to measurements of an I-131 point source at several distances. The proposed PSF-template-based approach is nearly non-parametric, captures the characteristics of the septal penetration tails, and minimizes the difference between the fitted and measured CDR at the distances of interest. The new model is applied to I-131 SPECT reconstructions of experimental phantom measurements, a patient study, and a MC patient simulation study employing the XCAT phantom. The proposed model yields up to a 16.5 and 10.8% higher recovery coefficient compared to the results with the conventional Gaussian model and the Gaussian plus exponential model, respectively.
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Affiliation(s)
- Se Young Chun
- Department of Electrical Engineering and Computer Science and Radiology, University of Michigan, Ann Arbor, MI 48109 USA
| | - Jeffrey A. Fessler
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 USA
| | - Yuni K. Dewaraja
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109 USA
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Dieudonné A, Hobbs RF, Lebtahi R, Maurel F, Baechler S, Wahl RL, Boubaker A, Le Guludec D, Sgouros G, Gardin I. Study of the impact of tissue density heterogeneities on 3-dimensional abdominal dosimetry: comparison between dose kernel convolution and direct Monte Carlo methods. J Nucl Med 2012; 54:236-43. [PMID: 23249540 DOI: 10.2967/jnumed.112.105825] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED Dose kernel convolution (DK) methods have been proposed to speed up absorbed dose calculations in molecular radionuclide therapy. Our aim was to evaluate the impact of tissue density heterogeneities (TDH) on dosimetry when using a DK method and to propose a simple density-correction method. METHODS This study has been conducted on 3 clinical cases: case 1, non-Hodgkin lymphoma treated with (131)I-tositumomab; case 2, a neuroendocrine tumor treatment simulated with (177)Lu-peptides; and case 3, hepatocellular carcinoma treated with (90)Y-microspheres. Absorbed dose calculations were performed using a direct Monte Carlo approach accounting for TDH (3D-RD), and a DK approach (VoxelDose, or VD). For each individual voxel, the VD absorbed dose, D(VD), calculated assuming uniform density, was corrected for density, giving D(VDd). The average 3D-RD absorbed dose values, D(3DRD), were compared with D(VD) and D(VDd), using the relative difference Δ(VD/3DRD). At the voxel level, density-binned Δ(VD/3DRD) and Δ(VDd/3DRD) were plotted against ρ and fitted with a linear regression. RESULTS The D(VD) calculations showed a good agreement with D(3DRD). Δ(VD/3DRD) was less than 3.5%, except for the tumor of case 1 (5.9%) and the renal cortex of case 2 (5.6%). At the voxel level, the Δ(VD/3DRD) range was 0%-14% for cases 1 and 2, and -3% to 7% for case 3. All 3 cases showed a linear relationship between voxel bin-averaged Δ(VD/3DRD) and density, ρ: case 1 (Δ = -0.56ρ + 0.62, R(2) = 0.93), case 2 (Δ = -0.91ρ + 0.96, R(2) = 0.99), and case 3 (Δ = -0.69ρ + 0.72, R(2) = 0.91). The density correction improved the agreement of the DK method with the Monte Carlo approach (Δ(VDd/3DRD) < 1.1%), but with a lesser extent for the tumor of case 1 (3.1%). At the voxel level, the Δ(VDd/3DRD) range decreased for the 3 clinical cases (case 1, -1% to 4%; case 2, -0.5% to 1.5%, and -1.5% to 2%). No more linear regression existed for cases 2 and 3, contrary to case 1 (Δ = 0.41ρ - 0.38, R(2) = 0.88) although the slope in case 1 was less pronounced. CONCLUSION This study shows a small influence of TDH in the abdominal region for 3 representative clinical cases. A simple density-correction method was proposed and improved the comparison in the absorbed dose calculations when using our voxel S value implementation.
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Affiliation(s)
- Arnaud Dieudonné
- Department of Nuclear Medicine, Beaujon Hospital, Assistance Publique-Hôpitaux de Paris APHP, Clichy, France.
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