1
|
Gustafsson J, Taprogge J. Future trends for patient-specific dosimetry methodology in molecular radiotherapy. Phys Med 2023; 115:103165. [PMID: 37880071 DOI: 10.1016/j.ejmp.2023.103165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023] Open
Abstract
Molecular radiotherapy is rapidly expanding, and new radiotherapeutics are emerging. The majority of treatments is still performed using empirical fixed activities and not tailored for individual patients. Molecular radiotherapy dosimetry is often seen as a promising candidate that would allow personalisation of treatments as outcome should ultimately depend on the absorbed doses delivered and not the activities administered. The field of molecular radiotherapy dosimetry has made considerable progress towards the feasibility of routine clinical dosimetry with reasonably accurate absorbed-dose estimates for a range of molecular radiotherapy dosimetry applications. A range of challenges remain with respect to the accurate quantification, assessment of time-integrated activity and absorbed dose estimation. In this review, we summarise a range of technological and methodological advancements, mainly focussed on beta-emitting molecular radiotherapeutics, that aim to improve molecular radiotherapy dosimetry to achieve accurate, reproducible, and streamlined dosimetry. We describe how these new technologies can potentially improve the often time-consuming considered process of dosimetry and provide suggestions as to what further developments might be required.
Collapse
Affiliation(s)
| | - Jan Taprogge
- National Radiotherapy Trials Quality Assurance (RTTQA) Group, Joint Department of Physics, Royal Marsden NHSFT, Downs Road, Sutton SM2 5PT, United Kingdom; The Institute of Cancer Research, 123 Old Brompton Road, London SW7 3RP, United Kingdom
| |
Collapse
|
2
|
Li Z, Benabdallah N, Abou DS, Baumann BC, Dehdashti F, Ballard DH, Liu J, Jammalamadaka U, Laforest R, Wahl RL, Thorek DLJ, Jha AK. A Projection-Domain Low-Count Quantitative SPECT Method for α-Particle-Emitting Radiopharmaceutical Therapy. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2023; 7:62-74. [PMID: 37201111 PMCID: PMC10191330 DOI: 10.1109/trpms.2022.3175435] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
Single-photon emission-computed tomography (SPECT) provides a mechanism to estimate regional isotope uptake in lesions and at-risk organs after administration of α-particle-emitting radiopharmaceutical therapies (α-RPTs). However, this estimation task is challenging due to the complex emission spectra, the very low number of detected counts (~20 times lower than in conventional SPECT), the impact of stray-radiation-related noise at these low counts, and the multiple image-degrading processes in SPECT. The conventional reconstruction-based quantification methods are observed to be erroneous for α-RPT SPECT. To address these challenges, we developed a low-count quantitative SPECT (LC-QSPECT) method that directly estimates the regional activity uptake from the projection data (obviating the reconstruction step), compensates for stray-radiation-related noise, and accounts for the radioisotope and SPECT physics, including the isotope spectra, scatter, attenuation, and collimator-detector response, using a Monte Carlo-based approach. The method was validated in the context of 3-D SPECT with 223Ra, a commonly used radionuclide for α-RPT. Validation was performed using both realistic simulation studies, including a virtual clinical trial, and synthetic and 3-D-printed anthropomorphic physical-phantom studies. Across all studies, the LC-QSPECT method yielded reliable regional-uptake estimates and outperformed the conventional ordered subset expectation-maximization (OSEM)-based reconstruction and geometric transfer matrix (GTM)-based post-reconstruction partial-volume compensation methods. Furthermore, the method yielded reliable uptake across different lesion sizes, contrasts, and different levels of intralesion heterogeneity. Additionally, the variance of the estimated uptake approached the Cramér-Rao bound-defined theoretical limit. In conclusion, the proposed LC-QSPECT method demonstrated the ability to perform reliable quantification for α-RPT SPECT.
Collapse
Affiliation(s)
- Zekun Li
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130 USA
| | - Nadia Benabdallah
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Diane S Abou
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Brian C Baumann
- Department of Radiation Oncology, Washington University, St. Louis, MO 63110 USA
| | - Farrokh Dehdashti
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - David H Ballard
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Jonathan Liu
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Uday Jammalamadaka
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Richard Laforest
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Richard L Wahl
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63110 USA
| | - Daniel L J Thorek
- Department of Biomedical Engineering, the Mallinckrodt Institute of Radiology, and the Program in Quantitative Molecular Therapeutics, Washington University, St. Louis, MO 63110 USA
| | - Abhinav K Jha
- Department of Biomedical Engineering and the Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO 63130 USA
| |
Collapse
|
3
|
Könik A, Zeraatkar N, Kalluri KS, Auer B, Fromme TJ, He Y, May M, Furenlid LR, Kuo PH, King MA. Improved Performance of a Multipinhole SPECT for DAT Imaging by Increasing Number of Pinholes at the Expense of Increased Multiplexing. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2021; 5:817-825. [PMID: 34746540 DOI: 10.1109/trpms.2020.3035626] [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] [Indexed: 11/08/2022]
Abstract
SPECT imaging of dopamine transporters (DAT) in the brain is a widely utilized study to improve the diagnosis of Parkinsonian syndromes, where conventional (parallel-hole and fan-beam) collimators on dual-head scanners are commonly employed. We have designed a multi-pinhole (MPH) collimator to improve the performance of DAT imaging. The MPH collimator focuses on the striatum and hence offers a better trade-off for sensitivity and spatial resolution than the conventional collimators within this clinically most relevant region for DAT imaging. Our original MPH design consisted of 9 pinholes with a background-to-striatal (Bkg/Str) projection multiplexing of 1% only. In this simulation study, we investigated whether further improvements in the performance of MPH imaging could be obtained by increasing the number of pinholes, hence by enhancing the sensitivity and sampling, despite the ambiguity in reconstructing images due to increased multiplexing. We performed analytic simulations of the MPH configurations with 9, 13, and 16 pinholes (aperture diameters: 4-6mm) using a digital phantom modeling DAT imaging. Our quantitative analyses indicated that using 13 (Bkg/Str: 12%) and 16 (Bkg/Str: 22%) pinholes provided better performance than the original 9-pinhole configuration for the acquisition with 2 or 4 angular views, but a similar performance with 8 and 16 views.
Collapse
Affiliation(s)
- Arda Könik
- Department of Imaging, Dana Farber Cancer Institute, Boston, MA, 02215, USA
| | - Navid Zeraatkar
- Department of Radiology, Univ. of Mass. Medical School, Worcester, MA, 01605, USA
| | - Kesava S Kalluri
- Department of Radiology, Univ. of Mass. Medical School, Worcester, MA, 01605, USA
| | - Benjamin Auer
- Department of Radiology, Univ. of Mass. Medical School, Worcester, MA, 01605, USA
| | | | - Yulun He
- MD Anderson Cancer Center, Houston, TX
| | - Micaehla May
- Department of Radiology, University of Arizona, Tucson, AZ, 85724 USA
| | - Lars R Furenlid
- Department of Radiology, University of Arizona, Tucson, AZ, 85724 USA
| | - Phillip H Kuo
- Department of Radiology, University of Arizona, Tucson, AZ, 85724 USA
| | - Michael A King
- Department of Radiology, Univ. of Mass. Medical School, Worcester, MA, 01605, USA
| |
Collapse
|
4
|
van Nierop BJ, Prince JF, van Rooij R, van den Bosch MA, Lam MG, de Jong HW. Accuracy of SPECT/CT-based lung dose calculation for Holmium-166 hepatic radioembolization before OSEM convergence. Med Phys 2018; 45:3871-3879. [PMID: 29858506 PMCID: PMC6099428 DOI: 10.1002/mp.13024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 04/26/2018] [Accepted: 05/14/2018] [Indexed: 11/06/2022] Open
Abstract
PURPOSE In intra-arterial hepatic radioembolization using Holmium-166 (166 Ho) microspheres, a predicted lung-absorbed dose of more than 30 Gy is a contraindication for therapy. Therefore, scout imaging by means of quantitative SPECT of the lungs after a low-dose pretreatment session is essential. Earlier we showed the superiority of Monte Carlo-based iterative SPECT reconstructions over conventional reconstructions due to its quantitative nature, required for dosimetry, at the cost of substantial computation times. In clinical routine, however, the limited available time between scout imaging and therapy constrains its application. To reduce computation times, we investigated the minimum number of iterations required to guarantee a clinical acceptable accuracy in lung dose estimation using patient and phantom data. METHODS 166 Ho scout SPECT data (range: 222-283 MBq) were used from 10 patients. SPECT images were Monte Carlo-based OSEM reconstructed (effective iterations: 240). Additionally, the 4D XCAT anthropomorphic phantom was used to mimic studies with an injected scout activity of 250 MBq and with varying lung-absorbed doses ranging from 0.9 to 225 Gy for a therapeutic dosage of 15 GBq. These studies were reconstructed in the same way as the patient data, and were also reconstructed using a clinically available, standard OSEM algorithm for comparison. Lung-absorbed dose was determined using VOI analysis as a function of iterations. RESULTS The estimated lung-absorbed dose in nine patients ranged upon MC-based OSEM convergence from 0 to 0.26 Gy for a therapeutic dosage. One patient had an estimated lung absorbed-dose for a therapeutic dosage of 20.3 Gy upon MC-based OSEM convergence, or 18.4 Gy after 40 iterations (-9%). The phantom data showed that the lung-absorbed dose upon OSEM convergence was underestimated by 15% as compared to the actual simulated lung dose, and the dose after 40 iterations was underestimated by 9% as compared to the dose upon convergence. Both underestimations were irrespective of the magnitude of the lung-absorbed dose (0.9 to 225 Gy) and thus can be easily corrected for. The quantitative accuracy of the MC-based OSEM reconstructions (40 iterations, before convergence) outperformed the clinical OSEM reconstruction while estimating the lung dose. CONCLUSIONS The number of effective iterations necessary for quantitative estimation of the lung dose using MC-based OSEM can be reduced from 240 to 40. The resulting sixfold reduction in calculation time enables processing of the scout images before therapy administration.
Collapse
Affiliation(s)
- Bastiaan J. van Nierop
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| | - Jip F. Prince
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| | - Rob van Rooij
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| | - Maurice A.A.J. van den Bosch
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| | - Marnix G.E.H. Lam
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| | - Hugo W.A.M. de Jong
- Department of Radiology and Nuclear MedicineUniversity Medical Centre UtrechtP.O. Box 85500UtrechtGA3508The Netherlands
| |
Collapse
|
5
|
KUPINSKI MEREDITHK, CLARKSON ERIC. Optimal channels for channelized quadratic estimators. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2016; 33:1214-25. [PMID: 27409452 PMCID: PMC8123080 DOI: 10.1364/josaa.33.001214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a new method for computing optimized channels for estimation tasks that is feasible for high-dimensional image data. Maximum-likelihood (ML) parameter estimates are challenging to compute from high-dimensional likelihoods. The dimensionality reduction from M measurements to L channels is a critical advantage of channelized quadratic estimators (CQEs), since estimating likelihood moments from channelized data requires smaller sample sizes and inverting a smaller covariance matrix is easier. The channelized likelihood is then used to form ML estimates of the parameter(s). In this work we choose an imaging example in which the second-order statistics of the image data depend upon the parameter of interest: the correlation length. Correlation lengths are used to approximate background textures in many imaging applications, and in these cases an estimate of the correlation length is useful for pre-whitening. In a simulation study we compare the estimation performance, as measured by the root-mean-squared error (RMSE), of correlation length estimates from CQE and power spectral density (PSD) distribution fitting. To abide by the assumptions of the PSD method we simulate an ergodic, isotropic, stationary, and zero-mean random process. These assumptions are not part of the CQE formalism. The CQE method assumes a Gaussian channelized likelihood that can be a valid for non-Gaussian image data, since the channel outputs are formed from weighted sums of the image elements. We have shown that, for three or more channels, the RMSE of CQE estimates of correlation length is lower than conventional PSD estimates. We also show that computing CQE by using a standard nonlinear optimization method produces channels that yield RMSE within 2% of the analytic optimum. CQE estimates of anisotropic correlation length estimation are reported to demonstrate this technique on a two-parameter estimation problem.
Collapse
Affiliation(s)
- MEREDITH K. KUPINSKI
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
- Department of Medical Imaging, University of Arizona, Tucson, Arizona 85721, USA
| | - ERIC CLARKSON
- College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA
- Department of Medical Imaging, University of Arizona, Tucson, Arizona 85721, USA
| |
Collapse
|