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Covert EC, Fitzpatrick K, Mikell J, Kaza RK, Millet JD, Barkmeier D, Gemmete J, Christensen J, Schipper MJ, Dewaraja YK. Intra- and inter-operator variability in MRI-based manual segmentation of HCC lesions and its impact on dosimetry. EJNMMI Phys 2022; 9:90. [PMID: 36542239 PMCID: PMC9772368 DOI: 10.1186/s40658-022-00515-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The aim was to quantify inter- and intra-observer variability in manually delineated hepatocellular carcinoma (HCC) lesion contours and the resulting impact on radioembolization (RE) dosimetry. METHODS Ten patients with HCC lesions treated with Y-90 RE and imaged with post-therapy Y-90 PET/CT were selected for retrospective analysis. Three radiologists contoured 20 lesions manually on baseline multiphase contrast-enhanced MRIs, and two of the radiologists re-contoured at two additional sessions. Contours were transferred to co-registered PET/CT-based Y-90 dose maps. Volume-dependent recovery coefficients were applied for partial volume correction (PVC) when reporting mean absorbed dose. To understand how uncertainty varies with tumor size, we fit power models regressing relative uncertainty in volume and in mean absorbed dose on contour volume. Finally, we determined effects of segmentation uncertainty on tumor control probability (TCP), as calculated using logistic models developed in a previous RE study. RESULTS The average lesion volume ranged from 1.8 to 194.5 mL, and the mean absorbed dose ranged from 23.4 to 1629.0 Gy. The mean inter-observer Dice coefficient for lesion contours was significantly less than the mean intra-observer Dice coefficient (0.79 vs. 0.85, p < 0.001). Uncertainty in segmented volume, as measured by the Coefficient of Variation (CV), ranged from 4.2 to 34.7% with an average of 17.2%. The CV in mean absorbed dose had an average value of 5.4% (range 1.2-13.1%) without PVC while it was 15.1% (range 1.5-55.2%) with PVC. Using the fitted models for uncertainty as a function of volume on our prior data, the mean change in TCP due to segmentation uncertainty alone was estimated as 16.2% (maximum 48.5%). CONCLUSIONS Though we find relatively high inter- and intra-observer reliability overall, uncertainty in tumor contouring propagates into non-negligible uncertainty in dose metrics and outcome prediction for individual cases that should be considered in dosimetry-guided treatment.
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Affiliation(s)
- Elise C Covert
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA
| | - Kellen Fitzpatrick
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA
| | - Justin Mikell
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Ravi K Kaza
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - John D Millet
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA
| | - Daniel Barkmeier
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA
| | - Joseph Gemmete
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA
| | - Jared Christensen
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA
| | - Matthew J Schipper
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA.,Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Yuni K Dewaraja
- Department of Radiology, University of Michigan, 1301 Catherine, 2276 Medical Science I/5610, Ann Arbor, MI, 48109, USA.
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EANM dosimetry committee recommendations for dosimetry of 177Lu-labelled somatostatin-receptor- and PSMA-targeting ligands. Eur J Nucl Med Mol Imaging 2022; 49:1778-1809. [PMID: 35284969 PMCID: PMC9015994 DOI: 10.1007/s00259-022-05727-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 02/13/2022] [Indexed: 12/25/2022]
Abstract
The purpose of the EANM Dosimetry Committee is to provide recommendations and guidance to scientists and clinicians on patient-specific dosimetry. Radiopharmaceuticals labelled with lutetium-177 (177Lu) are increasingly used for therapeutic applications, in particular for the treatment of metastatic neuroendocrine tumours using ligands for somatostatin receptors and prostate adenocarcinoma with small-molecule PSMA-targeting ligands. This paper provides an overview of reported dosimetry data for these therapies and summarises current knowledge about radiation-induced side effects on normal tissues and dose-effect relationships for tumours. Dosimetry methods and data are summarised for kidneys, bone marrow, salivary glands, lacrimal glands, pituitary glands, tumours, and the skin in case of radiopharmaceutical extravasation. Where applicable, taking into account the present status of the field and recent evidence in the literature, guidance is provided. The purpose of these recommendations is to encourage the practice of patient-specific dosimetry in therapy with 177Lu-labelled compounds. The proposed methods should be within the scope of centres offering therapy with 177Lu-labelled ligands for somatostatin receptors or small-molecule PSMA.
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Finocchiaro D, Gear JI, Fioroni F, Flux GD, Murray I, Castellani G, Versari A, Iori M, Grassi E. Uncertainty analysis of tumour absorbed dose calculations in molecular radiotherapy. EJNMMI Phys 2020; 7:63. [PMID: 33044651 PMCID: PMC7550507 DOI: 10.1186/s40658-020-00328-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/16/2020] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of a patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced. RESULTS Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14-102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. volume, recovery coefficient, calibration factor, activity, time-activity curve fitting, time-integrated activity and absorbed dose) were estimated. An equation was derived to describe the relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated. DISCUSSION To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.
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Affiliation(s)
- Domenico Finocchiaro
- Medical Physics Unit, Azienda Unità Sanitaria Locale di Reggio Emilia - IRCCS, Reggio Emilia, Italy.,Department of Physics and Astronomy, University of Bologna, Bologna, Italy
| | - Jonathan I Gear
- The Royal Marsden NHS Foundation Trust & Institute of Cancer Research, Downs Road, Sutton, SM2 5PT, UK
| | - Federica Fioroni
- Medical Physics Unit, Azienda Unità Sanitaria Locale di Reggio Emilia - IRCCS, Reggio Emilia, Italy.
| | - Glenn D Flux
- The Royal Marsden NHS Foundation Trust & Institute of Cancer Research, Downs Road, Sutton, SM2 5PT, UK
| | - Iain Murray
- The Royal Marsden NHS Foundation Trust & Institute of Cancer Research, Downs Road, Sutton, SM2 5PT, UK
| | - Gastone Castellani
- Department of Physics and Astronomy, University of Bologna, Bologna, Italy
| | - Annibale Versari
- Nuclear Medicine Unit, Azienda Unità Sanitaria Locale di Reggio Emilia - IRCCS, Reggio Emilia, Italy
| | - Mauro Iori
- Medical Physics Unit, Azienda Unità Sanitaria Locale di Reggio Emilia - IRCCS, Reggio Emilia, Italy
| | - Elisa Grassi
- Medical Physics Unit, Azienda Unità Sanitaria Locale di Reggio Emilia - IRCCS, Reggio Emilia, Italy
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Huizing DMV, Sinaasappel M, Dekker MC, Stokkel MPM, de Wit – van der Veen BJ. 177
Lutetium SPECT/CT: Evaluation of collimator, photopeak and scatter correction. J Appl Clin Med Phys 2020; 21:272-277. [PMID: 32790140 PMCID: PMC7497918 DOI: 10.1002/acm2.12991] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 06/26/2020] [Accepted: 07/09/2020] [Indexed: 11/10/2022] Open
Abstract
Purpose The goal of this study was to find the optimal combination of collimator, photopeak and scatter correction for 177Lutetium (177Lu) SPECT/CT imaging. Methods Three experiments [sphere‐to‐background ratios (SBR) 50:1, 10:1, and 2:1] were performed with the NEMA Image Quality phantom filled with 177Lu‐trichloride. SPECT/CT acquisitions were performed with the medium‐energy low‐penetration (MELP) collimator and 99mTc/Krypton collimator. For each acquisition six reconstructions, all with attenuation correction (AC), were made: the 113‐keV photopeak only, the 208‐keV photopeak only and both photopeaks combined, each with or without scatter correction (SC). Image quality was assessed using contrast‐to‐noise ratios (CNR), quantification accuracy by means of recovery coefficients (RCs) and the spatial resolution using line profiles. Results With SBR 50:1 and 10:1, both collimators met the Rose criterion (CNR > 5), whereas the MELP collimator showed a higher CNR for the 2:1 ratio. The RCmean was higher with the MELP collimator, most explicit after the 208‐keV AC/SC reconstruction for all acquisitions. The line profiles showed a better spatial resolution for the MELP collimator and the 208‐keV AC/SC reconstructions. Conclusion 177Lu SPECT/CT image quality and quantification was most optimal when acquired with the MELP collimator and reconstructed using the 208‐keV photopeak, with AC and SC.
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Affiliation(s)
- Daphne M. V. Huizing
- Department of Nuclear Medicine Netherlands Cancer Institute Amsterdam The Netherlands
| | - Michiel Sinaasappel
- Department of Physics Netherlands Cancer Institute Amsterdam The Netherlands
| | - Marien C. Dekker
- Department of Nuclear Medicine Netherlands Cancer Institute Amsterdam The Netherlands
| | - Marcel P. M. Stokkel
- Department of Nuclear Medicine Netherlands Cancer Institute Amsterdam The Netherlands
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Comparison of different calculation techniques for absorbed dose assessment in patient specific peptide receptor radionuclide therapy. PLoS One 2020; 15:e0236466. [PMID: 32764764 PMCID: PMC7413508 DOI: 10.1371/journal.pone.0236466] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 07/06/2020] [Indexed: 11/19/2022] Open
Abstract
Aim The present work concerns the comparison of the performances of three systems for dosimetry in RPT that use different techniques for absorbed dose calculation (organ-level dosimetry, voxel-level dose kernel convolution and Monte Carlo simulations). The aim was to assess the importance of the choice of the most adequate calculation modality, providing recommendations about the choice of the computation tool. Methods The performances were evaluated both on phantoms and patients in a multi-level approach. Different phantoms filled with a 177Lu-radioactive solution were used: a homogeneous cylindrical phantom, a phantom with organ-shaped inserts and two cylindrical phantoms with inserts different for shape and volume. A total of 70 patients with NETs treated by PRRT with 177Lu-DOTATOC were retrospectively analysed. Results The comparisons were performed mainly between the mean values of the absorbed dose in the regions of interest. A general better agreement was obtained between Dose kernel convolution and Monte Carlo simulations results rather than between either of these two and organ-level dosimetry, both for phantoms and patients. Phantoms measurements also showed the discrepancies mainly depend on the geometry of the inserts (e.g. shape and volume). For patients, differences were more pronounced than phantoms and higher inter/intra patient variability was observed. Conclusion This study suggests that voxel-level techniques for dosimetry calculation are potentially more accurate and personalized than organ-level methods. In particular, a voxel-convolution method provides good results in a short time of calculation, while Monte Carlo based computation should be conducted with very fast calculation systems for a possible use in clinics, despite its intrinsic higher accuracy. Attention to the calculation modality is recommended in case of clinical regions of interest with irregular shape and far from spherical geometry, in which Monte Carlo seems to be more accurate than voxel-convolution methods.
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Huizing DMV, Peters SMB, Versleijen MWJ, Martens E, Verheij M, Sinaasappel M, Stokkel MPM, de Wit-van der Veen BJ. A head-to-head comparison between two commercial software packages for hybrid dosimetry after peptide receptor radionuclide therapy. EJNMMI Phys 2020; 7:36. [PMID: 32488632 PMCID: PMC7266908 DOI: 10.1186/s40658-020-00308-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 05/20/2020] [Indexed: 11/24/2022] Open
Abstract
Background Dosimetry after peptide receptor radionuclide therapy (PRRT) is increasing; however, comparing or pooling of dosimetric results can be challenging since different approaches are used. The aim of this study was to perform a head-to-head comparison of post-PRRT curve fitting and dosimetry obtained from two commercial software Hybrid Viewer Dosimetry and PLANET Dose. Methods Post-therapy imaging included planar scintigraphy at 0.5, 4, 24 and 72 h post-injection of [177Lu]Lu-DOTA-TATE for kinetics and SPECT/CT at 24 h for quantification. On planar imaging, 2 cm regions-of-interest were positioned within the inferior pole of the kidneys and kidney cortex was segmented on low-dose CT. On both planar and SPECT/CT, 2 cm spheres were positioned in the proximal humerus (red marrow equivalent) and in the region with the highest uptake in tumour lesions. TACs were estimated with mono- and bi-exponential fits in both software systems, after which tissue absorbed (kidney, red marrow, tumour) and biological effective doses (kidney) were calculated. Agreement-ICC, Spearman correlation and Bland-Altman plots were used to compare results. Results Mono-exponential fits showed the most comparable correlation between the measured and fitted data between both software. The ICC between absorbed dose outcomes was > 0.7 in tumour lesions and kidneys, but negative for the red marrow. Spearman correlation was > 0.9 for mono-exponential fits in kidneys and tumour lesions, and −0.7 in red marrow. Bi-exponential fits resulted in lower correlations and agreement values. Concordance between both software packages concerning the number of PRRT cycles with 7.4 GBq was observed based on a biological effective dose limit of 27 Gy to the kidneys. Conclusion [177Lu]Lu-DOTA-TATE dosimetry results of two software packages were comparable in the same dataset, despite the limited number of imaging time-points. However, these results should be verified in a larger cohort before pooling of clinical data, as the obtained results will depend on acquisition protocol, timing and lesions definition.
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Affiliation(s)
- Daphne M V Huizing
- Department of Nuclear Medicine, Netherlands Cancer Institute, Plesmanlaan 121, 1066, CX, Amsterdam, The Netherlands.
| | - Steffie M B Peters
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michelle W J Versleijen
- Department of Nuclear Medicine, Netherlands Cancer Institute, Plesmanlaan 121, 1066, CX, Amsterdam, The Netherlands
| | - Esther Martens
- Department of Clinical Physics and Instrumentation, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Marcel Verheij
- Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michiel Sinaasappel
- Department of Clinical Physics and Instrumentation, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Marcel P M Stokkel
- Department of Nuclear Medicine, Netherlands Cancer Institute, Plesmanlaan 121, 1066, CX, Amsterdam, The Netherlands
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