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Vergnaud L, Dewaraja YK, Giraudet AL, Badel JN, Sarrut D. A review of 177Lu dosimetry workflows: how to reduce the imaging workloads? EJNMMI Phys 2024; 11:65. [PMID: 39023648 DOI: 10.1186/s40658-024-00658-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 06/07/2024] [Indexed: 07/20/2024] Open
Abstract
177 Lu radiopharmaceutical therapy is a standardized systemic treatment, with a typical dose of 7.4 GBq per injection, but its response varies from patient to patient. Dosimetry provides the opportunity to personalize treatment, but it requires multiple post-injection images to monitor the radiopharmaceutical's biodistribution over time. This imposes an additional imaging burden on centers with limited resources. This review explores methods to lessen this burden by optimizing acquisition types and minimizing the number and duration of imaging sessions. After summarizing the different steps of dosimetry and providing examples of dosimetric workflows for177 Lu -DOTATATE and177 Lu -PSMA, we examine dosimetric workflows based on a reduced number of acquisitions, or even just one. We provide a non-exhaustive description of simplified methods and their assumptions, as well as their limitations. Next, we detail the specificities of each normal tissue and tumors, before reviewing dose-response relationships in the literature. In conclusion, we will discuss the current limitations of dosimetric workflows and propose avenues for improvement.
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Affiliation(s)
- Laure Vergnaud
- CREATIS; CNRS UMR 5220; INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France.
| | - Yuni K Dewaraja
- Department of Radiology, University of Michigan, Ann Arbor, USA
| | | | - Jean-Noël Badel
- CREATIS; CNRS UMR 5220; INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
| | - David Sarrut
- CREATIS; CNRS UMR 5220; INSERM U 1044, Université de Lyon; INSA-Lyon; Université Lyon 1, Lyon, France
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
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de Nijs R. A novel model-based equation for size dependent mean recovery coefficients for spheres and other shapes. Phys Med 2023; 116:103174. [PMID: 38007296 DOI: 10.1016/j.ejmp.2023.103174] [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: 07/27/2023] [Revised: 10/10/2023] [Accepted: 11/16/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND In NM-imaging, theoretical curves for the recovery coefficient (RC) of the signal maximum and mean are known for spheres and cubes, if a 3D Gaussian PSF is assumed. The RC of the maximum is also known for cylinders. For these and other shapes empirical equations with one or two fit-parameters have been utilized. METHODS An equation for the RC for large objects of arbitrary shape is derived and generalized into an empirical equation for smaller objects, which is verified by numerical simulations. The proposed equation is compared to published results on SPECT kidney phantom measurements and to PET measurements on the NEMA IEC PET body phantom with six spheres. RESULTS The signal loss (1-RC) for large spheres is inversely proportional to the radius, where the slope is proportional to the FWHM of the spatial resolution. For non-spherical shapes the generalized instead of the volume equivalent radius should be utilized. For smaller objects, an equation with one added empirical fit-parameter is presented. It is demonstrated that the EANM-guidelines' two-parameter logistic function results in a poor fit if the theoretical slope and inverse proportionality are forced and it gives a suboptimal fit when both parameters are fitted. CONCLUSIONS A novel model-based equation for the mean RC-curve is derived. It can be used for arbitrary shapes as long as the sphericity is taken into account and it is accurate down to RC = 10 %. One parameter is directly related to the spatial resolution, while the other is a shape depending fit-parameter.
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Affiliation(s)
- Robin de Nijs
- Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark; Neurobiology Research Unit, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark.
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Vergnaud L, Badel JN, Giraudet AL, Kryza D, Mognetti T, Baudier T, Rida H, Dieudonné A, Sarrut D. Performance study of a 360° CZT camera for monitoring 177Lu-PSMA treatment. EJNMMI Phys 2023; 10:58. [PMID: 37736779 PMCID: PMC10516832 DOI: 10.1186/s40658-023-00576-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/05/2023] [Indexed: 09/23/2023] Open
Abstract
BACKGROUND The aim of this study was to investigate the quantification performance of a 360° CZT camera for 177Lu-based treatment monitoring. METHODS Three phantoms with known 177Lu activity concentrations were acquired: (1) a uniform cylindrical phantom for calibration, (2) a NEMA IEC body phantom for analysis of different-sized spheres to optimise quantification parameters and (3) a phantom containing two large vials simulating organs at risk for tests. Four sets of reconstruction parameters were tested: (1) Scatter, (2) Scatter and Point Spread Function Recovery (PSFR), (3) PSFR only and (4) Penalised likelihood option and Scatter, varying the number of updates (iterations × subsets) with CT-based attenuation correction only. For each, activity concentration (ARC) and contrast recovery coefficients (CRC) were estimated as well as root mean square. Visualisation and quantification parameters were applied to reconstructed patient image data. RESULTS Optimised quantification parameters were determined to be: CT-based attenuation correction, scatter correction, 12 iterations, 8 subsets and no filter. ARC, CRC and RMS results were dependant on the methodology used for calculations. Two different reconstruction parameters were recommended for visualisation and for quantification. 3D whole-body SPECT images were acquired and reconstructed for 177Lu-PSMA patients in 2-3 times faster than the time taken for a conventional gamma camera. CONCLUSION Quantification of whole-body 3D images of patients treated with 177Lu-PSMA is feasible and an optimised set of parameters has been determined. This camera greatly reduces procedure time for whole-body SPECT.
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Affiliation(s)
- Laure Vergnaud
- Centre de lutte contre le cancer Léon Bérard, Lyon, France.
- CREATIS, CNRS UMR 5220, INSERM U 1044, Université de Lyon, INSA-Lyon, Université Lyon 1, Lyon, France.
| | - Jean-Noël Badel
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
- CREATIS, CNRS UMR 5220, INSERM U 1044, Université de Lyon, INSA-Lyon, Université Lyon 1, Lyon, France
| | | | - David Kryza
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
- Hospices Civils de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, LAGEPP UMR 5007 CNRS, Lyon, France
| | | | - Thomas Baudier
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
- CREATIS, CNRS UMR 5220, INSERM U 1044, Université de Lyon, INSA-Lyon, Université Lyon 1, Lyon, France
| | - Hanan Rida
- Département de médecine nucléaire, Centre Henri Becquerel, Rouen, France
| | - Arnaud Dieudonné
- Département de médecine nucléaire, Centre Henri Becquerel, Rouen, France
| | - David Sarrut
- Centre de lutte contre le cancer Léon Bérard, Lyon, France
- CREATIS, CNRS UMR 5220, INSERM U 1044, Université de Lyon, INSA-Lyon, Université Lyon 1, Lyon, France
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Raskin S, Gamliel D, Abookasis D, Ben-Haim S, Chicheportiche A. Towards accurate 177Lu SPECT activity quantification and standardization using lesion-to-background voxel ratio. EJNMMI Phys 2023; 10:5. [PMID: 36689080 PMCID: PMC9871126 DOI: 10.1186/s40658-023-00526-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/11/2023] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Conventional calibration of the gamma camera consists of the calculation of calibration factors (CFs) (ratio of counts/cc and true concentration activity) as the function of the volume of interest (VOI). However, such method shows inconsistent results when the background activity varies. The aim of the present study was to propose a new calibration method by considering the sphere-to-background counts/voxel ratio (SBVR) in addition to the VOI for CFs calculation. A PET cylindrical flood phantom, a NEMA IQ body phantom, a Data spectrum Torso Phantom (ECT/TOR/P) and a LK-S Kyoto Liver/Kidney phantom were used. The NEMA IQ phantom was used to calibrate the camera and to produce CFs for the different spheres volumes and for varying sphere-to-background activity ratios. The spheres were filled with a uniform activity concentration of 177Lu, while the background was first filled with cold water and activity was added between each SPECT scan. SPECT imaging was performed for 30-s, 20-s, and 10-s exposure per view. The calculated CFs were expressed as function of the sphere volume and SBVR. The obtained CFs were validated for an additional NEMA IQ acquisition with different activities in spheres and background and for the Torso and Liver/Kidney phantoms with inserted NEMA IQ spheres. The quantification accuracy was compared with the conventional method not taking SBVR into consideration. RESULTS The relative errors in quantification using the NEMA IQ phantom with the new calibration method were 0.16%, 5.77%, 9.34% for the large, medium and small sphere, respectively, for a time per view of 30-s. The conventional calibration method gave errors of 3.65%, 6.65%, 30.28% for 30-s. The LK-S Kyoto Liver/Kidney Phantom resulted in quantification errors of 3.40%, 2.14%, 11.18% for the large, medium and small spheres, respectively, for 30-s; compared to 11.31%, 17.54%, 14.43% for 30-s, respectively, for the conventional method. Similar results were obtained for shorter acquisitions times with 20-s and 10-s time per view. CONCLUSION These results suggest that SBVR allows to improve quantification accuracy. The shorter time-per-view acquisitions had similar relative differences compared to the full-time acquisition which allows shorter imaging times with 177Lu and improved patient comfort. The SBVR method is simple to set up and can be proposed for standardization.
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Affiliation(s)
- Stanislav Raskin
- grid.411434.70000 0000 9824 6981Department of Physics, Ariel University, Ariel, Israel ,grid.411434.70000 0000 9824 6981Department of Electrical and Electronics Engineering, Ariel University, 407000 Ariel, Israel
| | - Dan Gamliel
- grid.411434.70000 0000 9824 6981Department of Physics, Ariel University, Ariel, Israel
| | - David Abookasis
- grid.411434.70000 0000 9824 6981Department of Electrical and Electronics Engineering, Ariel University, 407000 Ariel, Israel
| | - Simona Ben-Haim
- grid.9619.70000 0004 1937 0538Department of Nuclear Medicine and Biophysics, Hadassah Medical Organization and Faculty of Medicine, Hebrew University of Jerusalem, 91120 Jerusalem, Israel ,grid.83440.3b0000000121901201University College London, London, UK
| | - Alexandre Chicheportiche
- grid.9619.70000 0004 1937 0538Department of Nuclear Medicine and Biophysics, Hadassah Medical Organization and Faculty of Medicine, Hebrew University of Jerusalem, 91120 Jerusalem, Israel
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Ramonaheng K, van Staden JA, du Raan H. Accuracy of two dosimetry software programs for 177Lu radiopharmaceutical therapy using voxel-based patient-specific phantoms. Heliyon 2022; 8:e09830. [PMID: 35865988 PMCID: PMC9293745 DOI: 10.1016/j.heliyon.2022.e09830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/18/2022] [Accepted: 06/24/2022] [Indexed: 12/01/2022] Open
Abstract
Purpose Virtual dosimetry using voxel-based patient-specific phantoms and Monte Carlo (MC) simulations offer the advantage of having a gold standard against which absorbed doses may be benchmarked to establish the dosimetry accuracy. Furthermore, these reference values assist in investigating the accuracy of the absorbed dose methodologies from different software programs. Therefore, this study aimed to compare the accuracy of the absorbed doses computed using LundADose and OLINDA/EXM 1.0. Methods The accuracy was based on 177Lu-DOTATATE distributions of three voxel-based phantoms. SPECT projection images were simulated for 1, 24, 96, and 168 h post-administration and reconstructed with LundADose using 3D OS-EM reconstruction. Mono-exponential curves were fitted to the bio-kinetic data for the kidneys, liver, spleen, and tumours resulting in SPECT time-integrated activity (SPECT-TIA). The SPECT-TIA were used to compute mean absorbed doses using LundADose (LND-DSPECT) and OLINDA (OLINDA-DSPECT) for the organs. Pre-defined true activity images, were used to obtain TRUE-TIA and, together with full MC simulations, computed the true doses (MC-DTrue). The dosimetry accuracy was assessed by comparing LND-DSPECT and OLINDA-DSPECT to MC-DTrue. Results Overall, the results presented an overestimation of the mean absorbed dose by LND-DSPECT compared to the MC-DTrue with a dosimetry accuracy ≤6.6%. This was attributed to spill-out activity from the reconstructed LND-DSPECT, resulting in a higher dose contribution than the MC-DTrue. There was a general underestimation (<8.1%) of OLINDA-DSPECT compared to MC-DTrue attributed to the geometrical difference in shape between the voxel-based phantoms and the OLINDA models. Furthermore, OLINDA-DSPECT considers self-doses while MC-DTrue reflects self-doses plus cross-doses. Conclusion The better than 10% accuracy suggests that the mean dose values obtained with LND-DSPECT and OLINDA-DSPECT approximate the true values. The mean absorbed doses of the two software programs, and the gold standard were comparable. This work shall be of use for optimising 177Lu dosimetry for clinical applications.
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Affiliation(s)
- Keamogetswe Ramonaheng
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Johannes A van Staden
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Hanlie du Raan
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
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Morphis M, van Staden JA, du Raan H, Ljungberg M. Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification: a Monte Carlo study. EJNMMI Phys 2021; 8:61. [PMID: 34410539 PMCID: PMC8377107 DOI: 10.1186/s40658-021-00407-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/10/2021] [Indexed: 01/18/2023] Open
Abstract
Purpose The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well as image corrections incorporated in the iterative reconstruction process. These factors can be investigated and optimised using Monte Carlo simulations. This study aimed to evaluate SPECT quantification accuracy for 123I with both the low-energy high resolution (LEHR) and medium-energy (ME) collimators and 131I with the high-energy (HE) collimator. Methods Simulated SPECT projection images were reconstructed using the OS-EM iterative algorithm, which was optimised for the number of updates, with appropriate corrections for scatter, attenuation and collimator detector response (CDR), including septal scatter and penetration compensation. An appropriate calibration factor (CF) was determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere in water-filled (cold) cylindrical phantom, sphere in air and point-like source), investigated with different volume of interest (VOI) diameters. Recovery curves were constructed from recovery coefficients to correct for partial volume effects (PVEs). The quantitative method was evaluated for spheres in voxel-based digital cylindrical and patient phantoms. Results The optimal number of OS-EM updates was 60 for all isotope-collimator combinations. The CFpoint with a VOI diameter equal to the physical size plus a 3.0-cm margin was selected, for all isotope-collimator geometries. The spheres’ quantification errors in the voxel-based digital cylindrical and patient phantoms were less than 3.2% and 5.4%, respectively, for all isotope-collimator combinations. Conclusion The study showed that quantification errors of less than 6.0% could be attained, for all isotope-collimator combinations, if corrections for; scatter, attenuation, CDR (including septal scatter and penetration) and PVEs are performed. 123I LEHR and 123I ME quantification accuracies compared well when appropriate corrections for septal scatter and penetration were applied. This can be useful in departments that perform 123I studies and may not have access to ME collimators.
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Affiliation(s)
- Michaella Morphis
- Department of Medical Physics, Faculty of Health Sciences, University of the Free State, PO Box 339, Bloemfontein, 9300, South Africa.
| | - Johan 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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