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Tran-Gia J, Denis-Bacelar AM, Ferreira KM, Robinson AP, Calvert N, Fenwick AJ, Finocchiaro D, Fioroni F, Grassi E, Heetun W, Jewitt SJ, Kotzassarlidou M, Ljungberg M, McGowan DR, Scott N, Scuffham J, Gleisner KS, Tipping J, Wevrett J, Lassmann M. A multicentre and multi-national evaluation of the accuracy of quantitative Lu-177 SPECT/CT imaging performed within the MRTDosimetry project. EJNMMI Phys 2021; 8:55. [PMID: 34297218 PMCID: PMC8302709 DOI: 10.1186/s40658-021-00397-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/21/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Patient-specific dosimetry is required to ensure the safety of molecular radiotherapy and to predict response. Dosimetry involves several steps, the first of which is the determination of the activity of the radiopharmaceutical taken up by an organ/lesion over time. As uncertainties propagate along each of the subsequent steps (integration of the time-activity curve, absorbed dose calculation), establishing a reliable activity quantification is essential. The MRTDosimetry project was a European initiative to bring together expertise in metrology and nuclear medicine research, with one main goal of standardizing quantitative 177Lu SPECT/CT imaging based on a calibration protocol developed and tested in a multicentre inter-comparison. This study presents the setup and results of this comparison exercise. METHODS The inter-comparison included nine SPECT/CT systems. Each site performed a set of three measurements with the same setup (system, acquisition and reconstruction): (1) Determination of an image calibration for conversion from counts to activity concentration (large cylinder phantom), (2) determination of recovery coefficients for partial volume correction (IEC NEMA PET body phantom with sphere inserts), (3) validation of the established quantitative imaging setup using a 3D printed two-organ phantom (ICRP110-based kidney and spleen). In contrast to previous efforts, traceability of the activity measurement was required for each participant, and all participants were asked to calculate uncertainties for their SPECT-based activities. RESULTS Similar combinations of imaging system and reconstruction lead to similar image calibration factors. The activity ratio results of the anthropomorphic phantom validation demonstrate significant harmonization of quantitative imaging performance between the sites with all sites falling within one standard deviation of the mean values for all inserts. Activity recovery was underestimated for total kidney, spleen, and kidney cortex, while it was overestimated for the medulla. CONCLUSION This international comparison exercise demonstrates that harmonization of quantitative SPECT/CT is feasible when following very specific instructions of a dedicated calibration protocol, as developed within the MRTDosimetry project. While quantitative imaging performance demonstrates significant harmonization, an over- and underestimation of the activity recovery highlights the limitations of any partial volume correction in the presence of spill-in and spill-out between two adjacent volumes of interests.
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Affiliation(s)
- Johannes Tran-Gia
- Department of Nuclear Medicine, University of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany.
| | | | | | - Andrew P Robinson
- National Physical Laboratory, Teddington, UK
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
- The University of Manchester, Manchester, UK
| | - Nicholas Calvert
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
| | - Andrew J Fenwick
- National Physical Laboratory, Teddington, UK
- Cardiff University, Cardiff, UK
| | - 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
| | - Federica Fioroni
- 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
| | | | - Stephanie J Jewitt
- Radiation Physics and Protection, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Maria Kotzassarlidou
- Nuclear Medicine Department, "THEAGENIO" Anticancer Hospital, Thessaloniki, Greece
| | | | - Daniel R McGowan
- Radiation Physics and Protection, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Department of Oncology, University of Oxford, Oxford, UK
| | - Nathaniel Scott
- Radiation Physics and Protection, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - James Scuffham
- National Physical Laboratory, Teddington, UK
- Royal Surrey County Hospital, Guildford, UK
- Department of Physics, University of Surrey, Guildford, UK
| | | | - Jill Tipping
- Christie Medical Physics and Engineering (CMPE), The Christie NHS Foundation Trust, Manchester, UK
| | - Jill Wevrett
- National Physical Laboratory, Teddington, UK
- Royal Surrey County Hospital, Guildford, UK
- Department of Physics, University of Surrey, Guildford, UK
| | - Michael Lassmann
- Department of Nuclear Medicine, University of Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany
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