Investigation of image-based lesion and kidney dosimetry protocols for 177Lu-PSMA-I&T therapy with and without a late SPECT/CT acquisition

Background 177 Lu-PSMA therapy has been successfully used to prolong the survival of patients with metastatic castration-resistant prostate cancer. Patient-specific dosimetry based on serial quantitative SPECT/CT imaging can support the understanding of dose–effect relationships. However, multiple S...

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Veröffentlicht in:EJNMMI physics 2023-02, Vol.10 (1), p.11-11, Article 11
Hauptverfasser: Resch, Sandra, Takayama Fouladgar, Sarah, Zacherl, Mathias, Sheikh, Gabriel T., Liubchenko, Grigory, Rumiantcev, Mikhail, Unterrainer, Lena M., Wenter, Vera, Bartenstein, Peter, Ziegler, Sibylle I., Ilhan, Harun, Beyer, Leonie, Böning, Guido, Delker, Astrid
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Sprache:eng
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Zusammenfassung:Background 177 Lu-PSMA therapy has been successfully used to prolong the survival of patients with metastatic castration-resistant prostate cancer. Patient-specific dosimetry based on serial quantitative SPECT/CT imaging can support the understanding of dose–effect relationships. However, multiple SPECT/CT measurements can be challenging for patients, which motivates the investigation of efficient sampling schedules and their impact on dosimetry. In this study, different time samplings with respect to the number and timing of SPECT/CT acquisitions with and without a late measurement were investigated. Materials and methods In total, 43 lesions and 10 kidneys of 5 patients receiving 177 Lu-PSMA-I&T therapy were investigated. Whole-body SPECT/CT measurements were performed at 1, 2, 3 and 7 days post-injection. For both lesions (isocontour-based segmentation) and kidneys (CT-based segmentation), a reference model was employed including all four time points. To identify the best-matching fit function out of a pre-defined set of models, visual inspection, coefficients of variation and sum of squared errors were considered as goodness-of-fit criteria. Biologically effective doses (BEDs) calculated with different time samplings (days 1, 2, 3/1, 2, 7/1, 3, 7/2, 3, 7 and 1, 2/1, 3/1, 7) were compared to the reference. Results The best-fit function was found to be a mono-exponential model for lesions and a bi-exponential model with a population-based parameter and two free parameters for kidneys. The BEDs calculated with the time sampling 1, 3, 7 days showed the lowest deviations from the reference for lesions with 4 ± 5%. Without day 7, still 86% of all lesions showed deviations from the reference 
ISSN:2197-7364
2197-7364
DOI:10.1186/s40658-023-00529-8