Quantitative calibration of Tb-161 SPECT/CT in view of personalised dosimetry assessment studies

McIntosh, L; Jackson, P; Emmerson, B; Buteau, JP; Alipour, R; Kong, G; Hofman, MS

Author(s): McIntosh, L; Jackson, P; Emmerson, B; Buteau, JP; Alipour, R; Kong, G; Hofman, MS;
Details: Publication Year 2024-02-19,Volume 11,Issue #1,Page 18
Journal Title: EJNMMI Physics
Publication Type: Research article
Abstract: BACKGROUND: Terbium-161 ((161)Tb)-based radionuclide therapy poses an alternative to current Lutetium-177 ((177)Lu) approaches with the additional benefit of secondary Auger and conversion electron emissions capable of delivering high doses of localised damage to micro-metastases including single cells. Quantitative single-photon emission computed tomography, paired with computed tomography (SPECT/CT), enables quantitative measurement from post-therapy imaging. In view of dosimetry extrapolations, a Tb-161 sensitivity SPECT/CT camera calibration was performed using a method previously validated for (177)Lu. METHODS: Serial imaging of a NEMA/IEC body phantom with Tb-161 was performed on SPECT/CT with low-energy high-resolution collimators employing a photopeak of 75 keV with a 20% width. Quantitative stability and recovery coefficients were investigated over a sequence of 19 scans with buffered (161)Tb solution at total phantom activity ranging from 70 to 4990 MBq. RESULTS: Sphere recovery coefficients were 0.60 ± 0.05, 0.52 ± 0.07, 0.45 ± 0.07, 0.39 ± 0.07, 0.28 ± 0.08, and 0.20 ± 0.08 for spheres 37, 28, 22, 17, 13, and 10mm, respectively, when considered across all activity and scan durations with dual-energy window scatter correction. Whole-field reconstructed sensitivity was calculated as 1.42E-5 counts per decay. Qualitatively, images exhibited no visual artefacts and were comparable to (177)Lu SPECT/CT. CONCLUSIONS: Quantitative SPECT/CT of (161)Tb is feasible over a range of activities enabling dosimetry analogous to (177)Lu whilst also producing suitable imaging for clinical review. This has been incorporated into a prospective trial of (161)Tb-PSMA for men with metastatic prostate cancer.
Publisher: Springer Nature
Keywords: Dosimetry; Qspect; Spect; Tb-161
Department(s): Cancer Imaging
Publisher's Version: https://doi.org/10.1186/s40658-024-00611-9
Open Access at Publisher's Site: https://doi.org/10.1186/s40658-024-00611-9
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2024-03-13 05:11:28

Last Modified: 2024-03-13 05:25:38