Fast SPECT acquisitions for single time-point dosimetry in 177Lu-PSMA for metastatic castration-resistant prostate cancer (mCRPC) patients
2
Issued Date
2025-12-01
Resource Type
ISSN
0378603X
eISSN
20904762
Scopus ID
2-s2.0-105018617528
Journal Title
Egyptian Journal of Radiology and Nuclear Medicine
Volume
56
Issue
1
Rights Holder(s)
SCOPUS
Bibliographic Citation
Egyptian Journal of Radiology and Nuclear Medicine Vol.56 No.1 (2025)
Suggested Citation
Chuamsaamarkkee K., Charoenphun P., Amnuaywattakorn S., Sakulpisuti C., Thamnirat K., Chamroonrat W. Fast SPECT acquisitions for single time-point dosimetry in 177Lu-PSMA for metastatic castration-resistant prostate cancer (mCRPC) patients. Egyptian Journal of Radiology and Nuclear Medicine Vol.56 No.1 (2025). doi:10.1186/s43055-025-01596-w Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/112663
Title
Fast SPECT acquisitions for single time-point dosimetry in 177Lu-PSMA for metastatic castration-resistant prostate cancer (mCRPC) patients
Author's Affiliation
Corresponding Author(s)
Other Contributor(s)
Abstract
Background: Implementing multiple time-point dosimetry in clinical settings faces limitations due to the imaging burden, increased workload, and additional costs. Single time-point (STP) dosimetry has emerged as a critical technique for calculating radiation doses efficiently. It has been suggested that 48 hours post-administration is preferred as the optimal imaging time for determining the absorbed doses in the kidneys and tumours for metastatic castration-resistant prostate cancer (mCRPC) patients treated with <sup>177</sup>Lu-PSMA. This study aimed to evaluate a phantom study for fast SPECT acquisition and its clinical integration using STP dosimetry in <sup>177</sup>Lu-PSMA mCRPC patients. Methods: Phantom and patient acquisitions were conducted using a dual-head SPECT/CT GE Discovery 870 DR equipped with an MEGP collimator. Fast SPECT acquisition was quantitatively optimised and calibrated at 5 seconds per frame over 60 frames per head, totalling 7 minutes per bed, using the Jaszczak phantom with known <sup>177</sup>Lu activity. Images were quantitatively reconstructed using OSEM iterative reconstruction (16 iterations, 9 subsets, 128x128 matrix size) with Hybrid Recon 3.0. Whole-body SPECT/CT scans of eight treatment cycles (five patients), administered 5.6 – 8.1 GBq (mean of 6.8 GBq) of <sup>177</sup>Lu-PSMA I&T, were imaged at approximately 48 hours post-administration. STP voxel-based dosimetry was performed to calculate the absorbed doses in the kidneys and tumours using the Hanscheid method in Hermes Dosimetry Software. Results: The mean absorbed doses in the kidneys were 2.04 ± 0.37 Gy, confirming that the total absorbed dose delivered to the kidneys remained within the acceptable limit of 23 Gy. The tumours (n=25) showed absorbed doses ranging from 0.98 – 16.05 Gy. Notably, different tumour sites exhibited significant variation in absorbed doses, with most of tumours receiving higher doses compared to the kidneys. Conclusions: STP dosimetry for <sup>177</sup>Lu-PSMA, coupled with fast SPECT acquisition, demonstrates significant potential for clinical application. The successful transition from phantom studies to clinical settings marks a pivotal development towards more efficient and less time-consuming dosimetric practices in nuclear medicine, potentially improving patient care by reducing the imaging and procedural burden.