article · Journal of Nuclear Medicine
This research evaluates a streamlined method for calculating radiation doses absorbed by the kidneys during lutetium-177 labelled prostate cancer therapy. Standard protocols typically require multiple imaging scans over several days to calculate accurate absorbed doses. By evaluating imaging data from sixty-three patients across five time points, researchers applied nonlinear mixed-effects modelling and population-based model selection to determine whether a single scan could provide comparable accuracy. Thirteen mathematical functions were tested against comprehensive patient datasets. The results established that a single SPECT/CT scan performed roughly two days after injection, combined with population modelling, yields absorbed dose estimates with low relative deviations and lower errors than existing single-point methods. This demonstrates that reliable renal dosimetry can be achieved from just one imaging session.
Assessing kidney radiation exposure is vital for the safety of prostate cancer patients undergoing radiopharmaceutical therapy. However, repeated hospital visits for multiple scans are burdensome for patients and strain clinical imaging resources. Proving that a single scan taken two days post-injection provides reliable dosing data can reduce hospital burdens and simplify treatment monitoring.
This analytical methodology could be integrated into commercial medical imaging and treatment-planning software used by clinical oncology departments and nuclear medicine specialists. Because the technique has been tested on a clinical cohort of sixty-three patients, it represents applied and tested research that requires software validation and regulatory approvals before clinical deployment into routine workflow tools.
AI-generated from the published abstract. Always read the original work before citing.
The aim of this study was to investigate the accuracy of single-time-point (STP) renal dosimetry imaging using SPECT/CT data, a nonlinear mixed-effects (NLME) model, and a population-based model selection (PBMS) in a large population for <sup>177</sup>Lu-labeled prostate-specific membrane antigen therapy. <b>Methods:</b> Biokinetic data (mean ± SD) of [<sup>177</sup>Lu]Lu-PSMA-617 in kidneys at time points 1 (1.8 ± 0.8 h), 2 (18.7 ± 0.9 h), 3 (42.6 ± 1.0 h), 4 (66.3 ± 0.9 h), and 5 (160.3 ± 24.2 h) after injection were obtained from 63 patients with metastatic castration-resistant prostate cancer using SPECT/CT. Thirteen functions were derived from various parameterizations of 1- to 5-exponential functions. The function's parameters were fitted in the NLME framework to the all-time-point (ATP) data. The PBMS NLME method was performed using the goodness-of-fit test and Akaike weight to select the best function fitting the data. The best function from ATP fitting was used to calculate the reference time-integrated activity and absorbed doses. In STP dosimetry, the parameters of a particular patient with STP data were fitted simultaneously to the STP data at different time points of that patient with ATP data of all other patients. The parameters from STP fitting were used to calculate the STP time-integrated activity and absorbed doses. Relative deviations (RDs) and root-mean-square errors (RMSEs) were used to analyze the accuracy of the calculated STP absorbed dose compared with the reference absorbed dose obtained from the best-fit ATP function. The performance of STP dosimetry using PBMS NLME modeling was compared with the Hänscheid and Madsen methods. <b>Results:</b> The function [Formula: see text] was selected as the best-fit ATP function, with an Akaike weight of 100%. For STP dosimetry, the STP measurement by SPECT/CT at time point 3 (42.6 ± 1.0 h) showed a relatively low mean RD of -4.4% ± 9.4% and median RD of -0.7%. Time point 3 had the lowest RMSE value compared with those at the other 4 time points. The RMSEs of the absorbed dose RDs for time points 1-5 were 23%, 16%, 10%, 20%, and 53%, respectively. The STP dosimetry using the PBMS NLME method outperformed the Hänscheid and Madsen methods for all investigated time points. <b>Conclusion:</b> Our results show that a single measurement of SPECT/CT at 2 d after injection might be used to calculate accurate kidney-absorbed doses using the NLME method and PBMS.
This page summarises published work. The authoritative version sits with the publisher.
DOI: 10.2967/jnumed.123.266268
Is something wrong with this record? Report it or request removal.
Discussion
Have you built on this work, tried to replicate it, or seen it applied in practice? Share what you know. Verified researchers and MARATTO™ domain experts can open a discussion, and any member can reply. Contributions are reviewed before they appear.
No discussion yet. Open the first thread.
New to MARATTO™? Create a free account.
