Comparative dosimetric evaluation of 68Ga-PSMA and 18F-Choline PET/CT imaging in prostate cancer: implications for...

Comparative patient dosimetry for diagnostic PET/CT can guide radiation-safety procedures and tracer selection in prostate cancer. We compared [^68Ga]Ga-PSMA-11 and ^18F-choline PET/CT and examined whether kidney SUVmax predicts patient effective dose (ED).

Prospective single-center study of consecutive men undergoing clinically indicated PET/CT: 70 ^68Ga-PSMA-11 and 70 ^18F-choline examinations (Jan 2022-Dec 2023). Dose-rate measurements were recorded at the injection site and at 1 m, immediately post-injection and at 1 h. ED was derived from literature-based tracer coefficients (h_PSMA-11 = 0.0169 mSv/MBq; h_F-choline = 0.0173 mSv/MBq). Kidney SUVmax was extracted in a subset (n = 40 per tracer) to test ED-SUVmax associations (Pearson's r).

Mean surface dose rate was higher with ^68Ga-PSMA vs. ^18F-choline (4.9 ± 0.8 vs. 4.5 ± 0.7 µSv·h^{- 1}; p = 0.004). At 1 m, the difference persisted but was smaller (1.9 ± 0.3 vs. 1.7 ± 0.3 µSv·h^{- 1}; p = 0.02). Effective dose (ED) was similar between tracers (21.3 ± 3.6 vs. 20.7 ± 3.4 mSv; p = 0.28). SUVmax correlated with ED for ^68Ga-PSMA (r = 0.71; p < 0.001), but not for ^18F-choline (r = -0.12; p = 0.46).

^68Ga-PSMA yields slightly higher dose-rate readings than ^18F-choline, while overall ED is comparable. These exploratory correlations do not support SUVmax as a stand-alone safety surrogate or outcome predictor.