Can SUV_max of ⁶⁸Ga-labeled PSMA Ligand and ¹⁸F-choline PET/CT Be Used to Predict the Radiation Dose in Prostate Cancer Patients?

Abstract

Gallium-68 (⁶⁸Ga)-PSMA and ¹⁸F-Choline are two radionuclides that have already shown high potential for the detection of prostate cancer. The comparison between these two radionuclides has several advantages in radiation protection. The aim of this prospective study was to identify which of these two radionuclides can help in predicting the equivalent dose using the maximum standard uptake value (SUV_max) of normal organs, the kidneys. Two groups of 40 patients (total n = 80) who underwent PET/CT using ⁶⁸Ga or ¹⁸F for diagnosis of prostate cancer between April 2018 and December 2018 at the American University of Beirut Medical Center were included. First, the dose rates were measured after 1 h of radionuclide uptake at 1 m distance with background of 0.015 μSv h⁻¹. Then, SUV_max for kidneys were determined from images obtained with PET/CT 1 h after injection of both radionuclides. The ratios of the equivalent doses to the SUV_max for kidneys were compared for both ⁶⁸Ga-PSMA and ¹⁸F-Choline. There is a positive moderate relationship between the SUV_max for kidneys and the ⁶⁸Ga dose rate after 1 h of injection at 1 m distance from the abdomen (p-value = 0.023 < 0.05). This relationship is statistically significant. However, there is a very low negative relationship between the SUV_max kidney and ¹⁸F dose rate after 1 h of injection at 1 m distance from the abdomen (p-value = 0.93 > 0.05). This relationship is not statistically significant. This leads to the suggestion that we can predict the equivalent dose due to ⁶⁸Ga by indicating the SUV_max from the PET/CT images.