Comparison of PET imaging with a 68Ga-labelled PSMA ligand versus 18F-choline PET/CT for the diagnosis of Prostate Cancer & Radioprotection for involved personnel

To compare the radiation dose delivered by Positron Emission Tomography (PET) due to Gallium-68 (⁶⁸Ga) and Fluorine-18(¹⁸F) performed for patients with prostate cancer. The greatest importance is to understand how the extremely strong sources in use can be managed effectively and doses to persons and unwanted doses to patients can be minimized. Thus, Radiation safety measurements are necessary to achieve the lowest exposure with reasonable cost and effort. We prospectively analyzed studies from 70 patients who underwent PET-CT using ⁶⁸Ga or ¹⁸F for diagnosis of prostate cancer between January 2017 and December 2017 at the American University of Beirut Medical Center. The dose rates were measured during the uptake period at patient body surface (abdomen) and at 1 m distance; these two points were measured after one hour of radionuclide uptake with background of 0.018 μSv. Then, the equivalent dose is calculated. Patients were selected consecutively until 70 cases were selected for each type of radionuclide. Data on 140 patients are presented. The maximum dose given to ⁶⁸Ga PSMA (prostate-specific membrane antigen) patients was 5.80 mCi while doses to ¹⁸F-Choline patients reached 8.87 mCi. Cronbach’s Alpha values for the correlation between the masses and the dose rates was 0.530.Thus there is a small positive relationship between the body masses and the dose rates. This relationship is not statistically significant. Furthermore, the equivalent dose for both radionuclides was constant whatever the mass of the patient is. There is no effect of the body mass with respect to the dose rate, and equivalent dose due to both radionuclides ⁶⁸Ga and ¹⁸F, which coincides with the principles of radiation protection. This leads to the suggestion that PET/CT equivalent doses with ⁶⁸Ga-labelled PSMA ligand or ¹⁸F-Choline are similar and safe in the diagnosis of prostate cancer. However, ⁶⁸Ga PSMA coincides more with radiation protection principles since the maximum equivalent dose due to ⁶⁸Ga after 1 h at 1 m was 17.71 μSv while the maximum equivalent dose due to ¹⁸F after 1 h at 1 m was 39.51 μSv.