Abstract
To present the results of a local diagnostic reference level (LDRL) audit for 50th fluorodeoxyglucose (18F-FDG), Gallium-68 etraazacyclododecane tetraacetic acid–octreotide (68Ga-DOTATATE), and 68Ga prostate-specific membrane antigen (68Ga-PSMA) whole-body and 18F-FDG brain imaging positron emission tomography/computed tomography (PET/CT) scans.
Patients who underwent whole-body 18F-FDG (158 patients), brain 18F-FDG (50 patients), 68Ga-PSMA (20 patients) and 68Ga-DOTATATE (24 patients) PET/CT examinations at Prince Sultan Military Hospital in Riyadh, Saudi Arabia were selected for this study. For these patients, related data were collected that included demographic information, radiation dose quantities, PET/CT protocols and scanner specifications. The LDRL value of the radiation dose for each type of scan was determined based on the calculation of the 50th percentile.
The reported 50th percentile for 18F-FDG for whole-body (307.10 MBq) and brain (280.46 MBq) scans were in good agreement with reported national DRLs (NDRLs). The value of the 50th percentile related to 18F-FDG brain imaging was higher than the 50th percentile identified in the literature. The derived LDRLs for 68Ga-DOTATATE (172.05 MBq) and 68G-PSMA (183.89 MBq) were lower than those in the published Administration of Radioactive Substances Advisory Committee (ARSAC) United Kingdom report of 250 MBq and 200 MBq, respectively. The determined CT dose index volume (CTDIvol) and dose–length product (DLP) for diagnostic CT components associated with whole-body 18F-FDG PET/CT examinations were higher than the published Japanese NDRL and lower than the New Zealand NDRL. However, the derived 50th percentile of 68Ga PET/CT scans was higher than the CT radiation dose associated with a whole-body 18F-FDG PET/CT scan.
This study derived the LDRL for four common PET/CT procedures. There is room for lowering the 18F-FDG administered activity with good image quality, despite good agreement with previously published data on NDRLs. It is preferable to optimize the diagnostic CT component associated with all whole-body scans without compromising diagnostic CT image quality.