Purpose: 11C-Labeled 2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane (11C-CFT) is a commonly used positron emission tomography (PET) tracer for dopamine transporters imaging. The present study estimated human radiation absorbed doses of 11C-CFT based on whole-body PET imaging in healthy subjects.
Methods: Whole-body PET was performed on 6 subjects after injection of 472.06 ± 116.47 MBq of 11C-CFT. 7 Frames were acquired for about 70 min in 7 segments of the body. Regions of interest were drawn on PET images of source organs. Residence time was calculated as the area under the time-activity curve. Radiation dosimetry was calculated from organ residence time using the medical internal radiation dosimetry (MIDR) method.
Results: The organs with the highest radiation-absorbed doses were the urinary bladder, followed the spleen, pancreas, kidneys, and stomach. The dose-limiting critical organ was the urinary bladder. The effective dose was 8.89E−03 mSv/MBq (22.9 mrem/mCi). Biexponential fitting of mean bladder activity demonstrated that 18% of activity was excreted via the urine.
Conclusions: The potential radiation risks of 11C-CFT associated with in this study are well within accepted limits. 11C-CFT demonstrates a favorable radiation dose profile in humans and allows multiple PET examinations on the same subject per year.