AbstractID: 9043 Title: Aspects of PET Radiation Safety: the Good and the Bad
The number of positron emission tomography (PET) scans performed has undergone a dramatic rise in recent years, with many
hospitals acquiring dedicated PET scanners. Over 500 scans were performed with our institution’s combined PET/CT scanner during
its first six months of operation, and much higher study volumes are not uncommon. As with any imaging modality, PET presents
unique radiation safety concerns. Specifically, the patient must sit for approximately one hour between injection of the
radiopharmaceutical (FDG) and the actual scan. The 511 keV gamma rays are emitted by the patient in pairs and have a high halfvalue layer in lead, so proper shielding for the patient waiting rooms can be both heavy and expensive. In the first part of this study,
the radiation exposure from 50 patients was measured during the waiting period at two positions: 1 meter lateral to the patient and 2
meters anterior to patient. Compared with an in vitro control, a significant decrease in exposure (greater than 40%) was observed due
to attenuation within the patients. Using these more realistic exposure estimates when designing shielding for PET waiting rooms can
reduce both cost and weight. The second part of this study tracked the daily dose received by the PET technologists. The preparation
for a scan requires considerable technologist/patient interaction both during and following FDG administration. Despite shielding and
standard precautionary measures, the technologists’ dose was considerably higher than expected. This study points toward the need for
a more innovative approach to radiation protection for PET technologists.