Radiation protection and dosimetry in PET and PET/CT

The use of Positron Emission Tomography (PET) and combination with Computed Tomography (PET/CT) has been growing rapidly over the past 5 years. An increasing demand for use of 18F-FDG PET in oncology has been the main reason for its growth. New generation hybrid systems which combine PET with multi-slice CT (MSCT) is getting increased its use for radiation treatment planning, cardiac, breast and brain imaging. The physical characteristics of positron emissions result in higher radiation risk for staff and growing use of PET/CT for screening purposes increase public radiation exposure. An understanding of the radiation protection and safety issues are very important to keep clinical and occupational exposure as low as reasonably achievable (ALARA). In this study we investigated radiation doses to the PET staff and strategies to lower occupational exposure. Radiation doses measured by thermoluminescent dosimeters (TLD) for staff working in PET. Effects of implementing radiation protection methods and training were evaluated. We found that the radiation exposure of PET technicians was higher than that technologist working conventional general nuclear medicine studies at the beginning. After implementing radiation protection measures and procedures, PET technicians doses significantly reduced. Since high energy photons (511 keV) of positron emitters, facility planning for radiation protection, including shielding, containments of sources, strict radiation protection measures should be implemented to working environment. Training of staff is also very important to keep the dose levels within the accepted occupational guidelines. (author)