Ambient radiation levels in positron emission tomography/computed tomography (PET/CT) imaging center

To evaluate the level of ambient radiation in a PET/CT center. Previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. In none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. In the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed.