Effective doses to staff and dose rates emitted from patients undergoing positron emission tomography utilizing 18F- Fluorodeoxglucose

Abstract

Introduction The purpose of this two--folded quantitative study was to determine the radiation doses received by staff during 2014 at the PET--department at St. Olavs Hospital in Trondheim, Norway. Although studies show that the doses received by staff performing such examinations are far beneath the limits set by regulation, there was a need to determine how much radiation the staff at this clinic actually was exposed to. We investigated in detail both dose rates emitted by 18 F from different parts of the body to the surroundings along with effective doses to staff during 2014. Method Part one - Dose rates from 20 patients undergoing FDG-PET/CT--scans were measured with dosimeter RadEye B20 (Thermo Scientific, USA) from five measuring points at three different stages of a standard whole body PET-scan utilizing 18 F-FDG. Part two - Effective doses to five radiographers and four bioengineers were registered daily during 2014. The effective dose measurements were done daily by the staff with personal dosimeter RadEye EPD MK2+ (Thermo Scientific, USA). The dosimeter was worn at chest level. The automatic injector Medrad Intego (Bayer, Germany) administrate the radioactive doses. Results Part one - Dose rates emitted from different parts of patients show significant differences. The highest dose rate was measured from the head and sternum of the patients. The knees emit the least dose rate of all body parts and was considerably lower from one meterdistance. Part two - The average effective doses were far below the recommended limits for occupational radiation. The total average effective dose per member of staff was 0.13 mSv in 2014 and the daily average dose was 4.91 μSv/day. Conclusion Part one - 18 F-FDG showed irregular distribution in the body, the lowest dose rates originated from the lower extremities and reflects the metabolism of glucose in the body at rest. Part two - We found significant differences between staff working with both CT and the radioisotope injection compared to the staff working solely with one of these tasks. Nevertheless, all effective- doses were safely within the guideline limits for occupational radiation.