[National survey of radiation protection for workers in positron emission tomography facilities in Japan-1st report: occupational role assignment, radiation exposure to medical workers].

We have investigated the role assignment and radiation exposure of medical workers (including receptionists) in PET (positron emission tomography) facilities in Japan using a questionnaire. The survey period was from October 1st to November 15th 2006. The response rate for the questionnaire was 60.0% (72/120 facilities). Nurses were engaged in the intravenous administration of radioactive FDG in 66.9% of PET facilities. In 89.5% of PET facilities, radiological technologists mainly performed the PET examination. The average radiation exposure to medical workers was 0.13 mSv/month (n: 709, S.D.: 0.16) as the effective dose. It was shown that radiation exposure was significantly different depending on the occupation and content of work (p<0.01). The radiation exposure of cyclotron operators and radiological technologists was higher than that of the other occupations (p<0.01). The highest radiation dose to one worker per a PET facility was 0.60 [mSv month(-1)], which was 4.6 times higher than the average dose of 0.13 [mSv month(-1)]. We have clarified the actual conditions of radiation protection in PET facilities in Japan for the first time.