[Radiation Exposure in the Environment of Patients After Application of Radiopharmaceuticals. Part 1: Diagnostic Procedures]

Aim: After application of radiopharmaceuticals the patient becomes a radioactive source which leads to radiation exposure in the proximity. The photon dose rates after administration of different radiopharmaceuticals used in diagnostic nuclear medicine were measured at several distances and different time intervals. These data are of importance for estimating the exposure of technologists and members of the public.

Patients, Method: In this study dose rates were measured for 67 patients after application of the following radiopharmaceuticals: 99mTc-HDP as well as 99mTc-pertechnetate, 18F-fluorodeoxyglucose, 111In-Octreotid and Zevalin and 123I-mIBG in addition to 123I-NaI. The dose rates were measured immediately following application at six different distances to the patient. After two hours the measurements were repeated and--whenever possible--after 24 hours and seven days.

Results: Immediately following application the highest dose rates were below 1 mSv/h: with a maximum at 780 microSv/h for 18F (370 MBq), 250 microSv/h for 99mTc (700 MBq), 150 microSv/h for 111In (185 MBq) and 132 microSv/h for 123I (370 MBq). At a distance of 0.5 m the values decrease significantly by an order of magnitude. Two hours after application the values are diminished to 1/3 (99mTc, 18F), to nearly (1/2) (123I) but remain in the same order of magnitude for the longer-lived 111In radiopharmaceuticals.

Conclusion: For greater distances the doses remain below the limits outlined in the national legislation.