Background: People who have been administrated radiopharmaceuticals could be a source of radiation to their relatives, medical nurses, and people who are in contact with them. The aim of this work was to estimate radiation dose received by nuclear medicine nurses. Materials and Methods: In this study, the dose rates at various distances of 5 – 100 cm from 70 patients, who were administered diagnostic amounts of 201Tl-Chloride and 99mTc-MIBI, were measured using an ionization chamber. For determination of external radiation dose to the nurses, three different time intervals were used for measurements. Results: The maximum values of external dose rates of 201Tl and 99mTc-MIBI were 11.2 µSv/h ±2.3 and 43.1µSv/h ±11.9 respectively, at 5cm from the patients. Significant exposure from patients after injection of 99mTc-MIBI was limited to the day of administration. Departure dose rate of 201Tl fell gradually; so, it became significant by 3 days after administration. Maximum and average absorbed dose of nuclear medicine staff from 201Tl, was 4.6 and 2.7 µSv/h, and for 99mTc-MIBI was 18.1 and 9.8 µSv/h in each scan. Conclusion: Significant exposure from the patients is limited to the few hours after administratio n, therefore patients should be recommended to urinate frequently before leaving the nuclear medicine department. Iran . J. Radiat. Res., 2004; 2 (2): 59-62 | 
