Radiation exposure of the staff at the therapeutic and diagnostic nuclear medicine department. A single centre six years' retrospective study.

AIM

To assess a radiation exposure and the quality of radiation protection concerning a nuclear medicine staff at our department as a six-year retrospective study. Therapeutic radionuclides such as (131)I, (153)Sm, (186)Re, (32)P, (90)Y and diagnostic ones as a (99m)Tc, (201)Tl, (67)Ga, (111)In were used. MATERIAL, METHOD: The effective dose was evaluated in the period of 2001-2006 for nuclear medicine physicians (n = 5), technologists (n = 9) and radiopharmacists (n = 2). A personnel film dosimeter and thermoluminescent ring dosimeter for measuring (1-month periods) the personal dose equivalent Hp(10) and Hp(0,07) were used by nuclear medicine workers. The wearing of dosimeters was obligatory within the framework of a nationwide service for personal dosimetry. The total administered activity of all radionuclides during these six years at our department was 17,779 GBq ((99m)Tc 14 708 GBq, (131)I 2490 GBq, others 581 GBq). The administered activity of (99m)Tc was similar, but the administered activity of (131)I in 2006 increased by 200%, as compared with the year 2001.

RESULTS

The mean and one standard deviation (SD) of the personal annual effective dose (mSv) for nuclear medicine physicians was 1.9 +/- 0.6, 1.8 +/- 0.8, 1.2 +/- 0.8, 1.4 +/- 0.8, 1.3 +/- 0.6, 0.8 +/- 0.4 and for nuclear medicine technologists was 1.9 +/- 0.8, 1.7 +/- 1.4, 1.0 +/- 1.0, 1.1 +/- 1.2, 0.9 +/- 0.4 and 0.7 +/- 0.2 in 2001, 2002, 2003, 2004, 2005 and 2006, respectively. The mean (n = 2, estimate of SD makes little sense) of the personal annual effective dose (mSv) for radiopharmacists was 3.2, 1.8, 0.6, 1.3, 0.6 and 0.3. Although the administered activity of (131)I increased, the mean personal effective dose per year decreased during the six years.

CONCLUSION

In all three professional groups of nuclear medicine workers a decreasing radiation exposure was found, although the administered activity of (131)I increased during this six-year period. Our observations suggest successful radiation protection measures at our department.