[Evaluation of additional absorbed radiation dose from radioactive impurities in radiopharmaceuticals]

The additional absorbed radiation doses to total body from radioactive impurities in radiopharmaceuticals were estimated for a total of 10 samples (i.e., 99mTc generator eluates, 99mTc solutions, 67Ga, 81mKr generator eluates, 111In, 123I, 201Tl, 75Se, 197Hg, 198Au) selected from commonly used radiopharmaceuticals. The radioactive impurities in radiopharmaceuticals used in this estimation were previously identified. The radiation doses were calculated according to the MIRD procedures, assuming each radionuclide to be uniformly distributed throughout the body. In the case of the cyclotron-produced radioisotopes and 198Au, the additional total body absorbed doses from impurities were found to be rather high: 280% for 123I, 55% for 81mKr, 5% for 198Au, 4% for 111In and 2% for 201Tl. The absorbed doses due to impurities in the other radioisotopes were less than 1%.