.Technisium (^99mTc) is one of the most widely used radioactive isotopes for diagnosis in nuclear medicine. In general, technisium is produced inside the so called ^99mTc generator which is usually made out of lead to shield relatively high energy radiation from ⁹⁹Mo and its daughter nuclide ^99mTc. In this paper, a GEANT4 simulation is carried out to test the safety of the ^99mTc generator, taking the Daiichi product with radioactivity of 500 mCi as an example. According to the domestic regulation on radiation safety, the dose at 10 cm and 100 cm away from the surface of shielding container should not exceed 2.0 mSv/h and 0.02 mSv/h, respectively. The simulated dose turned out to be less than the limit, satisfying the domestic regulation.

KeywordsGEANT4, ^99mTc Generator, Domestic regulations on radiation safety