The Pharmaceutics and Compounding Laboratory
Radiopharmaceuticals:
TC-99M Sulfur Colloid

Radiation Safety

Tc-99m decays by isomeric transition with the emission of 140 keV gamma rays. No primary particulate radiation, such as beta particles is emitted. Since gamma rays readily penetrate matter, personal protection from Tc-99m sources is necessary. The 3 primary modes of protection are: (1) minimizing time of exposure, (2) maximizing the distance from the source, and (3) use of shielding material such as lead. The potential hazard from a radioactive source increases directly with the amount of radioactivity present. The maximum quantity of Tc-99m activity that you will be working with in this laboratory (about 20 µCi) is 2 to 3 thousand times less than the usual amount used to prepare 99mTc-SC and will not present a significant biological hazard to you. Nevertheless, you will be required to use standard safety precautions as one would routinely use in handling large amounts of radioactivity. That is, lead shields and vial pigs will be used, disposable gloves will be worn, adsorbent plastic backed paper will cover the work bench and radiation monitors (Geiger-Mueller meters) will be available. All solutions will be marked with radioactive labels stating the radionuclide, amount, time and date. You will be required to clean your work space and monitor its surface for radioactive contamination before leaving. Special receptacles will be provided and used for any radioactive waste.