Technetium-99m Radiopharmaceuticals: A Review on Basic and Applied Aspects

Abstract

Technetium-99m (99mTc) usage is increasing worldwide at a rate of 32% per annum. Enriched Uranium-235 is irradiated at nuclear reactor and subsequent process produces Molybdenum-99 (99Mo) whichdecays to 99mTc, and 99mTc converts to 99gTc. Organic molecules are used as 99mTc carriers, e.g., 99mTcmercaptoactyltriglycine.99mTc is excreted from body with feces and urine. It is estimated that 0.22%–38.41% of 99mTc remains in needles and rest is injected to the patient. Forty generators per week aresupplied to medical centers in Pakistan and 1.72 x105 Bq/y 99gTc is returned as radioactive waste. Everyused 99Mo/99mTc generator contains 99gTc ~ 83.3 Bq. 99gTc radioactive waste is increasing world-wide, asits global use is ~4.5×1014 Bq/week. No satisfactory method exists for 99gTc immobilization althoughincorporation of 99gTc into Fe(III) or Sn(IV) oxide matrix before glass immobilization is suggested. Thepresent review covers all aspect of 99mTc radiopharmaceutical life-cycle and suggests options for 99gTcradioactive waste management.