EFFECTS IN THE TESTES AFTER SPECT MYOCARDIAL PERFUSION WITH TL-201 ORTC-99M HEXAMIBI

Thallium-202 with a half-life of 73 hours, decays by electron capture and as a consequence emits numerous Auger electrons. When it localises in the cell nucleus it causes enhanced biological effects. Technetium -99m with a half-life of 6 hours, radiates gamma rays and the side eff ects are not as significant TI-202 and Tc-99m labelled with SESTAMIBI are used for the SPECT perfusion image of the heart In this study the tissue of interest are the testes which, after irradiation, can develo p stochastic effects: both somatic (cancel.) and hereditary. The activ ities of the radiopharmaceuticals used in common; practice (30 mCi of Tc-99m and 3 mCi of Tl-201) cause different probabilities for the indu ction of stochastic effects in the testes. The probabilities are about 30 times higher for Tl-201 than for Tc-99m. These results, in combina tion with the fact that the higher activity of Tc-99m yields better im ages within shorter time, must make the clinician carefully assess the choice of the radiopharmaceutical to be used for the studies of the h eart especially for patients of reproductive age.