1 Uptake and Dosimetry of Auger Emitting Diagnostic Radionuclides (in Particular Indium-111) in Human Male Germ

This paper concerns the uptake and dosimetry of Auger electron emitting radionuclides which are used during routine diagnostic nuclear medicine procedures, in human testes and spermatozoa (sperm). A computer model was developed to calculate the doses to sperm heads from cellular localisation of the Auger electron emitting radionuclides 99mTc, 111In, 123I and 201Tl. An assumption of ellipsoidal geometry was made to approximate the sperm head. S Factors were determined for differing sub-cellular localisations of radionuclide. The S-Factors determined were then combined with in-vitro data for quantification of radionuclide uptake for 99mTc pertechnetate, 111In chloride and 201Tl chloride, to estimate in-vivo doses to sperm heads following intravenous administration of radionuclide in typical diagnostic quantities. The uptake and resulting cellular radiation dose of 111In (from the chloride) was significantly larger than the other radionuclides in the chemical forms investigated. Further investigations were carried out to determine localisation of 111In on sperm. The results of these experiments indicate that the radiation dose to mature sperm following administration of 111In pharmaceuticals for diagnostic purposes might be large enough to result in DNA damage which is not expressed until after fertilisation of an oocyte. Consideration should therefore be given to providing some contraceptive advice following diagnostic administrations of this radionuclide