Determination of 99 Mo Contamination in a Nuclear Medicine Patient Submitted to a Diagnostic Procedure with 99 m Tc

Tc is a radionuclide widely used for imaging diagnosis in nuclear medicine. In Brazil it is obtained by elution from 99 Mo-Tc generators supplied by the Nuclear Energy Research Institute (IPEN). The elution is carried out in radiopharmacy laboratories located in hospitals and clinics. Depending of the quality of the generator and conditions of use during the elution process, Mo can be extracted from the column of the generator, becoming a radionuclidic impurity of the eluate used for the obtention of the radiopharmaceutical to be administered to the patient. Mo emits high-energy photons and beta particles and its presence degrades the quality of the image and unnecessarily increases the radiation dose delivered to the patient. An in-vivo measurement technique was developed to verify the occurrence of internal contamination by Mo in nuclear medicine patients. Direct measurements were made in a volunteer who underwent myocardial scintigraphy with Tc-sestamibi. The results indicated the presence of internal contamination of the patien by Mot. The activity was tracked for several days, and an assessment of the radiation dose from the contaminant Mo was made.