- Current, past or anticipated exposure to radiation in the workplace, or participation in nuclear medicine procedures, including research protocols (In case of previous exposure to activity due to research studies, subjects will be eligible if all conditions listed below are fulfilled: 1) The injected dose and dosimetry of the radiotracer are known; 2) Except for research studies, the subject has not been exposed to radiation (workplace and medical); 3) Adding prior exposure to the exposure due to the study will result in a yearly cumulative exposure lower than the FDA limit for research studies