Purpose: To test the possibility that (radio)activity of non-pertechnetate nature is excreted into the gastrointestinal tract at bone scintigraphy. Material and Methods: The distribution of a bone-seeking radiopharmaceutical (99mTc-HDP) was studied in an experimental mouse system by dissecting different organs and assessing their activity with a gamma-counter. Results: A comparison of the activity of the submandibular glands, which are assumed to accumulate only pertechnetate, and the gastrointestinal tract showed that a significant fraction of the activity excreted into the gastrointestinal tract did not consist of pertechnetate. Part of the excretion took place in the stomach. It was not connected to a specific bone-seeking agent or 99Mo/99mTc generator. Nor did it increase with time between make-up and injection. The excretion of the non-pertechnetate acitvity was reduced by cimetidine and omeprazole. These gastric-secretion blocking drugs did not reduce excretion of pertechnetate or significantly affect the general distribution of the radiopharmaceutical. Conclusion: There is a significant excretion of non-pertechnetate activity in the gastrointestinal tract. Part of this may be caused by excretion of the undegraded radiopharmaceutical by the stomach mucosa.
Assessment of internal radiation exposure of nuclear medicine workers using whole body gamma counter
