Abstract
Radiation surveys of technetium-99m (99mTc) MDP bone scan patients were performed at 5 min, 4 hr, and 24 hr post administration. The measurement distances chosen were surface, 1 ft (30.5 cm) and 3 ft (100 cm) resulting in variable radiation exposures as a function of time and bony pathology. As expected the highest exposures were immediately after tracer administration. Thereafter, urinary excretion and biologic redistribution dominated, resulting in significantly lower exposures at 4 hr and 24 hr for the negative bone scan group. Patients with bony metastases retained more of the injected dose than those with negative scintigrams. This was reflected with the 4 hr and 24 hr surveys.