DOSIMETRIC OPTIMIZATION OF POSTPRODUCTION NEUTRON-ACTIVATED ERBIUM-170-OXIDE-ENRICHED PANCREATIN

The feasibility of postproduction neutron activation of an enteric-coa ted pancreatic enzyme preparation for in vivo gastric emptying studies has been investigated. Methods: During production of this multicompon ent preparation, small amounts of Er-170-enriched erbium oxide, suitab le for neutron activation, were added. Results: Postproduction neutron irradiation of the labeled preparation resulted in short-lived (7.5 h r) gamma-emitting Er-171. Various radiocontaminants, however, are prod uced also. Because of variations in activation yields, half-lives, dec ay schemes and radiotoxicities, both major and trace constituents were considered for optimization of both dosimetry and the diagnostic meas urement. Conditions were optimized for the best ratio of the committed dose equivalent due to Er-171 to the total committed dose equivalent. Conclusion: The results show that postproduction neutron activation o f a Er-170-enriched multicomponent preparation can be performed safely within the guidelines set by the WHO for experiments in humans involv ing radioactive materials.