Efficient 169 Yb high-dose-rate brachytherapy source production using reactivation.

Abstract

PURPOSE\nTo present and quantify the effectiveness of a method for the efficient production of 169 Yb high-dose-rate brachytherapy sources with 27 Ci activity upon clinical delivery, which have about the same dose rate in water at 1\xa0cm from the source center as 10 Ci 192 Ir sources.\n\n\nMATERIALS\nA theoretical framework for 169 Yb source activation and reactivation using thermal neutrons in a research reactor and 168 Yb-Yb2 O3 precursor is derived and benchmarked against published data. The model is dependent primarily on precursor 168 Yb enrichment percentage, active source volume of the active element, and average thermal neutron flux within the active source.\n\n\nRESULTS\nEfficiency gains in 169 Yb source production are achievable through reactivation, and the gains increase with active source volume. For an average thermal neutron flux within the active source of 1\xa0×\xa01014 \xa0n\xa0cm-2 \xa0s-1 , increasing the active source volume from 1 to 3\xa0mm3 decreased reactor-days needed to generate one clinic-year of 169 Yb from 256\xa0days\xa0yr-1 to 59\xa0days\xa0yr-1 , and 82%-enriched precursor dropped from 80\xa0mg\xa0yr-1 to 21\xa0mg\xa0yr-1 . A resource reduction of 74%-77% is predicted for an active source volume increase from 1 to 3\xa0mm3 .\n\n\nCONCLUSIONS\nDramatic cost savings are achievable in 169 Yb source production costs through reactivation if active sources larger than 1\xa0mm3 are used.