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

Purpose: To present and quantify the effectiveness of a method for the efficient production of Yb high-dose-rate brachytherapy sources with 27 Ci activity upon clinical delivery, which have about the same dose rate in water at 1 cm from the source center as 10 Ci Ir sources.

Materials: A theoretical framework for Yb source activation and reactivation using thermal neutrons in a research reactor and Yb-Yb O precursor is derived and benchmarked against published data. The model is dependent primarily on precursor Yb enrichment percentage, active source volume of the active element, and average thermal neutron flux within the active source.

Results: Efficiency gains in 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 × 10  n cm  s , increasing the active source volume from 1 to 3 mm decreased reactor-days needed to generate one clinic-year of Yb from 256 days yr to 59 days yr , and 82%-enriched precursor dropped from 80 mg yr to 21 mg yr . A resource reduction of 74%-77% is predicted for an active source volume increase from 1 to 3 mm .

Conclusions: Dramatic cost savings are achievable in Yb source production costs through reactivation if active sources larger than 1 mm are used.