Efficient 169 Yb high‐dose‐rate brachytherapy source production using reactivation

Purpose To 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 cm from the source center as 10 Ci 192 Ir sources. Materials A theoretical framework for 169 Yb source activation and reactivation using thermal neutrons in a research reactor and 168 Yb‐Yb 2 O 3 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. Results Efficiency 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 × 10 14 n cm −2 s −1 , increasing the active source volume from 1 to 3 mm 3 decreased reactor‐days needed to generate one clinic‐year of 169 Yb from 256 days yr −1 to 59 days yr −1 , and 82%‐enriched precursor dropped from 80 mg yr −1 to 21 mg yr −1 . A resource reduction of 74%–77% is predicted for an active source volume increase from 1 to 3 mm 3 . Conclusions Dramatic cost savings are achievable in 169 Yb source production costs through reactivation if active sources larger than 1 mm 3 are used.