Dosimetric characterization of a novel 90Y source for use in the conformal superficial brachytherapy device

• Published in: Physica medica 2020-04, Vol.72, p.52-59
• Main Authors: Rogers, Brent, Lawrence, Jessica, Chmura, Jennifer, Ehler, Eric, Ferreira, Clara
• Format: Article
• Language: English
• Subjects: Brachytherapy; Dosimetry; Monte Carlo; Superficial Brachytherapy; Yttrium-90
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2020.03.002

•A novel yttrium-90 Superficial Brachytherapy source has been characterized.•Yttrium-90 is a highly conforming source, ideal for the treatment of superficial lesions.•The Conformal Superficial Brachytherapy applicator uses multiple brachytherapy sources.•The Conformal Superficial Brachytherapy applicator was designed to treat non-melanoma skin cancers. To characterize the dose distribution in water of a novel beta-emitting brachytherapy source for use in a Conformal Superficial Brachytherapy (CSBT) device. Yttrium-90 (90Y) sources were designed for use with a uniquely designed CSBT device. Depth dose and planar dose measurements were performed for bare sources and sources housed within a 3D printed source holder. Monte Carlo simulated dose rate distributions were compared to film-based measurements. Gamma analysis was performed to compare simulated and measured dose rates from seven 90Y sources placed simultaneously using the CSBT device. The film-based maximum measured surface dose rate for a bare source in contact with the surface was 3.35 × 10–7 cGy s−1 Bq−1. When placed in the source holder, the maximum measured dose rate was 1.41 × 10–7 cGy s−1 Bq−1. The Monte Carlo simulated depth dose rates were within 10% or 0.02 cm of the measured dose rates for each depth of measurement. The maximum film surface dose rate measured using a seven-source configuration within the CSBT device was 1.78 × 10−7 cGy s−1 Bq−1. Measured and simulated dose rate distribution of the seven-source configuration were compared by gamma analysis and yielded a passing rate of 94.08%. The gamma criteria were 3% for dose-difference and 0.07056 cm for distance-to-agreement. The estimated measured dose rate uncertainty was 5.34%. 90Y is a unique source that can be optimally designed for a customized CSBT device. The rapid dose falloff provided a high dose gradient, ideal for treatment of superficial lesions. The dose rate uncertainty of the 90Y-based CSBT device was within acceptable brachytherapy standards and warrants further investigation.