Investigating Acuros Brachy Vision dose calculation accuracy in various materials relevant to high dose rate brachytherapy using GATE. (2020)
Type of ContentTheses / Dissertations
Thesis DisciplineMedical Physics
Degree NameMaster of Science
PublisherUniversity of Canterbury
AuthorsTe Ruruku, Tyroneshow all
The AAPM Task Group No.43 has provided a standardised dose calculation methodology that is now the international benchmark for all brachytherapy dosimetry publications and treatment planning systems (TPS). However, limitations of this methodology has seen the development of model-based dose calculation algorithms. In 2009, Varian Medical Systems released Acuros BrachyVision (ABV) which calculates doses by explicitly solving the Linear Boltzmann Transport Equation. This study aims to investigate the accuracy of ABV dose calculations in various materials relevant to high dose rate (HDR) brachytherapy with an Iridium-192 GammaMed Plus source. This study is comprised of two main parts:
1. Construct and validate a monte carlo model of an Iridium-192 GammaMed Plus HDR source. Energy spectrum and TG43 parameters were simulated and compared to results collated in studies conducted by Taylor and Rogers  and Ballester et al. . 2. Calculate and compare doses calculated within a series of phantoms using both GATE and ABV. Comparison techniques used were; (i) point-to-point profile comparison; (ii) 1D gamma analysis; and (iii) correlation and statistical significance analysis.
Source validation results yielded good agreement with published data. Spectrum and TG43 comparisons showed no major differences, with TG43 comparisons agreeing within 1%. Point-to-point comparisons showed large differences between GATE and ABV near the source and in low density materials. 1D gamma analysis pass criteria of 2%/2 mm and 2%/1 mm produced pass rates ranging between 59% - 100% and 45% - 100% respectively. Correlation analysis Showed statistically there is no significant difference between doses calculated in ABV and GATE. A critical analysis of this study’s results suggest that ABV is unable to accurately calculate doses in low density materials. Furthermore, spatial distribution of dose near the source is within 2 mm.