Brachyplancheck: An Independent Monte Carlo Dose Calculation Tool for Brachytherapy Using Egs_Brachy πŸ“

Author: Amy Tien Yee Chang, Chi Wai Cheung, Tin Lok Chiu, Chen-Yu Huang, Chi Wa Kong, Pei-Xiong Li, Pak Hang Nam, Bin Yang, Siu Ki Yu πŸ‘¨β€πŸ”¬

Affiliation: Comprehensive Oncology Centre, Hong Kong Sanatorium and Hospital, Medical Physics Department, Hong Kong Sanatorium and Hospital 🌍

Abstract:

Purpose: This study introduces BrachyPlanCheck, an independent Monte Carlo (MC)-based dose calculation tool for 192Ir brachytherapy retrospective study or algorithm commissioning.
Methods: BrachyPlanCheck, a custom-developed software tool, automatically generates egs_brachy input files with user-defined parameters via the graphical user interface (GUI) and extracts data from DICOM RT plan files exported from Elekta or Varian TPSs. Preliminary validation of this tool involved absolute dose calculation with a single Flexisource in water, and point doses were compared to the High Energy Brachytherapy Source Dosimetry Working Group (HEBDWG) report. Further validation was conducted using a multi-catheter breast brachytherapy test case provided by the joint AAPM/IROC Houston Registry of Brachytherapy Sources, where CT images and DICOM RT plan files were used for benchmark calculations with Flexisource instead of the MBDCA-WG generic 192Ir source, and DICOM dose was for comparison.
Results: BrachyPlanCheck-guided Monte Carlo (MC) dose calculation with a single source in water, using both tracklength and energy deposition methods, achieved absolute point dose agreements with HEBDWG benchmark within 1%. The gamma map of the breast test case under 2 mm/3% criteria showed excellent agreement with the Registry in clinically relevant regions, at distances greater than 1 cm from the source. For Intel Xeon E5-2696 v3 (18 Core 36 Threadsβ€”2.3 GHz), energy deposition method required over 22 hours to achieve a 96.2% passing rate with 1mm grid spacing, 2 mm/3% criteria, and 3.23% uncertainty for an 8x8x8 cmΒ³ region encompassing all dwell positions. However, tracklength method achieved a corresponding 99.5% passing rate with 1.20% uncertainty within 15 minutes for the same physical setting, illustrating it is efficient and accurate enough for cases with comparable tissue heterogeneity.
Conclusion: This tool is validated to facilitate MC-based dose calculation for brachytherapy retrospective study and commissioning dosimetry algorithms.

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