egs_brachy

egs_brachy computes TG-43 dosimetry parameters for brachytherapy sources to update and expand the CLRP TG-43 database, focusing on low-energy (≤50 keV) photon-emitting low-dose-rate (LDR) sources and supporting photon and electron source models using the egs++ framework and EGSnrc.

Key Features:

• Comprehensive dosimetric parameters: Calculates dose-rate constants, radial dose functions with functional fitting parameters, 1D and 2D anisotropy functions, along-away dose-rate tables, primary–scatter separation dose tables for selected sources, and mean photon energies at the source surface.
• Source models: Includes detailed and fully described source models for multiple LDR seeds, explicitly including ^103Pd, ^125I, and ^131Cs and extending the CLRP database coverage to 40 LDR sources.
• Geometry recoding: Systematically recodes source geometries using the egs++ geometry package and its extensions to ensure geometric precision in calculations.
• Air-kerma strength calculation: Computes air-kerma strength per history for models of NIST's Wide-Angle Free-Air chamber (WAFAC) and for a point detector at 10 cm on the transverse axis.
• Scatter water phantom simulations: Uses full-scatter water phantoms in cylindrical coordinates with varying voxel resolutions to support spatially resolved dose calculations.
• Statistical uncertainties: Incorporates statistical uncertainty estimates related to source-volume corrections for phantom voxels that overlap brachytherapy sources.
• Validation by comparison: Validates results through comparisons with CLRPv1 and other existing literature sources.

Scientific Applications:

• Medical physics: Provides updated TG-43 parameters and source models for use in medical physics research and dosimetric evaluation.
• Dosimetry: Supplies dose-rate constants, radial functions, anisotropy functions, and along-away tables for accurate brachytherapy dosimetry.
• Brachytherapy treatment planning: Supports treatment-planning evaluations by providing detailed source models, air-kerma strength calculations, and spatial dose distributions.
• Research and database development: Enables expansion and benchmarking of the CLRP TG-43 dosimetry database for LDR sources.

Methodology:

Performs calculations using the EGSnrc application within the egs++ framework, systematically recodes source geometries with the egs++ geometry package, simulates full-scatter water phantoms in cylindrical coordinates with varied voxel resolutions, computes TG-43 parameters and air-kerma strength per history (WAFAC and 10 cm point detector), generates primary–scatter separation dose tables for selected sources, applies source-volume correction statistical uncertainty calculations, and updates the CLRP TG-43 database for 40 LDR sources.