Commissioning Validation of a Brachytherapy Treatment Planning System with EGSnrc Monte Carlo Code and EBT3 GAFChromic Film.

AIMS

Most brachytherapy treatment planning system (TPS) commissioning requires data input based on the American Association of Physicists in Medicine Task Group-43 formalism. The commissioning accuracy is very important for dose calculation. The aim of this study is the implementation of a brachytherapy TPS into a clinical environment and check the TPS calculated dose accuracy.

SUBJECTS AND METHODS

After introducing data of the different catheters (CIS Bio International, Saclay, France), composed of several Cesium-137 Eckert and Ziegler BEBIG CSM-11 radioactive sources; for XiO (CMS, St. Louis) brachytherapy TPS, the TPS dose calculation accuracy was investigated by comparing between the TPS calculated dose distribution (DD) for all the catheters with (1) the measuring DD using EBT3 GAFChromic film and (2) calculating DD by egs_brachy (Electron Gamma Shower, National Research Council of Canada) Monte Carlo simulation. The phantom used for this study consists of six PTW slabs 30 cm × 30 cm × 1 cm of polymethyl methacrylate with a Delouche MEDpro applicator on the top. The TPS DD was calculated on the computed tomography scan of this phantom.

STATISTICAL ANALYSIS USED

PTW VeriSoft version 6.0.1.7 (PTW-Freiburg, Germany) software was used for analyzing scanned films and to perform the comparison based on the gamma index distribution.

RESULTS

For each catheter, the gamma index distribution showed agreement >95% of all pixels in both verification methods, with gamma ≤1.

CONCLUSIONS

We confirm the commissioning accuracy and that the TPS can be used for clinical purposes.