Automated dose verification in specialized radiotherapy (ADViSR): a tool for Monte Carlo based dose verification

Abstract

Radiotherapy treatment planning can produce complex dose distributions which can be difficult to verify. An independent verification tool with Monte Carlo (MC) dose calculation can be a useful tool, however incorporating such a system for your specific clinic can be technically difficult. In this study an easy-to-use dosimetric plan verification system using a MC dose engine is developed. Software with a graphical user interface (GUI) was developed to automate the process for 3D conformal radiotherapy, intensity modulated radiation therapy or volumetric modulated arc therapy plans using MC dose calculation, called ADViSR. This includes various codes for extraction of DICOM information from the treatment planning system (TPS), MC dose calculation, combining segments and dose distribution comparison. Information is read from the plan-, structure-, dose- and CT DICOM files. Dose calculation is done using the EGSnrc MC code, DOSXYZnrc, which calculates dose to medium. Plan verification is done with DVH- and isodose comparisons, as well as 2D gamma analysis in 3rd party software. All components are incorporated into one software application running in Windows, with the option of using either Windows or Linux for the MC dose calculation. ADViSR was successfully developed and tested, and could verify treatment plans in a reasonable time. Some technical challenges that were addressed, included reading of DICOM information, generating input files, automation of MC dose calculation, combining dose files, optimal multi-core processor use, and history calculation for adequate statistics. The dose distribution comparison could provide adequately for troubleshooting of areas in dose calculation differing from that of the TPS. Optional inclusion of external contours like the treatment couch was also incorporated. Full 2D isodose comparison, beam-by-beam comparison, and DVHs were generated. The verification tool produces satisfactory analysis output with results presented in a familiar fashion. This simple-to-use tool can thus be used as secondary QA system, if a suitable linac source model is available.