A tool to include gamma analysis software into a quality assurance program

Purpose: To provide a tool to enable gamma analysis software algorithms to be included in a quality assurance (QA) program. Methods: Four image sets were created comprising two geometric images to independently test the distance to agreement (DTA) and dose difference (DD) elements of the gamma algorithm, a clinical step and shoot IMRT field and a clinical VMAT arc. The images were analysed using global and local gamma analysis with 2 in-house and 8 commercially available software encompassing 15 software versions. The effect of image resolution on gamma pass rates was also investigated. Results: All but one software accurately calculated the gamma passing rate for the geometric images. Variation in global gamma passing rates of 1% at 3%/3 mm and over 2% at 1%/1 mm was measured between software and software versions with analysis of appropriately sampled images. Conclusion: This study provides a suite of test images and the gamma pass rates achieved for a selection of commercially available software. This image suite will enable validation of gamma analysis software within a QA program and provide a frame of reference by which to compare results reported in the literature from various manufacturers and software versions. (C) 2015 Published by Elsevier Ireland Ltd.