title: A tool to include gamma analysis software into a quality assurance program.
abstract: OBJECTIVE
  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%/3mm and over 2% at 1%/1mm was measured between software and software versions with analysis of appropriately sampled images.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, UK. Electronic address: christina.agnew@belfasttrust.hscni.net.
authors.forename: Christina E
authors.initials: CE
authors.lastname: Agnew
authors.affiliation: Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, UK; Centre for Cancer Research, Queens University Belfast, UK.
authors.forename: Conor K
authors.initials: CK
authors.lastname: McGarry
mesh_terms: D000465:Algorithms; D005720:Gamma Rays; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012984:Software
keywords: Gamma analysis; IMRT; Quality control; VMAT