Doing tests on Elekta linacs

This page contains some notes about doing interesting tests on Elekta linacs with pyQAserver. The notes deal mostly with aspects of the linac that are important for radiosurgery: focal spot position, XVI calibration, MLC calibration, couch axis calibration.

Warning

The content on this site is based on my personal experience. It was not reviewed or approved by anybody. The notes are provided “as is”, and use them “at your own risk”. So, beware. And read this disclaimer before you read further: License and disclaimer.

Last change: Jul 23, 2026.

• Getting started
  • Configuring iView and XVI workstations
  • Using iCom CAT to send plans to Service
• Winston-Lutz test
  • What are the three main results of the WL test?
  • Influence of dose rate on focal spot position
  • End-to-end WL test
  • Should I adjust the 6 FFF beam symmetry or leave it?
  • Non-end-to-end WL test
  • Effect of focal spot position on WL test
  • Couch axis of rotation and WL test
  • How good can it get?
  • Are four gantry angles good enough for the WL test?
• XVI flexmap testing and calibration
  • What is a flexmap?
  • Why are flexmaps needed?
  • Catching flexmap errors
  • Effect of faulty flexmaps on geometric scaling
  • Fixing flexmaps
  • Detector skewness
• Focal spot position, collimator asymmetry
  • 6 MV focal spot position and adjustment
  • Multiple radiation isocenters
  • Asymmetry and Agility workflows
• Picket fence
• License and disclaimer