Characterization of the on-board megavoltage imager in a magnetic resonance-guided radiotherapy machine for beam output checks.

We characterized the on-board megavoltage imager (MVI) of a magnetic resonance-guided radiotherapy machine for beam output checks. Linearity and repeatability of its dose response were investigated. Alignment relative to the beam under clinical circumstances was evaluated for a year using daily measurements.

Beam output checks of a commercial high-field magnetic resonance-guided radiotherapy machine with its on-board megavoltage imager.

Beam output checks of a commercial high-field magnetic resonance-guided radiotherapy machine can be performed with its on-board megavoltage imager (MVI). This is a fast and efficient method, but only recommended for daily checks. The aim of our study was to show its suitability for weekly checks by investigating its long-term agreement with the golden standard: ionization chamber measurements in a water tank.

A quality assurance tool for helical tomotherapy using a step-wedge phantom and the on-board MVCT detector.

The purpose of this study was to develop and evaluate filmless quality assurance (QA) tools for helical tomotherapy by using the signals from the on-board megavoltage computed tomography (MVCT) detector and applying a dedicated step-wedge phantom. The step-wedge phantom is a 15 cm long step-like aluminum block positioned on the couch. The phantom was moved through the slit beam and MVCT detector signals were analyzed.