A novel and independent method for time-resolved gantry angle quality assurance for VMAT.

A novel and independent method for time-resolved gantry angle quality assurance for VMAT.
J Appl Clin Med Phys. 2017 Jul 13;:
Authors: Fuangrod T, Greer PB, Zwan BJ, Barnes MP, Lehmann J
Abstract
Volumetric-modulated arc therapy (VMAT) treatment delivery requires three key dynamic components; gantry rotation, dose rate modulation, and multi-leaf collimator motion, which are all simultaneously varied during the delivery. Misalignment of the gantry angle can potentially affect clinical outcome due to the steep dose gradients and complex MLC shapes involved. It is essential to develop independent gantry angle quality assurance (QA) appropriate to VMAT that can be performed simultaneously with other key VMAT QA testing. In this work, a simple and inexpensive fully independent gantry angle measurement methodology was developed that allows quantitation of the gantry angle accuracy as a function of time. This method is based on the analysis of video footage of a "Double dot" pattern attached to the front cover of the linear accelerator that consists of red and green circles printed on A4 paper sheet. A standard mobile phone is placed on the couch to record the video footage during gantry rotation. The video file is subsequently analyzed and used to determine the gantry angle from each video frame using the relative position of the two dots. There were two types of validation tests performed including the static mode with manual gantry angle...

Source: Journal of Applied Clinical Medical Physics - July 13, 2017 Category: Physics Authors: Fuangrod T, Greer PB, Zwan BJ, Barnes MP, Lehmann J Tags: J Appl Clin Med Phys Source Type: research