A Computer-Controlled Dynamic Phantom for Respiratory-Gated Medical Radiotherapy Research

Abstract

This paper describes the breathing phantom built to test a six-degree-of freedom sensing device designed for use in Respiratory-Gated Radiotherapy (RGRT). It is focussed on the construction of a test bed that was designed to address tumour motion issues while, at the same time, behaving in much the same way as the human tissues when irradiated. The phantom can produce respiratory movement in three dimensions. Shift differences between the motion axes can be introduced. The position error in the worst case scenario is not greater that 0.4mm. Emphasis is made on the technical limitations of current sensing technologies, especially with regard to acceleration sensitivity. This study demonstrates that the sensitivity of accelerometers used to sense tumour motion should be 0.05mG or less.