The use of an advanced composite material as an alternative to carbon fibre in radiotherapy

Abstract

Carbon fibre has become the material of choice for many radiotherapy accessories, as it is lightweight, radio-translucent and rigid. Unfortunately specialised equipment is required to manufacture devices from it and hence these tend to be expensive. Also carbon fibre is conducting which limits its compatibility with MRI. Other composite materials have now become available that are rigid and lightweight and may be equally radio-translucent. Here we describe the use, in radiotherapy, of such a composite made of polypropylene and fibre glass (PFGC) that is MRI compatible. We measured the 6 MV x-ray transmission and build-up properties of 2.5 cm thick panels made of either carbon fibre or PFGC. They are found to have equivalent x-ray transmission properties, varying from about 0.98 at perpendicular incidence to about 0.96 at 60° oblique incidence. The build-up dose was found to be approximately 82% of the maximum dose. We also demonstrate the use of PFGC as a flat couch top for MRI scanners and as a head board for shell immobilisation devices.