Abstract
In this paper we describe the particular considerations relating to ultra-rapid, true-3D scanners based on charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) imaging detectors. Central to our ability to image dose distributions has been the development of novel materials whose optical properties change in response to radiation and a survey of these will be given. Finally, we will speculate briefly on the future of the technique. © 2006 IOP Publishing Ltd.