The history and principles of optical computed tomography for scanning 3-D radiation dosimeters

摘要

It is now a decade since the first optical computed tomography (CT) images of a polymer gel radiation detector were published [1, 2]. Since that date, there have been considerable advances in both 3-D imaging techniques and dosimeter formulation and it is therefore timely to produce a thorough review of the field. Whilst it should be recognised that, in the limited space of an extended conference abstract, it is not possible to discuss fully all the contributions to the subject, a comprehensive reference list has nevertheless been assembled and the authors hope that this will provide a valuable resource for the 3-D dosimetry community. Of course, the roots of 3-D imaging via optical CT may be traced back much further than 1996. The first part of this review will place the current work in its historical context and also explain how it is related to other methods of optical imaging. An elementary theoretical description of the principles of optical CT will then be given, which will allow the reader to appreciate the differences between the various types of scanner currently being developed. A separate article [3] will discuss in more detail the class of optical-CT scanner based on a translating laser beam, whilst, here, we will 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.