Initial experience with a commercial cone beam optical CT unit for polymer gel dosimetry I: Optical dosimetry issues

摘要

Treatment validation of conformal plans is becoming a very important part of radiation therapy. Soon after its inception, gel dosimetry was shown to have a great potential for 3D dosimetry, particularly after the development of more spatially stable polymer-based dosimeters. However, despite its promise, gel dosimetry has not come into widespread clinical use, in part because of limited access to imaging modalities (particularly MRI) for dose readout. Optical Computed Tomography provides an inexpensive and easy-to-use alternative imaging modality [1-4]. However, optical CT approaches introduce novel challenges because of the inherent complications from index of refraction matching at interfaces, multiple scattering in polymer systems, etc. [2-4]. In this paper we present some initial investigations of the use of a Vista cone beam optical CT unit (Modus Medical Devices Inc., London, Canada) in conjunction with various polymer gel dosimeters.