[Optical Computed Tomography for Polymer Gel Dosimetry].

This article describes an optical computed tomography (OCT) for polymer gel dosimetry, focusing on two systems recently constructed by us. The first OCT system, which is categorized as a first-generation system, comprised a single He-Ne laser, photodiode, and mechanical stages for moving and turning gel dosimeter. Projection data per angle are acquired from turned gel dosimeter. In this system, the reconstructed image is obtained using filtered back-projection (FBP) method from projection data. The second OCT system is a 2D-OCT scanner that utilizes a light panel and a camera detector. The dose-response relationship between the optical density and radiation dose reconstructed from the scanning images is comparable to that obtained using magnetic resonance imaging. Although there is much room for improvement in the image artifacts due to reflection and refraction of light and so on, OCT is expected as a modality for the future polymer gel dosimetry as the rapid, high-resolution, highly accurate evaluation tool.