Experimental Evaluation of Refraction Contrast Portal Imaging for Image Guided Radiation Therapy Using Synchrotron Radiation

Abstract

High-dose radiation destroys cancer cells in radiation therapy. Portal imaging for geometric verification in image guided radiation therapy is performed to adjust the patient's position to deposit the prescribed dose correctly within the prescribed tumor region. However, conventional portal images have lower image contrast than diagnostic X-ray images because portal imaging uses a therapeutic high-energy X-ray beam. We have applied a refraction contrast technique to portal imaging to improve the accuracy of radiation therapy. The edge enhancement effect in refraction contrast portal imaging can provide images with higher contrast than those obtained by conventional portal imaging. In the present study, head images of rats were obtained using refraction contrast portal imaging and conventional portal imaging. The images were then compared to assess the degree of improvement in image quality.