The investigators propose to test the feasibility of developing a more efficient area detector for high energy x-rays by casting cesium iodide converter into the holes of a metal honeycomb structure and reading out by amorphous silicon diode array, as further described by their abstract: """"""""One of the most promising new approaches for rapid portal imaging in radiation therapy are the large area digital detectors currently under development. These systems use a two-dimensional array of amorphous silicon (a:Si) diodes to generate an image and have several desirable aspects, including the ability to produce an image in real-time. A fundamental problem with current portal imaging devices is that the inherent x-ray photon detection sensitivity is small. When acceptable patient doses are used, this low sensitivity results in poor image quality due to limited image contrast resolution. This poor image quality limits the usefulness in patient care. """"""""A key to achieving significant improvement in portal imaging is the use of a:Si with a high efficiency converter screen. We propose to develop a modified two-dimensional imaging system using a very thick segmented scintillator integrated with the a:Si detector to achieve this improvement. This has the potential to significantly improve the resulting image quality. Research will be carried out to produce large-area, thick segmented x-ray imaging converters with improved stopping power for high energy x-rays while providing a submillimeter spatial resolution. This method involves injection of the scintillator material into a metal collimater matrix. The proposed method overcomes limitations of standard fabrication procedures by producing a cost-effective technique of fabricating large-area segmented x-ray scintillators. """"""""In the Phase I program, we shall concentrate on the research of producing high quality, limited area converters. In the Phase II program, the converter will be scaled up to portal imaging dimensions and incorporated into a fully functional a:Si imaging system.""""""""
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