Gamma Ray Electronic Collimation Using a Large Volume CZT Crystal

Estanislao Aguayo

Juni 2007 · Universal-Publishers

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Gamma ray detection techniques for radioisotope imaging purposes are quickly evolving. Monte Carlo simulations show the possibility of achieving an outstanding image spatial resolution in the images obtained with techniques using electronic collimation. The great advantage of using electronic collimation is the increased efficiency of the gamma camera with respect to the usage of the mechanical collimation technique. These new imaging techniques require radiation detectors with very specific features, such as low noise, desired stooping power and compactness. In this thesis project, an apparatus for detection of a Compton deposition of gamma rays, capable of differentiating the position of interaction of the gamma ray in the active volume of the detector, has been developed. The design and manufacture of such an apparatus implies the selection and characterization of the radiation sensitive material and its calibration, as well as its associated electronics, in order to achieve the critical requirements to be used as part of the electronic collimated gamma camera. Along with the detector development, the electronic collimation requires a very specific control system. The required logic system that makes possible the usage of the apparatus as part of the the electronic collimation set-up, has also been developed as part of this thesis work. This electronic system is meant to work in coordination with other sensors, and its final output is to give exact information of the photon-electron interaction points, in order for an image to be deduced. The result of this thesis work is a radiation detector ready to be used as the tracker component in the application of the electronic collimation technique. Its control system allows it to be used to build a Compton camera by simply removing the mechanical collimator of a regular gamma-camera, and arranging both detectors in the desired radioisotope imaging electronic collimation scenario.