| Summary: | 博士 === 中原大學 === 生物醫學工程研究所 === 100 === By using the feature of radio-pharmaceutical tracking, molecular imaging modalities offer bio-functional information of living tissues. Compare to those modalities offering anatomical images, molecular imaging offers more specific diagnosis and earlier detections to the lesions. Applying small cameras with high-resolution capability to image specific target on human body at a close position to gain high quality images for diagnosis, has been showing its potential on clinical use. The purpose of this study is to develop a flat panel gamma camera and to study the required technology. The proposed camera is requested to satisfy the following three specifications to show its practicality of in-vivo imaging. First, the proposed camera should be capable of processing dual-modality imaging applications, i.e. positron and single-photon imaging. Second, a good resolution performance (better than 3 mm) should be shown. Third, a successive imaging area larger than 80×80 mm2 is required.
In this study, the architecture of crystal array composed of needle like elements coupling onto PSPMTs was chosen to be the development basis. Five terms of work were processed to achieve the objectives. The first term is to evaluate the imaging performances, manipulation, and availability of six scintillators. According to the test results, LYSO was chosen for processing the following terms of work. The second term is to build a base imaging unit (an imaging detector based on a single PSPMT) for technology validating and evaluate its performance. The results showed that the proposed imaging unit is capable of offering promising performances (pixel width < 0.8 mm and energy resolution < 15%) for the dual-modality imaging. The third term is to study the influences of the continuous light guide on degradations of imaging performances, and to evaluate the effectiveness of light guide thickness to make the imaging area successive. According to the experimental results, 2mm-thick light guide was chosen to develop the proposed dual-modality camera. In the fourth term of work, a camera meeting the purpose of this study and with the specifications obtained from the previous terms of work applied was built. The effective imaging area was extended successively to 89×89 mm3. The results showed that the proposed camera offers outstanding performances for positron (about 2 mm resolution) and single-photon imaging (sub-millimeter achievable with pin-hole collimation). The last term is to evaluate the influence of the camera’s intrinsic radiations on single-photon imaging. The results showed that the proposed camera is capable of offering correct and quality images in single-photon imaging applications.
In this study, by basic studies on scintillation materials and continuous light-guide influences, a dual-modality camera for positron and single-photon imaging was completed. It is shown that outstanding performances and a practical size of imaging area were achieved, therefore, the objectives and technical requests of this study are satisfied.
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