CdZnTe Detector Design for Photon-Counting Computed Tomography based on Weighting Potential
- 주제(키워드) CdZnTe detector
- 발행기관 고려대학교 대학원
- 지도교수 최종학
- 발행년도 2016
- 학위수여년월 2016. 8
- 학위구분 석사
- 학과 대학원 바이오융합공학과
- 세부전공 바이오융합공학전공
- 원문페이지 57 p
- 실제URI http://www.dcollection.net/handler/korea/000000068514
- 본문언어 영어
- 제출원본 000045884577
초록/요약
Computed Tomography (CT) systems are now commonly used to produce high-quality images in real time and play important roles in helping doctors make appropriate diagnoses. Reducing the patient dose is crucial because the CT image will be got by giving the high dose to patients. The development of improved semiconduc- tor radiation detectors would be facilitated that reduce patient doses to less than half of those received from conventional Computed Tomography(CT) and mammography systems. Especially, CdZnTe(CZT) operating at room temperature is a compound semiconductor material in Group II-VI, which has a high energy resolution and an excellent detective quantum efficiency. X-ray conversion efficiency and cross-talk are affected by the size and pitch of the pixels and determine the image quality. The weighting potential is the virtual potential determined by the positions and geometric arrangement of the electrodes. In this study, we calculated the weighting potential of CZT detector by employing the nite element analysis using LabVIEW/CVI 8.1 program. For determining the appropriate pixel size, we simulated the program by changing the pixel size from 200 um to 1000 um with fixed the pitch size as 1 mm and the detector's thickness as 2 mm. The pixel size for CT system was optimized by considering the Charge Induction Efficiency(CIE) and the signal cross-talk. The detector's pixel sizes were 200, 600 and 1000 um. And we compared pulse height spectra of Co-57(122 keV) when each CZT detector was biased at 100, 500, 1000 and 1500 V/cm. The best result of this study showed that the optimized pixel size and inter-pixel gap were 750 um, 250 um, respectively. To conclude, with this result, the CIE was maximized and the signal cross-talk was minimized.
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Table of Contents
Abstract
1 INTRODUCTION
2 THEORETICAL BACKGROUND
2.1 The Shockley-Ramo Theorem
2.2 Weighting Potential
2.3 Cross-talk
2.4 Charge Collection Efficiency(CCE)
2.5 Charge Induction Efficiency(CIE)
3 EXPERIMENT
3.1 Simulation
3.1.1 Potential Algorism
3.1.2 Fields Algorism
3.2 Experiment
3.2.1 Weighting Potential
3.2.2 Cross-talk
3.2.3 CCE and CIE
4 RESULTS AND DISCUSSION
4.1 Weighting Potential
4.2 Cross-talk
4.3 CCE and CIE
5 SUMMARY
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