(A) study on characteristics of X-ray detector for CCD-based EPID = CCD-based EPID의 엑스선 계측기 특성에 관한 연구

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The combination of the metal plate/phosphor screen as a x-ray detector with a CCD camera is the most popular detector system among various electronic portal imaging devices (EPIDs). There is a need to optimize the thickness of the metal plate/phosphor screen with high detection efficiency and high spatial resolution for effective transferring of anatomical information. In this study, the thickness dependency on the detection efficiency and the spatial resolution of the metal plate/phosphor screen was investigated by calculation and measurement. The result can be used to determine the optimal thickness of the metal plate as well as of the phosphor screen for the x-ray detector design of therapeutic x-ray imaging and for any specific application. Bremsstrahlung spectrum was calculated by Monte Carlo simulation and by Schiff formula. The detection efficiency was calculated from the total absorbed energy in the phosphor screen using the Monte Carlo simulation and the light output was measured. The spatial resolution, which was defined from the spatial distribution of the absorbed energy, was also calculated and the edge spread function was measured. It was found that the detection efficiency and the spatial resolution were mainly determined by the thickness of metal plate and phosphor screen, respectively. It was also revealed that the detection efficiency and the spatial resolution have trade-off in term of the thickness of the phosphor screen. As the phosphor thickness increases, the detection efficiency increases but the spatial resolution decreases. The curve illustrating the trade-off between the detection efficiency and the spatial resolution of the metal plate/phosphor screen detector is obtained as a function of the phosphor thickness. Based on the calculations, prototype CCD-based EPID was developed and then tested by acquiring phantom images for 6 MV x-ray beam. While, among the captured images, each frame suffered from quantum noise, the frame averaging ...
Advisors
Cho, Gyu-Seongresearcher조규성researcher
Description
한국과학기술원 : 원자력공학과,
Publisher
한국과학기술원
Issue Date
1999
Identifier
150485/325007 / 000973624
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 원자력공학과, 1999.2, [ vi, 48 p. ]

Keywords

Spatial resolution; Detection efficiency; Portal imaging: CCD-based EPID; Fluoroscopic detector; 제동복사선; 공간 분해능; 계측 효율; 포탈이미징; Bremsstrahlung x-ray

URI
http://hdl.handle.net/10203/49404
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=150485&flag=dissertation
Appears in Collection
NE-Theses_Master(석사논문)
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