한국의학물리학회지:의학물리 (Progress in Medical Physics)

  • 제21권3호
  • /
  • Pages.261-273
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  • 2010
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  • 2508-4445(pISSN)
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  • 2508-4453(eISSN)
한국의학물리학회 (Korean Society of Medical Physics)
권호 표지

선형시스템 전달이론을 이용한 간접변환방식 디지털 래디오그라피 디텍터의 신호 및 잡음 분석

Signal and Noise Analysis of Indirect-Conversion Digital Radiography Detectors Using Linear-systems Transfer Theory

  • Yun, Seung-Man (School of Mechanical Engineerig, Pusan National University) ;
  • Lim, Chang-Hwy (School of Mechanical Engineerig, Pusan National University) ;
  • Han, Jong-Chul (School of Mechanical Engineerig, Pusan National University) ;
  • Joe, Ok-La (School of Mechanical Engineerig, Pusan National University) ;
  • Kim, Jung-Min (Department of Radiologic Science, Korea University) ;
  • Kim, Ho-Kyung (School of Mechanical Engineerig, Pusan National University)
  • 투고 : 2010.07.13
  • 심사 : 2010.08.20
  • 발행 : 2010.09.30
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초록

간접변환방식 CMOS (complementary metal-oxide-semiconductor) 엑스레이 디텍터 시스템의 성능 분석 및 개선을 위하여 공간주파수에 따른 DQE (detective quantum efficiency)를 모델링 하였다. 모델의 검증을 위하여 마모그라피 W/Al 선질에 대한 modulation-transfer function (MTF), noise-power spectrum (NPS)를 측정하고 이로부터 DQE를 계산하였으며, 모델과 측정된 DQE는 전체 공간주파수 영역에서 서로 잘 일치함을 확인하였다. 검증된 모델을 이용하여 형광스크린 양자효율 및 MTF, Swank 잡음, 포토다이오드 양자효율 등 CMOS 디텍터 시스템의 DQE 성능에 영향을 미칠 수 있는 다양한 디자인 파라미터의 역할을 살펴보았다. 엑스레이 디텍터 시스템의 신호 및 잡음 분석에 대해 이와 같은 선형시스템 전달을 이용한 이론적인 접근법은 이미 개발된 의료영상시스템을 이해할 수 있는 유용한 도구일 뿐만 아니라 새로운 디텍터 개발 및 최적화를 위한 도구로 활용될 수 있을 것이다.

For the use of Indirect-conversion CMOS (complementary metal-oxide-semiconductor) detectors for digital x-ray radiography and their better designs, we have theoretically evaluated the spatial-frequency-dependent detective quantum efficiency (DQE) using the cascaded linear-systems transfer theory. In order to validate the developed model, the DQE was experimentally determined by the measured modulation-transfer function (MTF) and noise-power spectrum, and the estimated incident x-ray fluence under the mammography beam quality of W/Al. From the comparison between the theoretical and experimental DQEs, the overall tendencies were well agreed. Based on the developed model, we have investigated the DQEs values with respect to various design parameters of the CMOS x-ray detector such as phosphor quantum efficiency, Swank noise, photodiode quantum efficiency and the MTF of various scintillator screens. This theoretical approach is very useful tool for the understanding of the developed imaging systems as well as helpful for the better design or optimization for new development.

키워드

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