Journal of radiological science and technology (대한방사선기술학회지:방사선기술과학)

Korean Society of Radiological Science (대한방사선과학회)
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Measurement of Image Quality According to the Time of Computed Radiography System

시간에 따르는 CR장비의 영상의 질평가

  • Son, Soon-Yong (Department of Radiology, Asan Medical Center) ;
  • Choi, Kwan-Woo (Department of Radiology, Asan Medical Center) ;
  • Kim, Jung-Min (Department of College of Health Science, Radiologic Science, Korea University) ;
  • Jeong, Hoi-Woun (Department of Radiological Technology, Baekseok Culture University) ;
  • Kwon, Kyung-Tae (Department of Radiological Technology, Dongnam Health University) ;
  • Hwang, Sun-Kwang (Department of Radiology, Kyung Hee University Hospital at Gang-dong) ;
  • Lee, Ik-Pyo (Department of Radiology, Kyung Hee University Hospital at Gang-dong) ;
  • Kim, Ki-Won (Department of Radiology, Kyung Hee University Hospital at Gang-dong) ;
  • Jung, Jae-Yong (Department of Radiation Oncology, Sanggye Paik Hospital) ;
  • Lee, Young-Ah (Department of Bio-Technologist and Laboratory Animal, Shingu University College) ;
  • Son, Jin-Hyun (Department of Radiological Technology, Shingu University College) ;
  • Min, Jung-Whan (Department of Radiological Technology, Shingu University College)
  • 손순룡 (서울아산병원 영상의학과) ;
  • 최관우 (서울아산병원 영상의학과) ;
  • 김정민 (고려대학교 방사선학과) ;
  • 정회원 (백석문화대학교 방사선과) ;
  • 권경태 (동남보건대학교 방사선과) ;
  • 황선광 (강동경희대병원 영상의학과) ;
  • 이익표 (강동경희대병원 영상의학과) ;
  • 김기원 (강동경희대병원 영상의학과) ;
  • 정재용 (상계백병원 종양학과) ;
  • 이영아 (신구대학교 바이오 동물학과) ;
  • 손진현 (신구대학교 방사선과) ;
  • 민정환 (신구대학교 방사선과)
  • Received : 2015.10.02
  • Accepted : 2015.12.16
  • Published : 2015.12.31
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Abstract

The regular quality assurance (RQA) of X-ray images is essential for maintaining a high accuracy of diagnosis. This study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE) of a computed radiography (CR) system for various periods of use from 2006 to 2015. We measured the pre-sampling MTF using the edge method and RQA 5 based on commission standard international electro-technical commission (IEC). The spatial frequencies corresponding to the 50% MTF for the CR systems in 2006, 2009, 2012 and 2015 were 1.54, 1.14, 1.12, and $1.38mm^{-1}$, respectively and the10% MTF for 2006, 2009, 2012, and 2015 were 2.68, 2.44, 2.44, and $2.46mm^{-1}$, respectively. In the NPS results, the CR systems showed the best noise distribution in 2006, and with the quality of distributions in the order of 2015, 2009, and 2012. At peak DQE and DQE at $1mm^{-1}$, the CR systems showed the best efficiency in 2006, and showed better efficiency in order of 2015, 2009, and 2012. Because the eraser lamp in the CR systems was replaced, the image quality in 2015 was superior to those in 2009 and 2012. This study can be incorporated into used in clinical QA requiring performance and evaluation of the performance of the CR systems.

진단의 높은 정확성을 유지하기 위하여 영상 품질의 정기적인 quality assurance (QA) 검사는 필수적이다. 이 연구의 목적은 2006년부터 2015년까지 시간에 따른 (2006, 2009, 2012, 2015) computed radiography (CR) system의 modulation transfer function (MTF: 변조전달함수), the noise power spectrum (NPS: 잡음전력스펙트럼) and the detective quantum efficiency (DQE: 양자검출효율)를 측정하여 평가 하는 것이다. 우리는 edge method를 이용하여 pre-sampled MTF를 구하였고 international electrotechnical commission standard IEC: 62220-1의 RQA5가 측정에 적용되었으며, X선관 초점으로부터 CR 표면까지의 거리는 150 cm이며, 부가필터 21 mmAl을 사용하였다. 관전압은 $72{\pm}2kVp$였으며 관전압을 1~2 kVp조절하여 HVL이 $7.1{\pm}1mmAl$되도록 하였다. 연구결과는 MTF의 공간주파수 50% ($mm^{-1}$)에서 사용 기간 별로 2006년은 1.54, 2009년은 1.14, 2012년은 1.12, 2015년은 1.38 이었고 공간주파수 10% ($mm^{-1}$)에서 사용 기간 별로 2006년은 2.68, 2009년은 2.44, 2012년은 2.44, 2015년은 2.46 이었다. 각각의 노이즈 분포는 2006년이 가장 낮은 노이즈 분포를 보였으며 2015, 2009, 2012 순으로 낮은 노이즈 분포를 나타내었다. Peak DQE와 $1mm^{-1}$에서도 2006년이 가장 우수한 DQE를 보였으며 2015년, 2009년, 2012년 순으로 DQE값을 나타내었다. 정확한 진단을 위하여 주기적인 CR 시스템의 유지보수가 필요하며 본 연구는 CR 시스템의 QA 및 수행성능 평가에 기초가 될 것으로 생각된다.

Keywords

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