Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
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Modulation Transfer Function with Aluminum Sheets of Varying Thickness

다양한 두께의 알루미늄 판을 이용한 MTF 측정에 관한 연구

  • Rhee, Dong Joo (Research Center, Dongnam Institute of Radiological and Medical Sciences) ;
  • Kim, Me Young (Research Center, Dongnam Institute of Radiological and Medical Sciences) ;
  • Moon, Young Min (Department of Radiation Oncology, Dongnam Institute of Radiological and Medical Sciences) ;
  • Jeong, Dong Hyeok (Research Center, Dongnam Institute of Radiological and Medical Sciences)
  • 이동주 (동남권원자력의학원 연구센터) ;
  • 김미영 (동남권원자력의학원 연구센터) ;
  • 문영민 (동남권원자력의학원 방사선종양학과) ;
  • 정동혁 (동남권원자력의학원 연구센터)
  • Received : 2016.06.02
  • Accepted : 2016.06.10
  • Published : 2016.06.30
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Abstract

We studied the method to gain a clear LSF using a thick aluminum sheet and to acquire the spatial resolution value with a high accuracy for a low spatial resolution imaging modality. In this study, aluminum sheets with thicknesses varying from 0.3 mm to 1.2 mm were tested to derive a modulation transfer function (MTF) for the oversampling and non-oversampling methods. The results were evaluated to verify the feasibility of the use of thick sheets for periodic quality assurance. Oversampling was more accurate than non-oversampling, and an aluminum sheet with a correction factor less than 2 at the cut-off frequency, which was less than 0.8 mm in this case, was confirmed to be suitable for MTF measurements. Therefore, MTF derivation from a thick aluminum sheet with thickness correction is plausible for a medical imaging modality.

본 연구에서는 방사선치료기용 CBCT의 영상과 같이 해상도가 낮은 경우에 적용할 수 있는 MTF (modulation transfer function) 평가 방법을 고안하였다. 본 연구에서는 두꺼운 알루미늄 판의 영상을 이용하여 중복 표본(oversampling) 방법과 두께 보정 방법을 적용하여 MTF를 결정하였다. 다양한 알루미늄 판의 두께(0.3~1.2 mm)에 대해 MTF를 분석하였으며 경사 영상과 평행 영상의 경우에 대해서도 비교하였다. 연구 결과 치료계획용 CT인 경우에 알루미늄의 두께가 0.8 mm 이하 일 경우 MTF 측정이 가능한 것으로 나타났다. 따라서 두꺼운 알루미늄 판과 두께 보정을 이용한 MTF 측정이 CT 영상에서 가능하였다.

Keywords

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