Journal of radiological science and technology (대한방사선기술학회지:방사선기술과학)

Korean Society of Radiological Science (대한방사선과학회)
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Evaluation of Image Quality According to Presence or Absence of Upper limbs in Scan Field of View During CT Examinations (Including LUNG MAN)

CT 검사 시 스캔 범위 내 상지 유무에 따른 영상의 질 평가(LUNG MAN 포함)

  • Zhang, Yuying (Department of Radiological Science, Daegu Catholic University) ;
  • Zheng, Haoyang (Department of Radiological Science, Daegu Catholic University) ;
  • Jung, Kang-gyo (Department of Radiological Science, Daegu Catholic University) ;
  • Cho, Yu-Jin (Suhjoo Mir Radiology Clinic) ;
  • Cho, Pyong-Kon (Department of Radiological Science, Daegu Catholic University)
  • 장위잉 (대구가톨릭대학교 방사선학과) ;
  • 정하오양 (대구가톨릭대학교 방사선학과) ;
  • 정강교 (대구가톨릭대학교 방사선학과) ;
  • 조유진 (서주미르영상의학과의원) ;
  • 조평곤 (대구가톨릭대학교 방사선학과)
  • Received : 2017.11.04
  • Accepted : 2017.12.12
  • Published : 2017.12.31
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Abstract

The purpose of this study was to evaluate whether or not there was artifact when the upper limb could not be lifted to the top of the head during multi-detector computed tomography(MDCT) scans of the chest and abdomen. Contrast radiography of the human and chest phantom was performed with 128channal MDCT. Under the same conditions(120 kVp, 110 mAs, standard algorithm)both hands lifted up and put down each time in the human experiment. In the chest phantom experiment, the radiography was carried out when the upper limb phantom was adjusted at a certain distance(0, 3, 7 cm) from the chest phantom. Subsequently, the values of Noise, CT number, SNR, and CNR were measured in the field of concern. The noise value of fat, rib, and muscle increased when the arm was lifted in humans(0.79, 47.8, 27%). Furthermore, when the upper limb was lowered, the noise value of muscle and lung increased in the phantom(31.2, 9.4%). In addition, the noise value of the muscles and lung decreased by 5, 25.12% and 5.6, 15.35% as the upper limb moved about 0,3,7cm away from the chest. When the chest and abdominal radiography were performed, in the case of the presence of other parts outside the inspection area, the probability of artifact was minimal while the distance was more than 3cm away from the upper limb to the chest and abdomen.

본 연구의 목적은 흉 복부 다중검출기전산화단층촬영(multi-detector computed tomography; MDCT)에서 상지를 머리 위로 위치 잡이 할 수 없는 경우 흉 복부에서 거리에 따른 인공유무를 평가하고자 하였다. 128-채널 MDCT로 흉 복부 CT를 위한 인체대상과 흉부 팬텀을 현재 임상에서 검사하고 있는 조건(120 kVp, 110 mAs, standard algorithm)으로 검사하였다. 인체 검사 시 한번은 팔을 머리 쪽으로 올리고 검사하고, 팔을 내린 후 동일한 조건으로 한 번 더 검사하였다. 흉부 팬텀 실험은 환자와 동일한 조건으로 검사를 하고, 상지팬텀을 흉 복부에서 일정한 거리(0, 3, 7 cm)를 두고 검사하였다. 목적하는 부위에 관심영역을 설정하여 CT 값, 노이즈, 신호 대 잡음비, 대조도 대 잡음비를 측정하여 평가하였다. 인체를 대상으로 획득한 영상에서 노이즈는 팔을 올렸을 때와 비교하여 팔을 내렸을 때 지방, 갈비뼈, 근육 모두에서 증가하였다(0.79, 47.8, 27%). 팬텀 영상에서도 상지를 아래로 내렸을 경우 근육, 폐 실질에서 노이즈가 증가하였다(31.2, 9.4%). 또한 상지의 위치가 흉 복부에서 멀어질수록(0, 3, 7 cm) 노이즈가 감소하였다. 근육에서 노이즈는 상지가 흉부와 붙어있을 경우(0 cm)를 기준으로 3 cm, 7cm 떨어졌을 때 5, 25.12% 감소하였고, 폐실질에서 5.6, 15.35% 감소하였다. 흉 복부 CT 촬영 시 갠트리 내 검사 이외의 부위(상지 등)가 위치할 경우 흉 복부로부터 약 3 cm 이상 거리를 유지시킨 후 검사를 진행하면 발생할 수 있는 인공음영을 최소화시킬 수 있을 것으로 사료된다.

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