Radiation Dose and Image Quality of Low-dose Protocol in Chest CT: Comparison of Standard-dose Protocol

흉부 CT촬영에서 저선량 프로토콜의 선량과 화질: 표준선량 프로토콜과 비교

  • Lee, Won-Jeong (Occupational Lung Diseases Institute, KCOMWEL) ;
  • Ahn, Bong-Seon (Department of Radiological Technology, Daejeon Health Science College) ;
  • Park, Young-Sun (Department of Radiological Technology, Daejeon Health Science College)
  • 이원정 (근로복지공단 직업성폐질환연구소) ;
  • 안봉선 (대전보건대학교 방사선과) ;
  • 박영선 (대전보건대학교 방사선과)
  • Received : 2012.03.16
  • Accepted : 2012.06.05
  • Published : 2012.06.30


The purpose of this study was to compare radiation dose and image quality between low-dose (LDP) and standard-dose protocol (SDP). LDP (120 kVp, 30 mAs, 2-mm thickness) and SDP (120 kVp, 180 mAs, 1.2-mm thickness) images obtained from 61 subjects were retrospectively evaluated at level of carina bifurcation, using multi-detector CT (Brilliance 16, Philips Medical Systems). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated at ascending aorta and infraspinatus muscle, from CT number and back-ground noise. Radiation dose from two protocols measured at 5-point using acrylic-phantom, and CT number and noise measured at 4-point using water-phantom. All statistical analysis were performed using SPSS 19.0 program. LDP images showed significantly more noise and a significantly lower SNR and CNR than did SDP images at ascending aorta and infraspinatus muscle. Noise, SNR and CNR were significantly correlated with body mass index (p<0.001). Radiation dose, SNR and CNR from phantom were significant differences between two protocols. LDP showed a significant reduction of radiation dose with a significant change in SNR and CNR compared with SDP. Therefore, exposure dose on LDP in clinical applications needs resetting highly more considering image quality.


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