title: Reduced radiation exposure of the female breast during low-dose chest CT using organ-based tube current modulation and a bismuth shield: comparison of image quality and radiation dose.
abstract: OBJECTIVE
  The objective of our study was to evaluate the effect of organ-based tube current modulation and bismuth shielding on image quality and breast radiation dose in women undergoing low-dose chest CT.
  
  
  METHODS
  From March 2011 through July 2011, 80 women prospectively underwent low-dose chest CT to screen for lung cancer. The patients were randomly assigned to a control group (n = 20), organ-based tube current modulation group (n = 20), breast shield group (n = 20), or breast shield plus organ-based tube current modulation group (n = 20). Axial slice images of the aortic arch, carina, and inferior pulmonary vein were used to analyze image quality. Three radiologists scored the image quality in terms of artifact and noise and then characterized the overall image quality as optimal (does not affect the diagnostic accuracy) or suboptimal (affects the diagnostic accuracy). Noise levels were measured in the anterior and posterior lung in each image. A phantom dose study was conducted to measure radiation dose.
  
  
  RESULTS
  Images with artifacts or noise were more frequently obtained in the breast shield groups; however, the overall image quality was not significantly different among the four groups. Measured noise levels in the anterior lung were significantly higher in the breast shield groups than the control group; however, no statistical significance was found among the four groups with regard to noise level in the posterior lung. In the phantom dose study, a 16-37.5% dose reduction in the breast was achieved using the breast shield, organ-based tube current modulation protocol, or both.
  
  
  CONCLUSIONS
  The radiation dose in the female breast may be reduced using a breast shield or organ-based tube current modulation during low-dose chest CT with acceptable image quality. The use of organ-based tube current modulation reduced the radiation dose in the breast without inducing image quality deterioration.
authors: Department of Radiology, Gil Hospital, Gachon University of Medicine and Science, 1198, Guwol-dong, Namdong-gu, Incheon 405-760, South Korea.
authors: Yoon Kyung
authors: YK
authors: Kim
authors: Yon Mi
authors: YM
authors: Sung
authors: Jin Ho
authors: JH
authors: Choi
authors: Eun Young
authors: EY
authors: Kim
authors: Hyung Sik
authors: HS
authors: Kim
mesh_terms: D016477:Artifacts; D001729:Bismuth / Q000528:radiation effects; D001940:Breast; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D001729:Bismuth