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

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. SUBJECTS AND 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 meas...