Assessment of the efficiency of new bismuth composite shields in radiation dose decline to breast during chest CT

Abstract

Background: Bismuth shield has been recently introduced for radiation protection of patient radiosensitive organs such as breast during chest CT with image diagnosis capability. The purpose of this study was to evaluate the dose reduction and image quality conserve using new bismuth-silicon composite shields during chest CT. Materials and methods: Scans were performed on a PMMA phantom using a 6-slice MDCT system. Dose reduction was calculated by placing ion-chamber in the 12 o’clock position for breast dose measuring. Chest CT scans was performed with and without new bismuth composite shields 10% by 0.5 mm and 1 mm thicknesses. Image quality was assessed by CT numbers and noise evaluation. Results: The results of using bismuth composite shields induced to dose reduction to 7% and 12% for 0.5 mm and 1 mm thicknesses, respectively. As a result of the using 0.5 mm and 1 mm bismuth composite shields, the mean CT numbers and noise increased by a factor of 0.01 and 0.02 and also from 0.08 to 0.13, respectively. Significant dose decline was measured and no relevant noise was found. Conclusion: Results showed that new bismuth-silicon composite shields have good potential to breast dose reduction with smallest noise for diagnosis in chest CT. Keywords: Bismuth-silicon composite shield, Dose reduction, Chest CT, Image quality