, Volume 19, Issue 1, pp 100-108
Date: 09 Nov 2011

Effect of bismuth breast shielding on radiation dose and image quality in coronary CT angiography

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Abstract

Background

Coronary computed tomographic angiography (CCTA) is associated with high radiation dose to the female breasts. Bismuth breast shielding offers the potential to significantly reduce dose to the breasts and nearby organs, but the magnitude of this reduction and its impact on image quality and radiation dose have not been evaluated.

Methods

Radiation doses from CCTA to critical organs were determined using metal-oxide-semiconductor field-effect transistors positioned in a customized anthropomorphic whole-body dosimetry verification phantom. Image noise and signal were measured in regions of interest (ROIs) including the coronary arteries.

Results

With bismuth shielding, breast radiation dose was reduced 46%-57% depending on breast size and scanning technique, with more moderate dose reduction to the heart, lungs, and esophagus. However, shielding significantly decreased image signal (by 14.6 HU) and contrast (by 28.4 HU), modestly but significantly increased image noise in ROIs in locations of coronary arteries, and decreased contrast-to-noise ratio by 20.9%.

Conclusions

While bismuth breast shielding can significantly decrease radiation dose to critical organs, it is associated with an increase in image noise, decrease in contrast-to-noise, and changes tissue attenuation characteristics in the location of the coronary arteries.

Funding: Supported by NIH Grants 1R01 HL109711-01 and 5KL2 RR024157, a Nuclear Cardiology Foundation/Covidien Research Award, and an Irving Institute for Clinical and Translational Research/Columbia University Clinical Trials Office Pilot Study Award (UL1 RR024156).