Designing and making of silicone bismuth nanoparticle breast shields for chest CT scan

Abstract

In this regard, the purpose of this study was to evaluate the effectiveness of a homemade nano-bismuth oxide shield in reducing the breast dose irradiated in chest CT scan. Materials and methods: Bismuth oxide nanoparticles were prepared and synthesized in the Chemistry Laboratory by of Tabriz University. SEM, TEM, XRD, DLS tests were used to evaluate the properties of nanoparticles. Then, nano-bismuth oxide shields were designed and manufactured with 10% and 15% ratios in 0.5 to 1 mm thicknesses of silicon matrix. The dosimetry process was performed by TLD dosimeters in the skin layers and the fourth layers of large and normal breasts with and without shields in the chest CT scan. Dosimetry was also performed for CTDI phantom at the position of 12:00 o’clock. Signals and noises of the images obtained without and with the presence of shields were evaluated to study the effects of shield on image quality. Statistical data analysis was performed using t-test with SPSS version 16. Results: Nano bismuth oxide shields reduced dose valued 9% and 15% in the skin layer and 8% and 14% in the breast fourth layer of female chest phantom, for 10% and 15% bismuth ratio (0.5 mm thickness), respectively. Also, by increasing shields thickness to 1 mm, the dose of skin layer reduced by 18% and 24% and dose of fourth layer decreased by 16% and 22, for 10% and 15% bismuth ratio, respectively. In addition, applying 10% nano-bismuth oxide shield with thickness of 0.5 and 1 mm decreased the CTDI dose value by 7% and 14%, separately. The comparison between shielded and unshielded CT images showed 10% and 18% increase in noise for 10% and 15% bismuth shields, respectively.