The efficiency of lead and non-lead shielding on breast dose in head CT

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The aim of the study was to assess the effect of the shielding material and its thickness on the measured skin dose to the breasts during the CT examination of the head. The helical and axial head CT was performed on an anthropomorphic phantom (PBU 60). Two types of shielding were tested—lead and non-lead (antimony-bismuth) shielding. Measurements with different thicknesses were performed and the shielding efficiency of the materials was compared. Skin dose to the breasts was measured with an educational direct dosimeter (EDD-30). The shielding efficiency during both scanning protocols indicated an increased dose reduction with the thicker equivalent thickness in both shielding materials. Dose reduction was the highest at 0.5 mm equivalent thickness for both materials; lead shielding reduced the dose by 91% and 83%, the antimony-bismuth shielding by 90% and 86%, during the axial and helical head CT protocols, respectively. Statistically significant differences were found between the materials of the same equivalent thickness (0.175, 0.25 and 0.5 mm) during the helical protocol in favor of the antimony-bismuth shielding. During the axial protocol there were no statistically significant differences. Shielding of radiosensitive organs can prevent unnecessary exposure of radiosensitive organs outside the primary beam. Due to the significant decrease in radiation dose to the breasts, and many other positive attributes, use of the antimony-bismuth shielding instead of the lead shielding should be considered, especially during the helical CT scan of the head.