Room: Exhibit Hall | Forum 9
Purpose: The first aim of this study was to evaluate noise and CT numbers of the acquired images with 0, 1, 2, and 3-cm shield-to-phantom distance. The second aim was to assess radiation dose reduction by the shield and a qualitative assessment of image quality in an extensive clinical study.
Methods: 32-cm body phantom was scanned using adult thoracic CT protocol. Scanningwas repeated after placing 0, 1, 2 and 3-cm foam between shield and the phantom. The noiseand CT number of the phantom images was measured. In the clinical study, 180 femalepatients were scanned. The left breast was shielded, whereas the right breast remained nonshielded.The radiation dose and image quality were assessed.
Results: Three-cm shield-to-phantom distance has effectively lowered image noise; however,CT number was significantly increased at all phantom regions, when there was 0, 1, 2 and 3-cm shield-to-phantom distance (P<0.001). In the patient study, the shield has reduced breastdose by 43.42%. Qualitative image quality analysis showed no statistical difference betweenshielded and non-shielded sections of the thoracic images (P=0.997).
Conclusion: Combining bismuth shield with 3-cm shield-to-breast distance has significantlyreduced radiation exposure without deterioration of image quality in term of image noise andstreak artifacts. However, increasing the CT number of the images remains as a concern.