Assessment of Commercially Available In-plane Bismuth Breast Shields for Clinical Use in Patients Undergoing Thoracic Computed Tomography

Abstract

Objective:We aimed to assess qualitatively the effects of a bismuth breast shield by measuring image noise and computed tomography (CT) number changes with 0-, 1-, 2-, and 3-cm shield-to-phantom distances. We also sought to assess the dose reduction achieved by the shield and to evaluate its effect on image quality. Methods: A cylindrical body phantom was scanned using an adult thoracic CT protocol with 0-, 1-, 2-, and 3-cm foam spacers placed between the shield and the phantom, measuring the noise and CT numbers (in Hounsfield units [HU]) of the image data. We also used the shield with 3-cm spacer over the left breast in 180 female patients referred for chest CT. Dose measurements were performed using thermoluminescent dosimeters. The image quality was assessed following European guidelines. Results: A 0-cm shield-to-phantom distance significantly increased noise and CT numbers of the image data. The 3-cm shield-to-phantom distance effectively lowered shield-induced image noise; however, the HUs remained significantly increased over all shield-to-phantom distances (p < 0.001). In the patient study, the average absorbed doses to the shielded and non-shielded breasts were 13.6±3.1 mGy and 24.04±4.7 mGy, respectively; a 43.4% dose reduction. Conclusion:Combining a bismuth shield with a 3-cm shield-to-breast foam spacer significantly reduced radiation exposure without qualitative or quantitative deterioration of images in terms of image noise. However, increases in the HUs of the images persisted.

Tradeoffs between radiation exposure to the lens of the eyes and diagnostic image quality in pediatric brain computed tomography

“…[ 28 29 ] Before and after each use, TLDs were annealed in a Harshaw 3500 TLD reader (Harshaw, Solon, OH) at 245°C for 10 min and then left to cool down to room temperature. [ 30 31 ] The patients were positioned at the isocenter of the gantry and the scanogram was performed in lateral projection. The scan range and geometry profile were manually planned to the predefined scan protocol.…”

Radiation Exposure and Lifetime Attributable Risk of Cancer Incidence and Mortality from Low- and Standard-Dose CT Chest: Implications for COVID-19 Pneumonia Subjects

“…Several studies have addressed the LAR of cancer incidence and mortality from low- and standard-dose chest CT scans [ 89 , 90 , 91 , 92 , 97 , 98 ]. From Table 4 and Table 5 , it is evident that the effective dose resulting from a low-dose chest CT for COVID-19 is much lower than that from standard-dose chest CT (0.20–1.8 mSv Vs. 2.20–8.70 mSv).…”

“…Chest CT exposes several radiosensitive tissues such as the breasts, lungs and thyroid gland to radiation [ 89 , 101 ], and is shown to increase the risk of cancer induction in these tissues. A meta-analysis including seven studies assessing breast cancer induction by low-dose radiation from mammography or chest X-rays in women with familial or genetic predisposition of breast cancer found a 1.3-fold (Odd ratio = 1.3, 95% CI: 0.9–1.8) increased risk of breast cancer in <33 mSv doses.…”

“…A pooled analysis of seven cohort studies assessing thyroid cancer after exposure to external radiation supports thyroid cancer increase at 10–90 mSv doses [ 103 ]. Overall, it is estimated that a standard-dose chest CT may increase the risk of breast cancer by 20–287 [ 89 , 90 , 92 , 97 , 98 ] and lung cancer by 22–152 [ 90 , 91 , 97 , 98 ] per 100,000 people.…”

Overuse of computed tomography for mild head injury: A systematic review and meta-analysis

“…Computed tomography (CT) scan is a common imaging technique used to evaluate head injuries, especially in cases of mild head injuries [ 3 , 4 ]. It helps identify structural damages like bleeding or swelling, which could be life-threatening if not promptly treated [ 5 ]. CT scans also aid in determining the severity of the injury and guiding the appropriate management plan [ 6 ].…”