Affiliations: [a] Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| [b]
Department of Radiology, National Cancer Institute, Precint 7, 62250 Putrajaya, Malaysia
| [c]
Department of Quantum Medical Technology, Faculty of Health Sciences, Kanazawa University, Japan
| [d] Department of Physics, Faculty of Science, Universiti Teknologi Malaysia Johor Baru, Malaysia
| [e]
Department of Physics, College of Science, Imam Abdurrahman Bin Faisal University, Saudi Arabia, City Dammam, Saudi Arabia
Correspondence:
[*]
Corresponding author: M.K.A. Karim, Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. E-mail: khalis.karim@gmail.com.
Abstract: BACKGROUND:Numerous techniques had been proposed to reduce radiation exposure in computed tomography (CT) including the use of radiation shielding. OBJECTIVE: This study aims to evaluate efficacy of using a bismuth breast shield and optimized scanning parameter to reduce breast absorbed doses from CT thorax examination. METHODS:Five protocols comprising the standard CT thorax clinical protocol (CP1) and four modified protocols (CP2 to CP5) were applied in anthropomorphic phantom scans. The phantom was configured as a female by placing a breast component on the chest. The breast component was divided into four quadrants, where 2 thermoluminescence dosimeters (TLD-100) were inserted into each quadrant to measure the absorbed dose. The bismuth shield was placed over the breast component during CP4 and CP5 scans. RESULTS:The pattern of absorbed doses in each breast and quadrant were approximately the same for all protocols, where the 4th quadrant > 3rd quadrant > 2nd quadrant > 1st quadrant. The mean absorbed dose value in CP3 was reduced to almost 34% of CP1’s mean absorbed dose. It was reduced even lower to 15% of CP1’s mean absorbed dose when the breast shield was used in CP5. CONCLUSION:This study showed that CT radiation exposure on the breast could be reduced by using a bismuth shield and low tube potential protocol without compromising the image quality.
Keywords: Computed tomography, bismuth shielding, organ equivalent dose, scan
protocols, tube potential, breast
