Study on Different Method to Determine the Individual Diameter for Size-Specific Dose Estimates (SSDE) in Adult Patients
The CT dose index (CTDI) and dose length product (DLP) are the most frequently used indicators to represent radiation doses in CT examination. However, the limitation of both is that they only estimate dose based on the scanner output information for specific standardized condition and phantom sizes. This study was aimed in evaluation of the radiation dose based on the SSDE method for adult abdomen CT study at AMDI, Universiti Sains Malaysia, Penang. A total of 91 CT procedures were selected consisting only adult patients undergo CT thorax-abdomen-pelvis (TAP) examination. As recommended by American Association of Physicist in Medicine (AAPM), the individual dimensions of each patient were determined. The conversion factors for SSDE were multiplied with the displayed CTDIvol. The comparative study between displayed CTDIvol with SSDE-calculated dose were done and percentage difference were then determined. From the results, significant differences were observed between SSDE-calculated and displayed dose with variations of 3–47% for method of AP and LAT summation, and 1.96–46% with method of effective diameter. The SSDE calculated doses were significantly higher than the displayed dose values by CT scanner. Therefore, evaluation of patient dose by individual specific size is critical for optimization of radiation exposure in CT imaging.
KeywordsComputed tomography Size-specific dose estimation (SSDE) Effective diameter CT dose index (CTDI)
The authors would like to thank all radiographers and staff at Imaging Unit, AMDI USM, Malaysia for their help and support throughout this work.
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