Estimation of Radiation Dose in CT Chest and Abdomen Examinations Using Size-Specific Dose Estimates

Objective: This is a retrospective and cross-sectional-analytical design study aimed to estimate the radiation exposure dose for adult patients undergoing chest and abdomen CT examinations at Khartoum state hospitals. Material and Methods: Using Size-Specific Dose Estimates (SSDEs) to investigate the effect of body dimensions (Deff) on SSDE calculated from transverse or scout CT images. Scan parameters were collected for 330 adult patients with 165 chests and 165 abdomens for 161 females and 169 males at four hospitals in Khartoum state. For SSDE calculations, it depends on the conversion factor, conversion factors are based on 4 different measurements of torso or head thickness (in our case it’s torso) to represent patient size: by using digital calipers on the scanner console the anteroposterior dimension (AP), the lateral dimension (LAT), the sum of the dimensions (AP LAT), and the effective diameter (Deff) (square root of the product of AP and LAT), which measured from the mid-slice location from transverse or scout CT images. The (Deff) was converted into conversion factors (f) as mentioned in AAPM report 204. Then, the SSDE was calculated by multiplying the console displayed CTDIvol with the size-specific conversion factors (f), in which SSDE is given in mGy. Results: The study found in chest CT, mean CTDIvol and SSDE were 11.99 ± 6.94 mGy and 16.89 ± 9.82 mGy, respectively. In abdominal CT, mean CTDIvol and SSDE were 12.77 ± 8.72 mGy and 18.01 ± 12.30 mGy, respectively. Conclusion: Adding SSDE metric to CT systems and patient dose report is important to help reduce radiation dose to patients according to their dimensions.