Abstract:
The basic challenge with digital radiography systems is the large dynamic range which has the potential to increase patient radiation dose unnecessarily. The aim of this study was to optimize patient radiation protection in digital radiography systems. Entrance skin dose (ESD) of nine radiological examinations were estimated from five selected radiographic centers using mathematical equation. Anthropomorphic phantom images were acquired with different exposure factors for chest posterior anterior (PA), lumbar spine anterior posterior (AP) and lumbar spine lateral (LAT) at one of the centers. Clinical assessment of the images were done by three (3) senior radiographers to determine the optimal peak-kilo-voltage (kVp), milli-ampere seconds (mAs), Entrance skin dose and exposure indicator (EI). The average ESDs estimated were 0.66 ± 0.60, 2.47 ± 0.80, 3.77 ± 0.90, 0.47 ± 0.30, 0.49 ± 0.30, 1.37 ± 0.60, 1.29 ± 0.50, 1.74 ± 0.80 and 2.15 ± 0.90 mGy for chest PA, lumbar spine AP, lumbar spine LAT, cervical spine AP, cervical spine LAT, skull PA, skull LAT, pelvis AP, and abdomen AP respectively. The optimal exposure factors were 90 kVp, 2.5 mAs; 100 kVp, 2.0 mAs and 110 kVp; 1.6 mAs for chest PA. The optimal EI was obtained to be within the range of 2323 – 2355 with optimal ESD of 0.29 mGy. 70 kVp; 22 mAs with associated EI of 348 – 363 and optimal ESD of 1.97 mGy were obtained for lumbar spine AP. For lumbar spine LAT, 80 kVp; 25 mAs, and 90 kVp; 20 mAs, with EI values of 895 – 1005 were obtained. The optimal ESD obtained for lumbar spine LAT were 3.20 and 3.30 mGy. In conclusion, model equation of EI, mAs, and kVp, as well as optimization management flow chart were developed to help reduce patient radiation dose in digital radiography.
