RESUMO
PURPOSE: This study aims to determine the mean and 75th percentile entrance skin dose (ESDcal) from anteroposterior (AP) chest X-rays using machine parameters (indirect method). Also, a comparison was made between the ESDcal and already determined thermoluminescent dosimeter (TLD) measurements (ESDTLD) from a previous study from the same patients' data. In addition, the results were compared to similar articles, where the direct and indirect methods were used in estimating ESD to newborns. MATERIALS AND METHODS: The study determined the digital radiography (DR) X-ray machine output using a calibrated XR Multidetector (silicon photodiode). X-ray machine milliampere-seconds (mAs), peak kilovoltage (kVp), focus to detector distance (FDD) and focus to skin distance (FSD) were used from a previous study. The mean kVp and mAs were 56.63 (52-60) and 5.7 (5-6.3) and the patient thickness was 9.5 (8-11.5) cm. RESULTS: The mean ESDs of the newborn between 0 and 28 days were 0.67 ± 0.09 mGy, and the 75th percentile was 0.75 mGy. The effective dose (E) for the 40 patients was 0.19 mSv and the estimated prenatal cancer risk ranged from (5-24.7) 10-6 Sv-1. The variation between the indirect and the direct methods for assessing ESD was 39.6 (33.7-45.1)%. CONCLUSION: The 75th percentile ESD was the highest compared to the American College of Radiology-American Association of Physicists in Medicine-Society for Pediatric Radiology (ACR-AAPM-SPR), European Commission (EC) and United Kingdom (UK) reports. Comparison of both methods for assessing ESD was within 40% as compared to other studies. Based on the above results, the indirect method can be implemented for clinical dose audit.
