Study On Doses Delivered To Chinese Adult Patient Underwent Digital Chest X-ray Radiography

To study organ and tissue doses delivered to Chinese adult patient in digital chest radiography procedure in order to provide evidence for the evaluation of population radiation risk and patient radiation protection. Material and methods: Firstly, the clinic measurements were carried out in Hunan province. Local hospitals and the Centers of Disease Control (CDC) of different levels were sampled. Entrance skin dose (ESD) of every 10 adult patients who received chest postero-anterior view (PA) or lateral (LAT) diagnostic radiography were measured for all the equipment of the sampling units, Thermoluminescence detectors (TLD, the materials were LiF,Mg,Cu,P) were used to detect the ESD. Technical parameters used in clinical condition were recoded and were then used in the consequent studies. Secondly, a Monte Carlo (MC) technical with an adult "Medical Internal Irradiation Dose" (MIRD) mathematical model and the parameters used in clinical condition of chest radiography were used to calculate organ and tissue doses, and the doses were normalize to ESD, thus the dose converse factors (DCF) were archived. Thirdly, male and female Chinese adult anthropomorphic phantoms with TLDs placed in organs and tissues were irradiated by a direct radiography (DR) system with PA and LAT procedure, respectively. The technical parameters used in the procedures were the followings: the tube potential was 110kV, automatic exposure control (AEC), focus to skin distance (FSD) was 152cm. And then, the absorbed dose of the organs and tissues were measured to calculate the DCF. Finally, the result of each steps were summarized to obtain typical organ and tissue doses in the typical irradiation parameters. Results: 35 radiation equipments of 30 hospitals and CDCs were sampled, and the number of the patient who received chest PA and LAT procedure were 226 and 73, respectively. The mean patient ESD was 0.38±0.49mGy/graphy, 0.79±0.57mGy/graphy for chest PA and LAT procedure, respectively. Compared the results with that of the last national survey, it was found that for PA procedure, there were no significant difference between the national level and the result of this study, but lower than that of the Hunan provincial level. As for LAT procedure, the result of this study was significantly lower than that of last national survey. The high kV technical model used in PA procedure may be resulted in lower ESD in the screen-film system and the computed radiography (CR) system than the conventional kV model, except for the DR system. As for the LAT procedure, no difference was found between the two different tube potential models, without reference to different systems. Absorbed doses and DCF of organs or tissues in typical clinical chest radiography were archived using MC simulation and experiment measurement, respectively. Good agreement was found for organs and tissues which were lay under the direct radiation field between the two methods. For the typical condition of digital chest PA procedure, the calculated effective dose according to ICRP publication 60 was 0.14mSv, 0.17mSv for adult male and female, respectively, and for the LAT procedure, the patient effective dose for female was 0.99mSv. However, the corresponding effective doses were 0.24mSv, 0.53mSv and 2.0mSv when it was calculated according to ICRP publication 103. DCF from ESD to effective dose were also calculated according to ICRP publication 60 and 103. For male patient, the DCF was 0.19 and 0.32 for chest PA procedure, respectively. And for female, the DCF was 0.25, 0.78, respectively. As for LAT procedure, the female patient DCF was 0.31, 0.63, respectively. Conclusion: The result of Chinese adult patient dose in chest radiography provides scientific evidence for further chest image optimization, and can be of great useful to evaluate the radiation risk of population and to patient radiation protection. The use of adult Chinese Anthropomorphic phantom in the measurement of DCF from ESD to organ and tissue absorbed doses in chest digital radiography, the comparison of these to MC calculation, and the comparison of the calculation of effective dose in chest radiography according to ICRP 60 and 103 publication is the innovation point of this study.