Radiation distribution modeling for development of mobile diagnostic radiology with low-dose exposure

In the development of a mobile X-ray imaging apparatus, it is needed to pre-calculate the ambient leakage and stray radiation doses of the apparatus because the interest in exposure damage is increasing. This issue is strongly related to the additional radiation damage of the patients, caregivers, and radiologists around X-ray emission areas. Monte Carlo simulation with well-applied X-ray device's characteristics is a powerful method to estimate the leakage and stray radiation distribution. The first purpose of this study is to verify an MC simulation model with leakage radiation and stray radiation distribution for accurate scattered dose distribution. The second purpose is to optimize the lead shield part of the X-ray tube and predict various scattered dose distributions with the default and low-dose conditions in three clinical protocols (ChestAP, Abdomen Supine, and Pelvis AP). An X-ray mobile device was imported using a CAD import method for applying its complicated structures easily. X-ray photons were emitted on the anode with skipping the step of electrons hitting the anode for reducing the simulation time. We compared the air-kerma values between the experimental and simulation results under the leakage and stray radiation regulation. Then, we analyzed the dose distribution maps as a function of the size of the lead shield or the distance from the anode focal spot. The experimental and simulation results show similar leakage and stray radiation dose values as functions of the direction and the height, respectively. The analysis of the leakage and stray dose distribution maps shows that the maps strongly depend on the lead shield structures of the X-ray tube. Furthermore, all dose reduction rates of the three clinical protocols were over 40% and similar to the exposure dose reduction rates and remained constant as a function of the distance. This study demonstrates that our proposed simulation model can be used to develop other applications as well as a mobile X-ray imaging device and to protect against additional radiation damage with diverse clinical protocols.