의료용 X-선 조사 시 개인피폭선량계의 방향 및 에너지 의존성에 관한 연구

Abstract

Purposes We measured the scattered radiation occurred when low, medium, high energy x-ray were radiated to a human body phantom respectively by using 3 types of personal dosimeter; TLD, PLD, OSLD under the clinical environment. So that, we intended to understand the characteristics of the scattered radiation with different distances and directions and select the best dosimeter that has the lowest energy and direction dependency to present the basic information which can be the standards for the new personal dosimeter hereafter. Methods An anthropomorphic phantom was irradiated by a general x-ray machine for low energy, a fluoroscopy for medium energy while for high energy is a linear accelerator of radiation therapy machine and scattered radiation was measured by an ion chamber to check traceability of the standard source. We used 3 types of personal dosimeters including TLD, PLD, OSLD to test the sensitivity according to the direction and distance. For each experiment, we repeated the measurements more than 10 times to improve accuracy and comparatively analyzed the angular dependence by using the one way ANOVA method to understand differences on the distance and angle. And also, if there are any considerable differences between the groups from ANOVA methods, we applied SCHEFF’S method for further cause analysis. Results In the low energy category, the OSLD was best in sensitivity depending on distance, amount of radiation and intensity. The TLD is most accurate with kVp variance in energy dependency. The PLD is most superior with mAs variance in energy dependency. There are no differences in angular dependencies. In the medium energy category, the TLD is most accurate in sensitivity and the PLD is most accurate in angular dependency. In the high energy category, the PLD is most accurate from all of the dependencies. Conclusion These three devices are universally used as individual radiation monitoring devices. Results of the three measuring devices’ indicate that the OSLD is most accurate in determining low energies and the PLD is most accurate in determining the medium and high energy levels. And also the PLD is most accurate in angular dependencies in whole energy level. Based on the results that were acquired in a clinical environment, it is important to select the appropriate monitoring device that is best suited for the energy level and type of equipment being used. This will ensure that the safety of health care workers is maintained.