이중 X-선 영상 획득용 검출기 모듈에 관한 연구

Abstract

Dual X-ray imaging can be used to separate soft and dense-material images for medical and industrial applications. Detector Modules for dual X-ray imaging are consisted of low energy detector (LED) and high energy detector (HED). So this study has carried out simulation and experiment for detector modules that LED was coupled with Lanex Regular scintillator and HED were coupled with the Eu-doped (Gd,Y)₂O₃ ceramic scintillator new developed by KAIST and Lanex fast B scintillator considered in this study. First, the optimized thickness of copper filter coupled HED to separate low energy and high energy was simulated by the given X-ray energy (140 kVp, 1 mA) using Monte Carlo simulation codes, MCNPX. So as a result of simulation, the copper filter thickness is 0.7 mm. For the design of the PIN photodiode, ATLAS device simulation tool was used. 16 channels PIN photodiode of 1.5 mm x 3.2 mm for Dual X-ray imaging detector were fabricated in the process of ETRI. Leakage current of this photodiode was measured to range of 0.2 ~ 10 pA. Each component of the dual X-ray imaging detectors was fabricated and tested including Data Acquisition System (DAS). It was proven that the ceramic scintillator and Lanex Fast B coupled HED were a sufficient candidate to replace the CsI(Tl) commerced in dual X-ray system, since these give a strong signal, overcoming system noise. Comparing the Lanex Regular coupled photodiode for perpendicular imaging, the output signals of the ceramic scintillator and Lanex Fast B coupled photodiode were each 1/5, 1/2.5 at the same X-ray exposure condition at copper filter thickness 0.7 mm. This signal difference is enough to realize dual imaging in the dual X-ray scanner. In the near future, after improvements of the DAS, the acquired image will be analyzed.