Optimization of Large-Angle Pinhole Collimator for Environmental Monitoring System
Optimization of Large-Angle Pinhole Collimator for Environmental Monitoring System
复制标题
环境监测系统大角度针孔准直器的优化
DOI：
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复制
发表时间：
2010
影响因子：
1.8
通讯作者：
Y. Chung
中科院分区：
文献类型：
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作者：
Cheol;Seung;Yong Choi;Y. Chung
本研究的目的是使用蒙特卡罗模拟来优化一个大角度针孔准直器用于核测量成像。使用GATE（Geant 4应用断层扫描发射）进行模拟，以模拟针孔伽马相机系统。γ照相机由一个锥形针孔准直器和一个厚度为6.0mm、面积为50.0mm × 50.0mm的CsI（Tl）闪烁晶体组成。针孔准直器的焦距和接收角分别设定为14.5 mm和120°。通过改变针孔直径和通道高度模拟了本征空间分辨率和灵敏度。Tc-99 m的点源位于针孔中心上方30.0 mm处，针孔直径为0.5 ~ 4.0 mm，通道高度固定在刀口和3.0 mm之间，对投影数据进行估算，通过评价本征分辨率和灵敏度折衷曲线，确定了通道高度和针孔直径的最佳范围。模拟结果使我们能够确定针孔直径和通道高度的最佳值分别为1.5 mm和0.5 mm，以获得低于2.0 mm FWHM的固有分辨率，并具有本研究中配置的系统的合理灵敏度。实验测量了分辨率和灵敏度，模拟值与实测值吻合较好。结果显示，本研究所设计之针孔准直器可应用于大角度辐射监测系统。
The purpose of this study was to optimize a large-angle pinhole collimator using Monte Carlo simulation for nuclear survey imaging. Simulations using GATE (Geant4 Application for Tomographic Emission) were performed to model the pinhole gamma camera system. A gamma camera consists of a cone-shaped pinhole collimator with a tungsten aperture and a CsI(Tl) scintillation crystal 6.0 mm thick and 50.0 mm × 50.0 mm in area. The focal length and the acceptance angle of the pinhole collimator were set to 14.5 mm and 120°, respectively. The intrinsic spatial resolution and sensitivity were simulated by changing the pinhole diameter and channel height. The point source of Tc-99m was located 30.0 mm above the center of the pinhole, and the projection data was estimated for pinhole diameter values from 0.5 mm to 4.0 mm while the channel heights were fixed between knife-edge and 3.0 mm. The optimal ranges of channel height and pinhole diameter were determined through evaluation of the intrinsic resolution and sensitivity tradeoff curves. The simulation results allowed us to determine the optimal values of pinhole diameter and channel height to be 1.5 mm and 0.5 mm, respectively, to get intrinsic resolution below 2.0 mm FWHM with a reasonable sensitivity for the system configured in this study. The resolution and sensitivity were measured experimentally, and the simulated and measured data were in good agreement. The results demonstrated that the pinhole collimator designed in this study could be utilized to create a large-angle radiation monitoring system.