摘要
设计一种可以改变γ射线通道宽度的可调式多路平行束(MPB)准直器,γ射线通过该准直器后形成1个平行束和8个倾斜平行束组成多路平行束,8个倾斜平行束的灵敏度补偿使得可调式MPB准直器能获得更高的灵敏度。本文在两种可调方式下计算和模拟点源和面源的投影性能,可调式MPB准直器对点源的响应具有平行束(PB)准直器的特性,可以看为9个PB准直器的叠加,接受更多的γ光子;而面源的计算和模拟表明,MPB准直器投影随孔长的变化与PB准直器有明显的不同,MPB投影可以分为3个层次:PB方向投影、OPBA方向投影和OPBQ方向投影。OPBA方向投影和OPBQ方向投影随孔长拉伸,有一个凹下、水平和凸起的变化过程,该变化过程为研究在MPB准直器下获取数据的方式提供了基础。与PB准直器相比,MPB准直器具有接收γ光子多、灵敏度高和信噪比高的优势。
An adjustable multiplexing parallel beam（MPB） collimator capable of changing the width of γ-ray channel was designed. After passing through the collimator, γ-ray formed the MPB containing one parallel beam and eight oblique parallel beams. The sensitivity compensation of eight oblique parallel beams made the adjustable MPB collimator achieve higher sensitivity. Based on two adjustable ways, the projection performance of point source and plane source were calculated and simulated. The responses of adjustable MPB collimator to the point source had the characteristics of parallel beam（PB） collimator. Adjustable MPB collimator could be regarded as the superposition of nine parallel beam collimators,receiving more γ photons. The calculation and simulation of plane source indicated that the projection of MPB collimator changing with l was obviously different from that of PB collimator. The MPB projection was divided into three components,including PB projection, oblique parallel beam in axis（OPBA） projection and oblique parallel beam in quadrant（OPBQ）projection. While stretching l, projections of OPBA and OPBQ showed a changing process of concave, horizontal and convex. And the changing process provided the foundation for data acquisition of MPB collimator. Compared with PB collimator, the MPB collimator receives more γ photons and has higher sensitivity and signal noise ratio.
出处
《中国医学物理学杂志》
CSCD
2016年第5期481-490,共10页
Chinese Journal of Medical Physics
基金
基金项目 江苏高校优势学科建设工程
关键词
单光子发射断层成像技术
可调式多路平行束准直器
灵敏度
GATE程序
蒙特卡洛模拟
single photon emission computed tomography
adjustable multiplexing parallel beam collimator
sensitivity
GATE program
Monte Carlo simulation
