【摘要】 点源扩展函数PSF作为SPECT成像的一个重要参考,反映出相应准直器灵敏度和空间分辨率等的特性。本文在多通道平行束准直器MPB的几何框架下进行物理模型构建,解释了由探测器晶体厚度引起的PSF变化以及基于该变化进行的公式修正,指出了不利的因素,其结果与蒙特卡罗模拟基本吻合。在PSF基础上,结合蒙特卡洛模拟,指出了在准直器的拉伸过程中,斜平行束部分OPB的灵敏度变化特性和对准直器的补偿作用;通过两点源逐渐接近的过程,并与高灵敏度平行束准直器HSPB对比,指出MPB准直器在保持高灵敏度下,还能有高空间分辨率的原理,提出了一种设计高灵敏度和高空间分辨率准直器的方法。更多还原

【Abstract】 Point Spread Function is an important reference for SPECT image reconstruction,and it reflects the characteristic of collimator such as the sensitivity and the spatial resolution. We constructed the physical model which was based on the Multi Parallel Beam collimation in the paper,then explained the figure changes of the PSF caused by the thickness and modified the formula in order to find out what factors are against it. The calculation results agree with the Monte Carlo simulation result. Base on the PSF and Monte Carlo simulation,we discuss the change of the sensitivity and compensate it in the process of stretching length of collimator. Through the comparison of the Multi Parallel Beam Collimator and the Parallel Beam Collimator with reducing of the distance between two point sources,it is pointed out the reason why the MPB collimator can improve sensitivity while maintaining higher spatial resolution and the method of how to design the collimator which can have high sensitivity and high spatial resolution.更多还原