实体造型，通过半边数据结构实现变结构设计

在Linux系统中实现对PET的仿真，给予VGATE平台实现，初步提出变结构的设想，提高成像的空间分辨率，减弱DOI效应的影响。(In the Linux system, the simulation of PET is realized and the VGATE platform is implemented. The tentative idea of changing the structure is proposed, the spatial resolution of the ima