为验证利用正负电子对三光子湮灭事件进行PET(positron emission tomography)成像的原理,对正电子释放,正负电子对三光子湮灭,γ光子的输运和接收等物理过程用Geant4程序进行了Monte Carlo模拟。根据动量守恒和能量守恒定律,提出由3个γ光子的位置和能量直接计算湮灭位置的解析几何重建算法。进一步研究了探测器能量分辨率对重建图像分辨率的影响。结果表明:具有理想位置分辨能力的探测器对662keV的γ光子能量分辨率为16%时,重建图像断层内分辨率为1.6 mm,轴向分辨率为0.16 mm。 To validate the principle of positron emission tomography (PET) using three-photon annihilation events, the Geant4 program was used for the physical processes of positron emission, positron-electron pair annihilation, photon transport and reception. Monte Carlo simulation. According to the laws of conservation of momentum and conservation of energy, an analytic geometry reconstruction algorithm is proposed to directly calculate the position of annihilation by the location and energy of three γ-photons. The effect of detector energy resolution on the reconstructed image resolution is further studied. The results show that the detector with ideal position resolution has a resolution of 1.6 mm and an axial resolution of 0.16 mm when the energy resolution of γ-ray at 662 keV is 16%.