Smith M F, Floyd C E, Jaszczak R J, Coleman R E
Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710.
Phys Med Biol. 1992 Mar;37(3):605-22. doi: 10.1088/0031-9155/37/3/008.
In single photon emission computed tomography (SPECT), three-dimensional photon detection kernels characterize the probabilities that photons emitted by radio-isotopes in different parts of the source region will be detected at particular projection pixels of the projection images. Monte Carlo modelling is used to study these kernels for the case of parallel hole collimators. The use of vectorized Monte Carlo computer code speeds the modelling computations. The contributions of direct and scattered photons to projection data in a transverse plane from neighbouring planes are significant for the case of uniform activity within a water-filled cylinder. A reconstruction method using the 3D kernels is proposed in which projection measurements in three adjacent planes are used simultaneously to estimate the source activity of the center plane. This multiple slice method accounts for the fact that photons detected in a given transverse plane may have originated in other transverse planes with different activity distributions. The matrix equations for image reconstruction are solved using generalized matrix inverses. The new method shows compensation for 3D photon detection effects when applied to projection data from a numerical simulation and a cardiac phantom experiment. Quantitation for the numerical study is improved compared with results from a single slice reconstruction method.
在单光子发射计算机断层扫描（SPECT）中，三维光子探测核表征了源区域不同部位的放射性同位素发射的光子在投影图像的特定投影像素处被探测到的概率。蒙特卡罗建模用于研究平行孔准直器情况下的这些核。矢量化蒙特卡罗计算机代码的使用加快了建模计算速度。对于充满水的圆柱体内部均匀活性的情况，直接光子和散射光子对相邻平面横向平面投影数据的贡献很大。提出了一种使用三维核的重建方法，其中同时使用三个相邻平面中的投影测量来估计中心平面的源活性。这种多切片方法考虑了在给定横向平面中检测到的光子可能起源于具有不同活性分布的其他横向平面这一事实。使用广义矩阵逆来求解图像重建的矩阵方程。当应用于数值模拟和心脏模型实验的投影数据时，新方法显示出对三维光子探测效应的补偿。与单切片重建方法的结果相比，数值研究的定量得到了改善。
