Kemp B J, Prato F S, Nicholson R L
Department of Nuclear Medicine and Magnetic Resonance, St. Joseph's Health Center, Lawson Research Institute, London, Ontario, Canada.
Med Phys. 1995 Jun;22(6):733-41. doi: 10.1118/1.597478.
An analytic expression has been derived to calculate the geometric modulation transfer function of a transmission imaging system that uses parallel hole collimation for both the source and the SPECT camera. This expression describes the resolution of the transmission imaging system and replaces the need to use computer intensive Monte Carlo simulations for the system design. The geometric modulation transfer function, denoted as MTFg(rho) = [A2sc(Ssc rho)**A2cc(Scc rho)]D(rho), where ** denotes two-dimensional convolution; Asc(rho) and Acc(rho) are the Fourier transforms (FT) of the aperture functions for the parallel hole source collimator (SC) and the camera collimator (CC) holes, respectively; D(rho) is the FT of the camera response; and ssc and scc are scaling constants that depend on the respective collimator dimensions, the system dimensions, the object distance above camera collimator and whether MTFg(rho) is calculated for the object or image plane. The theoretical MTFg(rho) was verified with Monte Carlo simulations and experimental results. The formalism shows that the system resolution is characterized by the camera resolution and a combination of the resolutions of the source and camera collimators. This expression can be used to optimize the design of transmission imaging systems to be used in nuclear medicine.
已经推导了一个解析表达式，用于计算在源和单光子发射计算机断层显像（SPECT）相机均采用平行孔准直的透射成像系统的几何调制传递函数。该表达式描述了透射成像系统的分辨率，取代了在系统设计中使用计算量大的蒙特卡罗模拟的需求。几何调制传递函数表示为MTFg(ρ)=[A2sc(Ssc ρ)A2cc(Scc ρ)]D(ρ)，其中表示二维卷积；Asc(ρ)和Acc(ρ)分别是平行孔源准直器（SC）和相机准直器（CC）孔的孔径函数的傅里叶变换（FT）；D(ρ)是相机响应的FT；ssc和scc是缩放常数，它们取决于各自的准直器尺寸、系统尺寸、相机准直器上方的物体距离以及MTFg(ρ)是针对物体平面还是图像平面计算的。理论MTFg(ρ)通过蒙特卡罗模拟和实验结果得到了验证。该形式表明，系统分辨率由相机分辨率以及源和相机准直器分辨率的组合来表征。该表达式可用于优化核医学中使用的透射成像系统的设计。
