Ljungberg M, Strand S E
Radiation Physics Department, University of Lund, Sweden.
J Nucl Med. 1991 Jun;32(6):1278-84.
Single-photon emission computed tomography (SPECT) is important for imaging radioactivity distributions in vivo. Quantitative SPECT is limited due to attenuation and scatter contribution. Approximations such as constant attenuation and mono-exponential scatter functions will not be valid for non-homogeneous regions. A correction method is described where non-uniform density-maps are used in the attenuation correction. Correction for non-uniform scatter is made by a convolution technique based on scatter line-spread functions (SLSF) calculated for different locations inside a clinically realistic, nonhomogeneous, computer phantom. Calculations have been made for a myocardiac source, a uniform source in the lungs and a tumor located in the lungs. Projections were simulated for photon energies corresponding to 201Tl, 99mTc, and 111In. The results show that quantitative images can be obtained in nonhomogeneous regions. An increased contrast has also been demonstrated in the SLSF-corrected images. Comparison with measurements have been made to validate the Monte Carlo code and the scatter and attenuation method.
单光子发射计算机断层扫描（SPECT）对于体内放射性分布成像非常重要。由于衰减和散射的影响，定量SPECT受到限制。诸如恒定衰减和单指数散射函数等近似方法对于非均匀区域将无效。本文描述了一种校正方法，其中在衰减校正中使用非均匀密度图。通过基于为临床实际的非均匀计算机体模内不同位置计算的散射线扩展函数（SLSF）的卷积技术对非均匀散射进行校正。已针对心肌源、肺部均匀源和肺部肿瘤进行了计算。模拟了对应于201Tl、99mTc和111In的光子能量的投影。结果表明，可以在非均匀区域获得定量图像。在SLSF校正的图像中也显示出对比度增加。已与测量结果进行比较以验证蒙特卡罗代码以及散射和衰减方法。
