Tsui B M, Gullberg G T, Edgerton E R, Ballard J G, Perry J R, McCartney W H, Berg J
Department of Radiology, University of North Carolina, Chapel Hill 27599.
J Nucl Med. 1989 Apr;30(4):497-507.
Correction for photon attenuation in cardiac SPECT imaging using a measured attenuation distribution with an iterative expectation maximization (EM) algorithm and an iterative Chang algorithm were compared with the conventional filtered backprojection and an iterative EM algorithm without attenuation correction. The attenuation distribution was determined from a transmission computed tomography study that was obtained using an external collimated sheet source. The attenuation of the emitting photons was modeled in the EM algorithm by an attenuated projector-backprojector that used the estimated attenuation distribution to calculate attenuation factors for each pixel along each projection and backprojection ray. Results from a heart-lung phantom study and a 201Tl patient study demonstrated that the iterative EM algorithm with attenuation correction provided improved image quality in terms of reduced streak artifacts and noise, and more accurate quantitative information in terms of improved radioactivity distribution uniformity where uniformity existed, and better anatomic object definition.
使用测量的衰减分布并结合迭代期望最大化（EM）算法和迭代昌算法，对心脏单光子发射计算机断层显像（SPECT）成像中的光子衰减进行校正，并将其与传统的滤波反投影以及未进行衰减校正的迭代EM算法进行比较。衰减分布由使用外部准直平板源获得的透射计算机断层扫描研究确定。在EM算法中，发射光子的衰减通过衰减投影-反投影模型进行模拟，该模型使用估计的衰减分布来计算沿每个投影和反投影射线的每个像素的衰减因子。心肺模型研究和201铊患者研究的结果表明，具有衰减校正的迭代EM算法在减少条纹伪影和噪声方面提高了图像质量，在存在均匀性的放射性分布均匀性改善方面提供了更准确的定量信息，并且具有更好的解剖物体定义。
