Moore S C, Brunelle J A, Kirsch C M
J Nucl Med. 1982 Aug;23(8):706-14.
An iterative procedure to correct for attenuation has been developed for a multidetector, single-photon emission tomographic scanner. The difference between measured and estimated data projections is used at each iteration to form an error image which is used, in turn, to correct the image. A damping factor that minimizes chi2 is applied after each iteration to speed convergence. Several phantoms of different size, with various concentration distributions, have been used to compare this method with a first-order multiplicative attenuation correction used previously with this scanner. The first-order correction is inadequate for most of the phantoms studied, whereas relative and absolute quantitative capability is demonstrated for the iterative attenuation correction. The reconstructed average number of counts per pixel is a linear function of activity concentration up to 5 muCi/ml for all regions of uniform activity whose size is greater than or equal to 5 cm. The importance of using an accurate attenuation distribution with this method is demonstrated with a torso-like phantom.
已为多探测器单光子发射断层扫描仪开发了一种用于校正衰减的迭代程序。在每次迭代中，使用测量数据投影与估计数据投影之间的差异来形成误差图像，该误差图像又用于校正图像。每次迭代后应用一个使χ2最小化的阻尼因子以加快收敛速度。已使用几个不同大小、具有各种浓度分布的体模，将该方法与先前在此扫描仪上使用的一阶乘法衰减校正进行比较。对于大多数研究的体模，一阶校正并不充分，而迭代衰减校正则显示出相对和绝对定量能力。对于所有大小大于或等于5厘米的均匀活性区域，重建的每像素平均计数数量是活性浓度高达5μCi/ml的线性函数。使用躯干状体模证明了在此方法中使用准确衰减分布的重要性。
