Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Phys Med Biol. 2011 Sep 21;56(18):N183-93. doi: 10.1088/0031-9155/56/18/N01. Epub 2011 Aug 24.
Attenuation of photon flux on trajectories between the source and pinhole apertures affects the quantitative accuracy of reconstructed single-photon emission computed tomography (SPECT) images. We propose a Chang-based non-uniform attenuation correction (NUA-CT) for small-animal SPECT/CT with focusing pinhole collimation, and compare the quantitative accuracy with uniform Chang correction based on (i) body outlines extracted from x-ray CT (UA-CT) and (ii) on hand drawn body contours on the images obtained with three integrated optical cameras (UA-BC). Measurements in phantoms and rats containing known activities of isotopes were conducted for evaluation. In (125)I, (201)Tl, (99m)Tc and (111)In phantom experiments, average relative errors comparing to the gold standards measured in a dose calibrator were reduced to 5.5%, 6.8%, 4.9% and 2.8%, respectively, with NUA-CT. In animal studies, these errors were 2.1%, 3.3%, 2.0% and 2.0%, respectively. Differences in accuracy on average between results of NUA-CT, UA-CT and UA-BC were less than 2.3% in phantom studies and 3.1% in animal studies except for (125)I (3.6% and 5.1%, respectively). All methods tested provide reasonable attenuation correction and result in high quantitative accuracy. NUA-CT shows superior accuracy except for (125)I, where other factors may have more impact on the quantitative accuracy than the selected attenuation correction.
光子通量在源和小孔孔径之间的轨迹上的衰减会影响重建单光子发射计算机断层扫描（SPECT）图像的定量准确性。我们提出了一种基于 Chang 的小动物 SPECT/CT 非均匀衰减校正（NUA-CT），用于具有聚焦小孔准直的小动物 SPECT/CT，并将定量准确性与基于（i）从 X 射线 CT 提取的体轮廓（UA-CT）和（ii）在三个集成光学相机获得的图像上手工绘制的体轮廓（UA-BC）的均匀 Chang 校正进行比较。在含有已知放射性核素活动的体模和大鼠中进行了测量以进行评估。在（125）I、（201）Tl、（99m）Tc 和（111）In 体模实验中，与剂量校准器测量的金标准相比，平均相对误差分别降低至 5.5%、6.8%、4.9%和 2.8%，用 NUA-CT。在动物研究中，这些误差分别为 2.1%、3.3%、2.0%和 2.0%。在体模研究中，除了（125）I（3.6%和 5.1%）之外，NUA-CT、UA-CT 和 UA-BC 结果的平均精度差异小于 2.3%，在动物研究中差异小于 3.1%。所有测试的方法都提供了合理的衰减校正，并实现了高定量准确性。除了（125）I 之外，NUA-CT 显示出更高的准确性，在这种情况下，其他因素对定量准确性的影响可能大于所选的衰减校正。
