Mukai T, Links J M, Douglass K H, Wagner H N
Johns Hopkins Medical Institutions, Division of Nuclear Medicine and Radiation Health Sciences, Baltimore, Maryland 21205.
Phys Med Biol. 1988 Oct;33(10):1129-40. doi: 10.1088/0031-9155/33/10/003.
Quantitative assessment of activity levels with SPECT is difficult because of attenuation and scattering of gamma rays within the object. To study the effect of attenuation and scatter on SPECT quantitation, phantom studies were performed with non-uniform attenuation. Simulated transmission CT data provided information about the distribution of attenuation coefficients within the source. Attenuation correction was performed by an iterative reprojection technique. Scatter correction was done by convolution of the attenuation-corrected image and an appropriate filter. The filter characteristics depended on the attenuation and activity measurement at each pixel. The scatter correction could compensate completely for the 28% scatter component from a line source, and the 61% component from a thick, extended source. Accuracy of regional activity ratios and the linearity of the relationship between true radioactivity and the SPECT measurement were both significantly improved by these corrections. The present method is expected to be valuable for the quantitative assessment of regional activity.
由于伽马射线在物体内的衰减和散射，利用单光子发射计算机断层扫描（SPECT）对活动水平进行定量评估很困难。为研究衰减和散射对SPECT定量的影响，采用非均匀衰减进行了体模研究。模拟透射计算机断层扫描（CT）数据提供了有关源内衰减系数分布的信息。通过迭代重投影技术进行衰减校正。通过对经衰减校正的图像与适当滤波器进行卷积来完成散射校正。滤波器特性取决于每个像素处的衰减和活度测量。散射校正可以完全补偿来自线源的28%散射分量以及来自厚的扩展源的61%散射分量。通过这些校正，区域活度比的准确性以及真放射性与SPECT测量之间关系的线性都得到了显著提高。预计本方法对于区域活度的定量评估具有重要价值。
