Dept. of Appl. Sci. in Med., Alberta Univ., Edmonton, Alta.
IEEE Trans Med Imaging. 1992;11(4):539-45. doi: 10.1109/42.192689.
An indirect method for determining the point-spread-function (PSF) in computed tomography (CT) is described. Unlike experimental techniques in which a resolution phantom is scanned to obtain the system PSF, the approach estimates the parameters of a model which describes the two-dimensional X-ray beam profile at each point as a convolution of the appropriately scaled focal spot intensity and detector sensitivity distributions. The model was validated by experimental measurement of the focal spot intensity distribution. Using known X-ray beam profiles, the PSF of a CT scanner can be derived by simulating the data collection process and applying conventional image reconstruction techniques. Visual comparison of directly measured and computed PSFs reveals an asymmetry resulting from misregistration of the phantom wires and the image grid.
介绍了一种在计算机断层扫描（CT）中确定点扩散函数（PSF）的间接方法。与通过扫描分辨率体模来获取系统 PSF 的实验技术不同，该方法估计了一个模型的参数，该模型将描述在每个点处二维 X 射线束轮廓的函数描述为适当缩放的焦点强度和探测器灵敏度分布的卷积。通过实验测量焦点强度分布验证了该模型。使用已知的 X 射线束轮廓，可以通过模拟数据采集过程并应用常规图像重建技术来推导 CT 扫描仪的 PSF。直接测量和计算的 PSF 的视觉比较显示出由于体模线和图像网格的未对准而导致的不对称。
