Verly J G
Med Phys. 1980 Jan-Feb;7(1):27-34. doi: 10.1118/1.594655.
A loss of resolution in tomographic images is due to the well-known bimodal spatial variations in photon emission across the x-ray focal spot combined with the finite width of the x-ray detector. Such departures from the ideal infinitely narrow beams which are usually considered can be taken into account by replacing the customary line integrals by suitably chosen integrals over strips. The image degradation resulting from using those strip integrals as ingredients in conventional reconstruction formulas is expressible as a complicated point spread function, which can always be computed in any given situation. Restoring the reconstructed image to provide higher resolution is a nontrivial operation, which however greatly benefits from experience already gained in dealing with optical imagery degraded by the aberrations of astigmatism and curvature of field. Typical point spread functions are shown for a simple bimodal source intensity distribution of primordial importance.
断层图像分辨率的损失是由于众所周知的光子发射在X射线焦点上的双峰空间变化，再加上X射线探测器的有限宽度。与通常所考虑的理想无限窄光束的这种偏差，可以通过用适当选择的条带积分代替传统的线积分来考虑。将这些条带积分用作传统重建公式中的要素所导致的图像退化，可以表示为一个复杂的点扩散函数，在任何给定情况下都可以计算出来。恢复重建图像以提供更高的分辨率是一项复杂的操作，不过这从处理因像散和场曲像差而退化的光学图像时已经获得的经验中受益匪浅。对于具有基本重要性的简单双峰源强度分布，给出了典型的点扩散函数。
