Restoring Spline Interpolation of CT Images

In this paper a new technique is used to interpolate the sampled CT image data in the axial direction for a coronal display. This technique also compensates the high spatial frequency components in that direction to get a narrower point-spread function. Computer simulation results are presented here to show the effect of aperture convolution and the effect of spatial sampling in a practical imaging system. It is illuminating to describe the procedures of interpolation in terms of digital filtering. The advantage of restoring spline interpolation is due to the extra frequency compensation in the matrix inversion step. Both step function and sinusoidal function are used in the simulation. The enhanced transition edge and the smaller absolute error in the restoring spline interpolated results are shown. The absolute error depends to a certain extent on the sampling interval relative to the Nyquist interval which is also discussed. There is a small amount of amplification of existing noise or generation of new noise in this technique. Some initial results on a CT image using this technique are also presented.