  In this paper I show a matrix method to calculate the exact inverse
pseudopolar grid Fourier transform, and use this transform to do noise removals
in the k space of pseudopolar grids. I apply the Gaussian filter to this
pseudopolar grid and find the advantages of the noise removals are very
excellent by using pseudopolar grid, and finally I show the Cartesian grid
denoise for comparisons. The results present the signal to noise ratio and the
variance are much better when doing noise removals in the pseudopolar grid than
the Cartesian grid. The noise removals of pseudopolar grid or Cartesian grid
are both in the k space, and all these noises are added in the real space.
