Nowadays X ray computerized tomography has been one of the most important diagnostic tools in medicine. However

sometimes the metallic implants absorb the X rays and therefore introduce streaks on the reconstructed images

which interfere diagnosis severely. In this paper

a simple interpolation method using quartic polynomials to fill in the missing projections is presented. The clipping on the pixel values of the reconstructed image is also proposed. The polynomial is determined by several criteria

namely smooth transition at the ends of the gap of missing projections

being as linear as possible inside the gap

and constant sum of interpolated projections in every direction. Value clipping eliminates irrational pixel values by evaluating the distribution of pixel values. Experiments show that by our method

the streaks caused by the metallic implants can be greatly suppressed and the contrast can be significantly improved.