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9 May 2002Denoising of cone beam CT image using wavelet transform
We have developed a method to remove the noise from the cone beam CT image and consider the reduction of a patient's dose. In diagnostic medicine, cone beam CT increases a patient' exposure dose. The X-ray CT image is degraded by the noise that is called quantum mottle, and the noise becomes so remarkable with decreasing patient' dose. It is known that the image signal can be separated from the noise by measuring the Lipschitz exponents of the image singularities from the evolution of wavelet transform modulus maxima across scales. We identify the singularities of 2-D projections by computing the wavelet transform modulus sum (WTMS) in the direction which is indicated by the phase of wavelet transform. Our preliminary results show the validity of the method based on 2-D WTMS for removing quantum mottle from 2-D projection. And it shows the possibility that the patient's dose can be reduced by this method.