Local tomography in fan-beam geometry using wavelets
An algorithm is developed for wavelet based multiresolution reconstruction of a function directly from its fan beam projections. The algorithm uses the locality of wavelet and scaling functions to reconstruct a local region of interest with reduced exposure. In other words, our algorithm saves the radiation exposure in the cases where only a local region of the cross section of a body is to be reconstructed. For example, in order to reconstruct a region of 16 pixels in radius in a 256/spl times/255 image, our method can reduce the X-ray dosage down to 22% of full exposure.