Region of Interest Reconstruction of Tomographic Images using Filter Banks
Gomathi Sankar, Sumana Gupta · IETE Journal of Research · 2000
A new technique for ROI image reconstruction from projections using filter banks is reported in this paper. It is known that the convolution back projection operator, used for reconstruction of images from 1D-projections, has a non-local filter which requires global projection data. In X-ray tomography, the exposure time of the object to harmful radiation is thereby increased. Recently, it has been proved that this filtering operation can be done on a chosen wavelet function instead of the projections. This localizes the filter and leads to ROI image reconstruction with reduced projections. This concept was extended using 2D and 1D MRA filter banks, in which the filters are combined with the non-local CBP filter to get short length filters. In this paper it is proved that the presence of unwanted information in all previous algorithms is due to aliasing and a new technique is proposed for reconstruction without any aliasing. The proposed scheme is implemented using Shepp-Logan phantom head image and the performance is compared.