Limited Field of View Reconstruction in Computerized Tomography

A generalized method for the reconstruction of a region of interest within a slice in the presence of beam hardening is introduced. The method, limited field of reconstruction (LFV), is based on variable sampling of the projection data and a post-reconstruction correction scheme. An initial reconstruction of the whole slice is performed using the coarsely sampled projections. The low resolution reconstructed image is used to estimate the bone and tissue thicknesses along each ray. The bone and tissue lengths obtained from the first low resolution image are then used in subtracting the contribution of the external region from the region of interest and to correct for beam hardening. The finely sampled corrected projections are used in reconstructing a high resolution image of the region of interest without artifacts from the external region and beam hardening. Computer simulation results are presented and applicability of the present correction method to practical scanners is discussed.