system and method for spiral 3d computed tomography with exact reconstruction

摘要

A helical conebeam computed tomography imaging system includes an x-ray source (12) that produces an x ray conebeam, and an x-ray detector array (16) that detects the x ray conebeam after passing through an examination region (14). The x-ray detector array (16) generates projection data in a detector coordinate system defined with reference to the detector array (16). A derivative processor (60) computes a derivative of the projection data with respect to a helix angle of the helical trajectory at fixed projection direction to generate differentiated projection data. A convolution processor (64) convolves the differentiated projection data with a kernel function to produce filtered projection data. The convolving is performed in the detector coordinate system. A backprojector (42, 82) backprojects the filtered projection data to obtain an image representation.