Reconstruction algorithm for back projection weight cone-beam CT (Computed Tomography)

Abstract

The invention relates to a reconstruction algorithm for back projection weight cone-beam CT, belonging to the field of X-ray computed tomography. The reconstruction algorithm comprises the following steps of: introducing a ray back projection weight based on a filtering back projection reconstruction frame, acting the back projection weight based on distance and continuity of conjugate rays on filtered projection data during back projection so as to reconstruct a CT image, and performing certain compensation on Radon missing data to improve the intrinsic cone-beam artifact problem of an FDK (Feldkamp-Davis-Kress) algorithm under circular track and increase the reconstruction quality. According to the reconstruction algorithm disclosed by the invention, the frame based on the filtering back projection has simple and efficient reconstruction process and is insensitive to noise.

Description

technical field [0001] The invention belongs to the field of image reconstruction of a CT system, and is applied to an image reconstruction algorithm of a cone-beam CT system under a circular trajectory. Background technique [0002] Because circular motion has high motion stability and is mechanically simple and easy, and circular trajectory scanning has no displacement in the z-axis direction, it will not introduce motion deviation in the z-axis direction, so the circular scanning method is widely used in cone beam CT. . Cone-beam short-scan structures with circular trajectories such as figure 1 shown. figure 1 In , for the convenience of understanding and derivation, a virtual detector is introduced at the center of rotation, and its size is geometrically proportional to the actual detector. [0003] Currently the most widely used in commercial CT systems is the FDK algorithm of the filtered back-projection framework. This algorithm is an approximate cone beam reconst...

AI Technical Summary

Problems solved by technology

The central idea is to use some operations to reduce the artifacts caused by inaccurate reconstruction when the cone angle increases, and does not consider compensation for the inherent shadow area of ​​​​circular trajectory scanning, so these algorithms work when the cone angle is small (less than ±5° ) has higher reconstruction quality, the cone beam artifact is still very serious, and the improvement effect is limited

[0008] Since the cone beam scanning structure based on the circumference does not meet the complete reconstruction conditions, when the cone angle increases, the Radon data will be missing, and the larger the cone angle, the more serious the data loss

Images