US 6,148,056 A · Efficient cone-beam reconstruction system using circle-and-line orbit data

Abstract

A system is provided for reconstructing x-ray tomographic images based upon the circle-and-line orbit. The system includes the steps of combining, in the frequency domain, images reconstructed separately from the circular and linear orbit data. Specifically, the method involves the steps of (1) converting the shadow zone into a shadow cone in frequency domain, (2) mapping the shadow cone in 3D Fourier space onto a set of 2D Fourier planes, (3) removing data lying within the region marked as the projection of the shadow cone from the Fourier transform of the circular orbit data and patching the same from the Fourier transform of the line orbit data, (4) transforming each 2D Fourier plane into a respective 2D image plane, and (5) converting the horn-shaped volume back to a grid volume. An interpolation technique is also provided for reconstructing the line orbit data using a Direct Fourier method (DFM).

Claims19

Dependent claims

A method of reconstructing x-ray tomographic images comprising data from a circular orbit and data from a linear orbit, based on a shadow zone formed by projecting data of the circular orbit, such method comprising the steps of:

representing the image obtained from the circular orbit in a circular horn-shaped volume;
representing the image obtained from the linear orbit in a corresponding linear horn-shaped volume;
converting 2D images in the vertical planes of each said circular horn-shaped volume and each said linear horn-shaped volume into a plurality of 2D Fourier planes;
removing projections of a 3D shadow cone in each of said 2D Fourier planes from the circular orbit data and replacing said projections with the corresponding projections obtained from the linear orbit data, so as to generate a plurality of repaired 2D Fourier planes;
conducting an inverse 2D Fourier Transform on said plurality of repaired 2D Fourier planes to obtain a respective plurality of 2D image planes, representing a resulting horn-shaped volume;
and
converting said resulting horn-shaped volume back to the x-ray tomographic image.

4 more elements

An apparatus for reconstructing x-ray tomographic images comprising data from a circular orbit and data from a linear orbit, based on a shadow zone formed by projecting data of the circular orbit, such apparatus comprising:

means for representing the image obtained from the circular orbit in a circular horn-shaped volume;
means for representing the image obtained from the linear orbit in a corresponding linear horn-shaped volume;
means for converting 2D images in the vertical planes of each said circular horn-shaped volume and each said linear horn-shaped volume into a plurality of 2D Fourier planes;
means for removing projections of a 3D shadow cone in each of said 2D Fourier planes from the circular orbit data and replacing said projections with the corresponding projections obtained from the linear orbit data, so as to generate a plurality of repaired 2D Fourier planes;
means for conducting an inverse 2D Fourier Transform on said plurality of repaired 2D Fourier planes to obtain a respective plurality of 2D image planes, representing a resulting horn-shaped volume;
and
means for converting said resulting horn-shaped volume back to the x-ray tomographic image.

4 more elements

Dependencies are inferred from the claim text.

Efficient cone-beam reconstruction system using circle-and-line orbit data

Life of this patent

Efficient cone-beam reconstruction system using circle-and-line orbit data

Life of this patent

Abstract

Claims19