Reconstruction of images from cone beam data

• US 5,400,255 A
• Filed: 02/14/1994
• Issued: 03/21/1995
• Est. Priority Date: 02/14/1994
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hu, Hui
• Primary Examiner(s): Hayes, Gail O.
• Assistant Examiner(s): Thomas, Joseph
• Application Number:
  US08/194,894
• Time in Patent Office: 400 Days
• Field of Search: 364/413.13, 364/413.14, 364/413.15, 364/413.16, 364/413.17, 364/413.19, 364/413.21, 364/413.24, 382/6, 250/363.01, 250/363.02, 250/363.03, 250/363.04, 250/363.1, 345/149, 395/125, 395/126, 395/127, 378/901, 128/653.1, 128/659, 128/664
• US Class Current: 378/4
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G06T 11/008 Specific post-processing after tomographic reconstruction, e.g. voxelisation, metal artifact correction
• CPC Class Codes: G06T 2211/421 Filtered back projection [FBP]
• CPC Class Codes: H05G 1/60 Circuit arrangements for obtaining a series of X-ray photographs or for X-ray cinematography
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

A computed tomography x-ray imaging system acquires a three-dimensional array of x-ray attenuation values using a cone beam x-ray source [(13)] and a curved two-dimensional array of detector elements [(16)]. Two-dimensional image slices [(55)] are reconstructed using a filtered back projection method, and corrections are made to the images to account for inaccuracies in the reconstruction method and for incomplete data due to the cone beam geometry.

Claims

1. A computed tomography imaging system which comprises:

a two-dimensional array of detector elements for receiving photons emanating in a cone beam from a source;

a digital acquisition system for acquiring two-dimensional arrays of cone beam data from the array of detector elements at a series of views in which the array of detector elements revolves around a central axis;

a filter for receiving the cone beam data and filtering the same;

means for back projecting the filtered cone beam data to produce image data f_M0 (r);

row summing means for receiving the cone beam data and summing the values therein along one of two dimensions of said two-dimensional arrays of cone beam data to form one-dimensional arrays of row sum data;

means for filtering the row sum data;

means for back projecting the filtered row sum data to produce corrective image data f_M1 (r); and

summing means for combining the image data f_M0 (r) with the correction image data f_M1 (r) to produce an image slice.

2. The computed tomography system as recited in claim 1 which includes:

means for receiving the cone beam data and estimating values not provided by the received cone beam data;

means for receiving the estimated values and calculating corrected image data f_N (r); and

the summing means also combines the corrected image data f_N (r) to produce the image slice.

3. The system as recited in claim 1 which includes means for weighting the cone beam data prior to its application to the filter and the row summing means.

4. The system as recited in claim 1 in which the source produces x-rays and is located on the side opposite the array of detector elements from the central axis, and both the array of detector elements and x-ray source are revolved around the central axis during the acquisition of said series of views.

5. The system as recited in claim 4 in which the acquired cone beam data is preprocessed to provide x-ray attenuation data for a three-dimensional region about the central axis and between the x-ray source and the array of detector elements, and the image data f_M0 (r) and corrective image data f_M1 (r) is summed to produce a plurality of two-dimensional image slices through said three-dimensional region.