Method and apparatus for simplifying the correction of image inaccuracies caused by processing of masked cone beam projection data

• US 6,330,298 B1
• Filed: 10/17/2000
• Issued: 12/11/2001
• Est. Priority Date: 10/17/2000
• Status: Expired due to Fees

• Current Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Original Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Inventors: Tam, Kwok
• Primary Examiner(s): DUNN, DREW A
• Application Number:
  US09/690,629
• Time in Patent Office: 420 Days
• Field of Search: 378/4, 378/8, 378/15, 378/901, 382/131
• US Class Current: 378/4
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2211/416 Exact reconstruction
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

A method and apparatus for three dimensional (3D) computerized tomographic (CT) imaging of an object, wherein image reconstruction processing is applied to a plurality of sets of 2D cone beam projection data, each set being acquired on a 2D detector at a corresponding plurality of scan path source positions. A first image reconstruction processing step comprises applying a mask to each set of the projection data so that data inside the boundaries of each mask form a corresponding plurality of masked 2D data sets. Next, the data inside each masked 2D data set is processed along line segments formed in the masked 2D data set, and having their endpoints determined by the mask boundaries, to develop a first 2D estimate of data determined from a given set of the 2D cone beam projection data. The next step comprises developing 2D correction data for each of the first 2D estimates of data by performing a one-dimensional (1D) convolving procession portions of the masked projection data to develop said 2D correction data. The final step comprises combining each of the first estimates of data and the 2D correction data calculated therefore, in a process which reconstructs an exact 3D image of the object.

Claims

1. A method for three dimensional (3D) computerized tomographic (CT) imaging of an object, comprising:

acquiring a plurality of sets of 2D cone beam projection data by irradiating the object with energy from a cone beam source that is directed toward a 2D detector at a corresponding plurality of scan path source positions located about the object;

applying a mask to each set of the 2D cone beam projection data to form a corresponding plurality of masked 2D data sets;

processing line integrals in the 2D cone beam projection data along a plurality of line segments L(s,θ

) having their end points determined by the boundaries of each of the masked 2D data sets to develop a corresponding plurality of processed 2D data sets, each processed 2D data set corresponding to calculation of a first data estimate determined for a given set of the 2D cone beam projection data;

developing 2D correction data for each of the first data estimates by performing a one-dimensional (1D) convolving process on portions of said masked projection data to develop said 2D correction data; and

combining each of said first data estimates with the 2D correction data developed therefore during an image reconstruction process which reconstructs an exact 3D image of the object.

2. The method of claim 1, wherein said portions of said 2D cone beam projection data upon which said 1D convolving process is performed comprises first, second, third and fourth portions of said masked data, each of said portions being bound by the area between a boundary of said mask and a line drawn tangent to said mask.

3. The method of claim 1, wherein said 1D convolving process compirses a 1D Hilbert transform.