Method and apparatus for processing data from a tomographic imaging system

• US 5,953,388 A
• Filed: 08/18/1997
• Issued: 09/14/1999
• Est. Priority Date: 08/18/1997
• Status: Expired due to Fees

• Current Assignee: George Mason University
• Original Assignee: George Mason University
• Inventors: Rashid-Farrokhi, Farrokh, Walnut, David Francis, Berenstein, Carlos Alberto, Liu, K. J. Ray
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): Bruce, David Vernon
• Application Number:
  US08/912,838
• Time in Patent Office: 757 Days
• Field of Search: 378/4, 378/901
• US Class Current: 378/4
• CPC Class Codes: G06T 11/006 Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
• CPC Class Codes: G06T 2211/421 Filtered back projection [FBP]
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

An algorithm is created and applied to reconstruct the wavelet coefficients of an image from the Radon transform data for use in computed tomography, with a disclosed method that uses the properties of wavelets to localize the Radon transform such that a local region of the cross section of a body can be reconstructed using almost completely local data to significantly reduce the amount of exposure and computations in X-ray tomography. The described algorithm is based on the observation that for some wavelet bases with sufficiently many vanishing moments, the ramp-filtered version of the scaling function as well as the wavelet function has extremely rapid decay, with the variance of the elements of the nullspace is being negligible in the locally reconstructed image.

Claims

1. A method for processing data form a tomographic system to obtain an image of an object comprising the steps of (a) collecting tomographic data from a CT scan of said object;

(b) processing said tomographic data to obtain sampled parallel beam data (c) computing modified wavelet and scaling filters; and

(d) processing said sampled parallel beam data using said modified wavelet and scaling filters to construct an image of said object.

2. A method of claim 1, wherein said object is contained within a larger body.

3. A method of claim 1, wherein said output is displayed as an image of said object.

4. A method of claim 1, wherein said tomographic data (b) is selected from a larger data set obtained from said CT scan.

5. An apparatus for producing an image of a region contained within an object, said apparatus comprising:

(a) a radiation source focusable on a region contained within an object and producing a focused radiation beam;

(b) a receptor means for receiving said radiation beam form said radiation source, said radiation beam having passed through said region positioned between said radiation source and said receptor;

(c) a converter means for converting said received radiation beam at the receptor to digitized data;

(d) a computer means connected to said converter means comprising data processing means for converting said digitized data into a visual image; and

(e) an output means connected to said computer means for displaying the output of said data processing means.

6. An apparatus of claim 5, wherein said data processing means is a computer source code.

7. An apparatus of claim 5, wherein said data processing means is a logic circuit.

8. An apparatus of claim 5, wherein said focusable radiation source is effective to aim a fan-beam from said radiation source at said receptor means.

9. An apparatus of claim 5, wherein said radiation source is an X-ray source.

10. An apparatus of claim 5, wherein said region comprises an edge.

11. An apparatus of claim 5, wherein said data processing means comprises wavelet and scaling filters.

12. An apparatus for producing an image of an object:

(a) a radiation source producing a radiation beam;

(b) a means for collecting data from said radiation source, wherein said data is collected after said radiation beam has passed through said object;

(c) a first means for computing wavelet and scaling filters;

(d) a second means for processing said data using wavelet and scaling filters effective to construct an image of said object; and

(e) a display means for displaying an image said object.

13. An apparatus of claim 12, wherein said data is collected as parallel beam data.

14. An apparatus of claim 12, wherein said data is collected as fan-beam data and said system further comprises a third means for converting fan-beam data into parallel beam data, which parallel beam data is processed using wavelet and scaling filters by said second means.

15. An apparatus of claim 12, wherein said radiation source is focusable to produce a focused radiation beam.