Dynamic bandwidth reconstruction

• US 5,276,614 A
• Filed: 11/17/1989
• Issued: 01/04/1994
• Est. Priority Date: 11/17/1989
• Status: Expired due to Term

• Current Assignee: Picker International, Inc. (Marconi Holdings Company Limited)
• Original Assignee: Picker International, Inc. (Marconi Holdings Company Limited)
• Inventors: Heuscher, Dominic J.
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): CHUNG TRANS, XUONG MY
• Application Number:
  US07/438,687
• Time in Patent Office: 1,509 Days
• Field of Search: 364/413.16, 364/413.21, 364/413.23, 364/413.14, 364/724.05, 382/54, 382/6, 358/111
• US Class Current: 382/260
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating

Abstract

A scanner (A), such as a CT or MR scanner, non-invasively examines a region of interest of subject and generates a plurality of views indicative thereof which are reconstructible into an image representation. A filter control (14) generates a bandwidth scaling factor (BWF.sub.θ) and a bandwidth offset (BWO) for each view. Preferably, the selected bandwidth scaling factor is the maximum of a plurality of bandwidth scaling factors based on different criteria including noise, missing views, material surrounding the region of interest, or noise texture. The bandwidth scaling factor is then used to address a filter curve look up table (18) to select from a plurality (N_T) of filter values. The digital filter values are interpolated (20) or extrapolated as necessary to match the number of values (N_S) in each sampled view. The digital filter values and the view values are multiplied (22) point by point to create filtered views which are reconstructed (30) into the image representation for storage in an image memory (32) or displayed on a video monitor (34).

Claims

1. A diagnostic imaging apparatus comprising:

a scanner for generating a plurality of views for reconstruction into an image representation of an examined subject, each view including a set of data corresponding to a different angular orientation around the subject, each view being identified by a corresponding view identification, the view identification being identifying the angular orientation corresponding to the data set of each view;

a filter-function providing means for providing a plurality of filter functions for each view in accordance with the view identification, at least one or more of the filter functions changing from view to view;

a filter control means operatively connected with the scanner to receive the view identification of each view and with the filter function providing means for dynamically selecting one of the plurality of filter functions provided in accordance with each received view identification;

a filter means operatively connected with the scanner and the filter control means to receive concurrently each view and the one of the plurality of filter functions selected for the received view for filtering each received view with the filter function selected for the each received view;

a reconstruction means operatively connected with the filter means for reconstructing an image representation from the filtered views.

2. A diagnostic imaging apparatus comprising:

a scanner for generating a plurality of views for reconstruction into an image representation;

a filter control means for dynamically selecting at least one of a bandwidth scaling factor and a bandwidth offset for each generated view;

a filter function look up table which is addressed by the selected at least one of the bandwidth scaling factor and the bandwidth offset from the filter control means to retrieve a corresponding one of a plurality of filter functions the filter function look-up table being connected with the filter control means;

a filter means for filtering each view with the retrieved filter functions, the filter means being operatively connected with the scanner and the filter function look up table;

a reconstruction means for reconstructing an image representation from the filtered views, the reconstruction means being connected with the filter means.

3. The apparatus as set forth in claim 2 wherein each view has a first plurality of digital data values and the filter functions stored by the filter function look up table have a smaller plurality of digital filter values and further including an interpolating means for interpolating the filter values such that the filter function has the same number of digital values as each view, the interpolating means being operatively connected with the filter means.

4. The apparatus as set forth in claim 3 wherein the filter means includes a multiplying means for multiplying the interpolated filter values and the data values point by point.

5. The apparatus as set forth in claim 2 wherein the filter control means includes at least one of:

a noise filter providing means for providing bandwidth scaling factors for compensating for noise;

a missing view filter providing means for providing bandwidth scaling factors to compensate for missing views;

a noise texture filter providing means for providing bandwidth scaling factors for adjusting noise texture.

6. The apparatus as set forth in claim 2 wherein the filter control means includes a plurality of bandwidth filter function providing means for providing a plurality of bandwidth scaling factors for each view, the bandwidth scaling factors varying from view to view.

7. The apparatus as set forth in claim 7 wherein the bandwidth filter function providing means include at least two of:

a noise filter providing means for providing a view dependent bandwidth scaling factor for compensating for noise;

a missing view filter providing means for providing bandwidth scaling factors to compensate for missing views;

a noise texture filter means for providing a bandwidth scaling factor for adjusting noise texture;

a means for providing an out of region of interest material bandwidth scaling factor which adjusts the bandwidth of selected views to accommodate material adjacent an imaged region of interest.

8. A diagnostic imaging apparatus comprising:

a scanner for generating patient data including a plurality of views for reconstruction into an image representation of an imaged region;

a filter selecting means for selecting one of a plurality of filter functions, the filter functions including at least two of (i) a noise filter, (ii) a view dependent adjacent high density material filter which compensates for high density structures adjacent the imaged region, (iii) a view dependent noise texture filter, and (iv) a missing view filter function for weighting views interpolated to replace missing views and views adjoining the missing views;

a filter means for operating on each view with the selected filter function;

a reconstruction means for reconstructing an image representation from the filtered views.

9. A method of generating an image representation, the method comprising:

non-invasively examining an interior portion of a subject within an examination region and generating patient data including a plurality of views indicative thereof for reconstruction into an image representation of the examined region;

providing an identification of each view;

receiving each provided identification and providing a plurality of corresponding view dependent filter functions for each view such that the plurality of provided filter functions varies from view to view;

in response to each view identification, selecting one of the plurality of provided filter functions;

filtering each view with the selected one of the plurality of provided filter functions;

reconstructing the filtered views into the image representation.

10. A method of generating an image representation, the method comprising:

non-invasively examining an interior portion of a subject within an examination region and generating patient data including a plurality of views indicative thereof for reconstruction into an image representation of the examined region;

storing at least one of a bandwidth scaling factor and a bandwidth offset for each view;

addressing a filter function look up table with the one of the bandwidth scaling factor and offset to retrieve a corresponding filter function therefrom;

operating on the patient data with the addressed filter function of the corresponding view;

reconstructing the views which have been operated on by the addressed filter function into the image representation.

11. The method as set forth in claim 10 further including:

storing a plurality of bandwidth scaling factors for each view; and

,

comparing the plurality of bandwidth scaling factors with a preselected criterion and selecting one of the bandwidth scaling factors to address the look up table in accordance with the comparing.

12. The method as set forth in claim 16 wherein the plurality of bandwidth scaling factors compensate for at least two of noise, missing views, material surrounding the region of interest, and noise texture.

13. A method of generating an image representation, the method comprising:

non-invasively examining an interior portion of a subject within an examination region and generating patient data including a plurality of views indicative thereof for reconstruction into an image representation of the examined region;

selecting a filter function for each view from among a plurality of filter functions including at least two of;

a noise filter function for correcting for noise,

a missing views filter function for correcting for missing views, a surrounding material filter function for correcting for material surrounding the region of interest, and

a noise texture filter function for correcting for noise texture;

operating on each view the patient data with the selected filter function selected for that view;

reconstructing the filtered views into the image representation.

14. A diagnostic imaging apparatus comprising:

a scanner for generating a plurality of views, each view including a real component and an imaginary component;

a filter control means for dynamically selecting (i) one of a plurality of real bandwidth factors for each view and (ii) one of a plurality of imaginary bandwidth factors for each view, on a view-by-view basis;

a filter function look up table means which is addressed by the real and imaginary bandwidth factors to retrieve corresponding real and imaginary filter functions, the filter function look up table means being operatively connected with the filter control means;

a filter means for filtering the real component of each view with the retrieved real filter function and for filtering the imaginary component of each view with the retrieved imaginary filter function, the filter means being operatively connected with the scanner to receive the real and imaginary component of each view therefrom and with the filter function look up table means for receiving the retrieved real and imaginary filter functions therefrom; and

a reconstruction means for reconstructing an image representation from the filtered real and imaginary components, the reconstruction means being operatively connected with the filter means to receive the filtered real and imaginary components therefrom.