Computerized dynamic tomography system

• US 5,051,904 A
• Filed: 03/24/1988
• Issued: 09/24/1991
• Est. Priority Date: 03/24/1988
• Status: Expired due to Term

• Current Assignee: Olganix Corporation
• Original Assignee: Olganix Corporation
• Inventors: Griffith, Lionell K.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Kibby, Steven
• Application Number:
  US07/172,609
• Time in Patent Office: 1,279 Days
• Field of Search: 378/23, 378/25, 364/413.16, 364/413.19
• US Class Current: 378/23
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating

Abstract

An object is exposed to penetrating radiation at each of a plurality of partial rotations of the object. Radiation transmitted through the object strikes a separate sheet of radiographic film for each exposure to record an entire radiographic image of the object for each angular orientation. The radiographic images are digitized and stored in the memory of a computer. Each digitized image is registered by determining the error of rotation and center of rotation for each digitized image and correcting for the error of rotation by rotation and translation of pixel values. One or more displacement values are selected in correspondence with one or more desired levels of view and the digitized images are displaced according to the selected displacement values. The displaced images are then combined to produce images representative of the selected levels of view. Image planes non-parallel to the film image plane may be selected and interactive image enhancement and manipulation are provided. Data compression is accomplished in order to minimize the memory requirements of the images prior to general storage.

Claims

1. A method for representing the internal structure of an object, comprising the steps of:

exposing said object and at least one reference marker to penetrating radiation from a plurality of angles;

obtaining a separate radiological image for each said exposure;

digitizing each said radiological image to supply pixel values thereof to a computer;

locating a center of said at least one reference marker on each said digitized image;

determining an error of rotation from at least one of said centers;

registering each said digitized image, said registering step comprising rotation of said pixel values;

displacing selected pixel values relative to other pixel values; and

combining said selectively displaced pixel values to display at least one selected image of the internal structure of said object.

2. The method of claim 1, wherein said registering step further comprises translation of said pixel values.

3. The method of claim 2, further comprising the step of assigning weighted pixel values to four pixels immediately adjacent to a sub-pixel location to which a pixel value is rotated, translated or displaced.

4. The method of claim 2, wherein at least one of said pixel values is translated to a sub-pixel location.

5. The method of claim 4, further comprising the step of assigning a weighted pixel value to at least one pixel adjacent to said sub-pixel location.

6. The method of claim 1, further comprising the step of extracting pixels from successive levels to display an image plane non-parallel to the image plane of said radiological image.

7. The method of claim 1, further comprising the step of partially rotating said object before each said exposure to penetrating radiation.

8. The method of claim 1, wherein at least one of said pixel values is rotated to a sub-pixel location.

9. The method of claim 8, further comprising the step of assigning a weighted pixel value to at least one pixel adjacent to said sub-pixel location.

10. The method of claim 1, wherein at least one of said pixel values is displaced to a sub-pixel location.

11. The method of claim 10, further comprising the step of assigning a weighted pixel value to at least one pixel adjacent to said sub-pixel location.

12. A method of displaying a multiplicity of internal images of an object, comprising the steps of:

digitizing a plurality of radiological images of said object and at least one reference marker maintained in a fixed position irrespective of movement of the object to provide a separate digitized image for each of said plurality of radiological images;

registering each said digitized image;

the step of registering including, locating a center of the at least one reference marker;

determining an angle of error of rotation from the center; and

rotating the digitized image from the angle of error of rotation;

13. The method of claim 12, further comprising the steps of:

rotating said object by partial rotations;

exposing said object and at least one reference marker to penetrating radiation at each partial rotation; and

recording transmitted radiation through said object and said at least one reference marker as a separate radiological image at each partial rotation.

14. A method according to claim 13, further comprising the step of storing said multiplicity of images.

15. A method according to claim 14, further comprising the step of compressing said multiplicity of images prior to said storing step.

16. A method according to claim 13, further comprising the step of interactively enhancing the contrast of any of said digitized images.

17. A method according to claim 13, further comprising the step of interactively enhancing the edges of any of said digitized images.

18. A method according to claim 13, further comprising the step of interactively providing false color to any of said multiplicity of images.

19. An apparatus for representing the internal structure of an object, comprising:

means for exposing said object and at least one reference marker to penetrating radiation while maintaining the at least one reference marker in position irrespective of movement of the object;

means for converting radiation transmitted through said object and said at least on reference marker at each of a plurality of angles into a radiological image, said converting means being disposed in angular relationship to said exposing means;

means for digitizing each said radiological image into digitized information said digitizing means being positioned to receive each said radiological image;

means for registering, displacing and combining said digitized information to provide a selected image of the internal structure of said object, said displacing and combining means being connected to said digitizing means to receive electronic signals representative of said digitized information;

wherein said registering means further includes,

means to locate a center of the at least one reference marker;

means to determine an angle of error of rotation from the center; and

means to rotate the digitized information from the angle of error of rotation;

means for displaying said selected image, said displaying means being connected to said displacing and combining means to receive electronic signals representative of said selected image.

20. An apparatus according to claim 19 wherein said selected image is displayed in real time.

21. The apparatus of claim 19, wherein said converting means further comprises means for rotating said object, said rotating means being positioned between said object and said at least one reference marker.

22. An apparatus for representing the internal structure of an object, comprising:

means for exposing said object and at least on referenced marker to penetrating radiation;

means for converting radiation transmitted through said object and said at least on reference marker at each of a plurality of angles into a radiological image, said converting means being disposed in angular relationship to said exposing means;

said converting means further comprising means for rotating said object, said rotating means being positioned between said object and said at least one reference marker;

means for digitizing each said radiological image into digitized information said digitizing means being positioned to receive each said radiological image;

means for displacing and combining said digitized information to provide a selected image of the internal structure of said object, said displacing and combining means being connected to said digitizing means to receive electronic signals representative of said digitized information; and

means for displaying said selected image, said displaying means being connected to said displaying and combining means to receive electronic signals representative of said selected image.