Dental extra-oral x-ray imaging system and method

• US 7,336,763 B2
• Filed: 03/27/2006
• Issued: 02/26/2008
• Est. Priority Date: 05/02/2005
• Status: Active Grant

• Current Assignee: AJAT OY Limited, Oy Ajat Limited
• Original Assignee: Oy Ajat Limited
• Inventors: Spartiotis, Konstantinos, Pantsar, Tuomas
• Primary Examiner(s): Glick; Edward J.
• Assistant Examiner(s): MIDKIFF, ANASTASIA
• Application Number:
  US11/277,530
• Publication Number:
  US 20060203959A1
• Time in Patent Office: 701 Days
• Field of Search: 378 38- 40, 378/193, 378/197
• US Class Current: 378/40
• CPC Class Codes: A61B 6/466 adapted to display 3D data
• CPC Class Codes: A61B 6/51 for dentistry
• CPC Class Codes: A61B 6/5241 combining overlapping images of the same imaging modality, e.g. by stitching
• CPC Class Codes: A61B 6/547 involving tracking of position of the device or parts of the device
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• CPC Class Codes: G03B 42/042 for dental applications radiation diagnosis specially adapted for dentistry A61B6/51; individual packages for X-ray film G03C3/003
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/30036 Dental; Teeth
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: G06T 7/579 from motion
• CPC Class Codes: G06T 7/97 Determining parameters from multiple pictures depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A multi-layer dental panoramic and transverse x-ray imaging system includes an x-ray source; a digital imaging device capable of frame mode output with a sufficient frame rate; a mechanical manipulator having at least one rotational axis located in a position other than the focal point of the x-ray source; a position detection mechanism for detecting the camera position in 1D, 2D or 3D depending of the complexity of the trajectory; a final image reconstruction mechanism for reconstructing the final images out of the stored frames; a real time storage system such as RAM, hard drive or an drive array able to store all the frames captured during an exposure; and a digital processing unit capable of executing the reconstruction algorithm, such components being interconnected in operational arrangement. The system produces selectively dental panoramic x-ray images, dental transverse x-ray images and dental tomosynthetic 3D images from a frame stream produced by a high-speed, x-ray digital imaging device.

Claims

1. An extra-oral dental x-ray imaging system comprising:

a. an x-ray source adapted for generating x-rays for exposure of such x-rays to an object to be imaged;

b. an x-ray imaging device adapted for producing multiple frames during at least part of the exposure;

c. a manipulator for moving the imaging device between two consecutive radiated frames during exposure, the moving being of an amount greater than half the width of a pixel in the direction of movement to provide an overlap between consecutive frames of a significant portion of the frame width, the manipulator controlling movement of the x-ray source and the imaging device about at least one rotational axis around which at least one of the x-ray source and imaging device rotates along a spline, the axis being located between the x-ray source focal point and the x-ray imaging device; and

,

d. a fast memory having an access and storage speed comparable to a readout speed of the x-ray imaging device, the memory storing and holding substantially all the frames produced, and the stored and held frames being individually selectively accessible.

2. The imaging system of claim 1, wherein the memory stores and accesses information substantially in any order and in which all storage locations are substantially equally accessible, thereby providing sufficient speed for storing the multiple frames substantially concurrently with the exposure in a manner which permits retrieval and display substantially in real time.

3. The imaging system of claim 1, wherein the system further includes a processing device for taking data of a single exposure comprising multiple frames to compose selectively at least two of a group of elements, the elements consisting of:

(a) a predetermined dental panoramic layer image,

(b) a part of a non-predetermined dental panoramic layer image,

(c) a transverse slice to a selected part of a dental panoramic layer image; and

(d) a 3-D reconstruction of a volume corresponding to some part of a dental panoramic layer.

6. The system of claim 1, wherein a focus depth of a panoramic image is different in some parts of the image when compared to a focus depth of an analogous parts of a predetermined panoramic image.

7. The system of claim 1 wherein the imaging device is adapted to produce at least 30 frames per second.

8. The system of claim 1 wherein the imaging device is adapted to produce at least 100 frames per second.

9. The system of claim 1 wherein the x-ray imaging device is adapted to produce at least 300 frames per second.

10. The system of claim 1, wherein the x-ray source is adapted to move for the duration of the exposure.

11. The system of claim 1, wherein the x-ray source is adapted to move on a non-linear trajectory.

12. The system of claim 1 wherein the x-ray source is moving on a circular trajectory.

13. The system of claim 1, wherein the x-ray source is adapted to move on a trajectory covering an angle of 300 degrees or less.

14. The system of claim 1, wherein the x-ray source is adapted to move continuously with a variable speed profile.

15. The system of claim 1, wherein the x-ray imaging device comprises a CdTe radiation detector.

16. The system of claim 1, wherein the x-ray imaging device comprises a CdZnTe radiation detector.

17. The system of claim 1, wherein the x-ray imaging device comprises a scintillator radiation detector.

18. The system of claim 1, wherein the x-ray imaging device comprises a CMOS.

19. The system of claim 1, wherein the processing device comprises a computer memory.

20. The system of claim 1, further comprising a processing device processing an algorithm for shifting and adding corresponding pixels from at least two different frames to compose an image pixel in a panoramic image corresponding to a speed profile different from a predetermined speed profile.

4. An extra-oral dental x-ray imaging system comprising:

a. an x-ray source exposing x-rays to an object to be imaged;

b. an x-ray imaging device suitable for producing multiple frames during at least part of the exposure and a manipulator for moving the imaging device between two consecutive radiated frames during exposure, the moving being of an amount greater than half the width of a pixel in the direction of movement to provide an overlap between consecutive frames of a significant portion of the frame width; and

,

c. at least one rotational axis around which at least one of the x-ray source and imaging device rotates along a spline, the axis being located between the x-ray source focal point and the x-ray imaging device; and

wherein the x-ray imaging device has an active area with a long dimension m and a short dimension n and wherein m/n>

1.5 (one point five).

5. The system of claim 4 further comprising a processing device for inputting the multiple frames to compose a transverse slice with respect to a panoramic layer image.

21. An extra-oral dental x-ray imaging system comprising:

a. an x-ray source generating x-rays for exposure of such x-rays to an object to be imaged;

b. an x-ray imaging device adapted for producing multiple frames during at least part of the exposure;

c. a manipulator for moving the imaging device between two consecutive radiated frames during exposure, the moving being of an amount greater than half the width of a pixel in the direction of movement to provide an overlap between consecutive frames of a significant portion of the frame width, the manipulator controlling movement of the x-ray source and the imaging device about at least one rotational axis around which at least one of the x-ray source and imaging device rotates along a spline, the axis being located somewhere between the x-ray source focal point and the x-ray imaging device; and

,

d. a processing device for taking inputs of the multiple frames to compose a panoramic image of a layer of the object with a focus depth which is different in a part of the panoramic image from a focus depth corresponding to an analogous part of a predetermined panoramic image.

22. The system of claim 21, further comprising a fast memory having sufficient speed for storing the multiple frames substantially concurrently with the exposure.

23. The system of claim 21, wherein the processing device using multiple frames comprises shifts of sub-pixel shifting and adding of pixel values from different frames.

24. The system of claim 23 wherein the shifts are automatically optimized to obtain maximal focus in the layer-of-interest.

25. The system of claim 21, wherein the processing device using multiple frames comprises forming a transverse image by combining vertical pixel rows referring to a corresponding physical transverse slice from multiple panoramic images.

26. The system of claim 21, wherein the x-ray source is adapted for movement on a predetermined trajectory.

27. The system of claim 21 wherein the x-ray source is adapted for movement with a predetermined speed profile.

28. The system of claim 21, wherein the x-ray source and x-ray imaging device have a fixed geometry.

29. The system of claim 21, wherein the memory comprises a Random Access Memory for temporarily storing the multiple frames.