A method implemented in a computer to generate panoramic images of a patient's oral cavity.

Abstract

This invention provides a computer-aided X-ray system and a method for generating panoramic images of a patient's dental condition. [Solution] The method includes the steps of defining a focal curve (F) for the oral cavity (O) of a patient, wherein the focal curve (F) follows the shape of the jawbone (J) of the patient (P) and the focal curve (F) has a predetermined thickness (L) including at least the teeth (T) to be imaged; and acquiring a plurality of two-dimensional X-ray projection images of the patient (P) along the focal curve (F) by rotating an X-ray source (3), an X-ray collimator (12), and a flat-panel X-ray detector (4) around the head of the patient in a predetermined trajectory relative to the patient (P), wherein the X-ray collimator (12) is positioned between the head of the patient and the X-ray source (3), and the collimator has an X-ray aperture that limits the X-ray cone beam angle, and the width of the X-ray aperture is adjustable to change the X-ray cone beam angle.

Claims

1. A system for generating a panoramic image of a patient from multiple two-dimensional X-ray projection images of the patient, X-ray source and Flat panel X-ray detector and An X-ray collimator having an X-ray aperture having a variable X-ray aperture size, wherein the X-ray aperture defines an exposure region on the flat panel X-ray detector, and the exposure region has a variable exposure region size corresponding to the variable X-ray aperture size, The system comprises a control means, and the control means is A focal curve is defined for the oral cavity of the patient, the focal curve follows the shape of the patient's jawbone, the focal curve includes at least the molar region and the incisor region, and the focal curve has a predetermined thickness that is greater than the size of the patient's teeth being imaged. The system is configured to acquire the plurality of two-dimensional X-ray projection images of the patient along the focal curve, and the acquisition is performed as follows: A step of rotating the X-ray source, the X-ray collimator, and the flat panel X-ray detector around the patient's head along a predetermined trajectory relative to the patient, wherein the X-ray collimator is positioned between the patient's head and the X-ray source. A step of continuously changing the width of the X-ray aperture during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the X-ray aperture has a first width when the molar region is exposed, and the X-ray aperture has a second width smaller than the first width when the incisor region is exposed. A system comprising the step of continuously changing the horizontal range of the readout area of ​​the flat panel X-ray detector so that the readout area becomes a variable size greater than or equal to the variable exposure area size during the acquisition of the plurality of two-dimensional X-ray projection images.

2. The system according to claim 1, wherein the first width is 2 to 10 times larger than the second width.

3. The system according to claim 2, wherein the control means is configured to reduce the width of the X-ray aperture from the molar region toward the incisor region.

4. The system according to claim 1, wherein the control means is configured to continuously change the voltage of the X-ray source during the acquisition of the plurality of two-dimensional X-ray projection images, the X-ray source having a first voltage when the molar region is exposed, and the X-ray source having a second voltage greater than the first voltage when the incisor region is exposed.

5. The system according to claim 1, wherein the control means is configured to continuously change the current of the X-ray source during the acquisition of the plurality of two-dimensional X-ray projection images, the X-ray source having a first current when the molar region is exposed, and the X-ray source having a second current greater than the first current when the incisor region is exposed.

6. The system according to claim 1, wherein the control means is configured to continuously change the frame rate of the flat panel X-ray detector during the acquisition of the plurality of two-dimensional X-ray projection images, the flat panel X-ray detector having a first frame rate when the molar region is exposed, and the flat panel X-ray detector having a second frame rate greater than the first frame rate when the incisor region is exposed.

7. The system according to claim 6, wherein the control means is configured to increase the frame rate of the flat panel X-ray detector from the molar region toward the incisor region.

8. The system according to claim 1, wherein the control means is configured to continuously change the gain of the flat panel X-ray detector during the acquisition of the plurality of two-dimensional X-ray projection images, the flat panel X-ray detector has a first gain when the molar region is exposed, and the flat panel X-ray detector has a second gain different from the first gain when the incisor region is exposed.

9. The horizontal range of the reading area changes continuously between 50 pixels and 500 pixels. The flat panel X-ray detector has a native pixel size of 50 microns to 240 microns. The system according to claim 1.

10. The system according to claim 1, wherein the control means is configured to continuously change the center point of the X-ray aperture with respect to the flat panel X-ray detector along the horizontal direction during the acquisition of the plurality of two-dimensional X-ray projection images, so that the axis extending between the X-ray source and the center point of the readout area becomes at least substantially positive with respect to the focal curve.

11. A method for generating a panoramic image of a patient from multiple two-dimensional X-ray projection images of the patient, A step of defining a focal curve for the oral cavity of the patient, wherein the focal curve follows the shape of the patient's jawbone, the focal curve has at least a molar region and an incisor region, and the focal curve has a predetermined thickness that is greater than the size of the patient's teeth being imaged. The step of acquiring the plurality of two-dimensional X-ray projection images of the patient along the focal curve is included, and the acquisition step is A step of rotating an X-ray source, an X-ray collimator, and a flat panel X-ray detector around the head of the patient along a predetermined trajectory for the patient, wherein the X-ray collimator is positioned between the patient's head and the X-ray source, the X-ray collimator has an X-ray aperture having a variable X-ray aperture size, the X-ray aperture defines an exposure region on the flat panel X-ray detector, and the exposure region has a variable exposure region size corresponding to the variable X-ray aperture size, A step of continuously changing the width of the X-ray aperture during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the X-ray aperture has a first width when the molar region is exposed, and the X-ray aperture has a second width smaller than the first width when the incisor region is exposed. A method comprising the step of continuously changing the horizontal range of the readout area of ​​the flat panel X-ray detector so that the readout area becomes a variable size greater than or equal to the variable exposure area size during the acquisition of the plurality of two-dimensional X-ray projection images.

12. The method according to claim 11, wherein the first width is 2 to 10 times larger than the second width.

13. A step of reducing the width of the X-ray opening from the molar region toward the incisor region, The method according to claim 12, further comprising:

14. A step of continuously changing the voltage of the X-ray source during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the X-ray source has a first voltage when the molar region is exposed, and the X-ray source has a second voltage greater than the first voltage when the incisor region is exposed. The method according to claim 11, further comprising:

15. A step of continuously changing the current of the X-ray source during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the X-ray source has a first current when the molar region is exposed, and the X-ray source has a second current greater than the first current when the incisor region is exposed. The method according to claim 11, further comprising:

16. A step of continuously changing the frame rate of the flat panel X-ray detector during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the flat panel X-ray detector has a first frame rate when the molar region is exposed, and the flat panel X-ray detector has a second frame rate greater than the first frame rate when the incisor region is exposed. The steps include increasing the frame rate of the flat panel X-ray detector from the molar region toward the incisor region, The method according to claim 11, further comprising:

17. A step of continuously changing the gain of the flat panel X-ray detector during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the flat panel X-ray detector has a first gain when the molar region is exposed, and the flat panel X-ray detector has a second gain different from the first gain when the incisor region is exposed. The method according to claim 11, further comprising:

18. The horizontal range of the reading area changes continuously between 50 pixels and 500 pixels. The flat panel X-ray detector has a native pixel size of 50 microns to 240 microns. The method according to claim 11.

19. A step during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the center point of the X-ray aperture with respect to the flat panel X-ray detector is continuously changed along the horizontal direction, so that the axis extending between the X-ray source and the center point of the readout area becomes at least substantially positive with respect to the focal curve. The method according to claim 11, further comprising:

20. A computer-readable medium for generating a panoramic image of a patient from multiple two-dimensional X-ray projection images of the patient, wherein the computer-readable medium, when executed by a computing unit, stores instructions that cause the computing unit to perform an action, and the action is A step of defining a focal curve for the oral cavity of the patient, wherein the focal curve follows the shape of the patient's jawbone, the focal curve has at least a molar region and an incisor region, and the focal curve has a predetermined thickness that is greater than the size of the patient's teeth being imaged. The step of acquiring the plurality of two-dimensional X-ray projection images of the patient along the focal curve is included, and the acquisition step is A step of rotating an X-ray source, an X-ray collimator, and a flat panel X-ray detector around the head of the patient along a predetermined trajectory for the patient, wherein the X-ray collimator is positioned between the patient's head and the X-ray source, the X-ray collimator has an X-ray aperture having a variable X-ray aperture size, the X-ray aperture defines an exposure region on the flat panel X-ray detector, and the exposure region has a variable exposure region size corresponding to the variable X-ray aperture size, A step of continuously changing the width of the X-ray aperture during the acquisition of the plurality of two-dimensional X-ray projection images, wherein the X-ray aperture has a first width when the molar region is exposed, and the X-ray aperture has a second width smaller than the first width when the incisor region is exposed. A computer-readable medium comprising the steps of: continuously changing the horizontal range of the readout area of ​​the flat panel X-ray detector so that the readout area becomes a variable size greater than or equal to the variable exposure area size during the acquisition of the plurality of two-dimensional X-ray projection images.

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