Mobile radiography system and process

• US 6,702,459 B2
• Filed: 04/11/2002
• Issued: 03/09/2004
• Est. Priority Date: 04/11/2001
• Status: Expired due to Term

• Current Assignee: UAB Research Foundation (University of Alabama System)
• Original Assignee: UAB Research Foundation (University of Alabama System)
• Inventors: Barnes, Gary T., Gauntt, David T.
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): THOMAS, COURTNEY D
• Application Number:
  US10/121,367
• Publication Number:
  US 20020150215A1
• Time in Patent Office: 698 Days
• Field of Search: 378/197, 378/193, 378/198, 250/522.1
• US Class Current: 378/197
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: A61B 6/4021 involving movement of the focal spot
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/4405 the apparatus being movable or portable, e.g. handheld or mounted on a trolley
• CPC Class Codes: A61B 6/547 involving tracking of position of the device or parts of the device
• CPC Class Codes: A61B 6/587 Alignment of source unit to detector unit
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
• CPC Class Codes: H05G 1/26 Measuring, controlling or protecting measuring X-ray radiation G01T

Abstract

Disclosed is a mobile radiographic unit with improved x-ray scatter control. Improved x-ray scatter control is provided through the alignment of the system with the focal line of an anti-scatter grid. In a preferred embodiment, the system comprises an x-ray source assembly, a tube housing mounting, an automatic measuring means, a motion control means and a processing means in communication with the automatic measuring system and the motion control system. The alignment of the system occurs with minimal input by the operator.

Claims

1. A mobile radiographic system, the system comprising:

a. an x-ray source assembly comprising an x-ray tube housing having an x-ray source with a focal spot, and an x-ray collimator coupled to the tube housing;

b. a tube housing mounting that supports the x-ray source assembly and has a plurality of degrees of freedom to allow the x-ray tube housing to be moved to a desired position and desired orientation;

c. an anti-scatter grid, said anti-scatter grid and image receptor not being in a fixed orientation relative to the x-ray source;

d. a measuring means to determine the position of the anti-scatter grid and image receptor relative to a fixed point on the mobile radiographic system;

e. a motion control system to control the position and orientation of the x-ray source assembly relative to the anti-scatter grid and an image receptor, the motion control system comprising a drive means for at least one degree of freedom of motion in the tube housing mounting and x-ray source assembly and a means for determining the position of the x-ray source assembly relative to a console of the mobile radiographic system; and

f. a processing means in communication with the measuring means and the motion control system.

2. The system of claim 1 where the means for determining is in communication with the processing means and is selected from the group consisting of at least one encoder for each degree of freedom of motion in the tube housing mounting and x-ray source assembly and at least one inertial navigation unit on the x-ray source assembly.

3. The system of claim 1 where the measuring means is an automatic measuring system, the automatic measuring system comprising a grid tunnel and a detecting means mounted to the mobile radiographic system, the grid tunnel comprising the anti-scattering grid, the image receptor and an external object.

4. The system of claim 3 where the external object comprises a target array, the target array being removably coupled to the grid tunnel by a rigid arm and the target array comprising a plurality of fiducial markers, and where the detecting means is capable of generating an image of the fiducial markers on the target array.

5. A The system of claim 1 where the measuring means is an automatic measuring system, the automatic measuring system comprising a grid tunnel and one or more inertial navigation units attached to the grid tunnel, and optionally one or more inertial navigation units attached to the mobile radiographic system, the inertial navigation units on the grid tunnel and the inertial navigation units on the mobile radiographic system being in communication with the processing means, the inertial navigation units being selected from the group consisting of inertial navigation units having an acceleration sensor and a rotation sensor and inertial navigation units having an acceleration sensor.

6. The system of claim 1 where the measuring means is an automatic measuring system, the automatic measuring system comprising a direct mechanical linkage between the grid tunnel and the mobile radiographic system, the mechanical linkage being in communication with the processing means.

7. The system of claim 3 where the anti-scattering grid is incorporated into the grid tunnel and the grid tunnel has an internal cavity for receiving the image receptor.

8. The system of claim 3 where the detecting means is selected from the group consisting of an optical detector and an ultrasound detector.

9. The system of claim 3 where the detecting means is selected from the group consisting of a magnetic detector.

10. The system of claim 8 where the optical detector is selected from the group consisting of:

a still frame digital camera, a digital video camera, and an analog video camera.

11. The system of claim 4 where the processing means receives the image of the fiducial markers on the target array from the detecting means, determines the position and orientation of the fiducial markers from the image, and calculates the position and orientation of the target array relative to the position and orientation of the detecting means from the position and orientation of the fiducial markers.

12. The system of claim 11 where the processing means uses the position and orientation of the target array relative to the position and orientation of the detecting means to direct the drive means to position the x-ray source assembly so that the focal spot is in the state of alignment with respect to the focal line of the anti-scattering grid.

13. The system of claim 12 where the state of alignment is selected from the group consisting of an optimal state of alignment, and an acceptable state of alignment.

14. The system of claim 13 where the grid tunnel further comprises a sensing means to determine the orientation of the long axis of the grid tunnel relative to the target arm and to communicate the orientation of the long axis of the grid tunnel to the processing means.

15. The system of claim 14 where the processing means directs a drive means in communication with the collimator to automatically orientate the collimator along the long axis of the grid tunnel and automatically directs a drive means in communication with the collimator blades to adjust the width and length of the x-ray beam to substantially match the orientation of the image receptor.

16. The system of claim 15 where 2 degrees of freedom of the motion control system position the focal spot substantially on the focal line of the anti-scattering grid.

17. The system of claim 16 where 1 additional degree of freedom of the motion control system positions the focal spot substantially at the center of the focal line of the anti-scattering grid.

18. The system of claim 17 where 2 additional degrees of freedom of the motion control system align the central ray substantially on the center of the anti-scattering grid.

19. The system of claim 18 where 1 additional degree of freedom of the motion control system aligns the collimator with the long axis of the grid tunnel.

20. The system claim 19 where the x-ray source assembly further comprises an adjustable vertical column and an adjustable horizontal arm attached to the vertical column, the x-ray tube housing being mounted to the horizontal aim by an adjustable gimbal.

21. The system of claim 19 where the motion control system positions the x-ray source assembly to a state of alignment in a sequential manner.

22. The system of claim 19 where the motion control system positions the x-ray source assembly to a state of alignment in a parallel manner.

23. The system of claim 10 where the fiducial markers are selected from the group consisting of colored LEDs and monochrome LEDS.

24. The system of claim 23 where there are at least four fiducial markers on the target array, the fiducial markers separated from one another by a known distance.

25. The system of claim 24 where the fiducial markers are not located in any single plane.

26. The system of claim 3 where the anti-scattering grid is a high ratio anti-scattering grid.

27. The system of claim 12 further comprising a display means to inform the operator, directly or indirectly, of the condition of the system.

28. The system of claim 27 where the display means is selected from the group consisting of a plurality of indicator lights and a display panel, and the condition of the system represents the state of alignment of the system.

29. The system of claim 27 further comprising a control means on the x-ray source assembly by which the user can activate the motion control system to direct the x-ray source assembly to a state of alignment.

30. The system of claim 29 where the control means selected from the group consisting of a button and a toggle switch and where the operator is required to continually depress the control means for the motion control system to remain active.

31. The system of claim 1 where the measuring means is an analogue measuring system, and the analogue measuring system further comprises an alignment means and a grid tunnel, the grid tunnel comprising the anti-scattering grid, the image receptor and an external object.

32. The system of claim 31 where the alignment means indicates when the x-ray source assembly is in a state of alignment with reference to the anti-scattering grid.

33. The system of claim 32 where the state of alignment is selected from the group consisting of an optimal state of alignment and an acceptable state of alignment.

34. The system of claim 33 where the operator activates the motion control system to direct the x-ray source assembly to a state of alignment.

35. The system of claim 34 where the operator manually orientates the collimator so the collimator is orientated along the long axis of the grid tunnel and the collimator blades adjust the width and length of the x-ray beam to substantially match the orientation of the long axis of the grid tunnel and the associated image receptor.

36. The system of claim 34 where the operator activates the motion control system to orientate the collimator so the collimator is orientated along the long axis of the grid tunnel and the collimator blades are adjust the width and length of the x-ray beam to substantially match the orientation of the long axis of the grid tunnel and the associated image receptor.

37. The system of claim 35 where the system is an open loop system.

38. The system of claim 36 where the system is an open loop system.

39. The system of claim 35 where 2 degrees of freedom of the motion control system position the focal spot substantially on the focal line of the anti-scattering grid.

40. The system of claim 39 where 1 degrees of freedom of the motion control system positions the focal spot substantially at the center of the focal line of the anti-scattering grid.

41. The system of claim 40 where 2 additional degrees of freedom of the motion control system align the central ray substantially on the center of the anti-scattering grid.

42. The system of claim 41 where 1 additional degree of freedom of the motion control system aligns the collimator substantially with the long axis of the grid tunnel.

43. The system of claim 42 where the x-ray source assembly further comprises an adjustable vertical column and an adjustable horizontal arm attached to the vertical column, the x-ray tube housing being mounted to the horizontal arm by an adjustable gimbal.

44. The system of claim 42 where the motion control system positions the x-ray source assembly to a state of alignment in a sequential manner.

45. The system of claim 42 where the motion control system positions the x-ray source assembly to a state of alignment in a parallel manner.

46. The system of claim 34 further comprising a display means to inform the operator, directly or indirectly, of the condition of the system.

47. The system of claim 46 where the display means is selected from the group consisting of a plurality of indicator lights and a display panel, and the condition of the system represents the state of alignment of the system.

48. The system of claim 46 further comprising a control means on the x-ray source assembly by which the user can activate the motion control system to direct X-ray source assembly to a state of alignment.

49. The system of claim 48 where the control means selected from the group consisting of a button and a toggle switch and where the operator is required continually depress the control means for the motion control system to remain active.

50. The system of claim 31 where the external object is a target array removably coupled to the grid tunnel and the target array comprises a plurality of fiducial markers.

51. The system of claim 50 where the fiducial markers are selected from the group consisting of LEDs.

52. The system of claim 50 where there are at least 4 fiducial markers on the target array separated from one another by a known distance and the fiducial markers are not located in any single plane.

53. The system of claim 31 where the anti-scattering grid is a high ratio anti-scattering grid.