Method and apparatus for determining the position of a target relative to a reference of known co-ordinates and without a priori knowledge of the position of a source of radiation

• US 5,299,254 A
• Filed: 10/19/1992
• Issued: 03/29/1994
• Est. Priority Date: 11/24/1989
• Status: Expired due to Fees

• Current Assignee: Technomed Medical Systems
• Original Assignee: Technomed International
• Inventors: Lacoste, Francois, Dancer, Paul
• Primary Examiner(s): Church, Craig E.
• Application Number:
  US07/963,010
• Time in Patent Office: 526 Days
• Field of Search: 378/162, 378/163, 128/653.1
• US Class Current: 378/163
• CPC Class Codes: A61B 6/08 Auxiliary means for directing the radiation beam to a particular spot, e.g. using light beams
• CPC Class Codes: A61B 6/12 Arrangements for detecting or locating foreign bodies

Abstract

The invention relates to a method and to apparatus determining the exact position of a target relative to a reference of known co-ordinates. The apparatus comprises a source of radiation for forming an image of a target, which image is received by a receiver device situated beyond the target. A mask-forming device is interposed between the receiver device and the source of radiation, the mask-forming device including at least one localization means of known position relative to a reference point and suitable for forming an image in said image-forming radiation, means are also provided for displacing the radiation source in three dimensions, at least between two different angular positions, thereby displacing the co-ordinates of two different images of the target obtained from the two different angular positions of the source. The invention makes it possible to determine the exact position of a target with a very high degree of precision using a method which is simple and which limits the radiation dose. The target may be a cell or a stone or a bone to be treated.

Claims

1. A method of determining the position of a target relative to a reference point of a target treatment equipment, comprising the steps of:

emitting radiation from an X-ray source freely movable relative to said target treatment equipment and of unknown position relative thereto for forming an X-ray image of the target, the X-ray radiation being received by an X-ray receiver device of known position relative to said reference point, the X-ray source and X-ray receiver device being disposed on opposite sides of the target, said X-ray source being freely movable and of unknown position relative to said X-ray receiver;

disposing a mask-forming device between the receiver device and the X-ray source, the mask-forming device comprising at least one group of X-ray opaque localization means of known position coordinates relative to said reference point;

positioning the S-R source into a first unknown position relative to said target treatment equipment for which the XR radiation emitted by the XR source simultaneously encompasses the XR receiver device, the target and said at least one group of localization means;

emitting a first quantity of X-ray radiation from the X-ray source to form a first X-ray image of the target and the at least one group of localization means on the X-ray receiver device, and determining the respective first image position coordinates thereof in said first X-ray image;

calculating the position coordinates of the target on the basis of the known position coordinates of the at least one group of localization means, and at least some of the first image position coordinates of the at least one group of localization means and the target.

2. The method of claim 1, wherein said X-ray receiver device comprises an X-ray film and a holder for said film, said holder being of known position relative to said reference point and said film being of unknown X-ray relative to said reference point, said holder incorporating an opaque shadow means of known position coordinates relative to the reference point and encompassed by said X-ray source in said first position for forming an image of said shadow means on said film;

and

wherein said step of calculating the position coordinates of the target further comprises calculating the position coordinates of the target on the basis of at least some of the known position coordinates of the shadow means.

3. The method of claim 2, and further comprising the step of determining the first image position coordinates of said shadow means on said film, and wherein said step of calculating the position coordinates of said target further comprises calculating the position coordinates of the target on the basis of at least some of the first image position coordinates of said shadow means.

4. The method of claim 1, further comprising the steps of:

displacing the X-ray source to a second unknown position relative to said target treatment equipment which is different from the first unknown position, the X-ray radiation in the second position simultaneously encompassing the X-ray receiver device, the target, and said at least one group of localization means;

emitting a second quantity of X-ray radiation from the X-ray source to form a second X-ray image of the target and the at least one group of localization means on the X-ray receiver device, and determining respective second image position coordinates thereof in said second X-ray image; and

wherein said step of calculating the position coordinates of the target further comprises calculating the position coordinates of the target based on at least some of the second image position coordinates of the at least one group of localization means and the target.

5. The method of claim 4, wherein said step of disposing a mask-forming device comprises disposing a mask forming device having two non-coplanar surfaces, said at least one group of localization means comprising a first group of X-ray opaque localization means in one of said two non-coplanar surfaces and a second group of X-ray opaque localization means in the other of said two non-coplanar surfaces;

wherein said step of positioning the X-ray source into a first unknown position comprises positioning the X-ray source to encompass the first group of localization means;

wherein said step of displacing the X-ray source to a second unknown position comprises displacing said X-ray source to a second position encompassing said second group of localization means; and

wherein said step of calculating the position coordinates of the target further comprises calculating the position coordinates of the target on the basis of the known coordinates of the first and second groups of localization means and at least some of the first and second image position coordinates, respectively, of said first and second groups of localization means.

6. The method of claim 5, wherein said step of positioning said X-ray source into a first unknown position comprises positioning said X-ray source into a position wherein said X-ray radiation is substantially perpendicular to said one of said two non-coplanar surfaces, and said step of displacing said X-ray source to a second unknown position comprises displacing said X-ray source to a position wherein said X-ray radiation is substantially perpendicular to the other of said two non-coplanar surfaces.

7. The method of claim 4, wherein said X-ray receiver device comprises an X-ray film and a holder for said film, said holder being of known position relative to said reference point and said film being of unknown position relative to said reference point, said holder incorporating an opaque shadow means of known position coordinates relative to the reference point and encompassed by said X-ray source in said first and second positions for forming images of said shadow means on said film in said first and second X-ray images;

and

wherein said step of calculating the position coordinates of the target further comprises calculating the position coordinates of the target on the basis of at least some of the known position coordinates of the shadow means.

8. The method of claim 7, and further comprising the step of determining the first and second image position coordinates of said shadow means on said film, and wherein said step of calculating the position coordinates of said target further comprises calculating the position coordinates of the target on the basis of at least some of the first and second image position coordinates of said shadow means.

9. An apparatus for determining the position of a target relative to a reference point of a target treatment equipment, comprising:

an X-ray source for emitting radiation freely movable relative to said target treatment equipment and of unknown position relative thereto for forming an X-ray image of the target, an X-ray receiver device for receiving X-ray radiation, said X-ray receiver device being of known position relative to said reference point, the X-ray source and X-ray receiver device being disposed on opposite sides of the target, said X-ray source being freely movable and of unknown position relative to said X-ray receiver;

a mask-forming device disposed between the receiver device and the X-ray source, the mask-forming device comprising at least one group of X-ray opaque localization means of known position coordinates relative to said reference point;

positioning means for positioning the X-ray source into a first unknown position relative to said target treatment equipment for which the X-ray radiation emitted by the X-ray source simultaneously encompasses the X-ray receiver device, the target and said at least one group of localization means, said X-ray source in said first unknown position emitting a first quantity of X-ray radiation to form a first X-ray image of the target and the at least one group of localization means on the X-ray receiver device;

determining means for determining the respective first image position coordinates of the target and the at least one group of localization means in said first X-ray image;

calculating means for calculating the position coordinates of the target on the basis of the known position coordinates of the at least one group of localization means, and at least some of the first image position coordinates of the at least one group of localization means and the target.

10. The apparatus of claim 9, wherein said X-ray receiver device comprises an X-ray film and a holder for said film, said holder being of known position relative to said reference point and said film being of unknown position relative to said reference point, said holder incorporating an opaque shadow means of known position coordinates relative to the reference point and encompassed by said X-ray source in said first position for forming an image of said shadow means on said film;

and

wherein said calculating means comprises means for calculating the position coordinates of the target on the basis of at least some of the known position coordinates of the shadow means.

11. The apparatus of claim 10, wherein said determining means further comprises means for determining the first image position coordinates of said shadow means on said film, and wherein said calculating means further comprises means for calculating the position coordinates of said target on the basis of at least some of the first image position coordinates of said shadow means.

12. The apparatus of claim 9, further comprising:

displacing means for the X-ray source to a second unknown position relative to said target treatment equipment which is different from the first unknown position, the X-ray radiation in the second position simultaneously encompassing the X-ray receiver device, the target, and said a least one group of localization means, said X-ray source in said second unknown position emitting a second quantity of X-ray radiation from the X-ray source to form a second X-ray image of the target and the at least one group of localization means on the X-ray receiver device;

wherein said determining means comprises means for determining respective second image position coordinates thereof in said second X-ray image; and

wherein said calculating means comprises means for calculating the position coordinates of the target based on at least some of the second image position coordinates of the at least one group of localization means and the target.

13. The apparatus of claim 12, wherein said mask-forming device comprises a mask forming device having two non-coplanar surfaces, said at least one group of localization means comprising a first group of X-ray opaque localization means in one of said two non-coplanar surfaces and a second group of X-ray opaque localization means in the other of said two non-coplanar surfaces;

wherein said positioning means comprises means for positioning the X-ray source in a first unknown position encompassing the first group of localization means;

wherein said displacing means comprises means for displacing the X-ray source to a second unknown position encompassing said second group of localization means; and

wherein said calculating means comprises means for calculating the position coordinates of the target on the basis of the known coordinates of the first and second groups of localization means and at least some of the first and second image position coordinates, respectively, of said first and second groups of localization means.

14. The apparatus of claim 13, wherein said positioning means comprises means for positioning said X-ray source into a first unknown position comprises positioning said X-ray source into a position wherein said X-ray radiation is substantially perpendicular to said one of said two non-coplanar surfaces, and wherein said displacing means comprises means for displacing said X-ray source to a second unknown position wherein said X-ray radiation is substantially perpendicular to the other of said two non-coplanar surfaces.

15. The apparatus of claim 12, wherein said X-ray receiver device comprises an X-ray film and a holder for said film, said holder being of known position relative to said reference point and said film being of unknown position relative to said reference point, said holder incorporating an opaque shadow means of known position coordinates relative to the reference point and encompassed by said X-ray source in said first and second positions for forming, respectively, first and second images of said shadow means on said film in said first and second X-ray images;

and

wherein said calculating means comprises means for calculating the position coordinates of the target on the basis of at least some of the known position coordinates of the shadow means.

16. The apparatus of claim 15, wherein said determining means further comprises means for determining the first and second image position coordinates of said shadow means on said film, and wherein said calculating means comprises means for calculating the position coordinates of said target on the basis of at least some of the first and second image position coordinates of said shadow means.

17. A target positioning device for use with a target treatment equipment for treating a target in a portion of a patient'"'"'s body, comprising:

a frame member locatable in a known position relative to target treatment equipment;

an X-ray receiver device secured to said frame for receiving X-ray radiation emitted by an X-ray source; and

at least one group of X-ray opaque localization means secured to said frame and disposed in non-coplanar relation with said X-ray receiver and sufficiently spaced apart therefrom to accommodate disposition of said portion of said patient'"'"'s body therebetween, whereby X-ray radiation emitted by said X-ray source encompasses said target, said X-ray opaque localization means and said X-ray receiver device.

18. The device of claim 17, wherein said at least one group of X-ray opaque localization means comprises at least two groups of X-ray opaque localization means disposed in non-coplanar relation with said X-ray receiver device;

whereby in a first position of said X-ray source X-ray radiation emitted by said X-ray source encompasses said target, said first group of X-ray opaque localization means and said X-ray receiver device, and in a second position of said X-ray source X-ray radiation emitted by said X-ray source encompasses said target, said second group of X-ray opaque localization means and said X-ray receiver source.

19. The device of claim 17, wherein said X-ray receiver device is releasably secured to said frame.

20. The device of claim 17, wherein said frame further comprises an opaque shadow means located in a known position relative to said target treatment equipment for projecting an image on said X-ray receiver device for establishing the position of the X-ray receiver device relative to the target treatment equipment, whereby X-ray radiation emitted by said X-ray source encompasses said target, said X-ray opaque localization means, said opaque shadow means and said X-ray receiver device.

21. The device of claim 20, wherein said X-ray receiver device comprises a holder and a film received in said holder for receiving said X-ray radiation, and wherein said frame further comprises shadow means located in a known position relative to said target treatment equipment.

22. The device of claim 21, wherein said shadow means is incorporated in said holder.

23. A method of determining the exact position of a target relative to a reference point of target treatment equipment, comprising the steps of:

emitting radiation from an X-ray source freely movable relative to said treatment equipment and of unknown position relative thereto for forming an X-ray image of the target, the X-ray radiation being received by an X-ray receiver device, the X-ray source and the X-ray receiver device being disposed on opposite sides of the target with said X-ray source being freely movable and of unknown position relative to said X-ray receiver device, said X-ray receiver device being of known position relative to said reference point of said target treatment equipment;

disposing a mask-forming device between the receiver device and the X-ray source, the mask-forming device comprising at least one group of X-ray opaque localization means of known position relative to the reference point,

positioning the X-ray source into a first unknown position relative to said target treatment equipment for which the X-ray radiation emitted by the X-ray source simultaneously encompasses the X-ray receiver device, the target, and at least one group of localization means;

emitting a first quantity of X-ray radiation from the X-ray source to form a first X-ray image of the target and a first X-ray image of the localization means on the X-ray receiver device, and determining the respective first position coordinates thereof in said first X-ray image;

displacing the X-ray source to a second unknown position relative to said target treatment equipment which is different from the first unknown position, the X-ray radiation emitted by the X-ray source in the second position simultaneously encompassing the X-ray receiver device, the target, and at least one group of localization means;

emitting a second quantity of X-ray radiation from the X-ray source to form a second X-ray image of the target and a second X-ray image of the localization means on the X-ray receiver device, and determining respective second position coordinates thereof in said second X-ray image; and

calculating the coordinates of the target on the basis of the known coordinates of the at least one group of localization means, and of at least some of the first and second position coordinates of the target and the localization means.

24. A method according to claim 23, wherein the mask-forming device comprises a first group of localization means and a second group of localization means each having known position relative to the reference point, and further comprising the steps of:

disposing the first and second groups of localization means at two different known angular orientations relative to the reference point;

irradiating a first of the at least one group of localization means in the first image and a second of the at least one group of localization means in the second image; and

calculating the coordinates of the target on the basis of the known coordinates of the first and second groups of localization means, and of at least some of the first and second position coordinates of the target and the localization means.

25. A method according to claim 23, further comprising the steps of providing a first group of at least three localization means each having known coordinates and disposing the at least three localization means in a given plane, and providing a second group of at least three localization means of known coordinates disposed in a common oblique plane sloping at a known angle relative to the first group of localization means.

26. A method according to claim 23, further comprising the steps of disposing the localization means and the reference point on an axis of symmetry of the target treatment equipment.

27. A method according to claim 26, further comprising the step of disposing the plane of the first group of localization means substantially perpendicular tot he axis of symmetry of the treatment equipment.

28. A method according to claim 23, further comprising the step of disposing at least one shadow means having known coordinates relative to the reference point between the target and the receiver device to form a shadow on the receiver device while simultaneously emitting image-forming radiation through the target toward the receiver.

29. A method according to claim 28, further comprising the steps of providing a plurality of shadow means and disposing the shadow means on the receiver device in a plane perpendicular to an axis of symmetry of the treatment equipment.

30. A method according to claim 23, wherein the receiver is an X-ray sensitive film, said emitting step further comprising measuring at least some of the coordinates of the first and second images of the target and of at least some of the coordinates of the first and second images of the localization means formed on the X-ray sensitive film with a system for measuring cartesian coordinates.

31. A method according to claim 23, wherein the receiver is a fluoroscopic receiver device having a monitor screen, said emitting step further comprising measuring at least some of the coordinates of the first and second images of the target and of at least some of the coordinates of the first and second images of the localization means formed on the fluoroscopic receiver with a system for digitizing a video signal including a system measuring cartesian coordinates.

32. A method according to claim 23, further comprising the step of emitting a beam of collimation X-ray identical to the image-forming X-ray from the radiation source for aligning the emission device with the reference point.

33. A method according to claim 23, further comprising the step of emitting a beam of visible collimation radiation for aligning the X-ray source with the reference point.

34. A method according to claim 23, further comprising the steps of:

emitting a beam of collimation radiation which is collinear with image-forming X-ray emitted by the X-ray source; and

aligning the collimation radiation with at least one of the groups of localization means for each position of the X-ray source.

35. A method according to claim 23, wherein the reference point is a focus point or a point along an axis of symmetry of a shockwave treatment apparatus, further comprising the step of aligning the shockwave focus point with the target.

36. A method according to claim 35, wherein the shockwave focus point is an external focus point of a truncated ellipsoid having a magnetostrictive, hydraulic or electro-hydraulic shock wave generator of a focus point of a piezoelectric generator with a focusing device, further comprising the step of determining the shockwave focus point of the shockwave treatment apparatus.

37. The method according to claim 23, wherein the radiation source in the first position is between -5°

and +5°

from an axis of symmetry of the treatment apparatus, and the radiation source in the second position is about 20°

from the axis of symmetry.

38. A method according to claim 23, wherein the apparatus further comprises an adaptor for removably installing the mask-forming device, further comprising the step of removing the mask-forming device from the treatment equipment after the second image is received by the receiving device.

39. A method according to claim 23, wherein the apparatus further comprises a pivot for mounting the mask-forming device relative to the treatment equipment, comprising the further step of pivoting the mask relative to the treatment equipment at the pivot.

40. Apparatus for determining the exact position of a target relative to a reference point of equipment for treating the target, the apparatus including an external X-ray source freely movable relative to said treating equipment and of known position relative thereto for emitting radiation for forming an X-ray image of the target, and an X-ray receiver device for receiving X-ray radiation from said X-ray source, the X-ray source and the X-ray receiver device being disposed on opposite sides of the target, with said X-ray source being freely movable and of unknown position relative to said X-ray receiver device, said receiver device being of known position relative to said reference point, said apparatus comprising:

a mask-forming device interposed between the X-ray receiver device and the X-ray source and comprising at least one group of X-ray opaque localization means of known position relative to the reference point;

means for displacing the X-ray source in space between at least first and second different unknown positions relative to said target treating equipment for forming first and second images, respectively, of said target and said at least one group of localization means;

determining means for determining, respectively, first and second position coordinates in said first and second X-ray images of the target and the at least one group of localization means; and

calculating means for calculating the coordinates of the target on the basis of the known position of the at least one group of localization means, and of at least some of the first and second position coordinates of the target and said localization means.

41. The apparatus according to claim 40, further comprising means for displacing the mask-forming device out of a beam of radiation for forming an image of the target.

42. The apparatus according to claim 40, further comprising target treatment equipment associated with the reference point, said mask-forming device being connected to the target treatment equipment.

43. The apparatus according to claim 42, wherein the treatment equipment is a device selected from the group consisting of magnetostrictive, hydraulic, or electro-hydraulic equipment for generating and focusing shock waves at a focal point of a truncated ellipsoidal generator or a piezoelectric generator and focusing device having a focus point, said focus point being displaceable with respect to the target so that they may be made coincident.

44. The apparatus according to claim 40, wherein the target treatment has an axis of symmetry and one of the localization means as well as the reference point are both disposed on an axis of symmetry.

45. The apparatus according to claim 40, further comprising at least one shadow means disposed between the target and the surface of the receiver device for forming a shadow of attenuated radiation having features along at least two axes when radiation is emitted for forming an image of the target, said shadow means having predetermined coordinates relative to the reference point.

46. The apparatus according to claim 40, further comprising a first group of localization means and a second group of localization means, said first and second groups of localization means being disposed in two different predetermined angular orientations relative to the reference point.

47. The apparatus according to claim 46, wherein the first and second groups of localization means are disposed on portions of said mask-forming device, said mask-forming device comprising a frame connected to said receiver device, said frame including at least two substantially planar surfaces, one of which is mounted parallel to the surface of the receiver device and the other being mounted at a predetermined angle relative to the receiver device, each said planar surface containing either said first or said second groups of localization means in its plane.

48. In an apparatus for determining the exact position of a target relative to a reference point of equipment for treating the target, the apparatus including an external X-ray source freely movable relative to said treating equipment and of unknown position relative thereto for emitting radiation for forming an X-ray image of the target, said X-ray radiation being received by an X-ray receiver device, the X-ray source and the X-ray receiver device being disposed on opposite sides of the target with said X-ray source being freely movable and of unknown position relative to said X-ray receiver device, means for positioning the X-ray source in space between at least first and second different unknown positions relative to the equipment for treating the target for forming first and second X-ray images of the target, and means for measuring the coordinates of said target in said first and second X-ray images, the improvement comprising:

said X-ray receiver device being of known position relative to said reference point of said target treatment equipment;

a mask-forming device interposed between the X-ray receiver device and the X-ray source and comprising at last one X-ray opaque localization means of known position coordinates relative to the reference point, whereby said first and second X-ray images of said target include, respectively, first and second X-ray images of said localization means;

said means for measuring further comprising means for measuring the coordinates of the localization means relative to the reference point in said first and second X-ray images; and

means for calculating the position coordinates of the target on the basis of said known position coordinates of the localization means, and of at least some of said measured coordinates of the localization means and the target in said first and second X-ray images.

49. The apparatus according to claim 48, further comprising a first group of localization means and a second group of localization means, said first and second groups of localization means being disposed in two different predetermined angular orientations relative to the reference point.

50. The apparatus according to claim 48, further comprising means for displacing the mask-forming device out of a beam of X-rays emitted by said X-ray source for forming an image of the target.

51. The apparatus according to claim 50, further comprising:

means for pivotally mounting said mask-forming device for pivotal movement relative to the X-ray receiver device; and

an adapter means for releasably securing said mask-forming device to said X-ray receiver device.

52. The apparatus according to claim 51, wherein the first and second groups of localization means are disposed on said mask-forming device, said mask-forming device comprising a frame connected by an adapter to said X-ray receiver device, said frame including at least two substantially planar surfaces, one of said planar surfaces being mounted substantially parallel to the surface of the X-ray receiver device and the other of said planar surfaces being mounted at a predetermined angle relative to the X-ray receiver device, each of said planar surfaces containing one of said first and said second groups of localization means.

53. The apparatus according to claim 52, wherein said frame means includes a third substantially planar member disposed perpendicularly to the surface of the receiver device.