Proximity detector for body contouring system of a medical camera

• US 5,376,796 A
• Filed: 11/25/1992
• Issued: 12/27/1994
• Est. Priority Date: 11/25/1992
• Status: Expired due to Fees

• Current Assignee: Adam Laboratories Inc.
• Original Assignee: ADAC Laboratories, Inc. (Koninklijke Philips N.V.)
• Inventors: Bayer, Kenneth G., Kay, Robert L., Jones, Steven M., Chan, David A., Hug, Paul, Murphy, Matthew J., Hines, Horace H.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Glick, Edward J.
• Application Number:
  US07/981,833
• Time in Patent Office: 762 Days
• Field of Search: 378/87, 378/6, 250/363.02, 250/363.03, 250/363.04, 250/363.05, 250/363.07, 250/363.09, 356/376, 356/1
• US Class Current: 250/363.04
• CPC Class Codes: G01B 11/2433 for measuring outlines by shadow casting
• CPC Class Codes: G01T 1/1648 Ancillary equipment for scintillation cameras, e.g. reference markers, devices for removing motion artifacts, calibration devices adapted for flow studies G01T1/1647

Abstract

A direct measurement system for proximity detection of a body profile for use within nuclear medicine. The measurement system includes two or three proximity detector units mounted on a gantry structure of a nuclear medicine camera which each emit an energy beam which is swept across a portion of a target body. Each detector is capable of directly measuring the distance from the proximity detector unit to the target body with a beam sample. The detectors then create a body profile of the target body which is used to minimize the distance between the collimator of a scanning camera and the target body surface thus improving image quality of the scanning camera. There is relative motion between the object and the gantry along a cranial-caudal axis of a target body for scanning successive body profiles. Successive body profiles are combined together to achieve a complete body contour of the target body. The proximity detector units are stationary with respect to movement of the scanning camera toward said target body. Body contour data is also used for attentuation correction.

Claims

1. In a medical imaging system having an imaging surface of a scintillation detector, a gentry structure, a gentry control unit coupled a scanning camera for movement of said imaging surface relative to an object, and an apparatus for profile determination of said object, said apparatus comprising:

means for generating triangulation data, wherein said means for generating triangulation data further comprises;

means for illuminating said object by emitting an electromagnetic energy beam;

sweeping means optically coupled to receive and reflect said electromagnetic energy beam, said sweeping means for sweeping said electromagnetic energy beam across a plurality of discrete points of said object;

focusing means for focusing electromagnetic energy reflected frown said plurality of points of said object onto an electromagnetic energy detector means;

said electromagnetic energy detector means for detecting position and intensity information of electromagnetic energy received from said focusing means and based thereon for generating said triangulation data; and

a filter for preventing energy not of a same wavelength as said electromagnetic energy beam from entering said electromagnetic energy detector means; and

proximity calculation means for directly computing spatial locations of said plurality of points of said object based on said triangulation data for each of said plurality of points of said object illuminated by said electromagnetic energy beam by taking an average location of a plurality of location samples of each point of said plurality of points, said proximity calculation means coupled to receive said triangulation data from said means for generating triangulation data.

2. An apparatus for profile determination of an object as described in claim 1 wherein said proximity calculation means computes said locations of said plurality of points of said object by determining angles of incidence of said reflected electromagnetic energy with respect to said electromagnetic energy detector means.

3. An apparatus for profile determination of an object as described in claim 1 further comprising:

computer processing means coupled to said proximity calculation means, said computer processing means for storing said locations of said plurality of points of said object to create a surface profile database of said object, wherein said computer processing means further comprises;

means for computing attenuation correction factors based on a determined location of a radiation source within said object and said surface profile database of said object; and

means for increasing image quality of said object by increasing a number of detected scintillations of said imaging surface based on said attenuation correction factors.

4. An apparatus for profile determination of an object as described in claim 1 further comprising:

computer processing means coupled to said proximity calculation means, said computer processing means for storing said locations of said plurality of points of said object to create a surface profile database for said object; and

gantry control means communicatively coupled to said computer processing means and coupled to said gantry control unit for analyzing said surface profile database and based thereon for controlling said gantry control unit to adjust a position of said imaging surface to minimize a distance between said imaging surface and said object.

5. An apparatus for profile determination of an object as described in claim 4 wherein said proximity calculation means is located on said gantry structure which is stationary with respect to movement of said imaging surface.

6. An apparatus for profile determination of an object as described in claim 4 wherein relative movement exists between said gantry structure and said object and wherein said proximity calculation means computes said locations of said plurality of points of said object for positions of said gantry structure along a cranial caudal axis of said object.

7. An apparatus for profile determination of an object as described in claim 6 further comprising scanning means coupled to said scanning camera for scanning an image of said object based on radiated gamma rays, said scanning means for scanning an image for each of said positions of said gantry structure along said cranial-caudal axis of said object, said scanning means coupled to said computer processing means.

8. An apparatus for profile determination of an object as described in claim 7 wherein said proximity calculation means computes said locations of said plurality of points of said object at a position of said gantry structure along said cranial-caudal axis of said object while said scanning means simultaneously scans an image of said object at another position of said gantry structure along said cranial-caudal axis of said object.

9. An apparatus for profile determination of an object as described in claim 6 wherein said computer processing means generates a body contour database from said surface profile database, said body contour database comprising successive profiles of said surface profile database, each of said successive profiles associated with each of said positions of said gantry structure along said cranial-caudal axis of said object.

10. In a medical imaging system having at least one imaging surface of a scintillation detector a gantry structure, a gantry control unit coupled to said imaging surface for movement of said imaging surface, an axial track coupled to said gantry structure, and an apparatus for profile determination of an object, said apparatus comprising:

an electromagnetic energy emission device generating a modulated electromagnetic energy beam;

a sweeping device optically coupled to receive said modulated electromagnetic energy beam, said sweeping device sweeping said modulated electromagnetic energy beam across a plurality of points of said object;

an electromagnetic energy detector device detecting intensity and position of reflected electromagnetic beam energy;

a focusing device focusing said reflected electromagnetic beam energy from said plurality of points of said object onto said electromagnetic energy detector device;

a demodulation device demodulating said reflected electromagnetic beam energy; and

a proximity calculation device directly computing locations of each of said plurality of points of said object based on said reflected electromagnetic beam energy, said proximity calculation device coupled to said demodulation device, said proximity calculation device computing said locations of said plurality of said object by determining angles of incidence of said reflected electromagnetic beam energy with respect to said electromagnetic energy detector device.

11. An apparatus for profile determination of an object as described in claim 10 further comprising:

computer processing means for storing said proximity calculation means, said computer processing means for storing said locations of said plurality of points of said object to create a surface profile database of said object, wherein said computer processing means further comprises;

means for computing attenuation correction factors based on a determined location of a radiation source within said object and said surface profile database of said object; and

means for increasing image quality of said object by increasing a number of detected scintillations of said imaging surface based on said attenuation correction factors.

12. An apparatus for profile determination of an object as described in claim 10 wherein said electromagnetic energy detector device comprises two position sensitive detectors and wherein said angles of incidence of said reflected electromagnetic beam energy are each determined based on a location of a center of electromagnetic beam intensity reflected on each of said two position sensitive detectors;

and further comprising a filter for preventing energy not of a same wavelength as said modulated electromagnetic energy beam from entering said electromagnetic energy detector device.

13. An apparatus for profile determination of an object as described in claim 12 further comprising:

computer processing means coupled to said proximity calculation device, said computer processing means storing said locations of said plurality of points of said object to create a surface profile database of said object; and

gantry control device communicatively coupled to said computer processing means and coupled to said gantry control unit for analyzing said surface profile database and based thereon for controlling said gantry control unit to adjust a position of said imaging surface to minimize a distance between said imaging surface and said object.

14. An apparatus for profile determination of an object as described in claim 12 wherein each of said two position sensitive detectors has a dual mode output signal which is normalized based on a total intensity of said electromagnetic beam intensity reflected onto each position sensitive detectors.

15. An apparatus for profile determination of an object as described in claim 12 wherein said focusing device comprise two optic lens devices, each optic lens device optically coupled with an individual position sensitive detector to focus said reflected electromagnetic beam intensity onto said individual position sensitive detector.

16. An apparatus for profile determination of an object as described in claim 12 wherein said sweeping device comprises a mirror deflecting said electromagnetic energy beam and a rotation motor coupled to said mirror for rotating said mirror.

17. An apparatus for profile determination of an object as described in claim 12 wherein said electromagnetic energy emission device is an infrared laser and said modulated electromagnetic energy beam is a modulated infrared laser energy beam.

18. An apparatus for profile determination of an object as described in claim 12 wherein said sweeping device sweeps said modulated electromagnetic energy beam across said plurality of points of said object in a plane traverse to a cranial caudal axis of said object.

19. An apparatus for profile determination of an object as described in claim 12 wherein said sweeping device as well as said electromagnetic energy detector device are located on said gantry structure which is stationary with respect to said movement of said imaging surface.

20. An apparatus for profile determination of an object as described in claim 19 wherein said gantry structure is movable along said axial track which runs along a cranial-caudal axis of said object and wherein said proximity calculation device computes said locations of said plurality of points of said object for each position of said gantry structure along said axial track.

21. An apparatus for profile determination of an object as described in claim 20 further comprising a scanning device scanning an image of said object based on emitted energy, said scanning device scanning an image for each position of said gantry structure along said axial track, said scanning device coupled to said imaging surface.

22. An apparatus for profile determination of an object as described in claim 21 further comprising a computer processing means coupled to said proximity calculation device, said computer processing means for storing said locations of said plurality of points of said object to create a surface profile database of said object and wherein said computer processing means is also for generating a body contour database from said surface profile database said body contour database comprising successive profiles of said surface profile database, each of said successive profiles associated with each position of said gantry structure along said axial track.

23. An apparatus for profile determination of an object as described in claim 22 wherein said proximity calculation device computes said locations of said plurality of points of said object at a position of said gantry structure along said cranial-caudal axis of said object while said scanning device simultaneously scans an image of said object at another position of said gantry structure along said cranial axis of said object.

24. An apparatus for improving image quality in a medical imaging system having at least one imaging surface of a scintillation detector, a gantry structure, a gantry control unit coupled to said imaging surface to precisely displace said imaging surface relative to an object and an axial track coupled to said gantry structure, said apparatus comprising:

a plurality of profile detector means for determining successive profiles of said object, each of said successive profiles associated with a particular position of said gentry structure along said axial track, said plurality of profile detector means coupled to said gentry structure so that said plurality of profile detector means are stationary with respect to said gentry structure, each of said plurality of profile detector means further comprising;

an electromagnetic emission means for generating a modulated electromagnetic energy beam;

sweeping means for sweeping said modulated electromagnetic energy beam across plurality of points of said object in a plane across a cranial-caudal axis of said object;

a plurality of position sensitive detectors for detecting position and intensity of reflected electromagnetic energy;

a plurality of focusing means, each of said plurality of focusing means having an associated position sensitive detector of said plurality of position sensitive detectors, said plurality of focusing means for focusing said reflected electromagnetic energy from said plurality of points of said object onto said plurality of position sensitive detectors;

a demodulation means for demodulating said reflected electromagnetic energy;

location calculation means for directly calculating spatial location of each of said plurality of points of said object by measuring an angle of incidence of said reflected electromagnetic energy from each of said plurality of points of said object with respect to a position sensitive detector, said location calculation means coupled to said demodulation means; and

filter means for preventing energy not of a same wavelength as said modulated electromagnetic energy beam from entering said plurality of position sensitive detectors.

25. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 24 further comprising:

computer processing means coupled to said plurality of profile detector means, said computer processing means for storing said locations of said plurality of points of said object to create a body contour database of said object by combining said successive profiles; and

gantry control means communicatively coupled to said computer processing means and coupled to said gantry control unit, said gantry control means for analyzing said body contour database and based thereon for controlling said gantry control unit to adjust a position of said imaging surface to minimize a distance between said imaging surface and said object.

26. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 25 wherein said sweeping means comprises a mirror means for deflecting said modulated electromagnetic energy beam and a rotation motor coupled to said mirror means for rotating said mirror means.

27. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 25 wherein said electromagnetic emission means is an infrared laser and said modulated electromagnetic energy beam is a modulated infrared laser energy beam.

28. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 25 wherein said location calculation means directly calculates said locations of each of said plurality of points of said object by taking an average location of a plurality of measuring location samples of each of said plurality of points of said object.

29. An apparatus for improving image quality in a nuclear medicine camera system as described in claim, 25 wherein said plurality of position sensitive detectors comprises position sensitive diode linear arrays and wherein said angle of incidence of said reflected electromagnetic energy from each of said plurality of points of said object is determined based on a location of a center of electromagnetic beam intensity reflected onto said position sensitive diode linear arrays.

30. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 29 wherein each of said position sensitive diode linear arrays has a dual mode output signal which is normalized based on a total detected energy of an individual position sensitive diode linear array.

31. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 29 wherein said plurality of focusing means comprise optic lens devices, each of said optic lens devices optically coupled with an individual position sensitive diode linear array to focus said reflected electromagnetic energy on said individual position sensitive diode linear array.

32. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 25 wherein said plurality of profile detector means comprise two or three profile detector means, one of said profile detector means for generating successive profiles for a left side of said object and another of said profile detector means for generating successive profiles for a right side of said object.

33. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 32 wherein said gantry structure is moveable along said axial track which runs along a cranial-caudal axis of said object and wherein said plurality of profile detector means computes said locations of said plurality of points of said object for each position of said gantry structure along said axial track.

34. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 33 further comprising scanning means coupled to said imaging surface for scanning an image of said object based on emitted gamma rays, said scanning means for scanning an image for each position of said gantry structure along said axial track, said scanning means coupled to said computer processing means.

35. An apparatus for improving image quality in a nuclear medicine camera system as described in claim 34 wherein said plurality of profile detector means generates a successive profile of said successive profiles of said object at one position along said axial track while said scanning means simultaneously scans an image of said object at a different position along said axial track.

36. A medical imaging system for improved image quality comprising:

a) system means comprising an imaging surface, a gantry structure, a gantry control unit coupled to said gantry structure and coupled to said imaging surface for radial movement of said imaging surface and an axial track for moving said gantry structure along a cranial-caudal axis of said object;

b) a plurality of proximity detector means coupled to said gantry structure for determining successive profiles of said object, each profile of said successive profiles determined at a position of said gantry structure along said cranial-caudal axis of said object, each of said plurality of proximity detector means further comprising;

1) electromagnetic energy emission means for generating a modulated elecromagnetic energy beam;

2) sweeping means optically coupled to receive said modulated electromagnetic energy beam, said sweeping means for sweeping said modulated electromagnetic energy beam across a plurality of points of said object in a plane perpendicular to a cranial-caudal axis of said object;

3) electromagnetic energy detector means for detecting intensity and position of reflected electromagnetic beam energy;

4) focusing means for focusing said reflected electromagnetic beam energy reflected from said plurality of points of said object onto said electromagnetic energy detector means;

5) a demodulation means for demodulating said reflected electromagnetic beam energy; and

6) proxiity calculation means, coupled to said demodulation means, for directly computing locations of each of said plurality of points of said object based on said reflected electromagnetic beams energy from each of said plurality of points of said object, said proximity calculation means for computing said locations of said plurality of points of said object by computing angels of incidence of said reflected electromagnetic beam energy with respect to said electromagnetic energy detector means, wherein said proximity determination means directly computes said locations of each of said plurality of points of said object by taking an average location of a plurality of measuring location samples of each of said plurality of points of said object; and

b) computer processing means coupled to said plurality of proximity detector means, said computer processing means for storing and integrating said successive profiles of said object to create a body contour database of said object.

37. A medical imaging system for improved image quality as described in claim 36 further comprising:

gantry control means communicatively coupled to said computer processing means and coupled to said gantry control unit for analyzing said body contour database and based thereon for controlling said gantry control unit to adjust a position of said imaging surface to minimize a distance between said imaging surface and said object.

38. A medical imaging system for improved image quality as described in claim 37 wherein said sweeping means comprises a mirror means for deflecting said modulated electromagnetic energy beam and a rotation motor coupled to said mirror means for rotating said mirror means.

39. A medical imaging system for improved image quality as described in claim 37 wherein said electromagnetic energy emission means is an infrared laser and said modulated electromagnetic energy beam is a modulated infrared laser energy beam.

40. A medical imaging system for improved image quality as described in claim 37 wherein said electromagnetic energy detector means comprises two position sensitive detectors and wherein said angles of incidence are each determined based on a location of a center of electromagnetic beam intensity reflected on each of said two position sensitive detectors.

41. A medical imaging system for improved image quality as described in claim 40 wherein each of said two position sensitive detectors has a dual mode output signal which is normalized.

42. A medical imaging system for improved image quality as described in claim 40 wherein said focusing means comprises two optic lens devices, each of said two optic lens devices optically coupled with an individual position sensitive detector to focus said electromagnetic beam intensity on said individual position sensitive detector.

43. A medical imaging system for improved image quality as described in claim 37 wherein said plurality of proximity detector means comprises two proximity detector means positioned about and coupled onto said gantry structure so that said two proximity detector means are stationary with respect to said gantry structure, one of said two proximity detector means for determining successive profiles of a left side of said object and an other of said two proximity detector means for determining successive profiles of a right side of said object.

44. A medical imaging system for improved image quality as described in claim 43 wherein said gentry structure is movable along said axial track which runs along said cranial-caudal axis of said object and wherein said plurality of proximity detector means computes said locations of said plurality of points of said object for each position of said gentry structure along said axial track.

45. A medical imaging system for improved image quality as described in claim 44 further comprising scanning means for scanning an image of said object based on emitted gamma rays from said object, said scanning means for scanning an image for each position of said gantry structure along said cranial-caudal axis of said object, said scanning means coupled to said imaging surface and coupled to said computer processing means.

46. A medical imaging system for improved image quality as described in claim 45 wherein said plurality of proximity detector means generates a profile of said successive profiles of said object at one position along said cranial-caudal axis while said scanning means simultaneously scans an image of said object at another position along said cranial-caudal axis.

47. In a medical imaging system having an imaging surface of a scintillation detector a gentry structure, a gentry control unit coupled to said imaging surface for movement of said imaging surface toward an object and an axial track coupled to said gantry structure, a method for profile determination of said object to improve image quality, said method comprising the steps of:

generating a modulated electromagnetic energy beam;

sweeping said modulated electromagnetic energy beam across a plurality of points of said object in a plane across a cranial-caudal axis of said object;

focusing electromagnetic beam energy reflected from said plurality of points of said object;

detecting intensity and position of said focused reflected electromagnetic beam energy with a detector means;

demodulating said reflected electromagnetic beam energy;

filtering electromagnetic energy not of a same wavelength as said reflected electromagnetic beam energy out of said step of detecting;

directly computing locations of each of said plurality of points of said object based on angles of incidence of said reflected electromagnetic beam energy reflected from said plurality of points of said object with respect to said detector means;

using said locations of said plurality of points to minimize a distance between said object and imaging surface; and

scanning said object with said scintillation detector to generate an image thereof.

48. A method for profile determination of an object to improve image quality as described in claim 47 further comprising the steps of:

storing and combining said locations of said plurality of points of said object to create a surface profile database of said object;

computing attenuation correction factors based on a determined location of a radiation source within said object and said surface profile database of said object; and

increasing image quality of said object by increasing a number of detected scintillations of said imaging based on said attenuation correction factors.

49. A method for profile determination of an object to improve image quality as described in claim 47 further comprising the steps of:

storing and combining said locations of said plurality of points of said object to create a surface profile database of said object; and

based on said surface profile database, controlling said gantry control unit to adjust the location of said imaging surface to minimize a distance between said imaging surface and said object.

50. A method for profile determination of an object to improve image quality as described in claim 49 wherein said step of sweeping said electromagnetic energy beam across a plurality of points of said object is accomplished by a mirror means for deflecting said modulated electromagnetic energy beam and a rotation motor coupled to said mirror means for rotating said mirror means.

51. A method for profile determination of an object to improve image quality as described in claim 49 wherein said step of generating a modulated electromagnetic energy beam is accomplished by a modulated infrared laser.

52. A method for profile determination of an object to improve image quality as described in claim 49 wherein said step of detecting intensity and position of said reflected electromagnetic beam energy is accomplished by a plurality of position sensitive detectors as said detector means, and wherein each angle of said angles of incidence of said reflected electromagnetic beam energy reflected from said plurality of points of said object is determined based on a location of a center of electromagnetic beam intensity reflected onto each of said plurality of position sensitive detectors.

53. A method for profile determination of an object to improve image quality as described in claim 52 wherein each of said plurality of position sensitive detectors has a dual mode output signal which is normalized.

54. A method for profile determination of an object to improve image quality as described in claim 52 wherein said step of focusing electromagnetic beam energy reflected from said plurality of points of said object is accomplished by optical lens devices, each of said optical lens devices optically coupled with an individual position sensitive detector to focus said reflected electromagnetic beam intensity on said individual position sensitive detector.

55. A method for profile determination of an object to improve image quality as described in claim 49 further comprising the step of:

positioning said gantry structure along different positions of said axial track which runs along a cranial-caudal axis of said object; and

wherein said step of storing and combining said locations of said plurality of points of said object to create a surface profile database of said object operates at each position of said gantry structure along said axial track to create successive surface profiles of said object.

56. A method for profile determination of an object to improve image quality as described in claim 55 further comprising the steps of:

scanning said object with said imaging surface based on radiated gamma rays for each position of said gantry structure along said axial track to generate image data; and

processing said image data to create an image of said object.

57. A method for profile determination of an object to improve image quality as described in claim 56 wherein said step of storing and combining said locations of said plurality of points of said object to create a surface profile database of said object further comprises the step of creating a body contour database from said surface profile database, said body contour database comprising successive surface profiles of said surface profile database, each of said profiles associated with each position of said gantry structure along said axial track.

58. A method for profile determination of an object to improve image quality as described in claim 57 wherein said step of storing and combining said locations of said plurality of points of said object to create a surface profile database of said object creates a surface profile of said successive surface profiles of said object at one position along said cranial-caudal axis while said step of scanning an image of said object with said imaging surface simultaneously scans an image of said object at a different position along said cranial-caudal axis of said object.