Imaging of internal structures of living bodies by sensing implanted magnetic devices

• US 6,230,038 B1
• Filed: 02/01/1999
• Issued: 05/08/2001
• Est. Priority Date: 02/01/1999
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ziegler, James Francis, von Gutfeld, Robert Jacob
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): DAHBOUR, HENRY
• Application Number:
  US09/241,506
• Time in Patent Office: 827 Days
• Field of Search: 600/407, 600/409, 600/424, 128/899, 324/207.11, 324/207.13, 324/207.17, 324/207.22, 324/214, 324/207.26, 324/219
• US Class Current: 600/409
• CPC Class Codes: A61B 2090/3954 magnetic, e.g. NMR or MRI
• CPC Class Codes: A61N 2005/1051 using an active marker
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam

Abstract

The invention provides a system for therapeutic treatment of an organ, tumor, or other internal structure of a living body with therapeutic radiation after implantation, at the organ, of a magnetic element to identify the location of the organ, the element being capable of emitting a magnetic signal in response to an applied magnetic field. The system comprises a magnetic field generator for irradiating the magnetic element with an applied magnetic field, a movable magnetic field sensor for detecting the magnetic signal from a plurality of selected mutually displaced positions to produce a corresponding plurality of element-locating signals, a computing apparatus for converting the signals to a location image of the internal structure, and a controlled source of therapeutic radiation for focussing a selected degree and duration of therapeutic radiation at a target determined from the location image of the magnetic element. Preferably, the magnetic element is a length of wire of an amorphous magnetic material which produces a magnetic signal that exhibits non-linear Bark+hausen jumps in response to an applied ac magnetic field.

Claims

1. A method of determining the location of an internal structure of a living body comprising the steps of:

a) implanting, at said internal structure, an element comprising a magnetic material to identify a selected location of said internal structure, said element being capable of emitting a magnetic signal in response to an applied magnetic field,

b) irradiating said element with an applied magnetic field,

c) detecting said magnetic signal from a plurality of selected mutually displaced positions to produce a corresponding plurality of element-locating signals, and

d) converting said element-locating signals to a location image of said internal structure.

2. A method as set forth in claim 1, where said applied magnetic field is spatially and temporally uniform.

3. A method as set forth in claim 1, said applied magnetic field being a low frequency ac magnetic field.

4. A method as set forth in claim 3, wherein said magnetic signal is non-linear in response to said low frequency ac magnetic field.

5. A method as set forth in claim 1, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by Barkhausen jumps in response to an applied ac magnetic field.

6. A method as set forth in claim 5, wherein said element is elongated in form.

7. A method as set forth in claim 6, wherein said element is a length of wire comprising an amorphous magnetic material.

8. A method as set forth in claim 7, wherein said element is coated with absorbing material which absorbs therapeutic radiation and is pervious to magnetic fields.

9. A method as set forth in claim 1, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by non-linear Barkhausen jumps in response to an applied ac magnetic field.

10. A method as set forth in claim 9, wherein said element is spheroidal in form.

11. A method as set forth in claim 1, wherein said applied magnetic field is a dc field and said element comprises a ferromagnetic material.

12. A method as set forth in claim 1, wherein said location image is a target for focussing therapeutic radiation thereon.

13. A method of therapeutic treatment of an internal structure of a living body with therapeutic radiation, comprising the steps of:

a) implanting, at said internal structure, an element comprising a magnetic material to identify a selected location of said internal structure, said element being capable of emitting a magnetic signal in response to an applied magnetic field,

b) irradiating said element with an applied magnetic field,

c) detecting said magnetic signal from a plurality of selected mutually displaced positions to produce a corresponding plurality of element-locating signals,

d) converting said element-locating signals to a location image of said structure, and

e) focussing a selected degree and duration of therapeutic radiation at a target determined from said location image of said internal structure.

14. A method as set forth in claim 13, where said applied magnetic field is spatially and temporally uniform.

15. A method as set forth in claim 13, said applied magnetic field being a low frequency ac magnetic field.

16. A method as set forth in claim 15, wherein said magnetic signal is non-linear in response to said low frequency ac magnetic field.

17. A method as set forth in claim 13, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by Barkhausen jumps in response to an applied ac magnetic field.

18. A method as set forth in claim 17, wherein said element is elongated in form.

19. A method as set forth in claim 18, wherein said element is a length of wire comprising an amorphous magnetic material.

20. A method as set forth in claim 19, wherein said element is coated with absorbing material which absorbs therapeutic radiation and is pervious to magnetic fields.

21. A method as set forth in claim 13, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by non-linear Barkhausen jumps in response to an applied ac magnetic field.

22. A method as set forth in claim 21, wherein said element is spheroidal in form.

23. A method as set forth in claim 13, wherein said applied magnetic field is a dc field and said element comprises a ferromagnetic material.

24. A system for determining the location of an internal structure of a living body after implantation, at said internal structure, of an element comprising a magnetic material to identify a selected location of said internal structure, said element being capable of emitting a magnetic signal in response to an applied magnetic field, said system comprising:

a) a magnetic field generator for irradiating said element with an applied magnetic field,

b) a movable magnetic field sensor for detecting said magnetic signal from a plurality of selected mutually displaced positions to produce a corresponding plurality of element-locating signals, and

c) a computing apparatus for converting said signals to a location image of said internal structure.

25. A system as set forth in claim 24, where said applied magnetic field is spatially and temporally uniform.

26. A system as set forth in claim 24, said applied magnetic field being a low frequency ac magnetic field.

27. A system as set forth in claim 26, wherein said magnetic signal is non-linear in response to said low frequency ac magnetic field.

28. A system as set forth in claim 24, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by Barkhausen jumps in response to an applied ac magnetic field.

29. A system as set forth in claim 28, wherein said element is elongated in form.

30. A system as set forth in claim 29, wherein said element is a length of wire comprising an amorphous magnetic material.

31. A system as set forth in claim 30, wherein said element is coated with absorbing material which absorbs therapeutic radiation and is pervious to magnetic fields.

32. A method as set forth in claim 29, wherein said element is spheroidal in form.

33. A system as set forth in claim 24, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material that is characterized by non-linear Barkhausen jumps in response to an applied ac magnetic field.

34. A system as set forth in claim 24, wherein said applied magnetic field is a dc field and said element comprises a ferromagnetic material.

35. A system as set forth in claim 24, wherein said location is a target for focussing thereon of therapeutic radiation.

36. A system for therapeutic treatment of an internal structure of a living body with therapeutic radiation after implantation, at said internal structure, of an element comprising a magnetic material to identify a selected location of said internal structure, said element being capable of emitting a magnetic signal in response to an applied magnetic field, said system comprising:

a) a magnetic field generator for irradiating said element with an applied magnetic field,

b) a movable magnetic field sensor for detecting said magnetic signal from a plurality of selected mutually displaced positions to produce a corresponding plurality of element-locating signals,

c) a computing apparatus for converting said signals to a location image of said internal structure, and

d) a controlled source of therapeutic radiation for focussing a selected degree and duration of therapeutic radiation at a target determined from said location image of said internal structure.

37. A system as set forth in claim 36, where said applied magnetic field is spatially and temporally uniform.

38. A system as set forth in claim 36, said applied magnetic field being a low frequency ac magnetic field.

39. A system as set forth in claim 38, wherein said magnetic signal is non-linear in response to said low frequency ac magnetic field.

40. A system as set forth in claim 36, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material, said magnetic signal being characterized by Barkhausen jumps in response to an applied ac magnetic field.

41. A system as set forth in claim 40, wherein said element is elongated in form.

42. A system as set forth in claim 41, wherein said element is a length of wire comprising an amorphous magnetic material.

43. A system as set forth in claim 42, wherein said element is coated with absorbing material which absorbs therapeutic radiation and is pervious to magnetic fields.

44. A method as set forth in claim 41, wherein said element is spheroidal in form.

45. A system as set forth in claim 36, wherein said applied magnetic field is an ac field and said element comprises an amorphous magnetic material that is characterized by non-linear Barkhausen jumps in response to an applied ac magnetic field.

46. A system as set forth in claim 36, wherein said applied magnetic field is a dc field and said element comprises a ferromagnetic material.

47. A system as set forth in claim 36, wherein said location is a target for focussing thereon of therapeutic radiation.