Method and apparatus for conformal radiation therapy

• US 5,596,619 A
• Filed: 05/17/1994
• Issued: 01/21/1997
• Est. Priority Date: 08/21/1992
• Status: Expired due to Term

• Current Assignee: Best Medical International Incorporated (TeamBest Group)
• Original Assignee: Nomos Corporation (North American Scientific, Inc.)
• Inventors: Carol, Mark P.
• Primary Examiner(s): Church, Craig E.
• Application Number:
  US08/245,626
• Time in Patent Office: 980 Days
• Field of Search: 378/65, 378/150
• US Class Current: 378/65
• CPC Class Codes: A61B 2090/101 for stereotaxic radiosurgery
• CPC Class Codes: A61N 2005/1035 Simulated annealing
• CPC Class Codes: A61N 5/01 Devices for producing movement of radiation source during therapy A61N5/1077 takes precedence
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation
• CPC Class Codes: G21K 1/04 using variable diaphragms, shutters, choppers
• CPC Class Codes: G21K 1/046 varying the contour of the field, e.g. multileaf collimators

Abstract

A method and apparatus for conformal radiation therapy, with a radiation beam having a pre-determined, constant beam intensity, treats the entire tumor volume of a patient'"'"'s tumor, and the beam intensity of the radiation beam is spatially modulated across the tumor, by separating the radiation into a plurality of treatment beam segments and independently modulating the beam intensity of the plurality of radiation beam segments. The independent modulation of the beam intensities may be accomplished by selectively and independently filling, or removing, a flowable, radiation blocking material from a compartment associated with each radiation beam segment.

Claims

1. A method of conformal radiation therapy, with a radiation beam having a predetermined, constant beam intensity for treatment of a volume of tissue in a patient, the volume of tissue containing a tumor to be treated, the tumor having a total tumor volume and a varying thickness, comprising the steps of:

(a) directing the radiation treatment beam toward the volume of tissue;

(b) separating the radiation treatment beam into a plurality of radiation beam segments, with at least one beam segment being disposed contiguous to at least three adjacent beam segments; and

(c) independently modulating the beam intensity of the plurality of radiation beam segments to spatially modulate the beam intensity of the radiation treatment beam across the volume of tissue, to treat the tumor with the plurality of radiation beam segments, each radiation beam segment having a beam intensity related to the thickness of the portion of the tumor through which each radiation beam segment passes.

3. The method of claim 1, including the step of utilizing a conical shaped radiation beam.

4. The method of claim 1, including the steps of:

(e) rotating the radiation beam about the patient to successively direct the plurality of radiation beam segments toward the volume of tissue; and

(f) modulating the beam intensity of the plurality of the radiation beam segments independent of each other, to spatially modulate the beam intensity of the radiation treatment beam across the volume of tissue as the plurality of radiation beam segments are directed toward the volume of tissue.

5. The method of claim 4, including the step of rotating the radiation beam in 5 degree segments of a radial arc to treat the volume of tissue after each 5 degrees of rotation of the radiation beam.

6. The method of claim 1, wherein the at least one radiation beam is separated into a plurality of radiation beam segments by passing the radiation beam through a plurality of compartments extending through a housing, having a top and a bottom, each compartment defining a passageway for a radiation beam segment.

7. The method of claim 6, including the steps of:

providing the housing with a quantity of flowable, radiation blocking material in communication with the compartments; and

the beam intensities of each radiation beam segment are modulated by selectively filling at least a portion of a compartment with the flowable, radiation blocking material or removing at least a portion of the flowable, radiation blocking material from a compartment.

8. The method of claim 7, including the step of independently varying the amount of time each compartment is selectively filled with the flowable, radiation blocking material.

9. The method of claim 7, including the step of selectively, substantially completely filling a compartment with the flowable, radiation blocking material or substantially completely removing the flowable, radiation blocking material from a compartment.

10. The method of claim 7, including the step of utilizing mercury as the flowable, radiation blocking material.

11. The method of claim 7, including the steps of:

providing an expandable, radiolucent member in each compartment; and

expanding the radiolucent members within preselected compartments to remove at least a portion of the flowable, radiation blocking material from the preselected compartments.

12. The method of claim 11, including the steps of:

utilizing inflatable balloons as the expandable, radiolucent members; and

expanding the inflatable balloons with a source of pressurized fluid.

13. The method of claim 11, including the steps of:

providing each compartment with a substantially square cross-sectional configuration; and

providing each expandable, radiolucent member, when expanded, with a substantially square cross-sectional configuration substantially conforming to the cross-sectional configuration of the compartments.

14. The method of claim 13, including the step of:

increasing the size of the cross-sectional configuration of each compartment and each expandable, radiolucent member, when expanded, from the top of the housing to the bottom of the housing.

15. The method of claim 14, including the steps of:

utilizing inflatable balloons as the expandable, radiolucent members; and

disposing each inflatable balloon in fluid communication with a source of pressurized fluid.

16. The method of claim 15, including the step of selectively inflating and deflating the inflatable balloons.

2. An apparatus for use in conformal radiation therapy of a tumor, comprising:

(a) a radiation beam source for producing a radiation beam having a predetermined, constant beam intensity;

(b) means for separating the radiation treatment beam into a plurality of radiation beam segments, with at least one beam segment being disposed contiguous to at least three adjacent beam segments; and

(c) means for independently modulating the beam intensity of the plurality of radiation beam segments to spatially modulate the beam intensity of the radiation treatment beam across the tumor.

28. The apparatus of claim 2, wherein the radiation beam is conical shaped.

29. The apparatus of claim 2, wherein the means for separating the radiation treatment beam into a plurality of radiation beam segments includes:

a housing having a top and bottom;

the housing containing a plurality of compartments, extending from the top to the bottom of the housing, each compartment defining a passageway for a radiation beam segment.

30. The apparatus of claim 29, wherein the compartments are defined by a plurality of divider members disposed in the housing.

31. The apparatus of claim 29, wherein the means for independently modulating the beam intensity of the plurality of radiation beam segments includes:

an expandable, radiolucent member provided for each compartment;

a quantity of flowable, radiation blocking material disposed within the housing and within each compartment when the expandable member provided for a compartment is unexpanded; and

a reservoir for the flowable, radiation blocking material, whereby upon expansion of the expandable member, the expandable member displaces the flowable, radiation blocking material outwardly from the compartment and into the reservoir, so that a radiation beam segment may pass through the compartment toward a portion of the tumor.

32. The apparatus of claim 31, wherein each compartment has a substantially square cross-sectional configuration and the expandable member associated with each compartment, when expanded, has a substantially square cross-sectional configuration substantially conforming to the cross-sectional configuration of the compartment.

33. The apparatus of claim 32, wherein the cross-sectional configuration of each compartment and the expandable member, associated therewith when expanded, increases in size from the top of the housing to the bottom of the housing.

34. The apparatus of claim 33, wherein the expandable members are inflatable balloons;

each balloon having a source of pressurized fluid associated therewith; and

each source of pressurized fluid includes a means for selectively inflating or deflating the balloon associated therewith.

35. The apparatus of claim 34, wherein the means for selectively inflating, or deflating, a balloon is a solenoid valve.

36. The apparatus of claim 31, including a source of pressurized fluid associated with the reservoir for maintaining a preselected pressure force on the flowable, radiation blocking material.

37. The apparatus of claim 31, wherein the flowable, radiation blocking material is mercury.

17. An apparatus for use in conformal radiation therapy of a tumor with a radiation beam from a radiation beam source, the radiation beam having a predetermined, constant beam intensity, comprising:

(a) means for separating the radiation treatment beam into a plurality of radiation beam segments, with at least one beam segment being disposed contiguous to at least three adjacent beam segments; and

(b) means for independently modulating the beam intensity of the plurality of radiation beam segments to spatially modulate the beam intensity of the radiation treatment beam across the tumor.

18. The apparatus of claim 17, wherein the radiation beam is conical shaped.

19. The apparatus of claim 17, wherein the means for separating the radiation treatment beam into a plurality of radiation beam segments includes:

a housing having a top and a bottom;

the housing containing a plurality of compartments, extending from the top to the bottom of the housing, each compartment defining a passageway for a radiation beam segment.

20. The apparatus of claim 19, wherein the compartments are defined by a plurality of divider members disposed in the housing.

21. The apparatus of claim 19, wherein the means for independently modulating the beam intensity of the plurality of radiation beam segments includes:

an expandable, radiolucent member provided for each compartment;

a quantity of flowable, radiation blocking material disposed within the housing and within each compartment when the expandable member provided for a compartment is unexpanded; and

a reservoir for the flowable, radiation blocking material, whereby upon expansion of the expandable member, the expandable member displaces the flowable, radiation blocking material outwardly from the compartment and into the reservoir, so that a radiation beam segment may pass through the compartment toward a portion of the tumor.

22. The apparatus of claim 21, wherein each compartment has a substantially square cross-sectional configuration and the expandable member associated with each compartment, when expanded, has a substantially square cross-sectional configuration substantially conforming to the cross-sectional configuration of the compartment.

23. The apparatus of claim 22, wherein the cross-sectional configuration of each compartment and the expandable member, associated therewith when expanded, increases in size from the top of the housing to the bottom of the housing.

24. The apparatus of claim 23, wherein the expandable members are inflatable balloons;

each balloon having a source of pressurized fluid associated therewith; and

each source of pressurized fluid includes a means for selectively inflating or deflating the balloon associated therewith.

25. The apparatus of claim 24, wherein the means for selectively inflating, or deflating, a balloon is a solenoid valve.

26. The apparatus of claim 21, including a source of pressurized fluid associated with the reservoir for maintaining a preselected pressure force on the flowable, radiation blocking material.

27. The apparatus of claim 21, wherein the flowable, radiation blocking material is mercury.