System and method for high resolution radiation field shaping

• US 7,507,975 B2
• Filed: 10/30/2006
• Issued: 03/24/2009
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Mohr, Stephen
• Primary Examiner(s): Berman; Jack I
• Assistant Examiner(s): MASKELL, MICHAEL P
• Application Number:
  US11/589,415
• Publication Number:
  US 20080073591A1
• Time in Patent Office: 876 Days
• Field of Search: 250/492.1, 250/505.1, 250/492.3, 378/65, 378/145, 378/147, 378/150, 378/152
• US Class Current: 250/492.1
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• 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 system and method are provided for a high resolution radiation treatment system which provide for projecting a field of radiation energy at targeted patient tissue. The system uses a multi-leaf collimator, which is positioned such that a significant clearance is provided between the multi-leaf collimator and the isocenter plane where the targeted tissue is located. The leaves of the multi-leaf collimator are designed to provide for high step resolution in the projected radiation energy shape. Additionally, an embodiment of the system and method herein can provide for a high step resolution in the projected radiation energy shape, and for a dose calculation matrix which has matrix units which coincide with the high step resolution in the projected radiation shape.

Claims

1. A radiation treatment system including:

a radiation source which emits radiation energy;

a multi-leaf collimator positioned between the radiation source and an isocenter, such that a portion of the radiation energy from the radiation source is transmitted through the multi-leaf collimator to the isocenter;

wherein the multi-leaf collimator includes a plurality of leaves, each leaf being movable to allow a selected portion of the radiation energy to be blocked, whereby a shape is defined by the portion of radiation energy which is incident at the isocenter, and the shape is controlled by a positioning of the plurality of leaves; and

wherein the multi-leaf collimator includes a first set of leaves which provide for a first area of the shape that has a step resolution length in the range of approximately 3.0 mm or less and wherein the multi-leaf collimator is positioned such that there is a clearance in range approximately 400 mm or greater between the multi-leaf collimator and the isocenter; and

wherein the step resolution length corresponds to a length dimension of a dose calculation matrix.

2. The radiation system of claim 1 wherein the step resolution length is approximately 2.5 mm.

3. The radiation treatment system of claim 1, wherein a widest point in the first set of leaves is no greater than about 1.7 mm.

4. The radiation treatment system of claim 3, wherein the plurality of leaves includes a second set of leaves wherein a widest point in second set of leaves is no greater than about 3 mm.

5. The radiation treatment system of claim 1, wherein one or more of the leaves of the multileaf collimator has a stroke length of about 205 mm or greater.

6. The radiation treatment system of claim 1, wherein the shape defined by the portion of radiation energy provides a treatment area about 22×

40 cm² or greater.

7. A radiation treatment system including:

a radiation source which emits radiation energy;

a multi-leaf collimator positioned between the radiation source and an isocenter, such that a portion of the radiation energy from the radiation source is transmitted through the multi-leaf collimator to the isocenter;

wherein the multi-leaf collimator includes a plurality of leaves, each leaf being movable to allow a selected portion of the radiation energy to be blocked, whereby a shape is defined by the portion of radiation energy which is incident at the isocenter, and the shape is controlled by a positioning of the plurality of leaves; and

wherein the multi-leaf collimator includes a first set of leaves which provide for a first area of the shape that has a step resolution length in the range of approximately 3.0 mm or less and wherein the multi-leaf collimator is positioned such that there is a clearance in range approximately 400 mm or greater between the multi-leaf collimator and the isocenter; and

wherein the step resolution length corresponds to a whole number integer multiple of a unit length dimension of a dose calculation matrix.

8. A radiation treatment system including:

a radiation source which emits radiation energy;

a multi-leaf collimator positioned between the radiation source and an isocenter, such that a portion of the radiation energy from the radiation source is transmitted through the multi-leaf collimator to the isocenter;

wherein the multi-leaf collimator includes a plurality of leaves, each leaf being movable to allow a selected portion of the radiation energy to be blocked, whereby a shape is defined by the portion of radiation energy which is incident at the isocenter, and

the shape is controlled by a positioning of the plurality of leaves; and

wherein the multi-leaf collimator includes a first set of leaves which provide for a first area of the shape that has a step resolution length in the range of approximately 3.0 mm or less and wherein the multi-leaf collimator is positioned such that there is a clearance in range approximately 400 mm or greater between the multi-leaf collimator and the isocenter; and

wherein the step resolution length corresponds to a length dimension of a dose calculation matrix, and wherein the multi-leaf collimator includes a second set of leaves which provide for a second area of the shape that has a second step resolution length, and the second step resolution length corresponds to a whole number integer multiple of the length dimension of the dose calculation matrix, and the whole number integer is a number greater than one.

9. The radiation treatment system of claim 8, wherein the first step resolution length is about 2.5 mm, and the second step resolution length is about 5 mm.

10. A radiation treatment system including:

a radiation source which emits radiation energy;

a multi-leaf collimator positioned between the radiation source and an isocenter, such that a portion of the radiation energy from the radiation source is transmitted through the multi-leaf collimator to the isocenter;

wherein the multi-leaf collimator includes a plurality of leaves, each leaf being movable to allow a selected portion of the radiation energy to be blocked, whereby a shape is defined by the portion of radiation energy which is incident at the isocenter, and the shape is controlled by a positioning of the plurality of leaves; and

wherein at least a first area of the shape has a first step resolution length in the range of approximately 3.0 mm or less and, wherein the first step resolution length corresponds to a length dimension of a dose calculation matrix.

11. The radiation treatment system of claim 10, wherein the radiation source is positioned at a distance of approximately 800 mm or greater from the isocenter.

12. The radiation treatment system of claim 10, wherein the radiation source is positioned at a distance of approximately 1000 mm from the isocenter.

13. The radiation treatment system of claim 10 wherein the plurality of leaves includes a first set of leaves which have a maximum width provides for a step resolution length in the range of about 2.5 mm in at least the first area of the shape.

14. The radiation treatment system of claim 13 wherein the plurality of leaves include a second set of leaves having a second maximum width which provides for a step resolution length in the range of about 5 mm in a second area of the shape.

15. The radiation treatment system of claim 10 wherein at least a second portion of shape has a second step resolution length which is approximately twice the first step resolution length.

16. The radiation system of claim 15 wherein the first step resolution length is approximately 2.5 mm.

17. The radiation treatment system of claim 10, wherein a second area of the shape has a second step resolution length, and the second step resolution length corresponds to a whole number integer multiple of the length dimension of the dose calculation matrix, and the whole number integer is a number greater than one.

18. The radiation treatment system of claim 17, wherein the first step resolution length is about 2.5 mm, and the second step resolution length is about 5 mm.

19. The radiation treatment system of claim 10, wherein the plurality of leaves includes a first set of leaves wherein a widest point in first set of leaves is no greater than about 1.7 mm.

20. The radiation treatment system of claim 19, wherein the plurality of leaves includes a second set of leaves wherein a widest point in second set of leaves is no greater than about 3 mm.

21. The radiation treatment system of claim 10, wherein one or more of the leaves of the multileaf collimator has a stroke length of about 205 mm or greater.

22. The radiation treatment system of claim 10, wherein the shape defined by the portion of radiation energy provides a treatment area about 22×

40 cm² or greater.

23. A radiation treatment system including:

a radiation source which emits radiation energy;

a multi-leaf collimator positioned between the radiation source and an isocenter, such that a portion of the radiation energy from the radiation source is transmitted through the multi-leaf collimator to the isocenter;

wherein the multi-leaf collimator includes a plurality of leaves, each leaf being movable to allow a selected portion of the radiation energy to be blocked, whereby a shape is defined by the portion of radiation energy which is incident at the isocenter, and the shape is controlled by a positioning of the plurality of leaves; and

wherein at least a first area of the shape has a first step resolution length in the range of less than approximately 3.0 mm or less and the first step resolution length corresponds to a whole

number integer multiple of a length dimension of a dose calculation matrix.

24. The radiation treatment system of claim 23, wherein the radiation source is positioned at a distance of approximately 800 mm or greater from the isocenter.

25. The radiation treatment system of claim 23, wherein the radiation source is positioned at a distance of approximately 1000 mm from the isocenter.

26. The radiation treatment system of claim 23, wherein the plurality of leaves includes a first set of leaves which have a maximum width provides for a step resolution length of approximately 2.5 mm in at least the first area of the shape.

27. The radiation treatment system of claim 26 wherein the plurality of leaves include a second set of leaves having a second maximum width which provides for a step resolution length of approximately 5 mm in a second area of the shape.

28. The radiation treatment system of claim 23 wherein at least a second area of the shape has a second step resolution length which is approximately twice the step resolution length of the first area of the shape.

29. The radiation treatment system of claim 23, wherein a second area of the shape has a second step resolution length, and the second step resolution length is a whole number integer multiple of the width dimension of the dose calculation matrix, and the whole number integer is a number greater than one.

30. The radiation treatment system of claim 29, wherein the first step resolution length is about 2.5 mm, and the second step resolution length is about 5 mm.

31. The radiation treatment system of claim 23 wherein the plurality of leaves includes a first set of leaves wherein a widest point in first set of leaves is about 1.7 mm or less.

32. The radiation treatment system of claim 31, wherein the plurality of leaves includes a second set of leaves wherein a widest point in second set of leaves is about 3 mm or less.

33. The radiation treatment system of claim 23, wherein one or more of the leaves of the multileaf collimator has a stroke length of about 205 mm or greater.

34. The radiation treatment system of claim 23, wherein the shape defined by the portion of radiation energy provides a treatment area about 22×

40 cm² or greater.