Method and apparatus for modulating a radiation beam

• US 20060193441A1
• Filed: 02/24/2006
• Published: 08/31/2006
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Accuray Incorporated
• Original Assignee: Patrick F. Cadman
• Inventors: Cadman, Patrick F.
• Granted Patent: US 7,957,507 B2
• Time in Patent Office: Days
• US Class Current: 378/153
• CPC Class Codes: A61N 5/1042 with spatial modulation of the radiation beam within the treatment head
• 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

An apparatus and method to deliver intensity modulated radiation therapy by irradiating a treatment volume with rotation of the radiation beam. The system includes a collimation device comprising a two-dimensional array of pivoting attenuating leaves, which are temporarily placed into the radiation beam path as the gantry rotates around the patient. The leaves are independently movable between a first position and a second position. The radiation beam intensity is modulated by controlling the time that each leaf is present to attenuate the beam.

Claims

1. A radiation therapy treatment system comprising:

a collimator including a plurality of leaf assemblies having

a support structure,

a plurality of members supported by and extending from the support structure, and

a plurality of leaves, each leaf supported by one of the members and adapted to move between a first position and a second position upon actuation,

wherein the arrangement of the leaf assemblies provides a two-dimensional array, the collimator operable to deliver radiation as a sum of independent beamlets.

2. The system of claim 1 further comprising an actuator coupled to the leaf and the member, the actuator operable to selectively actuate the leaf to move between a first position and a second position.

3. The system of claim 2 further comprising a gantry and a controller operable to selectively instruct the actuator to move the leaf between the first position and the second position based on a radiation treatment plan and a position of the gantry.

4. The system of claim 1 wherein one of the first position and the second position is a closed position and one of the first position and the second position is an open position.

5. The system of claim 1 wherein when the leaf is in one of the first position and the second position, the leaf is operable to block radiation and when the leaf is in one of the first position and the second position, the leaf generates a path for the passage of radiation.

6. The system of claim 1 further comprising means for biasing the leaf to a closed position.

7. The system of claim 1 wherein the collimator further comprises attenuation material positioned above the leaves.

8. The system of claim 1 wherein the leaves are arranged vertically in the array.

9. The system of claim 8 wherein each of the leaf assemblies includes a plurality of leaves and wherein the arrangement of the leaf assemblies and the leaves provides a two-dimensional array to provide temporal and spatial modulation of a radiation beam.

10. The system of claim 1 wherein the leaf includes a member that extends outwardly therefrom, and wherein the member engages a slit of an adjacent leaf assembly when the leaf is in a closed position.

11. The system of claim 1 wherein the leaves are operable to pivot between the first and second positions.

12. The system of claim 1 wherein each of the leaf assemblies are oriented in a plurality of rows, and wherein the leaf assembly of one row is offset with respect to a leaf assembly of an adjacent row.

13. The system of claim 12 wherein the offset arrangement of the leaf assemblies provides a gap between the leaf assemblies in a single row.

14. A radiation therapy treatment system comprising:

a gantry;

a collimator supported by the gantry, the collimator including a plurality of leaf assemblies, each leaf assembly including

a support structure,

a plurality of members supported by and extending from the support structure,

a plurality of leaves, each leaf supported by one of the members and adapted to move upon actuation,

a plurality of actuators, each actuator supported by one of the members and coupled to one of the leaves, and

wherein the arrangement of the leaf assemblies provides a two-dimensional array; and

a controller operable to selectively instruct the actuators to move the leaves to provide temporal and spatial modulation of a radiation beam.

15. The system of claim 14 wherein the controller instructs an actuator to move a respective leaf based on a radiation treatment plan and a position of the gantry.

16. The system of claim 14 wherein the actuator is adapted to actuate the leaf and move the leaf between a first position and a second position.

17. The system of claim 16 wherein one of the first position and the second position is a closed position and one of the first position and the second position is an open position.

18. The system of claim 14 wherein each of the leaf assemblies includes a plurality of leaves and wherein the arrangement of the leaf assemblies and the leaves provides a two-dimensional array, the collimator operable to deliver radiation to a patient in a plurality of slices.

19. The system of claim 14 wherein the leaves are arranged to diverge in the array with respect to a radiation source supported by the gantry.

20. The system of claim 14 wherein the leaves are arranged vertically in the array.

21. The system of claim 14 wherein the leaves are operable to pivot.

22. A radiation therapy treatment system comprising:

a collimator; and

means for delivering a plurality of slices of radiation to a patient, the delivery means supported by the collimator.

23. The system of claim 22 further comprising a gantry and wherein the plurality of slices of radiation are delivered to the patient during a single gantry rotation.

24. The system of claim 22 wherein the delivery means includes a plurality of leaves operable to pivot between a first position and a second position.