Collimator apparatus and method

• US 4,739,173 A
• Filed: 08/15/1986
• Issued: 04/19/1988
• Est. Priority Date: 04/11/1986
• Status: Expired due to Fees

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Maughan, Richard L., Blosser, Henry G., Jemison, Emanuel B., Blosser, Gabe F.
• Primary Examiner(s): Anderson, Bruce C.
• Application Number:
  US06/896,730
• Time in Patent Office: 613 Days
• Field of Search: 250/505.1, 250/363 SH, 378/147, 378/150, 378/152
• US Class Current: 250/505.1
• CPC Class Codes: A61N 5/1045 using a multi-leaf collimator, e.g. for intensity modulated radiation therapy or IMRT
• CPC Class Codes: G21K 1/02 using diaphragms, collimators
• CPC Class Codes: G21K 1/04 using variable diaphragms, shutters, choppers

Abstract

A collimator apparatus (10 or 100) including one or more bundles of nested rods (11, 11a or 101 or 101a or 201) which define a surface (112, 112a) which interferes with a beam of radiation is described. The apparatus particularly uses coil spring (48) between and along the axis (a--a or c--c) of the rods which are compressed by blocks (13, 14, 13a and 14a or 103, 104, 103a and 104a) to lock the rods in position in holes in the blocks. The apparatus is particularly useful for shaping radiation beams for patient treatment.

Claims

1. A collimator apparatus for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) support plate means having a central opening around a beam axis through which the beam of radiation can pass;

(b) a bundle of nested rods mounted adjacent the support plate means each rod being movable into the beam at an angle to the beam axis to interfere with the beam, the rods having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends of the rods;

(c) a holder means including spaced apart blocks mounted on the support plate, each block having axially aligned holes mounting the rods so that the first surface is defined and the beam is shaped by the first ends of the rods; and

(d) releasable clamping means for moving the blocks so that the blocks or means between the blocks adjacent the rods are in engagement with the rods to secure the rods together in the shape defined by the first ends of the rods.

2. The apparatus of claim 1 wherein the blocks can be compressed together around the rods by the clamping means to reduce the diameter of the holes and thus secure the rods together.

3. The apparatus of claim 1 wherein coil springs are provided between the rods and blocks which can be compressed by moving the blocks along the rods towards each other to hold the rods in position and can be uncompressed to release the rods.

4. A collimator apparatus for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) support plate means having a central opening around a beam axis through which the beam of radiation can pass;

(b) a bundle of nested rods mounted adjacent the support plate means each rod being movable into the beam at an angle to the beam axis to interfere with the beam, the rods having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends of the rods;

(c) a holder means with two spaced apart blocks mounted on the support plate, each block having axially aligned holes mounting the rods so that the first surface is defined and the beam is shaped by the first ends of the rods and at least one block being movable relative to the other block;

(d) releasable clamping means mounted on the support plate means and engaging the blocks and rods between the first and second ends to secure the rods together in the shape defined by the first ends of the rods, wherein the releasable clamping means includes multiple coil spring means which have opposed ends which engage the blocks and which are positioned and mounted between the rods so that when at least one of the blocks is moved on the rods towards the other block and coil spring means is compressed and engages the rods surrounding the spring means to clamp the surrounding rods together and wherein the clamping means includes drive means mounted on the holder means and connected to at least one of the blocks for moving the blocks together to compress the coil spring against the rods to prevent movement of the rods in the holes in the blocks and for moving the blocks apart to release the spring means from the rods to allow movement of the rods in the holes in the blocks.

5. The collimator apparatus of claim 4 wherein there are two opposed bundles of rods mounted on the support plate means with the first ends opposite each other and axially displaced relative to each other.

6. The collimator apparatus of claim 4 wherein the rods are circular in cross-section and have a diameter of between about 1 mm and 10 mm.

7. The collimator apparatus of claim 4 wherein rods have a composition for interfering with a neutron beam.

8. The collimator apparatus of claim 4 wherein the rods have a composition for interference with a photon beam.

9. A collimator apparatus for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) support plate means having a central opening around a beam axis through which the beam of radiation can pass;

(b) a bundle of nested metal rods mounted adjacent the support plate means each rod having a longitudinal axis perpendicular to the beam axis and having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends;

(c) a holder means with two spaced apart blocks mounted adjacent the support plate means each block having axially aligned holes mounting the rods;

(d) rod shaping means adjacent the opposite second ends of the rods, wherein the rod shaping means has a second surface corresponding to the first surface which defines varying positions of the first ends of the rods so that the first surface is defined and the beam is shaped by the first ends of the rods; and

(e) releasable clamping means engaging the blocks for securing the rods together in the shape defined by the shaping means, wherein the releasable clamping means includes multiple coil spring means which have opposed ends which engage the blocks and which are positioned and mounted between the rods so that when the blocks are moved on the rods towards each other the coil spring means are compressed and engage the rods surrounding each of the spring means to clamp the surrounding rods together and wherein the clamping means includes drive means mounted on the holder means and connected to one of the blocks for moving the blocks together to compress the coil spring means against the rods to prevent movement of the rods in the holes in the blocks and for moving the blocks apart to release the spring means from the rods to allow movement of the rods in the holes.

10. The collimator apparatus of claim 9 wherein there are two opposed bundles of rods mounted on the support plate means with the first ends opposite each other and with the opposed rods having parallel longitudinal axis offset from each other on the axis.

11. The collimator apparatus of claim 9 wherein the rods are circular in cross-section and have a diameter of between about 1 mm and 10 mm.

12. The collimator apparatus of claim 9 wherein the metal composition of the rods is selected from the group consisting of tungsten and stainless steel.

13. The collimator apparatus of claim 9 wherein the rod shaping means is composed of polystyrene foam which is mounted on the holder means.

14. The collimator apparatus of claim 9 wherein the rods have a composition for interference with a neutron or photon beam.

15. The collimator apparatus of claim 9 wherein the rods have a polygonal cross-section.

16. The collimator apparatus of claim 9 wherein the rods have a circular cross-section and wherein the rod shaping means is composed of a polystyrene foam.

17. The apparatus of claim 9 wherein there are two opposed bundles of rods and blocks mounted on the support plate means with the first ends opposite each other and with the opposed rods having parallel longitudinal axis and wherein one bundle of rods and blocks is movable relative to the other bundle of rods and blocks so that the bundle of rods is shaped by a first shaping means, and wherein a second rod shaping means is movable with the movable bundle of rods and blocks to engage the opposite ends of the rods so that the first surfaces are defined and wherein motive means is provided on the support plate means to move the movable bundle of rods, and blocks and second rod shaping means.

18. The apparatus of claim 17 wherein the movable bundle of rods, blocks and shaping means are moved by an arm of a hydraulic or pneumatic cylinder as the motive means which is mounted on the support plate means.

19. The method for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) providing a collimator apparatus which comprises support plate means having a central opening around a beam axis through which the beam of radiation can pass;

a bundle of nested rods mounted adjacent the support plate means each rod being movable into the beam at an angle to the beam axis to interfere with the beam, the rods having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends of the rods;

a holder means including spaced apart blocks mounted on the support plate, each block having axially aligned holes mounting the rods so that the first surface is defined and the beam is shaped by the first ends of the rods and at least one block being movable relative to the other block;

releasable clamping means engaging the rods between the first and second ends to secure the rods together in the shape defined by the first ends of the rods, wherein the releasable clamping means includes multiple coil spring means which have opposed ends which engage the blocks and which are positioned and mounted between the rods so that when at least one of the blocks is moved on the rods towards the other block the coil spring means is compressed and engages the rods surrounding the spring means to clamp the surrounding rods together and wherein the clamping means includes drive means mounted on the holder means and connected to one of the blocks for moving the blocks together to compress the coil spring against the rods to prevent movement of the rods in the holes in the blocks and for moving the blocks apart to release the spring means from the rods to allow movement of the rods in the holes in the blocks;

(b) moving the rods in the holes in the blocks so that the rods define the first surface;

(c) clamping the rods with the releasable clamping means by moving the blocks so that the spring means is compressed to prevent movement of the rods; and

(d) producing the shaped beam defined by the first ends of the rods.

20. The method for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) providing a collimator apparatus which comprises support plate means having a central opening around a beam axis through which the beam of radiation can pass;

a bundle of nested metal rods mounted on the support plate means each rod having a longitudinal axis perpendicular to the beam axis and having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends;

a holder means with two spaced apart blocks mounted on the support plate each block having axially aligned holes mounting the rods;

rod shaping means adjacent the opposite second ends of the rods, wherein the rod shaping means has a second surface corresponding to the first surface which defines varying positions of the first ends of the rods so that the first surface is defined and the beam is shaped by the first ends of the rods; and

releasable clamping means for securing the rods together in the shape defined by the shaping means, wherein the releasable clamping means includes multiple coil spring means which have opposed ends which engage the blocks and which are positioned and mounted between the rods so that when the blocks are moved on the rods towards each other the coil spring means is compressed and engages the rods surrounding the spring means to clamp the surrounding rods together and wherein the clamping means includes drive means mounted on the holder means and connected to at least one of the blocks for moving the blocks together to compress the coil spring against the rods to prevent movement of the rods in the holes in the blocks and for moving the blocks apart to release the spring means from the rods to allow movement of the rods in the holes;

(b) moving the opposite rods in the holes in the blocks with the second ends against the rod shaping means to define the first surface;

(c) clamping the rods with the releasable clamping means by moving the blocks so that the spring means is compressed to prevent movement of the rods; and

(d) producing the shaped beam defined by the first ends of the rods.

21. The method of claim 20 wherein there are two bundles of rods and blocks each with a rod shaping means mounted on the support plate means with the first ends opposite each other and with the opposed rods having parallel longitudinal axis offset from each other wherein one bundle of rods and blocks are movable together relative to the other bundle of rods and blocks and wherein one bundle of rods and blocks is moved relative to the other bundle of rods and blocks so that the one bundle of rods is shaped by a first of the shaping means and wherein a second rod shaping means is moved with the movable bundle of rods so that the opposite second ends of the rods in the other bundle of rods engages a second of the rod shaping means so that the first surfaces are defined for each of the bundles of rods and wherein motive means mounted on the support plate means moves the second bundle of rods and blocks and second rod shaping means together and wherein the bundles of rods are secured together by the clamping means when each of the first surfaces are defined by the first ends of the rods.

22. The method for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises:

(a) providing a collimator apparatus for producing a cross-sectionally shaped beam of radiation from a radiation source which comprises;

support plate means having a central opening around a beam axis through which the beam of radiation can pass;

a bundle of nested rods mounted adjacent the support plate means each rod being movable into the beam at an angle to the beam axis to interfere with the beam, the rods having first ends which together define a first surface for shaping the beam around the beam axis and opposite second ends from the first ends of the rods;

a holder means including spaced apart blocks mounted adjacent the support plate, each block having axially aligned holes mounting the rods so that the first surface is defined and the beam is shaped by the first ends of the rods;

releasable clamping means for moving the blocks so that the blocks or means between the blocks adjacent the rods are in engagement with the rods to secure the rods together in the shape defined by the first ends of the rods;

(b) moving the rods in the holes in the block so that the rods define the first surface;

(c) clamping the rods with the releasable clamping means by moving the blocks to prevent movement of the rods; and

(d) producing the shaped beam defined by the first ends of the rods.