Radiation therapy with orthovoltage X-ray minibeams

Patent metadata

Field	Value
Publication number	US-10124194-B2
Application number	US-201615188643-A
Country	US
Kind code	B2
Filing date	Jun 21, 2016
Priority date	Aug 5, 2015
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A method for delivering therapeutic radiation to a target includes positioning a multi-aperture collimator on the skin within a trajectory of orthovoltage x-rays directed at the target, thus generating an array of minibeams, each of width between 0.1 mm to 0.6 mm. The skin is irradiated with the array. An effective beam of therapeutic radiation, which may be a solid beam, is delivered to the target at a predetermined tissue depth by merging adjacent orthovoltage x-ray minibeams sufficiently to form the effective beam. The effective beam may be formed proximal to the target. The depth at which the effective, preferably, solid, beam is formed is controlled by varying one or more of the spacing of the minibeams in the array, the minibeam width, the distance from the x-ray source to the collimator, and the x-ray source spot size. Planar minibeams can be arc-scanned while continuously modulating beam shape and intensity.

First claim

What is claimed is:

1. A method for delivering therapeutic radiation to a target within a subject, wherein the target is located at a predetermined depth, the predetermined depth being measured from an irradiated portion of a surface of the skin of the subject, the method comprising:
positioning a multi-aperture collimator within a trajectory of radiation produced by an x-ray source generating orthovoltage x-rays, the trajectory of orthovoltage x-rays being directed at the target, the multi-aperture collimator positioned and configured to generate an array of minibeams on the surface of the skin comprising slightly diverging spatially distinct minibeams having a predetermined center-center spacing between adjacent minibeams, and wherein a width of each minibeam is between about 0.1 mm and about 0.6 mm;
irradiating the surface of the skin with the array of minibeams; and
delivering an effective beam of therapeutic radiation to the target, said delivering including controlling a tissue depth from the irradiated surface of the skin at which the adjacent minibeams in the array merge sufficiently to form the effective beam of therapeutic radiation.

2. The method of claim 1 , wherein the step of controlling includes forming the effective beam proximal to the target.

3. The method of claim 1 , wherein controlling the tissue depth at which the adjacent minibeams merge sufficiently to form the effective beam includes adjusting at least one of the predetermined center-to-center spacing, the width, and a distance between the x-ray source and the multi-aperture collimator.

4. The method of claim 1 , wherein delivering the effective beam of therapeutic radiation further includes sparing irradiated tissue proximal to the target from radiation damage, the tissue depth also corresponding to a tissue sparing depth.

5. The method of claim 1 , further including limiting the width of the minibeams to be between about 0.25 mm and about 0.35 mm.

6. The method of claim 1 , wherein the multi-aperture collimator is further configured such that the array of minibeams is a two-dimensional array of pencil minibeams, the width corresponding to a diameter of each pencil minibeam.

7. The method of claim 6 , wherein a cross-sectional profile of each pencil minibeam is one of a round, elliptical, square, rectangular, and polygonal shape.

8. The method of claim 1 , wherein the multi-aperture collimator is a multi-slit collimator configured with elongated slits such that the array of minibeams is an array of narrow and elongated planar minibeams.

9. The method of claim 8 , the width corresponding to a thickness of each planar minibeam, the method further including limiting the width of each planar minibeam to a range of between about 0.25 mm to about 0.35 mm.

10. The method of claim 8 , wherein the x-ray source has an elongated shape, the method further including aligning the elongated slits of the multi-slit collimator with the elongated shape of the x-ray source.

11. The method of claim 1 , wherein controlling the tissue depth at which the adjacent minibeams merge sufficiently to form the effective beam includes adjusting a size of the x-ray source from which the orthovoltage x-rays are generated.

12. The method of claim 4 , including varying the tissue depth from about 1 cm to about 10 cm, the tissue depth being based on a predetermined depth of the target from the surface of the skin.

13. The method of claim 1 , including operating the x-ray tube in a range between about 100 kVp and about 500 kVp.

14. The method of claim 1 , wherein the multi-aperture collimator includes a multi-aperture, heavy-metal plate.

15. The method of claim 1 , wherein controlling the tissue depth includes selecting the width, the predetermined center-to-center spacing, and the distance between the x-ray source and the multi-aperture collimator such that each of the slightly diverging spatially distinct minibeams broaden to less than 1.0 mm in width before they merge to form the effective beam.

16. The method of claim 1 , the method further comprising changing an angular position of the x-ray source and the trajectory of orthovoltage x-rays generated therefrom relative to the target such that the target is irradiated from a different direction, and repeating the positioning, the irradiating and the delivering step for the different direction and for irradiating a different portion of the skin with the array of minibeams generated by the multi-aperture collimator, the delivering step being repeated to deliver the effective beam of therapeutic radiation to the target from the different direction.

17. The method of claim 16 , further comprising, for each angular position, adjusting a beam-shaping collimator positioned proximal to the multi-aperture array to conform a shape of the effective beam to a shape of the target based on the direction of the trajectory relative to the target.

18. The method of claim 1 , the irradiating step further comprising generating an arc of radiation around the target from each of the minibeams in the array, the delivering step including merging adjacent arcs of radiation at the tissue depth to form the effective beam of therapeutic radiation.

19. The method of claim 18 , wherein the minibeams are planar minibeams formed from elongated slits of a multi-slit collimator, each of the arcs of radiation being generated from the minibeams by rotating the x-ray source together with the multi-slit collimator, such that the arcs are generated around the target in planes parallel to the elongated slits of the multi-slit collimator.

20. The method of claim 18 , further comprising adjusting a shape and an intensity of a source beam comprising the orthovoltage x-rays generated by the x-ray source to conform the effective beam of therapeutic radiation to a shape of the target based on a direction from which the effective beam irradiates the target, the method further comprising continuously adjusting the distance between the x-ray source and the multi-aperture collimator to maintain the tissue depth, at which the arcs formed from the minibeams merge to form the effective beam of therapeutic radiation, to be proximal to the target.

21. The method of claim 1 , the method further comprising administering dose-enhancing agents to the subject prior to the irradiating step to radio-sensitize the target.

22. The method of claim 21 , wherein the agents include one or more of iodine, gadolinium, gold, and platinum.

23. The method of claim 21 , wherein the agents are encapsulated in one of liposomes or polymeric delivery vehicles.

24. The method of claim 1 , wherein the target encompasses one of a tumor and an epileptogenic foci.

25. A system for delivering therapeutic radiation to a target volume within a subject, wherein the target is located at a predetermined depth, the predetermined depth being measured from an irradiated portion of the skin of the subject, the system comprising:
an x-ray source generating orthovoltage x-rays; and
a multi-aperture collimator, the multi-aperture collimator being configured for positioning on or near the skin and within a trajectory of the orthovoltage x-rays generated from the x-ray source, the trajectory of orthovoltage x-rays being directed at the target, the multi-aperture collimator comprising an array of apertures having a width of between about 0.1 mm and about 0.6 mm and a predetermined center-center spacing to generate an array of slightly

Assignees

• The Research Foundation For State Univ Of New York
• Univ Texas

Inventors

• Dilmanian F Avraham
• Krishnan Sunil
• Eley John Gordon

Classifications

• A61B6/06

  Diaphragms · CPC title

• A61N2005/1098

  Enhancing the effect of the particle by an injected agent or implanted device · CPC title

• A61N5/1084 Primary

  for delivering multiple intersecting beams at the same time, e.g. gamma knives · CPC title

• A61N2005/1091

  Kilovoltage or orthovoltage range photons · CPC title