Orthovoltage radiosurgery
A radiosurgery system is described that delivers a therapeutic dose of radiation to a target structure in a patient. In some embodiments, inflammatory ocular disorders are treated, specifically macular degeneration. In some embodiments, ocular structures are placed in a global coordinate system, based on ocular imaging, which leads to direction of an automated positioning system. In some embodiments, the position of an ocular structure is tracked and related to a radiosurgery system. In some embodiments, a treatment plan is utilized for a specific disease to be treated and/or structures to be avoided. In some embodiments, a fiducial aids in positioning the system. In some embodiments, a reflection off the eye is used to aid in positioning. In some embodiments, radiodynamic therapy is described in which radiosurgery is used in combination with other treatments and can be delivered concomitant with, prior to, or following other treatments.
1. A system, for treating a target tissue with x-ray radiation, comprising:
an x-ray source that emits x-rays, the source configured to provide therapeutic x-ray treatment;
a collimator that collimates x-rays emitted by the x-ray source into an x-ray beam, the collimator having a outer perimeter as the x-ray beam is emitted from the collimator;
the collimator having at least one exit plane having a first cross-sectional pattern, coextensive with the outer perimeter, defined by a first cross-sectional dimension; and
the x-ray beam having a dose distribution at a beam spot in the exit plane of the collimator such that the x-ray beam at a region within the plane is characterized by a region of maximal intensity encompasses a region of minimal intensity.
2. The system of claim 1 , wherein said maximal intensity region defines at least one of a circular shape, an elliptical shape, and a polygonal shape.
3. The system of claim 1 , wherein said first cross-sectional pattern defines a first boundary that encompasses a second boundary of a second cross-sectional pattern, such that at the plane, the second cross-sectional pattern has a second cross-sectional dimension that is less than the first cross-sectional dimension.
4. The system of claim 3 , wherein each of said first and second cross-sectional patterns comprises a circular shape.
5. The system of claim 4 , wherein the second cross-sectional pattern defines an x-ray opaque region, and wherein the first cross-sectional pattern defines a doughnut-shaped x-ray transmitting region.
6. The system of claim 3 , wherein said second cross-sectional dimension is less than about 5 mm.
7. The system of claim 6 , wherein said x-rays have a maximal energy of less than about 500 keV.
8. The system of claim 3 , wherein said second cross-sectional dimension is less than about 1 mm.
9. The system of claim 3 , wherein said second cross-sectional dimension is less than about 500 microns.
10. The system of claim 3 , wherein said x-rays have a maximal energy of about 500 KeV.
11. The system of claim 3 , wherein said x-rays have a maximal energy of about 150 KeV.
12. The system of claim 1 , wherein the collimator includes a plurality of spaced-apart openings at the exit plane, and said x-ray beam cross-section is characterized by a plurality of regions of maximal intensity and minimal intensity.
13. The system of claim 12 , wherein the plurality of regions of maximal intensity are disposed in a spaced-apart checkered, speckled, or dotted arrangement, so as to provide micro-fractionated radiation application to a target area.
14. The system of claim 1 , wherein said maximal intensity region is configured to provide a weighted distribution of radiation intensity that is greater at one side of the maximal intensity region than an opposite side.
15. The system of claim 14 , wherein said region of maximal intensity defines an elongate, crescent-like shape, wherein said region of maximal intensity is distributed to partially surround said region of minimal intensity.
16. The system of claim 1 , wherein a shape and/or area of said maximal intensity region is adjustable to provide a distribution of radiation intensity adapted to a shape of an eye structure being treated.
17. A method, for treating a target tissue with x-ray radiation, comprising:
(a) providing a collimator that collimates x-rays emitted by an x-ray source into x-ray beam, the collimator having at least one selectable and/or adjustable exit plane collimation element configured to delimit the x-ray beam at the exit plane so that the beam has an emitted dose distribution pattern having at least one region of maximal intensity that encompasses at least one region of minimal intensity;
(b) determining an absorbed dose distribution pattern suitable for treatment of target tissue at a treatment zone of the eye;
(c) selecting and/or adjusting the exit plane collimation element so as to produce an emitted dose distribution pattern that, when the x-ray beam is propagated to the treatment zone along a selected first beam path, results in the absorbed dose distribution pattern at the treatment zone; and
(d) emitting an x-ray beam from the collimator along the first beam path, to provide an absorbed x-ray dose having substantially the absorbed dose distribution pattern at the treatment zone.
18. The method of claim 17 , wherein the determining step (b) includes correlating a region of minimal absorbed intensity with a vulnerable structure of the eye.
19. The method of claim 18 , wherein the vulnerable structure of the eye includes the optic nerve.
20. The method of claim 17 , wherein the selecting and/or adjusting step (c) includes selecting a exit plane collimation element configured to provide a weighted distribution of radiation intensity that is greater at one side of the maximal intensity region than an opposite side.
21. The method of claim 17 , wherein the selecting and/or adjusting step (c) includes selecting an exit plane collimation element configured to have a smaller pattern defining an x-ray opaque center region, and a larger pattern defining a concentric doughnut-shaped x-ray transmitting region.
22. The method of claim 17 , wherein the determining step (b) includes determining a region of micro-fractionated radiation application, and the selecting and/or adjusting step (c) includes selecting a exit plane collimation element configured to provide a spaced-apart checkered, speckled, or dotted absorbed x-ray dose distribution.
23. The method of claim 17 , further including repeating steps (b) through (d) for at least one additional beam path different than the first beam path.
24. The method of claim 23 , wherein the selecting and/or adjusting step (c) includes selecting a different exit plane collimation element for the additional beam path than selected for the first beam path.
25. The method of claim 17 , wherein said target tissue comprises a region of pathologic neovascularization.
26. The method of claim 17 , wherein said target tissue comprises a region of macular degeneration.