Methods and devices for orthovoltage ocular radiotherapy and treatment planning

• US 7,801,271 B2
• Filed: 10/30/2008
• Issued: 09/21/2010
• Est. Priority Date: 12/23/2007
• Status: Active Grant

• Current Assignee: Carl Zeiss Meditec Incorporated (Carl-Zeiss-Stiftung)
• Original Assignee: Oraya Therapeutics, Inc.
• Inventors: Liang, Junzhong, Gertner, Michael, Hansen, Steven D., Chell, Erik, Arnoldussen, Mark
• Primary Examiner(s): Kao; Chih-Cheng G
• Application Number:
  US12/262,031
• Publication Number:
  US 20090161826A1
• Time in Patent Office: 691 Days
• Field of Search: 378/65, 606/4
• US Class Current: 378/65
• CPC Class Codes: A61N 2005/1091 Kilovoltage or orthovoltage range photons
• CPC Class Codes: A61N 5/1017 Treatment of the eye, e.g. for "macular degeneration"
• CPC Class Codes: A61N 5/103 Treatment planning systems
• CPC Class Codes: A61N 5/1037 taking into account the movement of the target, e.g. 4D-image based planning
• CPC Class Codes: A61N 5/1064 for adjusting radiation treatment in response to monitoring

Abstract

A method, code and system for planning the treatment a lesion on or adjacent to the retina of an eye of a patient are disclosed. There is first established at least two beam paths along which x-radiation is to be directed at the retinal lesion. Based on the known spectral and intensity characteristics of the beam, a total treatment time for irradiation along each beam paths is determined. From the coordinates of the optic nerve in the aligned eye position, there is determined the extent and duration of eye movement away from the aligned patient-eye position in a direction that moves the patient'"'"'s optic nerve toward the irradiation beam that will be allowed during treatment, while still maintaining the radiation dose at the patient optic nerve below a predetermined dose level.

Claims

1. A treatment planning method for treating a lesion on or adjacent to the retina of an eye of a patient (retinal lesion), by directing collimated X-radiation at the lesion in a patient'"'"'s eye, comprising

(a) based on an aligned patient-eye position, establishing at least two treatment beam paths directed from a source of a collimated x-radiation beam through the patient'"'"'s sclera beyond the limbus and directed at the retinal lesion,

(b) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths and from the coordinates of the lesion in the aligned patient-eye position, a total treatment time for irradiation along the beam paths that is effective to produce a desired radiation dose at the lesion of the patient'"'"'s eye, and

(c) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths, and from the coordinates of the optic nerve in the aligned eye position, the extent and duration of eye movement away from the aligned patient-eye position in a direction that moves the patient'"'"'s optic nerve toward the irradiation beam that will be allowed during treatment, while still maintaining the radiation dose at the patient optic nerve below a predetermined dose level.

2. The method of claim 1, wherein the retinal lesion to be treated includes one of macular degeneration, a drusen, a tumor or a vascular abnormality, and step (c) includes determining the coordinates of the lesion and the optic nerve in an external coordinate system.

3. The method of claim 1, wherein the retinal lesion to be treated includes macular degeneration, and step (c) includes determining the coordinates of the macula and the optic nerve in an external coordinate system.

4. The method of claim 3, wherein step (a) includes establishing at least three beam paths having a total beam angular divergence of between 20-60 degrees.

5. The method of claim 4, wherein step (a) includes establishing a series of beam paths produced by continuously moving the beam source along an arcuate path.

6. The method of claim 3, wherein step (b) includes (i) measuring an ocular dimension of the patient'"'"'s eye, (ii) scaling a model of the eye that includes the coordinates of retinal features, including the macula and optic nerve, and a virtual ocular medium to a measured ocular dimension, and (iii) determining from the known distance of travel of the beam within the model along each path, and from the virtual ocular medium through which the beam travels, the dose of radiation from the source that needs to be delivered along each path, to produce the desired radiation dose at the macula of the patient'"'"'s eye.

7. The method of claim 6, wherein step (c) includes determining, from the known distance of travel of the beam within the model along each beam path, and from the virtual ocular medium through which the beam travels, the dose of radiation that is received by the optic nerve as a function of eye movement in a direction that moves the patient'"'"'s optic nerve toward the irradiation beam.

8. The method of claim 1, wherein the aligned patient-eye position places the optical axis of the eye in alignment with an axis normal to the cornea of the eye with the patient looking straight ahead.

9. The method of claim 8, wherein step (a) includes the steps of determining, for the source of collimated x-radiation beam,

(i) a beam-source collimator configuration that is based on an X-ray emission source-to-target distance, a collimator exit aperture-to-body surface distance, an emission or anode source size, and a collimator exit aperture size, and that is calculated to provide an X-ray beam-spot at the retina having a diameter or characteristic dimension to the 80% isodose of less than about 8 mm, and a penumbra width between the 80% isodose and the 20% isodose of less than about 40% of the beam-spot diameter or beam spot characteristic dimension;

and

(ii) a maximum photon energy and a beam filtration configuration to provide a maximum photon energy between 25-150 keV.

10. The method of claim 9, wherein the maximum photon energy and a beam filtration are such as to provide a sclera surface-to-retina target dose ratio for the beam of less than N:

1, where N is the number of established beams.

11. Non-transitory machine-readable medium which operates with a computer to execute machine-readable instructions for performing the steps in a treatment planning method for treating a lesion on or adjacent to the retina of an eye of a patient (retinal lesion), by directing collimated X-radiation beams at the lesion in a patient'"'"'s eye, comprising the steps of:

(a) based on an aligned patient-eye position, establishing at least two treatment beam paths directed from a source of a collimated x-radiation beam through the patient'"'"'s sclera beyond the limbus and directed at the lesion,

(b) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths and from the coordinates of the ocular lesion in the aligned patient-eye position, a total treatment time for irradiation along the beam paths that is effective to produce a desired radiation dose at the ocular lesion of the patient'"'"'s eye, and

(c) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths, and from the coordinates of the optic nerve in the aligned eye position, the extent and duration of eye movement away from the aligned patient-eye position in a direction that moves the patient'"'"'s optic nerve toward the irradiation beam that will be allowed during treatment, while still maintaining the radiation dose at the patient optic nerve below a predetermined dose level.

12. The medium of claim 11, wherein the retinal lesion to be treated includes one of macular degeneration, a drusen, a tumor or a vascular abnormality, and step (c) includes determining the coordinates of the lesion and the optic nerve in an external coordinate system.

13. The medium of claim 12, wherein the retinal lesion to be treated is macular degeneration, and step (c) includes determining the coordinates of the macula and the optic nerve in an external coordinate system.

14. The medium of claim 11, which is operable, in performing step (a), to determine, for the source of collimated x-radiation beam,

(i) a beam-source collimator configuration that is based on an X-ray emission source-to-target distance, a collimator exit aperture-to-body surface distance, an emission or anode source size, and a collimator exit aperture size, and that is calculated to provide an X-ray beam-spot at the retina having a diameter or characteristic dimension to the 80% isodose of less than about 8 mm, and a penumbra width between the 80% isodose and the 20% isodose of less than about 40% of the beam-spot diameter or beam spot characteristic dimension;

and

(ii) a maximum photon energy and a beam filtration configuration to provide a maximum photon energy between 25-150 keV.

15. The medium of claim 11, which is operable, in performing step (b) and based on a measured ocular dimension of the patient'"'"'s eye, to (i) scale a model of the eye that includes the coordinates of retinal features, including the macula and optic nerve, and a virtual ocular medium to the ocular dimension measured in step, and (ii) determining from the known distance of travel of the beam within the model along each path, and from the virtual ocular medium through which the beam travels, the dose of radiation from the source that needs to be delivered along each path, to produce the desired radiation dose at the macula of the patient'"'"'s eye.

16. A system for planning a treatment for a lesion on or adjacent to the retina of an eye of a patient (retinal lesion), by directing a collimated X-radiation beam at the lesion in a patient'"'"'s eye, comprising:

(a) a device for aligning the patient eye,

(b) a processor configured to receive coordinates of the aligned eye in an external coordinate system, and which stores information effective for determining, from the received coordinates, coordinates of the lesion and optic nerve in the patient eye, and

(c) a machine-readable medium which operates with the processor to execute machine-readable instructions for performing the steps of;

(i) based on the an aligned patient-eye coordinates, establishing at least two treatment beam paths directed from a source of a collimated x-radiation beam through the patient'"'"'s sclera beyond the limbus and directed at the lesion,

(ii) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths and from the coordinates of the lesion in the aligned patient-eye position, a total treatment time for irradiation along the beam paths that is effective to produce a desired radiation dose at the lesion of the patient'"'"'s eye, and

(iii) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths, and from the coordinates of the optic nerve in the aligned eye position, the extent and duration of eye movement away from the aligned patient-eye position in a direction that moves the patient'"'"'s optic nerve toward the irradiation beam that will be allowed during treatment, while still maintaining the radiation dose at the patient optic nerve below a predetermined dose level.

17. The system of claim 16, wherein the retinal lesion to be treated includes one of macular degeneration, a drusen, a retinal tumor or a retinal vascular abnormality;

and step (c)(iii) includes determining the coordinates of the lesion and the optic nerve in an external coordinate system.

18. The system of claim 17, wherein the retinal lesion to be treated includes macular degeneration, and step (c)(iii) includes determining the coordinates of the macula and the optic nerve in an external coordinate system.

19. The system of claim 17, wherein the medium is operable, in performing step (c), to determine, for the source of collimated x-radiation beam,

(i) a beam-source collimator configuration that is based on an X-ray emission source-to-target distance, a collimator exit aperture-to-body surface distance, an emission or anode source size, and a collimator exit aperture size, and that is calculated to provide an X-ray beam-spot at the retina having a diameter or characteristic dimension to the 80% isodose of less than about 8 mm, and a penumbra width between the 80% isodose and the 20% isodose of less than about 40% of the beam-spot diameter or beam spot characteristic dimension;

and

(ii) a maximum photon energy and a beam filtration configuration to provide a maximum photon energy between 25-150 keV.

20. The system of claim 19, wherein the medium is operable, in performing step (b) and based on a measured ocular dimension of the patient'"'"'s eye, to (i) scale a model of the eye that includes the coordinates of retinal features, including the macula and optic nerve, and a virtual ocular medium to the ocular dimension measured, and (ii) determining from the known distance of travel of the beam within the model along each path, and from the virtual ocular medium through which the beam travels, the dose of radiation from the source that needs to be delivered along each path, to produce the desired radiation dose at the macula of the patient'"'"'s eye.

21. A treatment planning method for treating macular degeneration in a patient, by directing collimated X-radiation at the macula in a patient'"'"'s eye, comprising

(a) measuring an ocular dimension of the patient'"'"'s eye,

(b) scaling a model of the eye that includes the coordinates of retinal features, including the macula, and a virtual ocular medium to the ocular dimension measured in step (a),

(c) establishing at least two treatment axes along which a collimated beam of X-radiation will be directed from an external radiation source at the macula in the eye model, and

(d) determining from the known distance of travel of the beam within the model along each treatment axis, and from the virtual ocular medium through which the beam travels, the dose of radiation from the source that needs to be delivered along each treatment axis, to produce a predetermined total radiation dose at the macula of the patient'"'"'s eye.

22. The method of claim 21, wherein step (a) includes measuring along an ocular axis, the ocular length of the patient'"'"'s eye between the cornea and retina of the eye, and step (b) includes scaling the ocular length of the model to the patient'"'"'s measured ocular length.

23. The method of claim 21 wherein step (c) includes establishing at least three treatment axes directed through the sclera and converging at the macula in the eye model, and having a total beam-to-beam angular divergence of between 20-60 degrees.

24. The method of claim 21, wherein the eye model includes coordinates of the optic nerve at the retina, the dose of radiation determined in step (d) is determined as specified beam intensity over a given irradiation period, and step (d) further includes determining a permitted extent of eye movement over the irradiation period that maintains the radiation dose received at the patient optic nerve below a predetermined level.

25. Non-transitory machine-readable medium which operates with a computer to execute machine-readable instructions for performing the steps in a treatment planning method for treating macular degeneration in a patient, by directing collimated X-radiation beams at the macula in a patient'"'"'s eye, comprising the steps of:

(a) scaling a model of the eye that represents retinal features, including the macula, and a virtual ocular medium to a patient-eye ocular dimension supplied as input,

(b) establishing at least two treatment axes along which a collimated beam of X-radiation will be directed from an external radiation source at the macula in the eye model, and

(c) determining from the known distance of travel of the beam within the model along each treatment axis, and from the virtual ocular medium through which the beam travels, the dose of radiation from the source that needs to be delivered along each treatment axis, to produce a predetermined total radiation dose at the macula of the patient'"'"'s eye.

26. A method of treating a patient with a radiation beam from an orthovoltage X-ray emission source to a treatment target region on or adjacent to the retina, comprising:

(a) determining a radiation treatment plan, the plan including

providing one or more X-ray beam collimators having a configuration including an X-ray emission source-to-target distance, a collimator exit aperture-to-body surface distance, an emission or anode source size, and a collimator exit aperture size, the collimator providing an X-ray beam having a X-ray beam-spot at the retina having a diameter or characteristic dimension to the 80% isodose of less than about 8 mm, and a penumbra width between the 80% isodose and the 20% isodose of less than about 40% of the beam-spot diameter or beam spot characteristic dimension;

(b) determining one or more of an X-ray beam duration and/or X-ray flux intensity level so as to provide a selected absorbed radiation dose to the retina target; and

(c) aiming the collimator of step (a)(ii) to align with at least one beam path determined treating the patient according to the radiation treatment plan; and

(d) emitting the calculated X-ray beam duration and/or flux level along each distinct X-ray beam path, so as to administer the selected beam radiation absorbed dose to the retina target.

27. The method of claim 26, wherein step (b) is based at least in part on one or more of:

(i) at least one measurement of patient-specific eye anatomy;

(ii) a selected sclera surface-to-retina target dose ratio for each X-ray beam; and

(iii) the number of distinct X-ray beam paths.

28. The method of claim 26, further including the steps of:

(e) engaging the treated eye during irradiation with an eye contact member; and

(f) supporting and/or controlling the eye contact member so as to substantially reduce eye motion during radiation treatment.

29. The method of claim 26, further including the steps of:

(e) tracking at least one motion of the treated eye during irradiation;

(f) determining at least one alignment of an X-ray beam path with the retinal target during irradiation based on tracked eye motion so as to determine an alignment error relative to the planned beam path; and

(g) in the event that a selected threshold of error is determined, either or both of interrupting or discontinuing irradiation of the treated eye;

or re-aligning the X-ray beam path with the retinal target.

30. A method of treating a patient with external radiation beam from a radiation source, the radiation beam emitted so as to propagate along a tissue path to reach a target tissue region within the patient'"'"'s body, the treatment carried out according to a radiotherapy treatment plan anatomically specifying the tissue path, the method comprising in any operative order the steps of:

(a) selecting one or more input parameters (P₁, P₂ . . . P_i,), the input parameters selected from human anatomical measurements, other human measurements, and other person-specific characteristics;

(b) characterizing variation with respect to the selected parameters in a human population which includes the patient, the variation correlated with the tissue path length (PL) for the radiotherapy treatment plan;

(d) determining a mathematical function and/or calculation algorithm effectively expressing a relationship between the selected parameters and the tissue path length (PL=f(P₁, P₂ . . . P_i));

(e) determining values of the selected parameters (P₁, P₂ . . . P_i,) for the patient;

(f) using the mathematical function and/or calculation algorithm, determining PL for the patient (PL₀);

(g) modifying or adjusting one or more aspects of the radiotherapy treatment plan based on the determined value PL₀; and

(h) treating the patient according to the modified or adjusted treatment plan.

31. The method of claim 30, wherein the modified or adjusted aspects of the treatment plan include one or more of beam duration, total radiation dose, beam spectral energy, beam filtration, beam collimation geometry, and beam orientation.

32. The method of claim 30, wherein the radiation beam includes an orthovoltage X-ray beam having a maximum photon energy of less than 500 keV.

33. The method of claim 30, wherein the target tissue region within the patient'"'"'s body includes tissue within an eye of the patient, wherein the target tissue region includes a portion of the retina, and the anatomical tissue path includes a path from an entry point on the sclera surface propagating through the eye to the target region.

34. The method of claim 30, wherein the selected parameters include an eye axial length.

35. A treatment planning method for treating an ocular lesion in a patient, by directing collimated X-radiation at the lesion in a patient'"'"'s eye, comprising

(a) based on an aligned patient-eye position, establishing at least two treatment beam paths directed from a source of a collimated X-radiation beam through the surface of the patient'"'"'s eye and directed at the ocular lesion,

(b) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths and from the coordinates of the lesion in the aligned patient-eye position, a total treatment time for irradiation along the beam paths that is effective to produce a desired radiation dose at the lesion of the patient'"'"'s eye, and

(c) determining, based on the known spectral and intensity characteristics of the source beam along the established beam paths, and from the coordinates of a selected radiation sensitive structure in the eye, in the aligned eye position, the extent and duration of eye movement away from the aligned patient-eye position in a direction that moves the patient'"'"'s radiation-sensitive structure toward the irradiation beam that will be allowed during treatment, while still maintaining the radiation dose at the patient radiation-sensitive structure below a predetermined dose level.

36. The method of claim 35, wherein

(i) the ocular lesion to be treated includes one of a pterygium, a vascular malformation;

an ocular tumor;

an ocular premalignant lesion;

a choroidal hemangioma;

an ocular metastasis;

a nervus;

a conjunctival tumor;

an eyelid tumor;

an orbital tumor, and tissue associated with glaucoma; and

(ii) the radiation-sensitive structure includes one of the lens of the eye, the cornea and the optic nerve.