Brachytherapy devices and methods of using them

• US 20040138515A1
• Filed: 01/15/2003
• Published: 07/15/2004
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Theragenics Corporation (Juniper Investment Co. LLC)
• Original Assignee: Theragenics Corporation (Juniper Investment Co. LLC)
• Inventors: Carr, Stephen N., White, Jack, Millage, Kyle
• Granted Patent: US 7,070,554 B2
• Time in Patent Office: Days
• US Class Current: 600/3
• CPC Class Codes: A61B 2090/0445 by absorption
• CPC Class Codes: A61B 2090/0481 against EM radiation, e.g. microwave
• CPC Class Codes: A61F 9/00 Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand caps with means for protecting the eyes A42B1/018; visors for helmets A42B3/22; retractors A61B17/02; manipulators specially adapted for use in surgery A61B34/70; appliances to aid invalids to move about A61H3/00; exercisers for the eyes A61H5/00; eye baths A61H35/02; sunglasses or goggles having the same features as spectacles G02C
• CPC Class Codes: A61N 2005/1094 Shielding, protecting against radiation
• CPC Class Codes: A61N 5/1017 Treatment of the eye, e.g. for "macular degeneration"
• CPC Class Codes: A61N 5/103 Treatment planning systems

Abstract

Brachytherapy devices are provided for delivering a substantially uniform dose rate of radiation to a treatment area at a predetermined treatment depth. The devices include a holder defining a cavity, and a radioactive material located within the cavity. The holder comprises radiation-shielding material therein. The holder and the radioactive material are positioned to cooperatively provide a substantially uniform dose rate of radiation to a treatment area at a predetermined treatment depth. Also disclosed are methods for treating macular degeneration or ocular melanoma. The methods involve positioning a brachytherapy device in contact with or in close proximity to tissue located in a treatment area and exposing the tissue located in the treatment area to a therapeutic dose of radiation, which is delivered at a substantially uniform dose rate over the treatment area at a predetermined treatment depth. The devices and methods of the invention also ensure that the radiation delivered outside the treatment area is substantially reduced relative to the radiation delivered within the treatment area to minimize exposure of healthy tissue to radiation. The provision of a substantially uniform dose rate in the treatment area prevents substantial over- and under-exposure to radiation of different portions of the tissue in the treatment area.

Claims

1. A brachytherapy device comprising:

a holder formed by a bottom and an annular sidewall affixed at a first end to said bottom to define a cavity within said holder, said holder having an opening at a second end of said annular sidewall;

a radioactive material located within the cavity of said holder, said radioactive material having a generally annular shape, and

said sidewall and bottom comprising a sufficient amount of a radiation shielding material to shield a substantial amount of the radiation emitted by said radioactive material.

2. A brachytherapy device as claimed in claim 1, further comprising a cap positioned in said cavity such that at least a portion of said cap is located between said radioactive material and the opening in the holder at the second end of the annular sidewall.

3. A brachytherapy device as claimed in claim 2, wherein said cap is retained within said sidewall be a device selected from the group consisting of a snap fit, a slip fit, a friction fit, a threaded fit, a mechanical fastener and combinations thereof.

4. A brachytherapy device as claimed in claim 3, wherein at least the portion of the cap located between the radioactive material and the opening is made from a radiation-transmitting material.

5. A brachytherapy device as claimed in claim 4, wherein at least the portion of the cap located between the radioactive material and the opening is made from a radiation-transmitting material that at least partially shields low energy x-ray radiation and transmits other radiation emitted by said radioactive material.

6. A brachytherapy device as claimed in claim 5, wherein the thickness of the portion of the cap located between the radioactive material and the opening is sufficient to prevent substantially all of the radiation emitted by the radioactive material from reaching said opening.

7. A brachytherapy device as claimed in claim 3, wherein the mechanical fastener comprises a peripheral lip attached to said sidewall around said opening.

8. A brachytherapy device as claimed in claim 1, wherein said substantially cylindrical cavity has a diameter of less than 15 mm, and a height of less than 3 mm.

9. A brachytherapy device as claimed in claim 1, wherein said annular radioactive structure is affixed to the bottom of said holder.

10. A brachytherapy device comprising:

a handle,

a wand that is releasably attachable to said handle at a proximal end of said wand,

a holder located at a distal end of said wand, said holder being formed by a bottom and an annular sidewall affixed at a first end to said bottom to define a cavity within said holder, said holder having an opening at a second end of said annular sidewall;

a radioactive material located within said cavity,

said annular sidewall and said bottom comprising a radiation-shielding material that shields a substantial portion of the radiation emitted by said radioactive material; and

said radioactive material and said holder cooperating to provide a substantially uniform dose rate of radiation at a predetermined treatment depth within a treatment area.

11. A brachytherapy device as claimed in claim 10, wherein said radioactive material and said holder cooperate to provide a substantial reduction of the dose rate outside the treatment area.

12. A brachytherapy device as claimed in claim 11, further comprising a cap positioned in said cavity such that at least a portion of said cap is located between said radioactive material and the opening in the holder at the second end of the annular sidewall.

13. A brachtherapy device as claimed in claim 10, wherein said radioactive material delivers a dose rate of about 0.01-10 Gy-min⁻

1 at a distance of about 3 mm from an upper surface of said cap.

14. A brachytherapy device as claimed in claim 13, wherein said radioactive material has an activity of about 0.1 Ci to about 5 Ci.

15. A brachytherapy device as claimed in claim 14, wherein said radioactive material emits predominantly photon radiation.

16. A brachytherapy device as claimed in claim 15, wherein said photon radiation comprises radiation selected from the group consisting of x-ray radiation, gamma-ray radiation and a combination thereof.

17. A brachytherapy device as claimed in claim 16, wherein said radioactive material comprises palladium-103.

18. A brachytherapy device as claimed in claim 10, further comprising a removable sheath covering at least the opening in said holder.

19. A radioactive therapeutic device as claimed in claim 10, wherein said radioactive material has an annular shape.

20. A radioactive therapeutic device as claimed in claim 10, wherein said radioactive material is attached to the bottom of said cavity.

21. A radioactive therapeutic device as claimed in claim 10, wherein said holder comprises a material selected from the group consisting of stainless steel, gold, tungsten, and lead.

22. A method for treating an eye by brachytherapy comprising the step of:

inserting a brachytherapy device containing a radioactive material between the sclera and the eyelid of said eye; and

exposing a portion of said eye located in a predetermined treatment area to radiation emitted from said brachytherapy device for a sufficient time to deliver a therapeutic dose of radiation, and in a manner whereby a substantially uniform dose rate is delivered at a particular treatment depth to the portion of the eye located in the treatment area.

23. A method as claimed in claim 22, wherein a surface of said brachytherapy device through which said radiation is delivered to the treatment area, is positioned in contact with or in close proximity to the portion of the eye located in the treatment area.

24. A method as claimed in claim 23, wherein said therapeutic dose is delivered at a dose rate of about 0.01-10 Gy-min⁻

1 at a distance of about 3 millimeters from said surface of said brachytherapy device.

25. A method as claimed in claim 24, wherein said radioactive material has a radioactivity of about 0.1 to about 5 Ci.

26. A method as claimed in claim 25, wherein said radioactive material emits predominantly photon radiation.

27. A method as claimed in claim 26, wherein said photon radiation is selected from the group consisting of x-ray radiation, gamma-ray radiation and a combination thereof.

28. A method as claimed in claim 27, wherein said radioactive material comprises palladium-103.

29. A method as claimed in claim 23, wherein said brachytherapy device further comprises a shield that covers said surface, and the exposing step comprises the step of displacing said shield.

30. A method as claimed in claim 22, wherein said brachytherapy device further comprises a radiation-transmitting cap, which forms at least a portion of said surface.

31. A method as claimed in claim 22, wherein the exposing step is carried out in a manner whereby there is a substantial reduction in the dose rate delivered outside the treatment area.

32. A method as claimed in claim 31, wherein the exposing step delivers a dose rate at a location in the treatment area at a predetermined treatment depth that varies by not more than 15% from the prescribed dose rate over the entire treatment area measured at said treatment depth.

33. A method as claimed in claim 32, wherein the exposing step delivers a dose rate at a radial distance from an outer edge of the treatment area of not more than one radius of the treatment area, and at a predetermined treatment depth, that is at least 33% less than the prescribed dose rate at said treatment depth, and the dose rate at a radial distance from the outer edge of the treatment are of not more that two radii of the treatment area and at a predetermined treatment depth is at least 60% less than the prescribed dose at said treatment depth.

34. A method as claimed in claim 33, wherein the dose rate varies by not more than 10% from the prescribed dose rate in said treatment area at said treatment depth.

35. A method as claimed in claim 34, wherein the dose rate delivered outside said treatment area at a radial distance from an outer edge of the treatment area of not more than one radius of the treatment area and at a predetermined depth is at least 50% less than the prescribed dose at said treatment depth, and the dose rate at a radial distance from the outer edge of the treatment area of not more than two radii of the treatment area and at a predetermined treatment depth is at least 75% less than the prescribed dose at said treatment depth.