Endocurietherapy
First Claim
1. A method of producing multilayer coats of a microsphere for mass-production of multilayer one-piece seamless radioactive seeds, comprising the steps of:
- coating a central sphere having an outside diameter no greater than 1 millimeter with a plurality of layers in succession;
one of which is a radioactive layer that contains a therapeutic amount of radioactivity, one of which is a diffusion barrier layer that provides a diffusion barrier coat, and one of which is a protective layer that provides an outer protective coat no more than 0.1 millimeters thick;
the step of coating a central sphere having an outside diameter no greater than 1 millimeter with a plurality of layers in succession including the substeps of applying radioactive material to form said radioactive layer, applying said diffusion layer, applying said protective layer and applying a material that reacts chemically with said radioactive material in the radioactive layer.
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Abstract
To provide versatile radioactive implants and methods of radiation therapy, plating methods such sputtering, as are used to coat single elements such as microspheres, wires and ribbons with radioactive metals, protective layers and identification layers. The resulting solid, radioactive, multilayered seamless elements are implanted individually or combined in intercavity applicators, with fabrics and in ribbons. Because they have selected half-lives and intensities, they provide flexibility in treatment, permitting low intensity or high intensity treatment using temporary or permanent implants and implants with high intensity or low intensity or contoured intensity to permit different therapies.
75 Citations
41 Claims
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1. A method of producing multilayer coats of a microsphere for mass-production of multilayer one-piece seamless radioactive seeds, comprising the steps of:
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coating a central sphere having an outside diameter no greater than 1 millimeter with a plurality of layers in succession;
one of which is a radioactive layer that contains a therapeutic amount of radioactivity, one of which is a diffusion barrier layer that provides a diffusion barrier coat, and one of which is a protective layer that provides an outer protective coat no more than 0.1 millimeters thick;
the step of coating a central sphere having an outside diameter no greater than 1 millimeter with a plurality of layers in succession including the substeps of applying radioactive material to form said radioactive layer, applying said diffusion layer, applying said protective layer and applying a material that reacts chemically with said radioactive material in the radioactive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
selecting at least two levels of radioactivity energy and half-lives;
selecting radioactive materials for the target and the operating conditions of a vacuum sputtering or plasma deposition apparatus corresponding to the radioactivity and half-life selected; and
sputtering or plasma deposition of the coats onto a central sphere from the selected target material and with the selected operating conditions.
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5. A method for producing coats for multilayer radioactive microsphere according to claim 4 wherein dc sputtering is used to produce radioactive microspherical coat from a radioactive metal target.
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6. A method in accordance with claim 4 in which the step of sputtering or plasma deposition includes the steps of:
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laminating coats of low boiling point elements that are likely to vacuum weld with high boiling point elements that are unlikely to vacuum weld;
levitating microspheres; and
biasing a levitating bouncing pan that is levitating the microspheres with an electric charge, whereby the tendency of the microspheres to vacuum weld together is reduced.
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7. A method according to claim 6 in which the step of sputtering or plasma deposition includes the steps of:
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introducing the microspheres into a vacuum chamber; and
applying material under vacuum pressure to the microspheres while the microspheres are levitated.
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8. A method according to claim 7 in which the step of levitating microspheres includes the step of vibrating the bouncing pan by vibrating the bouncing pan at an ultrasonic frequency between 1 and 10 percent of a resonant frequency of the bouncing pan.
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9. A method of making radioactive microspheres in a plurality of application steps comprising the steps of:
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forming microspheres having a diameter less than 0.1 micron;
applying an isotope to the microspheres whereby the microspheres are radioactive; and
applying one or more protective coats to protect the microspheres with no substantial voids between the microspheres and the protective coats and no end welds. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
selecting levels of radioactivity energy and half-lives;
selecting radioactive materials for the target and the operating conditions of a vacuum sputtering or plasma deposition apparatus corresponding to the radioactivity and half-life selected; and
sputtering or plasma deposition of the coats onto the microspheres from the selected target material and with the selected operating conditions.
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33. A method in accordance with claim 9 in which the step of applying an isotope includes the step of dc sputtering from a radioactive metal target.
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34. A method in accordance with claim 9 wherein the step of applying the isotope includes the step of rf or magnetron sputtering using a radioactive dielectric target.
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35. A method in accordance with claim 9 wherein the step of applying an isotope includes the step of sputtering a metal in the presence of a gaseous radionuclide such as a radioactive hydride gas or monoatomic gas wherein a radioactive metal compound coat is formed by combining the metal with the radioactive component of the gas.
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36. A method in accordance with claim 9 wherein sputtering is produced by magnetron sputtering using a radioactive dielectric target.
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37. A method in accordance with claim 9 wherein the isotope is applied by reactive sputter-deposition in an excited radioactive gas to produce a coat which is a radioactive compound of the radioactive gas and a sputtered target material.
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38. A method in accordance with claim 9 wherein the isotope is applied by reactive cathodic arc plasma deposition in an excited radioactive gas producing a coat which is a radioactive compound of the radioactive gas and a sputtered target material.
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39. A method in accordance with claim 9 wherein the isotope is applied by reactive ion beam sputtering using a cathodic arc ion source in an excited radioactive gas to produce a coat which is a radioactive compound of the radioactive gas and a sputtered target material.
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40. A method in accordance with claim 9 wherein the isotope is applied by reactive ion-plating using an electron-beam in an excited radioactive gas producing a coat which is a radioactive compound of the radioactive gas and a sputtered target material.
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41. A method in accordance with claim 9 wherein the isotope is applied by cathodic arc plasma deposition using a radioactive dielectric target.
Specification