Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
2000-08-07
2003-12-23
Lacyk, John P. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
C427S005000
Reexamination Certificate
active
06666811
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to radioactive implants, methods of making them and methods of using them.
It is known to use external beam supervoltage or megavoltage conventional fractionated radiation therapy to treat subclinical microscopic metastases in surgically undisturbed lymph node chains and to sterilize the postoperative tumor bed after the tumor is grossly excised. The uses of external beam radiation techniques have a disadvantage that they are not able to safely treat solid tumors because the solid tumors require an intensity of radiation that is harmful to the surrounding normal tissue.
It is also known to implant radioactive sources directly into solid tumors for the destruction of the tumors in a therapy referred to as brachytherapy (short-range therapy). This therapy permits the application of larger doses of radiation.
In the prior art brachytherapy, the sources are generally implanted for short periods of time and generally are sources of high radiation intensity. For example, radium needles and iridium-192 ribbons have been implanted into tumors (interstitial brachytherapy) or radium-226 capsules and cesium-137 capsules have been placed into body cavities such as the uterus (intracavitary brachytherapy).
The prior art interstitial brachytherapy treatment using radium needles has several disadvantages, such as for example: (1) dosimetry is difficult and imprecise; (2) local failures are caused, mainly by the large size of the radium needles (approximately the size of a lumber nail); (3) it is difficult to implant an adequate number of the needles uniformly throughout a tumor to produce homogeneous irradiation because they are large sources; and (4) the needles can only be left in place temporarily, and must be surgically removed.
It is known to implant iodine seeds temporarily or permanently. The prior art iodine seed consists of the radionuclide adsorbed onto a carrier which is placed into a metal tube that is welded shut. It has the disadvantages of: (1) being relatively large to be safely implanted in large numbers in the human body; and (2) due to its construction, producing inhomogeneous radiation.
The prior art iridium seeds in ribbon consist of solid iridium wire cut into pieces and placed in plastic tubing, which is then implanted into accessible tissues temporarily for several days. These seeds work well, but because they must be removed, their application is limited to a few accessible body sites. Also, they only come in one energy.
The prior art radium-226 intracavitary sources and cesium sources consist of metal cylinders containing radium salts or cesium. They have several disadvantages, such as for example: (1) dosimetry is difficult and imprecise; (2) they are bulky and difficult to use; (3) it is difficult to implant or otherwise insert an adequate number of the cylinders in the proper locations to produce homogeneous irradiation because they are large sources; (4) the cylinders can only be left in place temporarily, and under some circumstances, must be surgically removed; and (5) general anesthesia is required to dilate the cervix sufficiently to place a source in the uterus.
The applications of brachytherapy are still severely limited by the unavailability of a wide range of implantable radioactive sources that have a wide range of gamma energies (radiation energy is related to the volume irradiated) and varying half-lives (radionuclide half-life affects tumor dose rate, radiobiology, and normal tissue effects). Also the limited number of sources currently available are still physically unsatisfactory in their construction. There are few low energy limited lifetime radioactive seeds such as gold-198 and iodine-125 seeds that may be permanently implanted into solid cancers.
It is also known to apply heat to tumors by implanting metals that may be heated by radio frequency radiation and to move heatable or radioactive members about magnetically for positioning them without excessive surgery. This is especially significant in the treatment of highly vascular tumors. The existing hyperthermia radio frequency treatment is not well adapted for easy combination with endocurietherapy.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide novel radioactive implants.
It is a still further object of the invention to provide a novel electron-producing beta-seed.
It is a still further object of the invention to provide a perfectly spherical tantalum, tungsten, gold, platinum casing or compound tungsten carbide, tantalum carbide casing over a radioactive microspherical substrate when the radioactive material produces high energy gamma rays.
It is a still further object of the invention to provide a perfectly spherical titanium, hafnium or zirconium metal casing or a compound casing of titanium carbide, titanium nitride, titanium conbonitride, hafnium nitride or zirconium nitride over a radioactive microspherical substrate when the radioactive material produces low energy gamma rays.
It is a still further object of the invention to provide a perfectly spherical diamond casing over a radioactive microsphere when the radioactive material produces beta rays.
It is still further object of the invention to produce a novel low-energy permanent multilayered radioactive microsphere.
It is a still further object of the invention to provide a novel tissue-compatible (absorbable and non-absorbable) surgical fabric that contains multiple radioactive seeds to facilitate rapid implantation of a large number of radioactive seeds.
It is a still further object of the invention to provide a novel ribbon containing multiple low energy permanent multilayered radioactive microspheres.
It is a still further object of the invention to provide a novel multilayered low energy permanent or temporary radioactive wire that may be permanently or temporarily implanted into human tissues and that safely delivers low energy.
It is a still further object of the invention to provide a novel implant that safely delivers energy at levels less than or equal to 100 KeV average gamma energy to tumors at a low rate in less than 130 days to produce tumoricidal radiation doses that are 2.3 to 5.7 times higher than the maximum doses permissible with reasonable safety by modern megavoltage external beam radiation therapy techniques.
It is a still further object of this invention to produce a radioactive seed which has the clinical result of reducing the complication rate of treatment while increasing the local cure rate by allowing safe delivery of very high radiation doses to solid human tumors.
It is still further object of the invention to produce an improved radioactive seed, ribbon containing multiple seeds, or radioactive wire which may be permanently implanted into human tissues and safely deliver high energy (greater than 100 KeV average gamma energy) tumor irradiation at an average dose rate less than 1.50 Gy/hour (Gray/hour-one Gray is equal to 100 rad) in less than 15 to 20 days.
It is a still further object of the invention to provide a novel technique for making an improved radioactive seed, seed ribbon, or radioactive wire which may be temporarily implanted into human tissues by after-loading tubes or by implanting interstial needles.
It is a still further object of the invention to produce a novel multilayered radioactive microsphere, ribbon microsphere, or multilayered radioactive wire, which emits electrons or beta particles and have casings which are substantially transparent to electrons.
It is a still further object of the invention to provide a radioactive seed having a shape that is spherical rather than cylindrical to make it less likely to jam in an auto-feeding tissue implantation gun.
It is a still further object of the invention to increase the clinical utility and safety of the radioactive seed by making it significantly smaller in diameter to permit tissue implantation with thinner gauge needles.
It is a still further object of the invention to improve upon the uniformity of the radioactive coat used in radioactive seed
Carney Vincent L.
Endotech, Inc.
Lacyk John P.
LandOfFree
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