Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
1999-03-04
2001-06-26
Lacyk, John P. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
Reexamination Certificate
active
06251059
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to medical devices and, in particular, to medical radiation treatment delivery apparatus such as a catheter for administering a radiation treatment to a patient.
BACKGROUND OF THE INVENTION
Angioplasty is an established procedure for reducing the effect of atherosclerotic plaque on and intraluminal narrowing of the arterial walls within the vascular system of the patient. The effect is reduced by use of a catheter that is inserted into the site of the diseased-occluded vessel. A balloon portion of the catheter is then inflated to a predetermined pressure range and size, to radially compress the plaque occlusion, thereby increasing the internal diameter of the previously restricted artery. The balloon is then collapsed and the catheter is removed.
After the angioplasty procedure has been performed, as many as one-third to one-half of the patients soon develop restenosis. Restenosis can occur after angioplasty or other recannulation procedures, with or without stenting, wherein the migration and proliferation of benign cells cause a restenotic lesion to form, resulting in the further blockage of the intravascular structure.
Radiation is administered to patients for a variety of reasons, such as to treat restenosis, malignant or benign tumors, or the like. Examples of such treatments are disclosed in U.S. Pat. Nos. 5,059,166; 5,213,561; and 5,302,168.
It would be preferred to be able to provide a radiation delivery system which would:
a) deliver a predetermined totally-cumulative and homogeneous dose of radiation to the lesion site, at a predetermined penetration depth, while minimizing the exposure of surrounding healthy tissue to the radiation;
b) enable the treating physician or other health-care personnel to be bedside to the patient during the administration of the radiation therapy without exposing the physician or health care personnel to any unreasonable risk;
c) use radiation material that is readily and inexpensively available from a commercial provider;
d) use minimal special equipment storage, or delivery devices, except for routine facilities available in most nuclear medicine or radiation oncology departments;
e) use a radiation carrier material that if applied as an unsealed free-gas form, the inert, noble gas properties essentially enable the molecules of the carrier material to rapidly dissipate throughout the body of the patient without any prolonged organ accumulation or chemical interaction, and rapid dilution of the carrier material is quickly re-released from the bloodstream through the lungs;
f) minimize long term occlusion of normal blood flow during therapy, thereby providing more flexibility as to administration time and dosage;
g) use a radiation carrier material that is stable and which can be pressurized, stored, and made to high millicurie activity per cubic centimeter with reasonable cost and availability;
h) use beta particles having excellent initial dose rate delivery and energy transfer when directly adjacent to the targeted tissue within the first one millimeter, and not penetrate much beyond this depth;
i) use gamma photon energies having depth doses that provide complementary dose deposition with the beta particles for the first one millimeter, and primary additive dose delivery for an additional two to three millimeters of the targeted tissue;
j) use these beneficial physical and biological radiation properties for treating restenosis, and malignancies (for example—in the brain, lung, esophagus, trachea, cervix, biliary ductal system, colon or rectum, the gastrointestinal system, the gynecological system, or head and neck) and other internal ailments where an internal application of radiation directly applied to the tissue may be needed; and
k) attenuate the transmission dose to blood circulating through the apparatus, and while creating increased by-product radiation, delivering useful radiation dose over hundreds of micrometers of target tissue.
SUMMARY OF THE INVENTION
The foregoing problems are solved and a technical advance is achieved in illustrative medical radiation treatment delivery apparatus such as an inflatable balloon catheter for delivering radiation to a treatment site. In particular, the apparatus has a portion such as the inflatable balloon through which radiation from a radioactive fluid such as an isotope of xenon can be radiated. The balloon normally has a radiation dosimetry unit of measurement such as a radiation dose rate which heretofore had to be calibrated by a medical physicist or medical radiation expert for providing a prescribed radiation dose within prescribed limits to the patient. This radiation dosimetry unit of measurement is advantageously indicated by the manufacturer and affixed, disposed or positioned on the delivery device as an indicator of the radiation dosimetry unit of measurement.
In one embodiment, the dosimetry unit is simply displayed on or near an end of the catheter apparatus with one or more symbols, letters, or numbers indicative of the dosimetry unit. The indicator can be affixed, disposed, or positioned thereon by printing, photoetching, painting, embossing, raising, or any other method of marking.
In another aspect, the indicator can be a radiation sensitive film which is sensitive to radiation for changing from one visible shade to another. This advantageously can be used to supply information to the attending physician for the purposes of radiation treatment and, in particular, achieved total delivered dose in vivo. Furthermore, this radiation sensitive film can be used either alone or in combination with one or more other dosimetry use indicators to provide the attending physician with a host of information concerning the properties of the catheter or delivery apparatus or the use thereof in patients.
The elongated member of the catheter apparatus comprises at least one of a polyurethane, polyethylene, polyimide, polyvinyl chloride, polyamide, polytetrafluoroethylene, silicone material, or any other similar suitable material. A high density material of at least one of barium, tungsten, lead, tantalum, titanium, bismuth, gold, platinum, palladium, rhodium, or any other similar suitable material is also included in the elongated member to advantageously control the dosimetry unit of the catheter as well as provide radiation shielding for the patient and attending personnel. Similarly, the material of the portion of the delivery apparatus that comes in contact with the treated tissue such as the inflatable balloon(s) advantageously includes at least one of silicone, latex, a synthetic material similar to latex, polyamide, vinyl, polyethylene, polytetrafluoroethylene, polyethylene terephthalate, fluorinated ethylene propylene, or any other similar suitable material. Selection of the balloon material and its density and thickness affect the radiation dosimetry unit of measurement such as the radiation dosage rate. High density materials as previously mentioned, also are advantageously utilized to control the dosimetry unit.
The system of the present invention is useful for the administration of ionizing or other types of therapeutic radiation. The intravascular catheter system of the present invention uses either of several unique radiation carrier fluids. The catheter apparatus includes either a plurality of balloon sections or a single balloon unit which is inflatable by an inert radioactive carrier fluid (liquid or gas). In one aspect, blood or other body fluid flows through the artery or tube and possibly the catheter when the balloon sections are deflated and inflated. When the balloon(s) of the several embodiments is inflated, the blood flows through at least one section(s) disposed between and/or within the balloon section(s). The system can also be readily modified for tissue or organ-specific design to treat malignancies in passageways or tubes of cancer patients, or even injecting the radio-contents of the catheter into tissue in a limited, controlled manner.
In one embodiment of the present invention, one catheter can perform th
Apple Marc G.
Bates Brian L.
DeFord John A.
Fearnot Neal E.
Cook Incorporated
Godlewski Richard J.
Lacyk John P.
Ness Anton P.
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