Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Patent
1997-10-03
1999-07-20
Lacyk, John P.
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
A61N 500
Patent
active
059249749
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an elongated radioactive element to be attached to an end of an elongated wire-shaped element.
2. Description of the Prior Art
One application of such a radioactive element is its use in the event that local irradiation is desired, particularly, if the place of irradiation is not directly or readily accessible, for instance in the event of a tumor present in a body. In such cases, hollow needles for instance in the case of a mammary tumor, or hollow catheters for instance in the case of a uterine tumor are used within which the radioactive element can be pushed into the desired position for radiation treatment. In order to protect the persons performing the treatment from ionizing radiation, the radioactive element is contained in a shielding housing which is connected by a tube to a needle or catheter. The radioactive element is attached to an end of a wire-shaped element so that the radioactive element can be brought, by remote control, out of the shielding housing through the tube into the desired position for irradiation by the displacement of the wire-shaped element by a drive unit.
Another use also known as intravascular brachytherapy of such a radioactive element is use in the treatment against restenosis by neo-intima proliferation of a blood vessel after a recanalization treatment. Such a treatment of blood vessels around the heart is known, inter alia, as percutaneous transluminal coronary angioplasty (PTCA; in the case of blood vessels around the heart), and atherectomy. Upon such a treatment, a substantially occluded blood vessel (for instance as a result of the deposition of so-called plaque in the lumen of the blood vessel) is stretched by means of an expandable element such as a fluid-inflatable balloon (angioplasty balloon), fastened to an elongated element such as a catheter, in order to permit the blood to flow again substantially unimpeded through the stretched blood vessel. In certain cases, a so called "stent" (metal wire stretcher) is inserted in order, among other things, to prevent "elastic recoil".
In a large number of cases, a new recanalization treatment is found necessary after a relatively short period of time since a constriction again forms in the blood vessel or has already formed. The constriction may be a result of tissue (known as neo-intima hyperplasia or neo-intima proliferation) developing at the stretched place, probably because the wall of the blood vessel was damaged by the stretching. There are strong indications that this formation of tissue can be avoided or at least reduced to a great extent if, during or shortly after the recanalization treatment, the blood-vessel tissue concerned is irradiated with ionizing radiation, in particular .beta. and/or .gamma. radiation, so that a subsequent recanalization treatment is no longer necessary, or in any event a much longer period of time elapses before such a treatment is necessary.
In medical applications of radioactive sources for providing the ionizing radiation mentioned above, radioactive materials are used with half-lives suitable for medical applications. Depending on the application, this half-life is at least a few days. Moreover, for use in intravascular brachytherapy the radiation used should have an average energy E.sub.mean of at least 0.6 MeV. E.sub.mean is also referred to in the following as .beta.-energy. To this day, choosing a suitable radioactive material meant browsing through voluminous books with extensive tables indicating for each element of the periodical system, whether it is radioactive or not, and if so, in what ways the radioactive element may decay. Thus all radioactive elements whose decay consists of .beta.-decay with an E.sub.mean larger than 0.6 MeV and a half-life greater than a few days qualify. In addition to these criteria, other criteria also play a role, e.g., scarcity of the starting material, the toxicity thereof, its mechanical processibility, etc.
In practice, therefore, there is a great need for a
B.V. Optische Industrie "De Oude Delft"
Lacyk John P.
Marn Louis E.
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