Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
2002-10-11
2004-02-24
Winakur, Eric F. (Department: 3736)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
C623S017160, C606S192000
Reexamination Certificate
active
06695760
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to apparatus for use in treating proliferative tissue disorders, and more particularly to an apparatus for the treatment of such disorders in the body by the application of radiation.
BACKGROUND OF THE INVENTION
Malignant tumors are often treated by surgical resection of the tumor to remove as much of the tumor as possible. Infiltration of the tumor cells into normal tissue surrounding the tumor, however, can limit the therapeutic value of surgical resection because the infiltration can be difficult or impossible to treat surgically. Radiation therapy can be used to supplement surgical resection by targeting the residual tumor margin after resection, with the goal of reducing its size or stabilizing it. Radiation therapy, or surgical excision followed by radiation therapy, is commonly used to treat spinal metastases. Metastases are tumors that have grown in a location that is remote from the site that the tumor started, and spinal metastases result from the spread of cancer cells into a patient's vertebral column.
Radiation therapy can be administered through one of several methods, or a combination of methods, including external-beam radiation, stereotactic radiosurgery, and permanent or temporary interstitial brachytherapy. The term “brachytherapy,” as used herein, refers to radiation therapy delivered by a spatially confined radioactive material inserted into the body at or near a tumor or other proliferative tissue disease site. Owing to the proximity of the radiation source, brachytherapy offers the advantage of delivering a more localized dose to the target tissue region.
For example, brachytherapy is performed by implanting radiation sources directly into the tissue to be treated. Brachytherapy is most appropriate where 1) malignant tumor regrowth occurs locally, within 2 or 3 cm of the original boundary of the primary tumor site; 2) radiation therapy is a proven treatment for controlling the growth of the malignant tumor; and 3) there is a radiation dose-response relationship for the malignant tumor, but the dose that can be given safely with conventional external beam radiotherapy is limited by the tolerance of normal tissue. In brachytherapy, radiation doses are highest in close proximity to the radiotherapeutic source, providing a high tumor dose while sparing surrounding normal tissue. Interstitial brachytherapy is useful for treating malignant brain and breast tumors, among others.
While devices exist for delivering radiation to treat metastases, there is still a need for instruments which can be used to provide brachytherapy to target tissue within a load bearing portion of a human body, such as within a patient's spine.
SUMMARY OF THE INVENTION
The present invention generally provides a brachytherapy system for treating metastases within a load bearing portion of a patient's body. The system includes a structural support having an internal space and being adapted to fit within an interstitial space within a load bearing portion of a patient's body, and a catheter member having proximal and distal ends and at least one lumen extending therebetween. The structural support is preferably configured to fit within a resected cavity in a patient's bone, and more particularly in a patient's spine. At least one anchoring element is disposed proximate to the distal end of the catheter and is adapted to fit within the internal space in the structural support so as to anchor the distal end of the catheter therein. The system also includes a radiation source disposable within the internal space through the at least one lumen in the catheter for delivering radiation to the tissue surrounding the interstitial space.
The system can be adapted to control the distribution of radiation to tissue surrounding the interstitial space. In one embodiment, a shield can be formed on a portion of at least one of the structural support and the anchoring element for shielding radiation sensitive tissue from a portion of the radiation. Alternatively, or in addition, a portion of the structural support adapted to be positioned adjacent to a patient's spine or other vital organs and structures can be formed from a radio-opaque material adapted to shield the patient's spinal cord from radiation. In yet another embodiment, the radiation source can be configured to provide an asymmetric radiation dose within the tissue surrounding the interstitial space so that radiation sensitive tissue surrounding the interstitial space receives a lesser dose. In other aspects, the anchoring element can be an outer expandable member, and the system can include an inner expandable member disposable within the outer expandable member and effective to removably receive the radiation source. Preferably, the outer expandable member is adapted to be positioned substantially adjacent to tissue surrounding the interstitial space when expanded, and the inner expandable member is effective to position the radiation source at a predetermined distance apart from the outer expandable member to provide a minimum absorbed dose for delivering radiation to tissue adjacent the outer expandable member. In another embodiment, at least one of the outer expandable member and the inner expandable member can be partially coated with a radio-opaque material effective to shield radiation sensitive tissue from a portion of the radiation source. Alternatively, or in addition, a shield effective to shield radiation sensitive tissue from a portion of the radiation source can be disposed between the outer expandable member and the inner expandable member.
In another embodiment of the present invention, a brachytherapy system for delivering radioactive emissions to an interstitial space in a resected vertebral body is provided. The system includes a cage member adapted to fit within an interstitial space in a resected vertebral body and having an internal space, a catheter body having proximal and distal ends, and a first expandable balloon member disposed adjacent the distal end of the catheter body and defining an inner spatial volume having a radiation source disposed therein. The first expandable balloon member is adapted to be disposed within the internal space in the cage member.
In other aspects of the present invention, a method for treating spinal metastases is provided. The method includes the steps of surgically resecting a vertebral body to create an interstitial space, providing an interstitial brachytherapy apparatus for delivering radioactive emissions, intraoperatively placing the interstitial brachytherapy apparatus into the interstitial space, providing a controlled dose of radiation to tissue surrounding the apparatus, and removing the interstitial brachytherapy apparatus. The apparatus preferably includes a catheter member having proximal and distal ends and at least one lumen, at least one anchoring element disposed proximate to the distal end of the catheter and adapted to anchor the distal end of the catheter within the interstitial space, and a radiation source disposable within the internal space through the at least one lumen in the catheter for delivering radiation to the tissue surrounding the interstitial space. The step of surgically resecting a vertebral body can further include the step of providing a structural support adapted to fit within the interstitial space, and positioning the structural support in the interstitial space, wherein the interstitial brachytherapy apparatus is positioned in an internal space within the structural support. The radiation source is preferably placed into the interstitial brachytherapy apparatus after placement of the apparatus into the internal space in the structural support, and is preferably removed from the internal space in the structural support before removal of the apparatus.
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patent: 3324847 (1967-06-01), Zoumboulis
patent: 3872856 (1975-03-01), Clayton
patent: 4417576 (1983-11-01), Baran
patent: 4706652 (1987-11-01), Horowitz
patent: 4754745 (1988-07-01), Horow
Patrick Timothy J.
Ramey Carribeth B.
Winkler Rance A.
Nutter & McClennen & Fish LLP
Proxima Therapeutics
Veniaminov Nikita R
Winakur Eric F.
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