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Implantable radiotherapy/brachytherapy radiation detecting apparatus and method

Implantable radiotherapy/brachytherapy radiation detecting apparatus and method description/claims

This application is a continuation of U.S. patent application Ser. No. 10/704,340, filed Nov. 7, 2003, the contents of which are specifically incorporated herein by reference.

The invention relates generally to apparatus and methods for use in treating proliferative tissue disorders, and more particularly to apparatus and methods for the treatment of such disorders by delivering radiation with a brachytherapy device that also measures treatment characteristics.

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 malignant cells after resection, with the goal of sterilizing them, reducing the rate of recurrence or delaying the time to recurrence. Radiation therapy can be administered through one of several methods, or a combination of methods, including permanent or temporary interstitial brachytherapy, and external-beam radiation.

Brachytherapy refers to radiation therapy delivered by a spatially confined source of therapeutic rays inserted into the body at or near a tumor or other proliferative tissue disease site. For example, brachytherapy can be 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 or 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. Brachytherapy is useful for treating malignant brain and breast tumors, among others.

Prior art brachytherapy devices have provided a number of advancements in the delivery of radiation to target tissue. For example, Winkler U.S. Pat. No. 6,413,204 describes a brachytherapy method and apparatus for treating tissue surrounding a surgically excised tumor with radioactive emissions to kill cancer cells that may be present in the tissue surrounding the excised tumor. The radiation is delivered in a predetermined dose range defined as being between a minimum prescribed absorbed dose for delivering therapeutic effects to tissue that may include cancer cells, and a maximum prescribed absorbed dose above which healthy tissue necrosis may result. The resulting treatment helps to prevent over-exposure to tissue at or near the brachytherapy device, while still delivering the minimum prescribed dose at the maximum prescribed distance from the device.

While such advancements have improved the treatment of proliferative tissue diseases, some challenges remain. Currently, the desired radiation dose is calculated based on the characteristics of the brachytherapy applicator (device), the radiation source and the surrounding tissue, yet the actual dose delivered is not tested to assure that over and/or under treatment do not occur. For example, if the radiation source is a radioactive seed positioned in the center of an expanded balloon, the calculated dose is based on the central positioning of the radiation source. If for some reason the radioactive seed was positioned off center, prior art brachytherapy devices do not have the means to determine that this harmful situation has or is occurring. Prior art brachytherapy devices also lack the ability to directly sense the surrounding tissue and determine the effectiveness of the proliferative tissue disorder treatment.

The present invention provides brachytherapy apparatus and methods for delivering and monitoring radioactive emissions to an internal body location. The device includes a catheter body member having a proximal end, a distal end, and an outer spatial volume disposed proximate to the distal end of the body member. A radiation source is preferably positioned in the outer spatial volume, and a treatment feedback sensor is disposed on the device.

In one embodiment, the treatment feedback sensor is a radiation sensor which can detect radiation emitted by the radiation source. The radiation sensor preferably produces data useful for determining if the delivered radiation dose was within the prescribed range. The data can also preferably be used to determine if the desired radiation profile was delivered to the surrounding tissue. In another aspect of the invention, the treatment feedback sensor is capable of detecting tissue temperature, oxygenation, pH, treatment agent concentration, cytokine concentration, or other characteristics related to radiation treatment.

In one embodiment, the treatment feedback sensor is positioned within the catheter body member. Other locations where the sensor may preferably be located include disposed on an expandable surface member which defines the outer spatial volume, or outside the device.

In another embodiment, the present invention includes a radiation therapy apparatus for delivering and monitoring radioactive emissions to a resected tumor cavity. The apparatus includes a catheter body member with proximal and distal ends, an expandable surface member disposed proximate to the distal end of the catheter body, a treatment feedback sensor, and an external radiation source positioned outside the tissue cavity for delivering radiation to target tissue surrounding the tissue cavity. The expandable surface member can be positioned within a resected tissue cavity and expanded to position the surrounding tissue such that the delivery of a radiation beam from the external radiation source is accurately delivered and measured by the treatment feedback sensor positioned within the tissue cavity.

In another embodiment, the invention includes the method of delivering and monitoring radioactive emissions to an internal body location. The method includes inserting a brachytherapy device into a resected cavity, the brachytherapy device including a catheter body member with proximal and distal ends, and an expandable surface member disposed proximate to the distal end of the catheter body member. A radiation source is preferably disposed within the expandable surface member. The method further includes inserting a radiation sensor into the resected cavity and delivering a minimum prescribed absorbed radiation dose to a target tissue, the target tissue being defined between the expandable surface member and a minimum distance outward from the expandable surface member. The radiation sensor senses the delivered radiation dose and data output from the sensor confirms that the brachytherapy device delivers the minimum prescribed dose.

In another embodiment, the present invention includes a brachytherapy apparatus for delivering and monitoring radioactive emissions to an internal body location. The apparatus includes a catheter body member having a proximal end, a distal end, and an outer spatial volume disposed proximate to the distal end of the body member. A radiation source is disposed in the outer spatial volume and a treatment feedback sensor is provided on the device. The treatment feedback sensor can be used to evaluate the treatment of proliferative tissue disorders.

The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings:

FIG. 1 illustrates the device of the present invention including a sectioned view of the outer spatial volume showing radiation sensors positioned therein;

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