WO2005086702A2 - Device for performing brachytherapy - Google Patents

Abstract

An applicator for performing brachytherapy includes a first elongated member suitable for receiving a radioactive source; a second elongated member, the second tubular member being spaced apart from the first elongated member; a first shielding member capable of being positioned at a first location along one of the elongated members; a second shielding member capable of being positioned at a second location spaced apart from the first shielding member along one of the elongated members; and a spacer capable of being positioned between the first and the second shielding members. The spacing of the first and second shielding members may be capable of adjustment by addition of one or more spacers between the first and second shielding members.

Description

DEVICE FOR PERFORMING BRACHYTHERAPY SPECIFICATION PRIORITY APPLICATION This application claims priority to U.S. Provisional Application Serial No. 60/550, 100, filed March 4, 2004, titled "Applicator for Treatment of Breast Cancer," which is hereby incorporated by reference in its entirety. FIELD OF INVENTION The present invention relates generally to radiation treatment for cancer, and more particularly to an apparatus for delivering intraoperative brachytherapy. BACKGROUND INFORMATION In the field of medicine, radiation therapy may be used to eradicate malignant cells. With respect to the location of the application of radiation, at least two general approaches to radiation therapy are recognized: conventional teletherapy treatment, and brachytherapy. Conventional radiation treatment systems used for medical treatment, such as the linear accelerators that produce high-energy x-rays, utilize a remote radiation source external to the targeted tissue. A beam of radiation is directed at the target area, for example a malignant tumor inside the body of a patient. The x-rays penetrate the patient's body tissue and deliver x-ray radiation to the cancer cells, usually seated deep inside the body. This type of treatment is referred to as teletherapy because the radiation source is located at some distance from the target. Electron beam, photon therapy, and x-ray therapy are all examples of teletherapy. One disadvantage of this treatment is that tissue disposed between the radiation source and the target is exposed to radiation. To reach the cancer cells, the x-rays from an external radiation source must usually penetrate through normal surrounding tissues. A second disadvantage is that non-cancerous tissues and organs beyond the target site may also be damaged by the penetrating x-ray radiation. Brachytherapy, on the other hand, is a form of treatment in which the source of radiation is located within or close to the area receiving treatment. Brachytherapy offers significant advantages over teletherapy, for example, the radiation is applied primarily to treat only a predefined tissue volume, without significantly affecting the tissue at a distance from the treatment volume. The term brachytherapy is commonly used to describe the use of a "seed" or "source," i.e., an encapsulated radioactive isotope which can be placed directly within or adjacent the target tissue to be treated. With respect to the timing of radiation of treatment (as opposed to location), generally three approaches are recognized: pre-operative, post-operative, and intra-operative treatment. Pre-operative treatment relates to radiating a tumor and its surrounding portion prior to surgically removing the tumor itself. In post-operative treatment, radiation is applied to the tumor be and surrounding area. In intraoperative radiation treatment, the radiation treatment is applied at the time of surgery generally after the tumor is resected, generally during the same surgical procedure, e.g., prior to sending the patient to post-operative recovery. Interest in intraoperative radiation treatment for breast cancer is increasing as the potential benefits of this technique for the patient become apparent. Intra-operative radiation treatment offers the ability to target the radiation dose to areas at greatest risk with precision (because the surgeon knows the exact location of the cavity). The treatment by delivering a single therapeutic radiation dose during surgery may obviate the need for a six week course of external beam. Moreover, intra-operative radiation treatment may allow a patient an earlier return to normal life. Previously, intra-operative techniques have been used along with electron radiation treatment, as discussed in Umberto Veronesi et al., "Full-dose intraoperative radiotherapy with electrons during breast-conserving surgery," Archives of Surgery, vol. 138(11), pp. 1253-56, Nov. 2003. Other discussions of intraoperative techniques include Umberto Veronesi et al., "Intraoperative radiation therapy for breast cancer: technical notes," Breast Journal, vol. 9(2), pp. 106-12, Mar- Apr. 2003; Mattia Intra et al., "Surgical technique of intraoperative radiotherapy in conservative treatment of limited-stage breast cancer,"Archives of Surgery, vol. 137(6), pp. 737-40, Jun. 2002; Umberto Veronesi et al, "A preliminary report of intraoperative radiotherapy (IORT) in limited-stage breast cancers that are conservatively treated" [see comment] Comment in: Eur J Cancer, 2001 Nov;37(17):2143-6; PMID: 11677099; European Journal of Cancer, vol., 37(17), pp. 2178-83, Nov. 2001. When intraoperative electron radiation therapy is used in the treatment of breast cancer, the malignant cells removed and then a lead plate is typically placed in the surgical site before the radiation treatment is applied. This plate offers shielding capabilities and substantially reduces the radiation from passing through into the patient's chest cavity. Introduction of this shield is a tedious process in which the patient's skin must be pulled back from the treatment area and held in that position until the radiation treatment is complete. Keeping the patient's skin pulled back during treatment prevents damage to the patient's skin from the radiation. A traditional method of intra-operative brachytherapy treatment employs the HAM applicator, manufactured by Mick Radionuclides. The HAM applicator 200 is a flat design, with multiple catheters 210 and members 212 having radioactive sources. (See Fig. 1). The HAM applicator design delivers radiation does by flat geometry which may not be appropriate for treating breast cancer cavity.

Moreover, the HAM applicator typically requires a separate shield to be placed in the surgical site to prevent excess radiation from passing through to internal organs. It is desirable to reduce the risk of recurrent tumorous growth near or around the operative site, while at the same time preventing radiation damage to non- cancerous tissue. Thus, a need exists to perform "intra-operative brachytherapy" with an applicator for treating breast cancer which overcomes the disadvantages of current techniques and which, for example may accommodate various breast sizes and incision sizes, and provide built-in shielding properties. SUMMARY OF THE INVENTION An object of the current invention is to overcome the drawbacks of the prior art. One exemplary embodiment of the present invention concerns an applicator for use in intraoperative brachytherapy. The applicator can be used to deliver high dose rate intraoperative brachytherapy as boost treatment or as monotherapy for early stage breast cancer at the time of initial lumpectomy or re- excision. High dose rate intraoperative brachytherapy may be delivered in a lead- lined operating room, and may be accomplished by a Remote Afterloader. An applicator in accordance with an embodiment includes a first elongated member suitable for receiving a radioactive source, and a first shielding member capable of being positioned at a first location along the first elongated member. An exemplary embodiment of the present invention has the following advantages: it has adjustable size to accommodate various cavity size and breast sizes; it has shielding properties built into one end of the applicator to eliminate the need for a lead plate under the treatment area to prevent radiation from passing through to a patient's chest area; it has shielding properties built into the other end of the applicator to eliminate the need for keeping the patient's skin retracted during the entire time of treatment (usually 15- 45 minutes depending on the dose required.) In another exemplary embodiment of the present invention, an applicator for performing brachytherapy includes a first elongated member suitable for receiving a radioactive source; a second elongated member, the second tubular member being spaced apart from the first elongated member; a first shielding member capable of being positioned at a first location along one of the elongated members; a second shielding member capable of being positioned at a second location spaced apart from the first shielding member along one of the elongated members; and a spacer capable of being positioned between the first and the second shielding members. In an optional arrangement, both elongated members are approximately parallel to each other suitable for receiving radioactive source. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an isometric view of an applicator in accordance with the prior art. Fig. 2 is an isometric view with parts separated of first exemplary embodiment according to the present invention. Fig. 3 is a side view in partial cross-section of the first exemplary embodiment in accordance with the present invention, with several components removed. Fig. 4 is a side view in partial cross-section of the embodiment of Fig. 2 in accordance with the present invention. Fig. 5 illustrates an assembly view of another embodiment of the present invention. Fig. 6 is an exploded view of the embodiment of Fig. 5 Fig. 7(a) is an end view of the embodiment Fig. 5. Fig. 7(b) is a cross-sectional view of Fig. 7(a) taken along line AA. Fig. 7(c) is a cross-sectional view of Fig. 7(a) taken along line BB. Fig. 8(a) is an end view of a non conductive member according to an exemplary embodiment of the present invention. Fig. 8(b) is a cross-sectional view of Fig. 8(a) taken along line AA. Fig. 8(c) is a cross-sectional view of Fig. 8(a) taken along line BB. Fig. 9(a) is a spacer of Fig. 5 according to an exemplary embodiment of the present invention. Fig. 9(b) is a cross-sectional view of Fig. 9(a) taken along line AA. Fig. 9(c) is a cross-sectional view of Fig. 9(a) taken along line BB. Fig. 10 is a sectional view of a portion of Fig. 5. Fig. 11(a) is a second shielding member of Fig. 5 according to an exemplary embodiment of the present invention. Fig. 11(b) is a cross-sectional view of Fig. 9(a) taken along line AA. Fig. 11(c) is a cross-sectional view of Fig. 9(a) showing detail B. Fig. 12(a) is a second shielding member of Fig. 5 according to an exemplary embodiment of the present invention. Fig. 12(b) is a cross-sectional view of Fig. 9(a) taken along line AA. Fig. 12(c) is a cross-sectional view of Fig. 9(a) showing detail B Fig. 13 pictorially illustrates a remote afterloader in conjunction with the embodiment of Fig. 1. Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the present invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. DETAILED DESCRIPTION Fig. 2 depicts an exemplary embodiment according to the present invention. The applicator may be in the shape of an elliptical obturator 10. A first member 12 may be connected to a first tube 14 and second tube 16. hi an exemplary embodiment, first tube 14 and second tube 16 are hollow tubes positioned 2 cm apart. Although two tubes are depicted herein, it is understood that one or more tubes may be used in the apparatus. The connection may be via a weld, for example. The first member 12 may be fabricated from stainless steel. The first and second tubes 14, 16 may be fabricated from stainless steel. A first shielding member 18, made of a material with shielding properties, such as tungsten alloy, may be provided adjacent to the first member 12. In an optional arrangement the first member 12 and the first shielding member 18 may be the same part, and thus may have shielding properties. (See Fig. 7). The tungsten alloy may assist in modifying the radiation distribution and reduce or eliminate the doses to adjoining structures. Optionally, a non-conductive member 20, such as delrin, may be provided adjacent to the shield. Spacers 22 may be provided with apertures 21 which are adapted to receive the tubes 14, 16 therethrough. The quantity of spacers may be selected to properly adapt the applicator to the lumpectomy cavity and provide the desired spacing 23 between shielding elements 18 and 24. This may take into account the size of the surgery cavity and the size of the patient's breast as well. The use of shielding may be based on proximity to normal structures (i.e., the patient's chest and ribcage). The spacers 22 may be fabricated from liquid silicone rubber and may be disposable. In an optional arrangement, the spacers may be fabricated from a thermoplastic or thermoset material. (See Fig. 9). A further shield 24 may be provided adjacent to a spacer and may be capable of cooperating with the first shield 18. The further shield 24 may prevent radiation from reaching the patient's skin, for example, that may have been temporally stretched and covering a portion of the further shield when the applicator is inserted into the patient's breast. A collet or suitable locking mechanism 28 may be used to secure spacers between the further shield 24 and the first shield 18, as depicted in Fig. 3. Thus, the collet or suitable locking mechanisms may permit adjustability in the overall length of the applicator device. A first and second catheter 30,32 may be used to introduce the radioactive source into the first and second tubes 14, 16. The catheters 30, 32 may be attached to the tubes by a collet or other suitable mechanism 34. The catheters 30, 32 may be connected to a remote afterloader Model 510 (k), manufactured by Nucletron. (See Fig. 13). A remote afterloader is well known in the medical art. It is a device which stores the radioactive seen and through computer control remotely positions the seed in the applicator for a specified dwell time. Fig. 4 depicts a more detailed view of Fig. 3, and is shown with a radiation source 40 positioned within the hollow interior portion of the tube 14. As described herein, applicator 10 including the tubes 14 and 16 containing the radioactive source 40 and the shielding members 18 and 24 may be inserted into the operative site as an integrated single element, without the need to separately insert a shielding element and displace tissue from the radioactive source to prevent damage. The applicator 10 may be used as an accessory to high dose rate remote controlled radionucleotide applicator systems cleared for market by the FDA. Connectors manufactured by Nucleotron and the remote afterloader may be used in conjunction with this applicator to deliver the treatment. The radioactive source may travel through plastic disposable catheters 30, 32 attached to the tubing 14, 16. The radioactive source may be attached by a moveable cable, to a controlling unit in the Remote Afterloader 50. The Remote Afterloader 50, assisted by a computer, may control the dwell time and specific location of the sources in the tubing 14, 16. Each source may be at different locations in the tubing if the treatment requires such. Thus the applicator of the present invention allows for customized treatment in ways not afforded by the prior art. In addition to visual and manual inspections to assure the secure connection to the source guide tubes, a quality assurance check with the Ir-192 source should be performed. Auto-radiograph technique to document source position in situ should be obtained. Fig. 5 illustrates an assembly view of an alternate embodiment of the present invention, referred to herein as applicator 110. Applicator 110 is substantially identical to applicator 10, which the differences noted herein. Fig. 6 is an exploded view of Fig. 5, and illustrates that the spacers 22a when added to increase the length of the applicator may be oriented 180 degrees with respect to an adjacent spacer. As noted below, spacers 22a may include elongated slots 21a. Figs. 7 - 12 illustrate more detailed designs for the components depicted in Figs. 5-6. A method of use of an embodiment of the present invention is described herein. Typically, an operative procedure such as a lumpectomy occurs in which cancerous cells are removed from the breast creating a cavity. An applicator, such as applicator 10 described herein, is selected with the appropriate size shielding members 18 and 24 and the desired spacing 23 therebetween, and is inserted into the lumpectomy cavity in apposition to the region adjoining the tumor bed, such that the shielding elements 18 and 24 are positioned to shield portions of body tissue (the incision is typically the same incision through which the cancerous cells were removed). It is understood that the applicator has at least the following uses: 1) at the time of the initial surgery, 2) separate from the original surgery, for example when auxiliary surgery for the source of the breast cancer (or for lymph node sampling), and 3) during reoperation of a lumpectomy site to clear the margins. The foregoing merely illustrates the principles of the invention. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods which, although not explicitly shown or described herein, embody the principles of the invention and are thus within the spirit and scope of the invention

Claims

I claim: 1. An applicator for performing brachytherapy comprising: a first elongated member suitable for receiving a radioactive source; a second elongated member, the second tubular member being spaced apart from the first elongated member; a first shielding member capable of being positioned at a first location along one of the elongated members; a second shielding member capable of being positioned at a second location spaced apart from the first shielding member along one of the elongated members; and a spacer capable of being positioned between the first and the second shielding members. 2. The applicator of claim 1 wherein the spacing of the first and second shielding members is capable of adjustment by addition of one or more spacers between the first and second shielding members. 3. The applicator of claim 1 wherein the spacer is comprised of a material substantially without shielding properties. 4. The applicator of claim 1 wherein the applicator is capable of being connected to a Remote Afterloader. 5. A device for performing brachytherapy comprising: a Remote Afterloader, and an applicator capable of receiving a radioactive source from the Remote Afterloader, the applicator comprising: a first elongated member suitable for receiving the radioactive source; a second elongated member, the second tubular member being spaced apart from the first elongated member; a first shielding member capable of being positioned at a first location along one of the elongated members; a second shielding member capable of being positioned at a second location spaced apart from the first shielding member along one of the elongated members; and a spacer capable of being positioned between the first and the second shielding members. 6. The device of claim 5 wherein the spacing of the first and second shielding members is capable of adjustment by addition of one or more spacers between the first and second shielding members. 7. An applicator for performing brachytherapy comprising: a first elongated member suitable for receiving a radioactive source; and a first shielding member capable of being positioned at a first location along the first elongated member. 8. The applicator of claim 7 further comprising a second elongated member wherein the second tubular member is approximately parallel to the first elongated member. 9. The applicator of claim 8 further comprising a second shielding member capable of being positioned at a second location spaced apart from the first shielding member along one of the elongated members and capable of cooperating with the first shielding member.