Abstract:
A multicomponent vaginal cylinder system composed of a tandem capable of housing one or more radiation sources, one or more removable ovoid cartridges, each cartridge capable of housing a radiation source, and a vaginal cylinder structure having corresponding hollow cavities to accommodate the insertions of the tandem and the ovoid cartridges. Radiation shielding may be removably attached to portions of the vaginal cylinder structure to shield tissues from unwanted radiation. A method for using this vaginal cylinder system to treat gynecological cancers is also disclosed.

Description:
[0001]    This application claims the benefit of U.S. provisional application Ser. No. 60/199,139, filed Apr. 24, 2000, the entire contents of which are hereby incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to the treatment of gynecological cancers, and more specifically to radiation delivery devices for insertion into a patient&#39;s vagina and cervix.  
           [0004]    2. Description of Related Art  
           [0005]    Approximately 70,000 women every year in the United States are diagnosed with an invasive gynecologic malignancy. Of this group of tumors, roughly ⅓ receive radiation as part or all of their treatment. In a majority of the patients treated with radiotherapy, the placement in the body of low-dose-rate radioactive sources (brachytherapy) is utilized to maximize control of the cancer while minimizing long-term normal tissue complications from such treatment.  
           [0006]    Traditionally, women with gynecologic cancers have radiation therapy as all or part of their treatment. A major portion of their radiotherapy involves the loading of radioactive materials into special applicators that are surgically placed into the patient&#39;s vagina. For approximately forty years, the delivery system utilized for low-dose-rate brachytherapy of patients with cancers of the cervix has involved vaginal colpostats (ovoids) and an intra-uterine tandem. Several drawbacks of this system include the inability to deliver sufficient radiation dose to treat tumors involving both the cervix and mid to lower portions of the vagina during the duration of the application. The vaginal ovoids must be replaced by the insertion of a tandem and vaginal cylinder with or without the placement of transperineal radioactive sources into the para-vaginal tissues (interstitial implantation), in order to treat this distal vaginal disease. A separate implant procedure from the initial cervical treatment is usually required under anesthesia, followed by a separate subsequent hospital stay for the duration of this brachytherapy application. Thus, there is increased risk of morbidity and mortality from this second implantation of sources in addition to the increased costs arising from a second hospitalization.  
           [0007]    Another problem associated with conventional tandem and ovoid application systems is the requirement of ovoids stabilization during the implant procedure. Stabilization is usually effected by intra-vaginal packing of gauze by the radiation oncologist to prevent movement of the ovoids once in place. Due to physician error during the implant attempt or to narrowing of the vaginal apex from the previous external beam irradiation, the vaginal ovoids may not rest directly in contact with the cervix, thereby resulting in dose inhomogeneity and increased risk of tumor persistence or recurrence. Again, a vaginal cylinder is often used instead of ovoids to complete the brachytherapy procedure. However, typical vaginal cylinders do not deliver sufficient radiation dose to the prescription points of interest for cervical cancer, without significantly increasing the risk of vaginal injury, ultimately resulting in a reduced likelihood of achieving long-term patient survival.  
           [0008]    Postoperative radiotherapy of patients having cancer of the endometrium utilizes conventional vaginal ovoids or cylinder if the patient is at risk of tumor recurrence at the vaginal apex or lower aspects of the vagina, respectively. However, should both the apex proximally and distal regions of the vagina be at risk, two separate procedures would be needed to achieve adequate radiation dosage to the entire vagina without increased toxicity.  
           [0009]    Attempts have been made to solve these problems. U.S. Pat. Nos. 4,244,357 and 5,947,891, for example, disclose typical apparatus and methods for treating patients with cervical cancers. In these patents, the tandem, which contains the radioactive sources, is inserted into the vagina, and two ovoid half-cylinders are used as spacers around the tandem. The two half-cylinders disclosed in these patents are locked together with various interlocking mechanisms. In the devices taught by these two patents, the tandem is the sole radiation source.  
           [0010]    In U.S. Pat. No. 4,554,909, the typical ovoid half-cylinders are replaced by a single, contiguous cylindrical structure. This cylindrical structure may reduce the need to pack the vagina with gauze to stabilize the device, and includes cavities for housing radioactive sources. However, in the device taught by this patent, the cavities provided to house radioactive sources are metal, and these metal cavities are connected to a metal loading tube. The presence of these metal structures within the cylinder causes an inhomogeneous radioactive dose distribution. Additionally, the disclosed design provides neither rectal nor bladder shielding.  
           [0011]    Therefore, a need exists for an improved multicomponent application system for delivering low-dose brachytherapy to cancerous tissue in patients.  
         SUMMARY OF THE INVENTION  
         [0012]    The inventive multicomponent vaginal cylinder system for low-dose-rate brachytherapy is ideal for addressing each of these problem areas without compromising the delivery of homogenous radiation dose to treat patients with malignant gynecologic tumors. Utilizing low-dose-rate gynecological brachytherapy, it is physically impossible to combine tandem, vaginal cylinder and ovoids in one implantation attempt to deliver a homogeneous dose to both the ectocervix/vaginal apex along with the remaining lower vagina via a traditional Fletcher-Suit-Delclos applicator system. This is because the typical ovoids have hollow steel handles that extend outside of the patient&#39;s vagina, blocking the insertion of a standard vaginal cylinder. The inventive multicomponent vaginal cylinder system overcomes this drawback, and allows such combined treatment.  
           [0013]    A preferred embodiment of the invention is a multicomponent vaginal cylinder system comprising a tandem configured to house at least one radiation source, a vaginal cylinder structure, and one or more removable ovoid cartridges. The vaginal cylinder structure has a tandem slot into which the tandem can be inserted so as to be slidably engaged with the vaginal cylinder structure, one or more hollow cartridge spaces, and a proximal flared portion constructed and arranged to abut patient tissue. The removable ovoid cartridges are constructed and arranged to house at least one radiation source and to be inserted into the hollow cartridge spaces of the vaginal cylinder structure.  
           [0014]    The tandem slot may be centrally positioned within the vaginal cylinder structure. Once the tandem is inserted into the slot, it may be fixedly engaged by means of a fastener, such as a set screw.  
           [0015]    The removable ovoid cartridges may include generally cylindrical cavities for the storage of radioactive sources. These cavities may be forwardly positioned at proximal ends of the cartridges, and may extend perpendicular to a long axis of the removable ovoid cartridges.  
           [0016]    The hollow cartridge spaces of the vaginal cylinder structure extend parallel to a long axis of the vaginal cylinder structure, and may extend through a substantial portion of the vaginal cylinder structure, generally from openings in a distal surface of the vaginal cylinder structure to an interior wall formed at the origin of the proximal flared portion of the cylinder structure. The removable ovoid cartridges may be fixed within the vaginal cylinder structure by a fastener.  
           [0017]    The vaginal cylinder structure itself may be molded from a biocompatible plastic, and optionally, the biocompatible plastic may be transparent. In general, the vaginal cylinder structure is designed to be disposable.  
           [0018]    The vaginal cylinder structure may also comprise radiation shielding extending over at least a portion of the proximal flared portion. This radiation shielding may be, for example, steel plate constructed and arranged to be attached to the proximal flared portion.  
           [0019]    Another preferred embodiment of the invention is a vaginal cylinder structure having a proximal flared portion; the vaginal cylinder structure comprising a tandem slot extending through the entire length of the vaginal cylinder structure; one or more removable ovoid cartridges capable of housing at least one radiation source; one or more hollow cartridge spaces, each capable of housing an ovoid cartridge; and optionally, removable radiation shielding. The vaginal cylinder structure may comprise a tandem slot centrally positioned within the vaginal cylinder structure. The one or more removable ovoid cartridges may comprise one or more radiation sources. These one or more radiation sources may be forwardly positioned at proximal ends of the removable ovoid cartridges. The vaginal cylinder structure may be molded from a biocompatible plastic, and optionally, a substantially transparent biocompatible plastic. Such plastic vaginal cylinder structures may be disposable.  
           [0020]    A method of treating a gynecological cancer comprising inserting a tandem housing one or more radiation sources into a patient&#39;s vagina such that the tandem extends from a contact point within the patient&#39;s body exteriorly through the patient&#39;s vagina; inserting a vaginal cylinder into the vagina such that the tandem is situated within a tandem slot of the vaginal cylinder structure and the vaginal cylinder structure surrounding the tandem proximally abuts cervical tissue; and inserting one or more ovoid cartridges capable of housing one or more radiation sources into hollow cartridge spaces of the vaginal cylinder structure positioned adjacent to and extending in parallel to the tandem, thereby irradiating targeted tissues to treat a gynecological cancer. The vaginal cylinder may comprise radiation shielding for protecting non-target tissues from irradiation. The shielding may comprise steel-type shielding.  
           [0021]    The method may further comprise afterloading one or more radiation sources into proximal ends of the one or more ovoid cartridges prior to insertion into the hollow cartridge spaces of the vaginal cylinder. The one or more radiation sources may be employed via this method to deliver radiation to at least one target tissue selected from the group consisting of ovarian, vaginal, uterine and cervical tissue. In particular, malignancies of the uterine cervix and endometrium may be treated via the inventive multicomponent vaginal cylinder system. Preferably, the one or more radiation sources comprise Cesium-137. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The invention is illustrated in the following Figures in which  
         [0023]    [0023]FIG. 1 a  is a perspective view of a vaginal cylinder according to the present invention;  
         [0024]    [0024]FIG. 1 b  is a perspective view of a tandem according to the present invention;  
         [0025]    [0025]FIG. 1 c  is a perspective view of a set of ovoid cartridges according to the present invention;  
         [0026]    [0026]FIG. 2 a  is a perspective view of one side of an assembled vaginal cylinder, tandem and ovoid cartridges;  
         [0027]    [0027]FIG. 2 b  is a perspective view of the other side of the assembled vaginal cylinder, tandem and ovoid cartridges;  
         [0028]    [0028]FIG. 3 a  is a schematized perspective view of one side of the assembled tandem and vaginal cylinder, illustrating the various cavities provided for radioactive material;  
         [0029]    [0029]FIG. 3 b  is a schematized perspective view of the other side of the assembled tandem and vaginal cylinder, illustrating the various cavities provided for radioactive material;  
         [0030]    [0030]FIG. 4 a  is a side elevational view of one side of the assembled tandem and vaginal cylinder illustrating the various cavities provided for radioactive material; and  
         [0031]    [0031]FIG. 4 b  is a side elevational view of the other side of the assembled tandem and vaginal cylinder, illustrating the various cavities provided for radioactive material. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    The inventive multicomponent vaginal cylinder system may be composed of at least the following components: a cylinder structure, one or more removable ovoid cartridges, and a tandem. The components can be used individually or combined allowing low dose-rate brachytherapy for cancers of the uterine cervix, endometrium and vagina in either separate or simultaneous modalities. Thus, the vaginal cylinder and its components can be used as an individual unit combined with any standard intra-uterine/cervical/vaginal, intra-uterine/cervical, or intra-vaginal tandem for low-dose-rate brachytherapy of gynecologic cancers.  
         [0033]    As shown in FIGS. 1 a - c,  the inventive multicomponent vaginal cylinder system, generally indicated at  100 , comprises a tandem  110 , a semi-solid vaginal cylinder structure  120  and one or more removable ovoid cartridges  130 . The vaginal cylinder structure  120  is a cylindrical structure having one or more generally ovoid hollow cartridge spaces  122  formed within, each of the hollow cartridge spaces  122  extending in parallel with the long axis of the vaginal cylinder structure  120 . These hollow cartridge spaces  122  extend through a substantial portion of the vaginal cylinder structure  120 , in this embodiment, originating at ovoid openings  126  in the distal surface  128  of the vaginal cylinder structure  120  and terminating at the interior wall  129  formed where the vaginal cylinder structure  120  flares into a proximal flared portion  124 .  
         [0034]    In this embodiment, the vaginal cylinder structure  120  has two hollow cartridge spaces  122  formed therein, each hollow cartridge space  122  offset radially from the central long axis of the vaginal cylinder structure  120 . Ovoid cartridges  130  are designed to be inserted into the hollow cartridge spaces  122 .  
         [0035]    The vaginal cylinder structure  120  also includes a tandem slot  112  formed within. The tandem slot  112  extends along the long axis of vaginal cylinder structure  120  through its entirety, originating at a hole  113  in the distal surface  128  of the vaginal cylinder structure  120  and terminating at a hole  131  in the proximal surface  132  of the vaginal cylinder structure  120 . The tandem slot  112  is configured to house the tandem  110  upon assembly of the multicomponent vaginal cylinder system  100 , as shown in FIGS. 2 a - b.  Preferably, the tandem slot  112  is centrally located within the vaginal cylinder structure  120 .  
         [0036]    The tandem  110  is substantially hollow, permitting insertion therein of radioactive sources  140 , as shown in FIGS. 3 a - b.  Radioactive sources  140  may also be housed within cavities  134  formed in the proximal ends of the ovoid cartridges  130 . These cavities  134  are generally cylindrical, extending inside the ovoid cartridges  130  perpendicular to the long axis of the vaginal cylinder structure  120 , and are designed to hold tubes containing radioactive sources  140 . For example, Cs 137  tubes may be afterloaded into the cavities  134 . In general, any radiation source suitable for brachytherapy may be used in the multicomponent vaginal cylinder system  100 .  
         [0037]    When assembled and properly inserted, the proximal flared portion  124  of the vaginal cylinder structure  120  is designed to abut the ecto-cervix/vaginal apex, thus allowing the cavities  134  containing radioactive sources  140  to abut the ectocervix/vaginal apex. In order to reduce the amount of radiation to which the bladder and rectum are exposed, steel shielding may be positioned over portions of the anterior and posterior aspects of the proximal flared portion  124  of the vaginal cylinder structure  120 . This steel shielding may comprise, for example, steel sheet material contoured to cover a portion of the proximal flared portion  124 . The steel shielding may be removably secured to the proximal flared portion  124  by, for example, a screw inserted through a hole in the steel sheet into a corresponding threaded hole in the proximal flared portion  124  of the vaginal cylinder structure  120 .  
         [0038]    Once the ovoid cartridges  130  have been inserted into the vaginal cylinder structure  120 , they are secured therein by the placement of a screw-on flange over the distal end of the tandem  110 . The tandem  110  itself is secured within the vaginal cylinder structure  120  by a set screw which extends radially through the thickness of the vaginal cylinder structure  120 , contacting the surface of the tandem  110  and fixing it in place. Additionally, a screw-on flange is typically inserted over the proximal end of the tandem  110  to secure the tandem to the vaginal cylinder structure  120 .  
         [0039]    The vaginal cylinder structure  120  may be molded from any material suitable for use in the human body that is also compatible with exposure to radiation. Plastics, such as polystyrene crosslinked with divinylbenzene, are preferred, particularly because they are lightweight and inexpensive. Additionally, it may be desirable to mold the vaginal cylinder structure  120  from a transparent plastic material so as to facilitate the positioning of the vaginal cylinder structure  120  in relation to the tandem  110  during use. Plastic vaginal cylinder structures  120  may be designed for a single use, after which they may be disposed of in an appropriate fashion. The tandem  110  is typically made of stainless steel, or another similar biocompatible metal.  
         [0040]    The vaginal cylinder structure  120  and accompanying ovoid cartridges  130  may be formed in a variety of dimensions to accommodate the vaginal cavities of patients of differing physical size. A preferred dimension of the vaginal cylinder structure  120  is about 15 cm in length, about 3.5 to 4.5 cm in diameter at the proximal end, and about 3 to 4 cm in diameter at the distal end, as shown in FIGS. 4 a - b.    
         [0041]    The invention will be further illustrated in the following example.  
       EXAMPLE  
       [0042]    In a preferred embodiment, after a patient has been administered general anesthesia, use of the inventive multicomponent vaginal cylinder system  100  initiates with the insertion of a tandem  110  into the patient&#39;s uterus. The tandem  110  is positioned to extend from the top or fundus of the uterus to the exterior of the patient&#39;s vagina. The vaginal cylinder structure  120  is then inserted into the vagina such that the tandem  110  is situated within the tandem slot  112  of the vaginal cylinder structure  120 . The vaginal cylinder structure  120  is then advanced until the proximal flared portion  124  of the vaginal cylinder structure  120  abuts the cervix. Once the vaginal cylinder structure  120  is in proper position, it is fixed in relation to the tandem  110  by the set screw.  
         [0043]    After the tandem  110  and vaginal cylinder structure  120  have been positioned properly, radiation sources  140  are loaded into the cavities  134  in the ovoid cartridges  130 . Radiation sources  140  are also be loaded into a plastic transfer tube for insertion into the tandem  110 . The ovoid cartridges  130  are then inserted into the hollow cartridge spaces  122  of the vaginal cylinder structure  120 , and the plastic transfer tube is inserted into the tandem  110 . Finally, a screw-on flange is inserted over the exposed end of the tandem  110  to secure the ovoid cartridges  130 .  
         [0044]    If treatment of the cervix and entire vagina are both required, the proximal portion of the tandem  110  within the vaginal cylinder structure  120  is loaded with an inert material in lieu of active sources to prevent over-dosage at the vaginal apex when the ovoid cartridges  130  are in place. The middle and distal portions of the centralized tandem  110  within the vaginal cylinder structure  120  may be loaded with Cesium-137 to irradiate regions of the vagina associated therewith. When in use, source loading can be varied in any combination for the treatment of the endometrium, cervix, and vagina. The inventive multicomponent vaginal cylinder system  100  assures a homogeneous dose distribution to tissues of interest without the placement of intra-vaginal gauze packing. This is in sharp contrast to traditional stabilization by gauze packing of the conventional ovoid applicators. Due to patient anatomy with respect to tumor or operator error, packing can lead to an undermining of the radiation dose.  
         [0045]    Once the insertion procedure is complete, surgical suture is employed to temporarily ligate the perineum closed to keep the multicomponent vaginal cylinder system  100  in position for the duration of the implant. In addition, medical adhesive tape may be applied to the distal end of the inserted multicomponent vaginal cylinder system  100  and then anchored to the skin of the groin areas in order to further externally stabilize the application system.  
         [0046]    A distinct aspect of this multicomponent vaginal cylinder system  100  is its uniquely designed vaginal cylinder structure  120  with associated ovoid cartridges  130 . This array allows for any specified combinations radiation dose delivery to the cervix the proximal vaginal apex, or both, in conjunction with the more distal regions of the vagina during the same implantation procedure. Thus, the discomfort of a second brachytherapy attempt under general anesthesia and attendant hospital stay, together with the risk of significant morbidity or mortality, is avoided. The invention is unique in this regard, enabling the appropriate delivery of radiation doses in one hospital stay for cancers of the female genital tract without increasing the risk of injury or death of the patient. In addition, the multicomponent vaginal cylinder system  100  may be employed in conjunction with interstitial low-dose-rate brachytherapy of the parametrial tissues.  
         [0047]    While the invention has been described above with respect to certain embodiments thereof, it will be appreciated by one skilled in the art that variations and modifications may be made without departing from the spirit and scope of the invention.