FIELD OF INVENTION:

The present invention relates to a medical device useful for brachytherapy, more particularly to a device used along with the Fletcher suit applicator in the treatment of cervical cancers.

BACKGROUND OF THE INVENTION:

Radiotherapy is widely used for the eradication of cancer. Cancer of the uterine cervix is the second common cancer in India. A common approach to the treatment of this cancer is by combining the two main modalities coming under radiotherapy viz, teletherapy and brachytherapy in combination with or without chemotherapy or surgery. The frequency and severity of complications in the treatment of cervical cancer have been correlated with the intracavitary-plus-external-beam dose to the bladder and rectum (Montana, et al., 1989, Int. J. Radiol. Oncol. Biol. Phys., 16:95-100, Perez, et al., 1984, Cancer, 54:235- 246, Pourquier, et al., 1982, Int. J. Radiol. Oncol. Biol. Phys., 8:1887-1895, Stockbine, et al., 1970, Am. J. Roentgenol., 108:293-304)

Brachytherapy involves directly implanting a radioactive source within or near to the tumors thereby delivering a high-localised radiation and minimizing the dose to the surrounding structures. Brachytherapy can be classified into four - mould, interstitial, intracavitary and intraluminal. The radioactive sources (tubes or needles) in the order of mi Hi curies are arranged on a tissue equivalent material such as wax according to certain rules and placed on the surface of tumor over a period of 6 to 7 days for delivering a dose of around 60 to 65 Gy. This type of treatment is called mould therapy. If these sources are arranged into the tumor, it is called interstitial implantation.

In intracavitary implantation, the radioactive sources can be placed inside the natural cavities of human body using specially devised applicators thereby one can deliver the required amount of dose. This can be done in different ways. One such way is keeping the applicator inside the cavity and placing the radioactive source manually inside the applicator. This procedure is called manual after loading. The main disadvantage is that the person associated with this procedure is exposed to higher amount of dose. But the use of remotely operated machines (remote after loaders) that will drive the sources into the applicator by its own when it is activated can eliminate the dose to the associated person.

The main aim of brachytherapy for cancer of the uterine cervix is to provide maximum dose to the tumor while delivering very low dose to the rectum and bladder. There are several methods available for the reduction of rectal and bladder doses due to brachytherapy. One way is to use a rectal retractor for keeping the rectum away from the radioactive source. Specially shielded colpostats are used for the reduction of rectum and bladder dose. If displaced, the shielding not only fails to diminish exposure of healthy tissues but also may obstruct exposure of targeted proliferative tissues. But use of any one of these will restrict the information content from the radiographic films taken for dosimetric purpose as its radiographic shadow completely shields the lower part of the applicator.

Overcoming this, special types of applicators are designed by different scientists with a single aim of delivering the required amount of dose in a desired fashion. The Fletcher- Suit applicator is one among them, which is commonly used for the treatment of this cancer. This has three parts- intrauterine tube (IU), which directly goes into the uterus and two ovoids; ovoid 1 and ovoid 2, which sit inside the vaginal cavity. IU tubes of various length and angulations and ovoids of different diameters are available to meet the anatomical variations from patient to patient (Delclos, et al., 1980, Int. J. Radiol. Oncol. Biol. Phys., 6:1195-1206, Fletcher, 1953). In the Fletcher system, it is preferable to separate the ovoids as far as possible while maintaining their position as close to the vaginal apex as possible. Once satisfied with the separation, the physician utilizes a locking screw to hold the separation after manual release of the colpostats. The largest possible colpostat diameter is usually employed to improve the tumor-to-normal structure dose ratio. A planned irradiation through these tubes provides a pear shaped dose distribution, which should encompass the tumor completely. Variations of the Fletcher- Suit applicator for intrauterine brachytherapy have evolved from its original form.

Further improvements have been instituted over the years, Fletcher tandem device provides shielding for protection of untargeted tissues for example, U.S. Pat. No. 5,562,594 to Weeks. Based on the dose rate, at the point of prescription one can classify brachytherapy into low dose rate (40cGy/hr to 2Gy/hr), medium dose rate (2 to 12 Gy/hr) and high dose rate (>12Gy/hr) brachytherapy. The low dose rate technique has proved its efficiency in the eradication of tumor by reduced normal tissue complications and high local cure with a disadvantage of having prolonged treatment time for the delivery of a desired amount of dose. Moreover, the stability of the applicator position cannot be maintained throughout the treatment. Using high dose rate technique the desired amount of dose can be delivered at the point of prescription in a short time that would reduce the patient inconvenience due to the prolonged confinement in bed as against in LDR but with higher positional accuracy of the applicator. In addition to this, prolonged procedures result in patient aggravation, inconvenience, and discomfort while also significantly increasing treatment costs attributable to extended hospitalization, all without any significant augmentation in efficacy. Several studies have proved that high dose rate brachytherapy is able to provide clinical results on par with or even better than LDR. High dose rate brachytherapy now becomes the most widely used treatment for cancer of the uterine cervix.

In most of the cancer hospitals in developing countries, the conventional method of delivery of radiation by brachytherapy for uterine cancer, is to keep the IU tube of the applicator into the intrauterine after locating and dilating it, and then keep the two ovoids-one on the right side and the other on the left side inside the vaginal cavity. Packing is done using wet cotton above and below the applicator both for increasing the separation between the critical tissues and the applicator and for immobilization of the applicator. All these are done with patient under sedation. The packing procedure especially causes a lot of pain and discomfort to the patient. On radiographic verification if the packing is found to be inadequate once again the whole procedure has to be repeated and this will cause additional discomfort and loss of precious time of the associated staff that can otherwise be utilized for other patients. Moreover the amount of packing using wet gauze piece may not be uniform in the successive treatments which can affect the reproducibility of the treatment.

Further, it is generally believed that a modified Fletcher-Suit tandem tube applicator as described in U.S. Pat. No. 6,699,171 provides an inflatable balloon for protecting untargeted tissues. The balloon expands only radially and it is not possible to use the balloon with all types of cervical applicator. The balloon is to be bonded on the applicator before use and after treatment it has to be removed. Moreover, pre-determined planning for dose reduction of bladder or rectum is needed and it is not a ready to use device. This leads to patient's discomfort along with consumption of more time and labour.

Further, the balloon brachytherapy applicator as described U.S. Pat. No. 7,771,340 is used to move sensitive tissue farther away from a radiation source in the breast cancer treatment, but these balloons cannot be used with applicators of cervical cancer treatment.

The present invention is a modification of the original application that was published on September 14, 2007 by the same applicant. This original application 857/CHE/2006 discloses a novel twin rubber bag device for brachytherapy of the uterine cervix.

In order to make brachytherapy especially for cervical cancer treatment available to more patients while protecting the untargeted areas from being affected from radiation, the present invention uses a modified inflatable spacer balloon device applicable for use with any Fletcher Suit applicator. The present invention overcomes the above disadvantages and also it takes less time and reduces patient's pain and inconvenience or discomfort during the treatment.

SUMMARY OF THE INVENTION

The present invention relates to a rubberized spacer balloon device used along with the Fletcher-Suit applicator. The device can expand independently as and when required by injecting radiation attenuating solutions. This device is used to increase the distance between the radioactive source and the critical organs-rectum and/or bladder and positionally stabilize the applicator within the patient.

The new improved design for spacer balloon device has two parts or sacs called B-part and R-part which surround the applicator. When the two parts are connected, a hole is made through which the ovoid-IU applicator passes. The thickness of balloon is made in such a way that the part of the balloon against the critical organs expands more. The device is also provided with a narrow tube that extends out. The tube attached with a one way valve prevents air/liquid from escaping and helps to adjust the pressure of the air/liquid maintained inside. The two sacs are filled with air or liquid (radiation attenuation) to different levels depending upon patient's convenience during the treatment process. The one-way valve is used for adjusting the size of the sacs.

The device of the present invention is used in brachytherapy, especially for treating cervical cancer. The device is transparent which adds to the visualization during the treatment. The device reduces the pain and discomfort caused by usual cotton packing to the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a spacer balloon device for cervical radiation purposes

DETAILED DESCRIPTION OF THE INVENTION:

The present invention relates in general to the field of brachytherapy and in particular, includes the design and method of production of a rubberized spacer balloon used along with the Fletcher suit applicator. The spacer balloon can expand independently when required with radiation attenuating solutions. This increases the distance between the radioactive source and the critical organs like rectum and/or bladder and positionally stabilize the applicator within the patient.

FIG. 1 shows the rubberized spacer balloon device. According to FIG. 1, B represents the bladder part (a) and R represents the rectal part (b).

B-part sits on the applicator in contact with the anterior part of the vagina and the lower part called the R-part sits below the applicator in contact with the posterior part of the rectal wall.

One complete side and half portion of B (al & a2) and that of R (bl & b2) are made thicker. The thickness of thin part varies from 1-0.4 mm and that of thicker region varies froml .2-2mm. In both B and R part of the balloon, the sides in contact with the applicator are made much thicker than the other parts so that the expansion towards the applicator side is minimum and hence it sits comfortably on the applicator. The other side of B part of the balloon against the anterior part of the vagina has a varying thickness so that the expansion of the balloon pushes bladder part only. Similarly, another part(R) of the balloon in contact with the rectal wall has a varying thickness so that the expansion of the balloon pushes the rectal wall only.

Width of the B or R part is determined by the width of the applicator set in position with a particular ovoid. For a medium ovoid-IU applicator combination, the maximum width is taken as nearly 60mm and the width tapers to a width of 20mm towards the joining part (c) of B and R part. From the centre of the B-part to the other end, the width reduces to 5mm and it extends to a length of 200mm as a tube of diameter 5mm (d and e). At the extreme end of the tube a one-way valve (g and f) is attached. The total length of the B or R part is again depending on the total projection length of the ovoid part.

At the centre of the joining part (c) a hole of 5mm diameter is made through which the IU passes. The C-part is having slightly higher thickness which varies from 1.5 to 2.5mm. The total width of the joining part is 20mm equal to the diameter of the flange.

Each B or R part of the device is provided with a narrow tube that extends out of the vaginal wall. The one-way valve at the end of the tube prevents any outflow of fluid pushed in. A graduated syringe can be used for pushing a known volume of fluid into it. On expanding the B or R part of the balloon, the separation between the radioactive sources and tissue gets increased thereby reducing the unwanted dose to the critical structures. The tendency of the fluid contained in an elastic container to expand towards the low-pressure area can also be utilized to keep the applicator in position by pushing from the lower inferior part of the applicator. Hence a secure position of the applicator (immobilization) and a drastic reduction in dose due to combined effect of reduction in intensity of radiation owing to its inverse square law dependence and that of attenuation by a medium (fluid) can be achieved by using this device along with the already available standard Fletcher-Suit applicator.

The spacer balloon device are inflatable in nature and made with extra pure double- centrifuged natural rubber latex which is free of coagulants, powder and lubricated with silicone oil. The other materials used for making the rubber latex are any other synthetic lattices of styrene-butadiene copolymers, acrylonitrile-butadiene copolymer, vinyl acetate polymers and coplymers, polyacrylate and polymethacrylate esters, vinyl chloride- vinylidene chloride copolymers etc., and artificial lattices of isobutene-isoprene rubbers, synthetic cis-1, 4-polyisoprene rubbers, reclaimed rubbers, polyurethane polymers, artificial lattices and lattices of other polymers. In another aspect of the invention, other natural and synthetic dry rubber formulations and processing methods can also be used for making the device.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.

WE CLAIM:

1. An inflatable spacer balloon device useful for brachytherapy along with a cervical applicator comprising:

a) an inflatable upper balloon to be kept in the intravaginal portion constituting the anterior bladder part 'B' and

b) a lower balloon to be kept in the intravaginal portion consisting of posterior rectal part 'R'.

2. A spacer balloon device as claimed in 1, wherein the two sacs surround the applicator.

3. A spacer balloon device as claimed in 1, where the thickness of said balloon is made in such a way that the part of the said balloon against the critical organs expands more. The other part of said balloon expands less which will lead to patient comfort.

4. A spacer balloon device as claimed in 1, where the said sacs are inflatable made with extra pure double-centrifuged natural rubber latex and free of coagulants, powder and lubricated with silicone oil; wherein the said rubber latex used for making the device may also be from any other synthetic lattices of styrene-butadiene copolymers, acrylonitrile-butadiene copolymer, vinyl acetate polymers and coplymers, polyacrylate and polymethacrylate esters, vinyl chloride-vinylidene chloride copolymers etc., and artificial lattices of isobutene-isoprene rubbers, synthetic cis-1, 4-polyisoprene rubbers, reclaimed rubbers, polyurethane polymers, artificial lattices and lattices of other polymers; other natural and synthetic dry rubber formulations and processing methods can also be used.

5. The method of using the spacer balloon device according to claim 1, includes the steps of introducing the said rubber balloons into the patient's vagina, inflating the said sacs with the radiation attenuating fluid and introducing the radiation source/probe through the hole at the joining portion of the balloons.

6. The method of claim 5, wherein the said rubber balloons surrounding the ovoids can be independently positioned

7. A brachytherapy method comprising:

insertion of an applicator through the central hole at the joining portion of the spacer balloon of a length sufficient to project intracervically where the said rubber sacs are positional within the vaginal canal. Inflating the said balloons with a radiation attenuating fluid where said balloons expand against the walls of the vaginal canal urging the vaginal canal away from the tube.

8. The method of claim 7 comprises of balloons, which could be filled with air or liquid to different levels depending upon patient's convenience during the process.

9. The method of claim 8, wherein the said balloon has attached rubber tubes with one way valve which prevents air/liquid from escaping and helps adjust the pressure of the air/liquid maintained inside.

10. The method of claim 5, where the said rubber balloons are joined using latex adhesive and the joined portion is provided with a hole for the passage of applicator.

11. The method of claim 5, where the joined portion of the said balloon is having a higher thickness (1.5mm to 2.5mm) which helps to keep the said balloon in position while expansion