BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system and method for delivering medicament, and more specifically this invention relates to radioisotope vehicles and methods for configuring vehicles to optimize in vivo treatment.

2. Background of the Invention

There are a variety of ways to access and treat tissues in vivo. Often, one or a plurality of apertures near the treatment site are made to allow access of surgical instruments, sutures, cauterizers, and the like. Cannulas, associated trocars, wire guides, catheters are all vehicles to access the deep tissue treatment sites for the eventual surgical or brachytherapy follow up.

The smaller the intervention physically, the more adaptable to multiple situations. Attempts have been made to miniaturize instruments, stents, etc., to access narrow passageways (called lumens) such as ducts, arteries and veins, and generally hard to reach structures.

Brachytherapy usually involves the positioning of radioactive materials (packaged into discrete individual seeds) at tumor or vascular locations so as to eradicate or shrink the tumors or positively affect revascularization. Commercially available seeds generally have a central core of liquid or powder enclosed in a titanium shell or other rigid material to filter out undesirable radiations. They are then batched by activity.

Sometimes these tumor locations are accessed surgically or endoscopically near the surface (or exposed sites). Other times a large bore injection needle or catheter or other access device is required to position the radio isotopes into hard to reach areas such as hollowed out vertebrae, the esophagus, small diameter ducts and other situations where direct surgical access is unavailable without causing collateral damage from either external beam radiation or surgical intervention. For example, needles are often relied upon to access the interiors of vertebra for kyphoplasty treatment. Typical needles used for such injections are about 14 gauge diameters. This is because needle bore sizes having an inner diameter of approximately 1.6 mm) are required inasmuch as the smallest radio-isotope seeds have a cross sectional diameter of about 0.8 mm.

State of the art brachytherapy stents and devices are only slightly smaller, with the limiting factor being the size of the radioisotope seeds utilized for treatment. That the seeds have to be a certain size to provide an effective therapeutic dose combined with the fact that seeds are typically not manufactured smaller than 0.8 mm in diameter means that brachytherapy vehicles are too bulky to access small diameter lumens.

Brachytherapy, particularly with very low energy sources has the advantage of minimizing collateral radiation but is very sensitive to optimal seed placement. Either too high a dose or too low may have unfortunate outcomes. Higher doses (e.g. delivered to the tissues adjacent to the sources) have been necessary to deliver a cancerocidal dose to the tumor but this may lead to hemorrhage ulceration fistulization, etc.

Strategies useful to decrease this gradient include the following:increasing the number of radioactive seeds;filtration of the radiation emanating from the closest sources;padding (i.e., increases the distance between radiation sources and sensitive tissues);increasing the radioactive source energy but while also minimizing exposure of healthy tissues;increasing the distance between radiation sources and sensitive tissues; andusing liquid isotopes. This use approaches an equivalence of an infinite number of sources while also increasing dose homogeneity.

Additionally, radiation oncologists are most comfortable if an homogenous radiation dose distribution is achieved.

A need exists in the art for a system and method for treating deep seated neoplasms. The system and method should be capable of delivering medicaments through small pores. Also, the system and method could incorporate shielding to prevent in situ over exposure of tissue to radiation. The system and method should be inserted and removed with general surgical tools or medical instruments, and by medical personnel typically familiar with those tools, such as surgeons, pulmonologists, radiologists, radiation oncologists, gastroenterolgists, physician assistants, and surgical nurses.

SUMMARY OF INVENTION

An object of the invention is to provide a system and method for conducting brachytherapy that overcomes many of the drawbacks of the prior art.

Another object of the invention is to provide a system and method for positioning medicament in deep seated tissue sites. A feature of the invention is utilization of fluid-phase medicament encapsulated in reversibly deformable material. An advantage of the invention is that the size, such as the cross diameter, of the deformable vehicle could be minimized. Another advantage is that the vehicle replaces the shielding inherent in solid radioactive seeds.

Still another object of the invention is to provide a system and method for enabling in vivo positioning of radioisotopes in brachytherapy. A feature of the invention is encapsulating free flowing liquid-phase radioisotopes within a solid phase vehicle having semi-radio-opaque characteristics. An advantage of the invention is that the vehicle may be reversibly inserted into heretofore inaccessible tissue sites, such as very narrow ducts, collapsed vertebrae, cavities, surgical sites, and other lumens. Another advantage is that liquid isotopes makes smaller preloaded catheter ribbons, rectangles, triangles, semicircular, and other shaped delivery vehicles feasible.

Briefly, the invention provides a method for delivering and positioning radio-isotopes into the body, the method comprising encapsulating free flowing radio-isotope into a leak proof vehicle; and positioning the vehicle into the body. The step of positioning the vehicle in the body comprises inserting the vehicle into the body via syringe, needles, trocars, endoscopic instruments, interventional radiology techniques, and combinations thereof. The use of liquid or otherwise fluidized isotopes is a means for providing the effect of an unlimited number of radiation sources, thereby improving the dose homogeneity while simultaneously decreasing maximal surface dose.

Also provided is a system for delivering and positioning radio-isotopes into the body, the system comprising fluid radio-isotope encapsulated in a leak proof material.

