Patent ID: 7056274

Claim:
A catheter assembly providing a radiation treatment in a target tissue of a patient, comprising a balloon arrangement having an outer balloon for containing a radioactive fluid and a coaxially disposed inner displacement balloon that is separately fillable with nonradiofluid fluidically distinct from the radioactive fluid; the inner balloon of a substantial diameter relative to a diameter of the outer balloon whereby upon inflation, the volume in which the radioactive fluid resides within a vicinity of the target tissue is reduced, thereby reducing the amount of radioactive gas required for treatment, and lumens for communicating the radioactive fluid and the nonradioactive fluid from respective supplies to the outer balloon and the inner balloon respectively, whereby, upon inflation of both inner and outer balloons, the outer balloon defines a cylinder of radioactive fluid of limited thickness pressing against an interface of the target tissue at a target site, while conforming well to said interface, wherein an inflation lumen for the outer balloon has a first diameter and an inflation lumen for the inner balloon has a second diameter greater than the first diameter, whereby radioactive fluid in the catheter is reduced relative to the volume of radioactive fluid in the outer balloon while providing for delivery of the nonradioactive fluid to the inner balloon.