A
catheter assembly for use in
radiation therapy of a patient by
insertion into a vessel, passageway or cavity to deliver radioactive material to a treatment site within the patient. The distal end of the
catheter assembly (10) includes a noncompliant inner
balloon (18) therearound that is
inflatable with a non-radioactive fluid (such as CO2 or
saline or
contrast medium), and an outer
balloon (16) therearound that is inflated with radioactive fluid (such as radiogas like
xenon-133 ) and is noncompliant to conform the vessel wall to the
balloon's shape at the treatment site for optimal distribution of
dose. The inner balloon allows reduction in volume of the amount of radioactive fluid necessary to achieve a desired
dose. The inner and outer balloons (112,108) may be affixed to inner and outer catheters (104,102), respectively. Further, a booster
radioactive source, preferably removable from the
catheter, may also be used to supplement the
dose from the outer balloon, such as a radioactive
line source (a wire or a seed
train (118,234)) within the
central catheter lumen (116,230) at the distal end, or a plurality of seeds (320) within flexible cylinders (318) spaced circumferentially around the inner balloon (308) but within the outer balloon (310), or a sleeve (402) around the inner balloon (406) that may be impregnated with
iodine-125. A method of providing
radiation therapy is disclosed.