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Background-Ionizing radiation administered intraluminally via catheter-based systems using solid ␤ and ␥ sources or liquid-filled balloons has shown reduction in the neointima formation after injury in the porcine model. We propose a novel system that uses a 133-Xenon ( 133 Xe) radioactive gas-filled balloon catheter system. Methods and Results-Overstretch balloon injury was performed in the coronary arteries of 33 domestic pigs. A novel 133 Xe radioactive gas-filled balloon (3.5/45 mm) was positioned to overlap the injured segment with margins. After vacuum was obtained in the balloon catheter, Ϸ2.5 cc of 133 Xe gas was injected to fill the balloon. Doses of 0, 7.5, 15, and 30 Gy were delivered to a distance of 0.25 mm from the balloon surface. The dwell time ranged from 1.0 to 4.0 minutes, depending on the dose. Localization of 133 Xe in the balloon was verified by a ␥ camera. The average activity in a 3.5/45-mm balloon was measured at 67.7Ϯ12.1 mCi, and the total diffusion loss of the injected dose was 0.26% per minute of the injected dose. Bedside radiation exposure measured between 2 and 6 mR/h, and the shallow dose equivalent was calculated as 0.

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