title: Radioactive 133-Xenon gas-filled balloon to prevent restenosis: dosimetry, efficacy, and safety considerations.
abstract: BACKGROUND
  Ionizing radiation administered intraluminally via catheter-based systems using solid beta and gamma 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 (133Xe) radioactive gas-filled balloon catheter system.
  
  
  RESULTS
  Overstretch balloon injury was performed in the coronary arteries of 33 domestic pigs. A novel 133Xe 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, approximately 2.5 cc of 133Xe 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 133Xe in the balloon was verified by a gamma camera. The average activity in a 3.5/45-mm balloon was measured at 67.7+/-12.1 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 0.037 mrem per treatment. Histomorphometric analysis at 2 weeks showed inhibition of the intimal area (intimal area corrected for medial fracture length [IA/FL]) in the irradiated segments of 0.26+/-0.08 with 30 Gy, 0.07+/-0.24 with 15 Gy, and 0.12+/-0.89 with 7.5 Gy versus 0.76+/-0.08 with control P<0.001.
  
  
  CONCLUSIONS
  133Xe gas-filled balloon is feasible and effective in the reduction of neointima formation in the porcine model and safe for use in coronary arteries.
authors.affiliation: Parkview Radiation Oncology Center, Fort Wayne, Ind, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Apple
authors.forename: Ron
authors.initials: R
authors.lastname: Waksman
authors.forename: Rosanna C
authors.initials: RC
authors.lastname: Chan
authors.forename: Yoram
authors.initials: Y
authors.lastname: Vodovotz
authors.forename: Jana
authors.initials: J
authors.lastname: Fournadjiev
authors.forename: Bill G
authors.initials: BG
authors.lastname: Bass
mesh_terms: D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000379:methods*; D000818:Animals; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D023903:Coronary Restenosis / Q000473:pathology / Q000517:prevention & control*; D004307:Dose-Response Relationship, Radiation; D005740:Gases / Q000627:therapeutic use; D011829:Radiation Dosage; D013552:Swine; D014980:Xenon Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D005740:Gases; D014980:Xenon Radioisotopes