Study On Dosimetry Of Intravascular Brachytherapy For Restenosis Of Coronary Artery

Coronary artery disease is the leading cause of morbidity and mortality all over the world. Over 1, 000, 000 patients undergo percutaneous transluminal coronary angioplasty annually. Although major complication from angioplasty occurs in only l%-2% of patients, angiographically diagnosed restenosis occurs in 35%-40% of patients within six months. Coronary stent placement in conjunction with angioplasty can reduce the restenosis rate to 22%-32%. Restenosis is the major drawback of angioplasty. In attempt to reduce the rate of restenosis, researchers have made a variety of separate trials evaluating a range of pharmacologic and other method, the intracoronary brachytherapy is the only method shown to be effective I reducing the incidence of restenosis. Both in vitro and animal studies, and more recently early clinical studies, have provided evidence that intravascular brachytherapy by beta- or gamma-emitting isotopes can inhibit proliferation and there help to prevent restenosis after angioplasty. Delivery of the radionuclides into coronary artery is achieved through radioactive stent, radioactive liquid-filled balloon and catheter-based systems of seeds or wires.In intravascular brachytherapy, the entire lesion may be 1-3mm in thickness. However, dosimetry at distances of the order of a millimeter from radioactive source is poorly known. To understand the results of various preclinical and animal studies using a variety of radionuclides and delivery systems, it is essential to determine the dosimetry in the millimeter range. A better understanding of dosimetry in the millimeter range will help the development of optimum clinical devices and their efficacious use in different institutions using different radionuclides and devices.This work investigated the dosimetry in vascular tissue and studied some questions that would happen in clinical application, which included effect for dose of both air bubble in balloon and radioactive liquid in catheter while using radioactive liquid-filled balloon, and source not-centering on catheter and source...