Design and dosimetry of a novel Y-90 beta source to prevent restenosis after angioplasty

Purpose: Post-dilatation irradiation of the vessel wall is currently under investigation for prevention of restenosis after balloon dilatation, For th e irradiation, special sources were designed for animal experiments which w ould give equivalent irradiation conditions and doses to the vessel wall th at would later be employed for human application. Methods and Materials: For the planned irradiations, a specially designed y ttrium-wire of 0.45-mm diameter coated with a thin shrink tube to prevent c ontamination was deployed. Several leakage tests applied before and after a pplication proved that the irradiation source was leakproof. Dosimetry was performed by using 0.1-mm-thick thermoluminescent dosimeters (TLD-100) cali brated against a primary standard. A shielding transport and application co ntainer was designed to facilitate the handling of the source during use, w hile reducing exposure of the medical personnel. Results: The designed source proves to be flexible for the insertion into p roximal coronary vessels, and positioning at the site of stenosis, It provi des an optimum protection of the animal and requires little radiation prote ction efforts on behalf of the medical staff. Dosimetric calculations and m easurements showed that a centering of the source inside the vessel could b e achieved with a maximum deviation of 50% between maximum and average dose levels. Conclusion: A yttrium-90 beta brachytherapy source was designed which provi des high flexibility within proximal coronary arteries, ensures an adequate centering inside the artery, and provides irradiation conditions to the ve ssel wall of the experimental animal comparable to the application inside a human artery. (C) 2000 Elsevier Science Inc.