Guidance of intracoronary radiation therapy based on dose-volume histograms derived from quantitative intravascular ultrasound

Application of ionizing radiation to prevent restenosis in atherosclerotic vessels treated by balloon angioplasty is a new treatment under investigati on in interventional cardiology and radiology, There is variability in dose prescription, and both gamma- and beta-emitters are used, leading to a wid e range of dose distribution over the arterial vessel wall, We present a ne w modality of dosimetry based on a method that three-dimensional (3-D) imag e reconstruction of electrocardiogram (ECG)-gated intravascular ultrasound (IVUS) images. Dose volume histograms (DVH) are used to describe the cumula tive distribution of dose over two specific volumes: i) at the level of the luminal surface, defined with a thickness of 0.1 mm from the automatically detected contour of the highly echogenic blood-vessel interface, and ii) t he adventitia volume is computed considering a 0.5-mm thickness from the ec hogenic media-adventitia interface, DVH provide a tool for reporting the ac tual delivered dose at the site believed to be the target: the adventitia, and to detect excessive radiation which could lead to vascular complication s, Simulation of a gamma-emitter or of a radioactive source train in the ce nter of the lumen are possible. The data obtained from the first ten patien ts included in the beta-irradiation trial (BERT 1.5) conducted in our insti tution are presented, supporting the use of DVH based on quantitative IVUS measurements for optimal dose prescription in vascular interventional radia tion therapy.