In this paper, we present a method for the automated detection of lumen and media-adventitia border in sequential intravascular ultrasound (IVUS) frames. The method is based on the use of deformable models. The energy function is appropriately modified and minimized using a Hopfield neural network. Proper modifications in the definition of the bias of the neurons have been introduced to incorporate image characteristics. A simulated annealing scheme is included to ensure convergence at a global minimum. The method overcomes distortions in the expected image pattern, due to the presence of calcium, employing a specialized structure of the neural network and boundary correction schemas which are based on a priori knowledge about the vessel geometry. The proposed method is evaluated using sequences of IVUS frames from 18 arterial segments, some of them indicating calcified regions. The obtained results demonstrate that our method is statistically accurate, reproducible, and capable to identify the regions of interest in sequences of IVUS frames.

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Endovascular brachytherapy (EVBT) is an established treatment to reduce the probability of restenosis after a percutaneous coronary intervention. The purpose of this study was to assess (1) the manufacturer's stated dosimetric data for (90)Sr/(90)Y source trains to be used in EVBT and (2) the procedure-related radiation burden. The radiation fields in water around six (90)Sr/(90)Y source trains were studied using phantoms made of 'solid water' and MD55-2 radiochromic films. The water equivalence of the phantom material was tested by applying quantitative computed tomography. Thermoluminescence dosemeters were used to assess personal radiation burden and crosscheck the dose distribution along the source trains. Technical failure was observed in one source train and this train was excluded from analysis. The measured dose rate in water at 2 mm radial distance was on average 8% higher than the manufacture's stated value (range of measured to stated values 1.05--1.15). The dose rate decreased exponentially with radial distance between 2 and 6 mm. The dose rate in contact with the source viewing window of the delivery devices ranged between 0.5 and 7.5 mGy h(-1). Low-energy photons were the main contributors to personal dose.

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