PhD defence R. (Reza) Pakdaman Zangabad

This thesis investigates several innovative approaches for enhancing ultrasound image resolution and diagnosis and can be subsumed into two main categories: a.) novel transducer architectures and b.) novel imaging techniques.

Intravascular Ultrasound (IVUS) is a well-established technique that uses a catheter-mounted transducer to image the vessel wall and atherosclerotic plaque. It can be used to guide percutaneous coronary intervention (PCI), and it has significant outcomes benefits, such as a 50% reduction in cardiovascular death following PCI. To date, the majority of IVUS transducer technology has been based on piezoelectric materials. The inherent limited bandwidth and sensitivity of piezoelectrics is a major drawback, limiting ultrasound image quality. 
A Capacitive Micromachined Ultrasound Transducer (CMUT) array was discussed in the first approach as a promising alternative to piezoelectric transducers. The advantages of CMUT over piezoelectric technology include a relatively large bandwidth with comparable sensitivity, being lead free, and the ease of large-scale production, all of which reduce the end product cost. This thesis describes the development of an ultrasound system for realizing the first-ever cylindrical CMUT phased array for IVUS imaging. Furthermore, a dual-frequency probe for ultrasound and photoacoustic (PA) imaging of the human carotid arteries was designed. 

The second approach involves a system development using a fast pulsed laser diode and a novel quantitative method based normalized field autocorrelation function of PA field fluctuations to estimate and image the flow velocities.

The PhD defences do not take place publicly in the usual way in the Senate Hall at campus Woudestein or in the Professor Andries Querido Room at the Erasmus MC. The candidates will defend their dissertation either in a small group or online.