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Medical physics applications



Latest research results for 2008

Research results for 2007

The BIAS group at the University of Edinburgh Medical Physics are following two tracks of research, experimental and theoretical in the form of computer modelling.

Much of our experimental activities centre on our test rig which consists of XY stepper motor driven stages mounted over a water tank.

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Experimental test rig for characterising transducers, testing/evaluating transmission signals and scanning phantoms etc











Ultrasonic transducers used with the test rig




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This image shows some of the transducers used in the experimental rig. All are single element and cover a range of diameters, beam profiles and frequencies

The University of Leeds group supplied a database of bat signals to assist in the understanding of bats and their capabilities. We have developed custom software to analyse these signals. The screen shot below is of a “bat signal data base browser”. This tool was developed to allow investigation of the main features of each bat signal type in the database.



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The bat signal browser makes easy work of searching through a data base of bat signals.
It allows the user to readily gain information about the nature of each chirp, both in frequency and in time.

Ultrasonic contrast agents consisting of micron sized encapsulated gas bubbles are the subject of much research both for image enhancement and for use as drug delivery agents. One of the main areas of research in this field is to develop methods to enhance the contrast effect by using specifically designed transmission signals. This fits well within the BIAS project as both bats and dolphins modulate their signals to suit the task or environment.

Here in Edinburgh we have a unique in vitro system which enables us to analyse the echoes from single microbubbles. This allows us to gain greater insight into how they oscillate when in an acoustic field, and therefore to exploit the nonlinearities produced. Using this knowledge it becomes possible to increase the contrast-to-tissue ratio when used clinically. Bubble responses from various types of pulses and pulses sequences similar to those used by bats (linear frequency chirps for example), are investigated to evaluate their potential for improving diagnostic techniques.

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Experimental in-vitro system used to probe the signals from single microbubbles

We use a combination of theoretical simulations and real experimental data to interrogate the response of contrast agents to pulse sequences, in order to identify any possible improvements that can be made. These improvements may be achieved through either changes in the nature of the transmitted ultrasound signals that are used to excite the microbubbles, or in the signal-processing techniques used to create the image for diagnosis, or a combination of the two

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A bubble signal and its time-frequency analysis, in response to a typical clinical imaging pulse.

As part of our out-reach activities, Dr. Michael Bennett (pictured) has developed and run a science communication show called 'Seeing with Sound' in connection with National Museums Scotland. This picture shows the use of a slinky spring to demonstrate the principles of how sound propagates through the air. Dr. Bennett has run this show twice at the Royal Museum in Edinburgh and was invited to talk at London Zoo in April 2007.

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Young visitors to the museum learn the basics of sounds waves in a presentation on how animals use sound for communication and hunting at the Royal Museum of Edinburgh.