PhD Studentship in “Inverse Problems in Ultrasound Computed Tomography of the Breast”

University College London - The Department of Medical Physics & Biomedical Engineering and the Department of Computer Science

The Department of Medical Physics & Biomedical Engineering and Department of Computer Science at UCL is inviting applications for two studentships in the area of “Inverse Problems in Ultrasound Computed Tomography of the Breast”

Studentship Description

We are seeking two highly motivated students for PhD studentships in the rapidly developing field of advanced Inverse Problems in Ultrasound Computed Tomography of the Breast.

Ultrasound has been used for clinical diagnostic imaging for decades. Most commonly, ultrasound scanners provide 2D planar images through tissue in real time. However, 3D ultrasound computed tomography (USCT) is also possible, and can offer superior image characteristics for some applications, eg. breast imaging. Ultrasonic waves are usually detected using an array of transducers that exploit the piezoelectric effect, but recently, novel acoustic detectors that exploit the pyroelectric effect have been developed at the UK's National Physical Laboratory (NPL). They have also conducted a proof of principle study successfully demonstrating USCT of the breast using these devices. This raises a number of theoretical and practical questions, for example, about the extent to which the pyroelectric data complements the piezoelectric data, about what advantages it offers to the reconstruction of 3D images of breast soft tissue, and about how best to both acquire the data and reconstruct the images. During these two studentships, the students will explore these issues mathematically and using numerical acoustic models, and they will develop reconstruction algorithms for use with data measured at NPL.

This project, funded by the National Physical Laboratory (NPL), seeks two students to investigate 3D ultrasound computed tomography of the breast using novel pyroelectric detectors developed at NPL. Theoretical, computational, and engineering aspects of the design and implementation of a practical imaging technique will be studied. The project will interest Physics, Applied Mathematics or Engineering students with a strong knowledge in developing all aspects of imaging science and experimental design.

Work to be undertaken in the course of this project:

There are several directions that the research could take, depending on the student's interests. One direction might be to focus on the theoretical aspects of USCT with a view to improved experimental design. For example, one aim might be to determine the amount and type of data that is required for an inversion for sound speed, attenuation, and density to be unique. In other words, the question of whether certain combinations or possible arrangements of the pyroelectric and piezoelectric detectors lead to a better-posed inversion than others, and indeed whether and when these parameters can be separated. There is also the related question of what the minimum amount of data is that will still result in accurate images, and whether sparsity or compressive sensing techniques could be used to advantage to reduce data acquisition time without affecting image quality. Another aim might be to see if there are aspects of the inversion that can be performed analytically, or investigate which numerical techniques are best suited to performing the inversion efficiently. Adjoint models to the forward models of acoustic propagation and detection could be derived, for instance. Another direction might be to concentrate on the development of realistic 3D computational breast tissue phantom with realistic ultrasonic properties and heterogeneity, or numerical models of the ultrasound sources the responses of the pyroelectric and piezoelectric detectors. Also, while full-wave models of ultrasound propagation exists (eg. www.k-wave.org or FEM/BEM solvers) they may be too computationally intensive in practice, and reconstruction using more efficient but approximate ray-based methods might need to be explored.

One of the successful candidates will be based primarily in Centre for Medical Image Computing in the Department of Computer Science, and the other primarily in Biomedical Ultrasound Group in the Department of Medical Physics and Biomedical Engineering.

Person Specification

Funding will be for 3 years, with a tax free stipend of £16,553 per year plus UK/EU-level university fees. Outstanding students from outside the EU may apply if they have funding to support international fees. The closing date is 15th September 2017 and the anticipated start date is October 2017.

Applicants must have or expect to obtain, a UK first class or 2:1 honours degree or the international equivalent in the appropriate area of physical science

Applicants must be UK students or EU students who will have spent the previous 3 years in the UK.

Clear interest in medical physics. Well-developed experimental skills. Sufficient level of mathematics and numerical skills. Creative and critical thinking. Excellent writing and oral communication skills. Self-management and good working habits. Capability to work independently and used to take initiative and Programming skills are desirable

Eligibility

If you have any scientific queries please contact Professor Simon Arridge (Computer Science) s.arridge@ucl.ac.uk or Dr Ben Cox (Medical Physics) b.cox@ucl.ac.uk

Applications (including a covering letter, CV and names of two referees) should be sent to

Miss Mohini Nair (m.nair@ucl.ac.uk) Medical Physics and Bioengineering, and Miss Sarah Turnbull (s.turnbull@ucl.ac.uk) Department of Computer Science we will also be happy to handle any informal enquiries

Further information on the research and the research groups available at:

https://bug.medphys.ucl.ac.uk/

www.ucl.ac.uk/medical-image-computing

http://www.npl.co.uk/news/ultrasound-breast-imaging-system-shortlisted-for-engineering-award