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Details of Grant 

EPSRC Reference: GR/A00539/01
Principal Investigator: Morgan, Professor SP
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Department: Sch of Electrical and Electronic Eng
Organisation: University of Nottingham
Scheme: Advanced Fellowship (Pre-FEC)
Starts: 01 April 2000 Ends: 30 September 2003 Value (£): 92,201
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Summary on Grant Application Form
The aim of this project is to design and optimise a continuous wave (cw) multi-source instrument for imaging and localised spectroscopy of scattering media. The main scattering media under investigation will be biological tissue although the general conclusions will be applicable in numerous other fields such as LIDAR, underwater imaging and food spectroscopy. The major advantages of a cw optical system are that it is relatively inexpensive, the radiation is not harmful to the patient and therefore has the potential for widespread use as a bedside monitoring instrument. The main drawback is that the light is heavily scattering so there is uncertainty in the exact path taken and the volume probed. The system is novel as it combines two instruments into a portable one at no additional cost to provide imaging and spectroscopy over a wide range of scattering' situations. The first mode of operation uses a heterodyne interferometer as a coherent' detection instrument capable of detecting unscattered photons with a high sensitivity. This will provide high resolution images in relatively weakly imaging situations such as imaging fingers for joint disorders or characterisation of tissue samples. When the medium becomes more heavily scattering, such as breast or brain tissue, the instrument can also be used to perform frequency domain imaging and spectroscopy. Recent research has demonstrated that multi-source phased array systems can offer excellent localisation of a single object embedded in a scattering medium. The second mode of the instrument will, in itself, be novel as it will generate two anti-phase sources from a single source to eliminate noise due to uncorrelated amplitude fluctuations. A framework of quantifying system performance using probabilistic detection theory will be applied to fundamental research on the optimum instrument configuration, both in coherent and phased array modes. This method of quantifying detection performance has not previously been applied to any technique in this field so detailed comparisons will be made with other methods such as single beam frequency domain and pulsed laser systems. A quantitative evaluation of system performance could potentially have a huge impact on this field as it will enable (i) setting of optimum detector thresholds and criteria for individual systems, (ii) setting of optimum configurations for different systems, (iii) comparison between systems of different research groups and different techniques, (iv) quantitative evaluation of such instruments in various clinical applications. It is essential to the development and credibility of such instruments that one can determine with what confidence they can be used in clinical diagnosis e.g. a breast tumour has a relatively low contrast compared to healthy breast tissue whereas some functional changes in the brain produce a large increase in blood volume and oxygenation levels near the surface and thus can be detected with greater certainty. The instrument, once optimised, will be used in trials at the University Hospital, Nottingham to determine the best clinical and commercial applications.The construction of the instrument will be complemented by numerical modelling with a spherical harmonics approximation to the transport equation. The main focus of this area of research will be to find the optimum configuration and to solve the problem of more than one inhomogeneity occupying the volume probed. A novel reconstruction algorithm will be developed for phased array imaging which will weight the response in different configurations according to the quantified system performance. This will also be applied to different imaging methods.
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Organisation Website: http://www.nottingham.ac.uk