HEXITEC: Translation grant. The application of colour X-ray imaging

X-ray colour imaging has the potential to visualise the physical and chemical nature of a specimen spatially resolved within a three dimensional density contrast image. X-ray colour imaging makes it possible to recognise, for example, whether complex manufactured components used in the aerospace industry are likely to fail through cracks or fatigue stress; or whether a suitcase contains illicit substances such as semtex or cocaine; or whether a biopsy sample contains normal or abnormal tissue. A full X-ray colour imaging system requires energy sensitive detectors that are divided into small discrete pixels and can stop high energy X-rays. In addition the scattered radiation from the sample often has to be very finely collimated because we are looking for very weak signals. Five years ago neither suitable detector material nor scatter control systems were available. The latter problem was addressed (by another EPSRC grant) but there was no reliable source of detector material anywhere in the world. The lack of technological expertise within the UK to produce suitable detector systems led to the formation of the HEXITEC consortium (High Energy X-ray Imaging Technology; www.hexitec.co.uk). HEXITEC has developed every stage of detector system manufacture and has very recently demonstrated its first 20 by 20 pixel prototype as a forerunner of a full 80 by 80 device that will be delivered early in 2010. We are now requesting funds to take the HEXITEC developed technology to the next stage of development in three work programmes covering four broad applications at different stages of development. Work package 1: Fluorescence tomography for materials imaging We will use the 80 by 80 pixel detector systems developed by HEXITEC for both purposes. Fluorescence tomography is based on a standard absorptive method where the sample is rotated in the beam and many sections are mathematically recombined to give a 3D image. The crucial difference here is that we will be able to do this in discreet energy ranges. We will obtain slices that can be energy selected in 800eV ranges or better. We will deliver a lab based system to produce element specific images. Work package 2: The appliaction of TEDDI to materails identificatication and security scanningThe TEDDI method uses scattered (not directly transmitted) X-rays which contain information on the crystal structure at each point within the sample. TEDDI uses multiple parallel collimators to obtain its spatial resolution and the sample does not need to be rotated in the same way as standard tomography. We will make a lab based TEDDI system to identify specific materials at each part of a complex sample on a 1x10-3 mm3 spatial scale. We will also work with our partners Kromek ltd who originally spun out of the Durham University Physics Department. They are developing scanners for threat identification at airports. We will jointly develop the TEDDI technology with HEXITEC detectors to recognise materials based on their coherent scattered signals. This is a much more reliable test than relying on purely absorptive information. In conjunction with existing methods the false alarm rate can be significantly reduced. Work package 3: Tissue BiopsyMany soft tissue types have very similar diffraction patterns especially those with a high water content, however certain types of breast cancers have been shown to be quite easily distinguishable from normal tissue by energy dispersive diffraction methods. We intend to develop, jointly with the Royal Surry and Marsden hospitals, an X-ray tissue biopsy modality. By using HEXITEC detector systems we will obtain unique information about specific tissue types that will significantly reduce the number of false positives. This is a vital aim because a false diagnosis leads to great deal of unnecessary discomfort and distress to the patient.

X-ray tomography systems are widely used in hospitals, airports and engineering environments to provide three dimensional images for diagnosis, substance identification or to check the structural integrity of complex fabricated components. These tomographic images are formed by measuring transmitted X-rays at a variety of angles through the sample and mathematically reconstructing slices to render a full three dimensional density contrast image. However the structural information that is carried by the coherently scattered wavelengths (or colours) of X-rays is not utilised. This information is potentially very useful and can be used to identify materials located within a specific gauge volume (~10-3 mm3) of a much larger object. The scattered information is energy dispersed and contains crystallographic information such as lattice parameters (+ or - 0.005+), atomic positions (+ or - 0.08+) and degree of crystallinity (preferred orientation). This information can be used to identify the substance within the sampled gauge volume either analytically or by pattern recognition. The potential impact of this substance recognition capability is huge and has been recognised in the national press as outlined in the full impact plan. The main impact of this grant will be felt in three areas: Fluorescence tomography and Topographic Energy dispersive diffraction imaging: HEXITEC technology will allow fast analysis of structure and strain distributions as well as chemical contamination profiles within complex fabricated components. This will be especially useful for the evaluation of fail safe components used for aerospace applications. The impact here will be deliver an imaging modality that is not currently available anywhere in the world. Security scanners: HEXITEC technology will facilitate much faster and more reliable identification of explosive materials and recognise the signatures of other illicit substances. The number of false alarms can be significantly reduced by using optimised TEDDI systems in conjunction with existing security X-ray scanners. Tissue biopsy: HEXITEC technology will bring significant benefits to this area allowing identification of cancerous tissue which will optimise surgical procedures and steer post-operative radiological treatment. The number of false positives will drop saving patients from unnecessary, expensive and painful treatment. The general impact of the HEXITEC technology platform is even wider it is not possible to cover every aspect of that potential in one application. For example in oil and gas exploration one of the principal survey requirements is for real time analysis of core samples. Rapid identification of mineral and rock species will save rig time and deliver data for geo-steering and formation evaluation. Pharma companies have a continuing interest in the crystallisation of polymorphic forms as they critically affect the bioavailability of product. In the worst cases they can have a deleterious effect on the health of the patient. TEDDI methods can be used to study in-situ crystallisation as a function of growth parameters. This analysis is equally applicable to other applications in chemical engineering to study reactions deep within hidden recesses of stainless steel plant.