Energy dispersive X-ray transmission imaging and coherent scatter tomography

Lead Research Organisation: University College London
Department Name: Medical Physics and Biomedical Eng

Abstract

Key Objectives and Aims of the Research
X-ray imaging is a key technique used in many fields such as medical diagnostics, quality control and materials testing, permitting the investigation of otherwise opaque volumes. 3D images can be produced by taking many flat X-ray images and performing a process known as computed tomography (CT) reconstruction. This project aims to develop a 3D imaging technique that, unlike normal X-ray imaging, discriminates different materials based on how they scatter X-rays. A sample is illuminated by a narrow beam of X-ray and 'off-axis' measurements recorded the scattering profile. Features are observed in the scattering profile which depend on the atomic structure of material due to a phenomena known as X-ray diffraction (XRD). Since every material has a different structure, the profile can be used as a fingerprint to identify unknowns. Ultimately, by applying the same CT reconstruction process, this technique can provide a 3D map of any volume of interest to determine what materials are present and where they are located.
Novel Science
Current approaches to XRD CT involve a lengthy process of making individual point measurements as the sample is translated and rotated. The novel aspect of this project is to develop this technique further to reduce scan times. This will be through a combination of implementing multi beam techniques and sparse data collection strategies. The student will use a cutting edge X-ray detector (HEXITEC) which will enable the most efficient data collection, removing the need for the slow sample translation step. The data produced will be complicated and the student will also develop software to organise, interpolate and reconstruct the spatially resolved scattering profiles in 3D.
Potential Applications
The technique has the power to provide 3D spatially resolved material identification. This has wide ranging potential in the following application areas:
Analysis of excised tissue at the time of cancer surgery to ensure that all diseased tissue has been removed. Patients who, post-surgery, are discovered to have had insufficient tissue removed are at greater risk of recurrence and may require further treatment (i.e. additional cost to the health care provider and increased patient anxiety).
Drug, explosive and contraband detection in security screening where the layout and content of baggage (for example) is unknown.
Defect identification in manufacturing processes. For example, in composites fabrication there is a need to identify voids, inclusions and resin rich areas which could lead to structural failure.
In the meat industry there is a requirement to identify foreign objects or damaged products for food safety. There is also a shift towards using technology to digitally grade products in order to increase yield (increasing economic value) and reduce waste (reducing environmental impact).

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R513143/1 01/10/2018 30/09/2023
2277225 Studentship EP/R513143/1 23/09/2019 22/09/2022 Ashkan Ajeer