Advanced X-Ray Imaging Group (AXIm)

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Research

We are a multi-PI collaboration aiming to develop novel X-ray image formation techniques and to deploy them with the very latest developments in source and detector technology.

One of our key interests is x-ray phase contrast imaging (XPCI) – a revolutionary approach where variations in x-ray phase are exploited to generate image contrast, rather than attenuation, as has been the convention since x-ray imaging was first developed. XPCI has been shown to significantly enhance the visibility of all details in an x-ray image, and to enable the detection of features classically considered x-ray invisible – with applications in a variety of areas, from earlier detection of life-threatening diseases in medicine to improved detection of threat objects in security scans and of minute defects/blemishes in industrial inspections. Scientific applications are also wide ranging, spanning medicine, biology, energy, materials science, archeology, cultural heritage preservation and others.

As well as XPCI our research covers topics such as x-ray microscopy, novel x-ray detectors, new x-ray source technologies, methods for fast CT and micro-CT, resolution enhancement, dark-field and ultra-small angle scattering, dual and multiple-energy imaging and the development of theoretical models which underpin these techniques.

Key Advances

XPCI with conventional, incoherent laboratory sources

Most XPCI methods are limited to very specialized facilities called synchrotrons, of which there are approximately only 50 in the world. This is because such methods require a source of high spatial coherence (i.e., all of the x-rays originate from a very small spot) in order to work. The only alternatives to synchrotron radiation are microfocal sources, or collimated conventional sources to artificially increase the source coherence – both of which limit the available x-ray flux leading to unfeasibly long exposure times. The AXIm group has developed a method that employs uncollimated conventional sources, i.e. x-ray tubes like those found widely in clinics throughout the world, without filtering the x-ray beam in any way. This means that the full flux generated by the source is used in image formation, thus allowing clinically compatible image acquisition times. 

howthemethodworks.pdf

. More information can be found in the following links from Nature and Scientific American. A summary of our tech-transfer activities was recently provided in an EPSRC press release. 

Staging tumours with x-rays

Use of edge-illumination (EI) X-Ray Phase Contrast imaging (XPCI) CT on oesophageal specimens resected in oesophagectomy operations revealed muscle layers with exquisite definition. (T) staging of oesophageal tumours is based on the determination of how many layers the tumour has penetrated into: the ability to visualize the layers very clearly allowed doing this based on the x-ray images alone. Obtaining precise tumour staging already during surgery would prompt additional intervention if and where possible, provide a more precise prognosis and allow treatment planning and patient management already at that stage (https://doi.org/10.1364/OPTICA.501948).

T2 Cancer image

T2 cancer example, with XPCI CT slide with lesion segmented by the radiologists (a) presented side-by-side with its histopathology counterpart (b), where two points where the tumor is invading into the muscle layers have been highlighted with red arrows by the pathologist.

Femtosecond multimodal imaging 

Laser-driven x-ray sources can provide incredibly short x-ray pulses. This experiment combined their use with a single-mask implementation of our edge-illumination technology (“beam tracking”, see “Previous Advances”), which enables the simultaneous retrieval of attenuation, phase and dark-field images from a single frame. As a result, all three images were obtained from a single shot of 22 fs duration, which open new possibilities for e.g. pump-probe experiments.  (https://doi.org/10.1038/s42005-023-01412-9)

Multi-modal images

Multi-modal images (from left to right: attenuation, refraction, dark-field) of cell following electrochemical deposition, with the lithium stratification on the Li side most clearly visible in the dark-field image. 

Direct measurement of scattering signals 

“Dark-field” (or Ultra-small angle scattering) measurements with the edge-illumination (EI) method are connected to the general theory of x-ray scattering, showing EI allows absolute measurement of the scattering signals with no influence from the characteristics of the imaging system (e.g. auto-correlation length). An additional contrast channel is also introduced – the variance of refraction – that plays an analogous role as dark field for sample features larger than the system’s spatial resolution (https://doi.org/10.1063/5.0168049).

image of scattering distribution

Modelling of the scattering distribution from an ensemble of microspheres, when multiple scattering is and is not negligible (left and right hand panels, respectively). The article shows how this model is compatible both with the classic theory of x-ray scattering and with the experimental measurements performed with EI

    Overview

    Personnel

    Team members

    Alumni

    • Jure Aleksejev, Postdoctoral Research Associate 2022-23
    • Dario Basta, PhD Student 2013-17
    • Luca Brombal, Visiting scientist 2018
    • Paul C Diemoz, Research Fellow 2012-18
    • Erik Schou Dreier, Visiting scientist 2018
    • Spyros Gkoumas, Postdoctoral Research Associate 2012
    • Amy Ha, PhD student 2019-22
    • Wehliye Hashi, Systems Engineer, 2020-2021
    • Konstantin Ignatyev, Postdoctoral Research Associate 2009-13
    • Jinxing Jiang, Postdoctoral Research Associate, 2018-2019 
    • Gibril Kallon, PhD Student 2013-2016, Postdoctoral Research Associate 2017-2021
    • Lorenzo Massimi, Postdoctoral Research Associate, 2018-2021
    • Charlotte Maughan Jones, PhD student 2015-19; Research Fellow 2020-24
    • Callum McDonald, Postdoctoral Research Associate 2021
    • Tom Millard, PhD Student 2011-14
    • Peter Modregger, Research Fellow 2015-19
    • Rimcy Palakkappilly Alikunju, PhD Student 2019-24
    • Amir Reza Zekavat, Postdoctoral Research Associate 2020-23
    • Savvas Savidis, PhD student 2017-21; Research Fellow 2021-23  
    • Nima Seifnaraghi,  Postdoctoral Research Associate, 2019-2020 
    • Dana Shoukroun, PhD student 2017-21; Postdoctoral Research Associate 2021-22
    • Magdalena Szafraniec, PhD Student 2009-12
    • Chris Thornton, Systems engineer 2021-22
    • Alfio Torrisi, Postdoctoral Research Associate 2017-18
    • Fabio Vittoria, PhD Student 2012-15; Research Fellow 2016-19
    • Paul Wolfson, Clinical Fellow, 2018-2021
    • Anna Zamir, PhD Student 2013-17

    Collaborators

    Industrial 

    • Nikon
    • Creatv Microtech
    • Rigaku
    • Scintacor
    • Direct Conversion
    • Anglo Scientific
    • Iconal
    • Quantum Detectors
    • Microworks
    • Photonic Science
    • Nylers
    • Unilever
    • ​​​Testing Industries

    Academic

    • QMUL
    • Imperial College London
    • University of Oxford
    • Ludwig-Maximillian University, Munich
    • University of Manchester
    • University of Southampton
    • University of Bristol
    • University of Strathclyde
    • University of Copenhagen/Technical University of Denmark
    • University of Antwerp
    • University of Trieste
    • University of Pisa
    • University of Milano Bicocca
    • University of Los Andes 
    • University of Waterloo
    • University of Leiden
    • University of Ghent
    • University of Sheffield
    • University of Siegen
    • University of Warwick
    • University of Edinburgh

    At UCL:

    • Francis Crick Institute
    • Royal Vetinary College
    • Department of Mechanical Engineering
    • Department of Chemical Engineering
    • London Centre for Nanotechnology
    • Institute of Child Health
    • Great Ormond Street Hospital
    • Department of Targeted Interventions
    • WEISS
    • Earth Sciences
    • Department of Cell and Developmental Biology
    • Institute of Ophthalmology
    • Respiratory Medicine
    • Centre for Inflammation and Tissue Repair
    • Centre for Advanced Biomedical Imaging
    • Department of Electronic and Electrical Engineering

    • Department of Computer Science

    Research Institutes and Facilities

    • Diamond Light Source
    • ELETTRA Sincrotrone Trieste ScpA
    • European Synchrotron Radiation Facility
    • Research Complex at Harwell
    • CNR Institute of Crystallography – Italy
    • EMPA Switzerland
    • Barts Health NHS Trust
    • INFN Istituto Nazionale di Fisica Nucleare, Pisa and Trieste Sections 
    • Natural History Museum
    • Centrum Wiskunde & Informatica, Netherlands
    • Central Laser Facility
    • Sloan Kettering Memorial Cancer Institute
    • NIST
    • Argonne National Labs
    • Institut National de la Reserche Scientific
    • Zayed Centre for Research
    • CNR Rome Nanotech
    • Imperial College Healthcare NHS Trust
    • Christie NHS Foundation Trust