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Mouse brain- copyright- F. Pfeiffer et al, Technical University Munich
Scientific discussion meeting organised by Dr Alessandro Olivo and Professor Ian Robinson
X-ray phase contrast imaging (XPCi) emerged in the mid-90s at synchrotrons, showing potential to revolutionize all applications of x-ray imaging. Recently methods have emerged that could take XPCi out of the synchrotrons and deploy it into hospitals, industries, etc. This meeting brings together the leading experts in the area to discuss what is still needed to achieve this important goal.
Biographies of the organisers and speakers are available below and you can also download the programme (PDF). Recorded audio of the presentations are available by clicking on the names of the speakers below and the papers will be published in a future issue of Philosophical Transactions A.
Dr Alessandro Olivo, University College London
Dr Olivo obtained his undergrad (1995) & postgrad (1999) degrees from the University of Trieste in Italy, starting his PhD after a short stint as a hospital physicist. After the PhD he was employed for 5 years by the same university to develop and support the imaging beamline at the local synchrotron. After participating in the design of the station for in vivo synchrotron mammography, he applied for a Marie Curie Fellowship, on the basis of which he moved to UCL where he started working on the translation of synchrotron techniques into laboratory environments. Soon afterwards, he was awarded an EPSRC Career Acceleration Fellowship and then a Challenging Engineering grant, which led to his current Senior Lectureship. On the basis of these and other grants, he has set up an x-ray phase contrast lab and currently lead an 8-strong group to develop and apply the technique in a variety of fields including radiology, biology, material science and security.
Professor Ian Robinson, University College London
Professor Robinson’s research interest is X-ray diffraction using synchrotron radiation (SR). During the Bell Labs years, he developed the methods for studying surface structure using X-ray diffraction. These methods, based on crystal truncation rods, have become the definitive technique for the determination of the atomic positions at surfaces and interfaces. These surface methods are still used today at the major SR facilities, NSLS (Brookhaven), ESRF (Grenoble), APS(Chicago) and SLS (Villigen). He was awarded two prizes for the surface structure work, the Warren Prize in 2000 and the Surface Structure Prize in 2011. To develop the methodology of X-ray diffraction with SR, he built two beamlines. The first was a dedicated surfaces and interface structure beamline X16A at the National Synchrotron Light Source (Brookhaven). The second was 34-ID for coherent diffraction at the Advanced Phoyon Source(Chicago). More recently he has been developing methods of using the very high coherence of the latest SR sources to enable direct 3D imaging of structure. This is potentially useful for examining strain distributions inside complex materials on the nanometre length scale.The coherent X-ray diffraction methods will develop and expand further at the Diamond Light Source (DLS) located at Rutherford Appleton Lab (RAL) near Oxford. He is a founding "Diamond Fellow" of the Research Complex at Harwell (RCaH), also located at RAL. This is a meeting place of physical and live scientists interested in the transfer of methodologies from the physical to the life sciences. Materials and biological imaging are the main directions under development there. Three major grants are supporting the work of his group, which is now divided between the UCL and RCaH centres. The first, entitled "nanosculpture", looks at strains induced in nanometre-sized crystals either synthesised from atoms in a 'bottom up' procedure, or else carved by lithography from bulk materials in a 'top down' approach. The second is to study the structure of the human chromosome by X-ray imaging methods. The third is to develop new X-ray imaging methods based on deliberate modulation of the phase by suitably developed X-ray optics.
Dr Alberto Bravin, European Synchrotron Radiation Facility (ESRF)
Dr. Alberto Bravin got a PhD in Physics at the University of Trieste (Italy) on the development of X-ray phase contrast imaging techniques. In 1999, he joined the ESRF in Grenoble (France) and since 2003 he has been in charge of the Bio-medical laboratory ID17. At the ESRF, he is leading the preclinical phase contrast imaging programs applied to mammography and cartilage studies. Since 2009 he is deputy Group head of the X-ray Imaging group at the ESRF. He has co-authored more than 100 peer-reviewed scientific papers on medical applications of synchrotron radiation.
Professor Philip Withers, University of Manchester
Professor Philip Withers was a lecturer in Cambridge University’s Materials Science & Metallurgy Department, before moving to a Chair in Manchester in 1998. His interests lie in the application of advanced techniques to assess the structural integrity of engineering materials and components. To this end he has built instruments for residual stress measurement and 3D imaging at central neutron and synchrotron facilities, as well as founding a Unit for Stress and Damage Characterisation in Manchester. In 2007 he became the founding Director of the University of Manchester Aerospace Research Institute linking over 100 academics with the aim of undertaking cross disciplinary research. In 2010 he set up the Manchester X-ray Imaging Facility combining both lab. X-ray scanners and a beamline at the Diamond Light Source for 3D X-ray imaging across scales from 1m to 50nm. He was awarded the Royal Society Armourers & Brasiers’ Company Prize for pioneering use of neutron and x-ray beams to map stresses and image components in 2010. In 2012 Phil became the Director of the new BP International Centre for Advanced Materials, aimed at advancing the fundamental understanding and use of materials across a variety of oil and gas industrial applications.
Dr Stephen Wilkins, The Commonwealth Scientific and Industrial Research Council (CSIRO)On the genesis of XPCI – free space propagation and other implementations
Undoubtedly, the simplest form of X-ray phase-contrast imaging to implement is that based on free-space propagation (i.e. Fresnel diffraction). Such phenomena have been known in the case of conventional light optics (but not necessarily understood) going back to antiquity. In the case of X-rays, the effects of phase contrast appear to have been initially considered a nuisance in the context of X-ray imaging and termed “blurring” or “defocus”. However, more recently, the method of propagation-based X-ray phase-contrast imaging has been exploited with great effect to obtain improved contrast on weakly absorbing features in a wide class of objects, in many cases at high spatial resolution [1-4]. The present lecture will briefly outline some of the different modes of X-ray phase-contrast imaging and their specific features, including some of their relative merits. From this more general viewpoint, it will then focus on some of the principal practical outcomes of XPCI to date as well as the prospects for translation to even wider areas of practice in X-ray imaging.
Stephen Wilkins is an Honorary Fellow in the Division of Materials Science and Engineeering at CSIRO and an Adjunct Professor in the School of Physics, Monash University. He received his PhD working on order-disorder theory in binary alloys under Professor John Cowley at the University of Melbourne and also at Arizona State University. For his Postdoctoral studies he worked on solid-state physics and diffraction theory in the Physics Department at Imperial College under Professor Norman March, before joining CSIRO. His research activities in CSIRO have spanned; dynamical diffraction theory from imperfect crystals, maximum-entropy based methods of structure determination from diffraction data and the development of novel X-ray instrumentation. For some time, the focus of his research has been on the development of methods of X-ray phase-contrast imaging and related instrumentation, including for X-ray microscopy.
Professor Franz Pfeiffer, Technischen Universität MünchenDevelopment and recent applications of grating-based X-ray phase contrast for biomedical imaging
The basic principles of x-ray image formation in radiography have remained essentially unchanged since Röntgen first discovered x-rays over a hundred years ago. The conventional approach relies on x-ray attenuation as the sole source of contrast and draws exclusively on ray or geometrical optics to describe and interpret image formation. This approach ignores another, potentially more useful source of contrast, namely the phase information. Phase-contrast imaging techniques, which can be understood using wave optics rather than ray optics, offer ways to augment or complement standard attenuation contrast by incorporating phase information. This presentation will review the recent development of phase-contrast imaging in general, and focus particularly on our contributions to the development of grating-based x-ray phase-contrast computed tomography. A variety of experimental results will be shown that highlight the potential of this novel method for biomedical, clinical, and industrial applications. The presentation concludes with an outlook concerning the translation to pre-clincial and finally clinical practice.
After studying physics at Ludwig Maximilian University of Munich, Franz Pfeiffer completed his doctorate at Saarland University, conducting a number of experiments at major research facilities such as DESY in Hamburg. Pfeiffer carried out his post-doctoral research at the University of Illinois before joining the renowned Paul Scherrer Institute in Switzerland. In 2007 he took up an assistant professorship at the ETH Lausanne, and in 2009 he was called to the Chair of Biomedical Physics at the Technical University of Munich, where he is currently establishing a laboratory for biomedical x-ray imaging. Pfeiffer has received many prestigious research awards, such as the Leibniz Price of the German Science Foundation and the National Latsis Award of Switzerland.
Professor Atsushi Momose, Tohoku UniversityX-ray phase imaging - from synchrotron to hospital
In 1990s, X-ray phase imaging was extensively studied at synchrotron facilities. Its sensitivity to weakly absorbing objects, such as biological soft tissue and polymers, was excellent, and therefore practical application of X-ray phase imaging was strongly expected especially to medicine. However, the technology available at synchrotron facility limits its usage, and clinical diagnosis with X-ray phase imaging is not straightforward. In order to benefit patients, X-ray phase imaging technology should be realized outside of a synchrotron facility. X-ray grating interferometry developed in 2000s gives us a solution, because it functions with polychromatic cone-beam X-rays. X-ray phase imaging is attainable with a practical exposure time with a conventional X-ray source. I conducted a project to develop clinical machines that can be used by radiologists in hospitals. A system based on X-ray Talbot-Lau interferometer was constructed, aiming at diagnosis of rheumatoid arthritis and breast cancer. The former is now used for patients. The current status of this project will be reported.
Atsushi Momose, a professor with Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan, is an expert in X-ray phase imaging. He gained an idea of X-ray phase tomography in the end of 1980s when he was a freshman with Hitachi, Ltd., Japan, after his master course of the graduate school of The University of Tokyo. In early 1990s, he realized X-ray phase tomography for the first time by performing X-ray phase measurements with a Bonse-Hart X-ray interferometer in combination with a CT scan. He is one of key persons during the bloom of X-ray phase imaging in 1990s, and furthermore he initiated X-ray grating interferometry in 2000s to realize X-ray phase imaging not only in synchrotron radiation facilities but also in laboratories and hospitals. His first machine of X-ray phase imaging is now in operation in a hospital for the clinical study by medical doctors.
Dr Zhong Zhong, Brookhaven National LaboratoriesCrystal-based methods: from synchrotron to x-ray tube
Crystal-based phase contrast imaging introduces fine selectivity for the angular deviation of x rays traversing the subject. Experiments at the NSLS to investigate Diffraction Enhanced Imaging (DEI), also called Analyzer Based Imaging (ABI) in areas of radiology of clinical relevance, including breast, lung, and cartilage imaging will be introduced. Recent advancement in DEI instrumentation using an x-ray tube as the source of x-rays will be discussed. From the measurement and simulations, it will be argued that DEI with x-ray tube is possible in a clinical setting. DEI is extremely simple both in theory and in practice, making it rewarding to implement DEI for solving scientific and technical problems. The goal as envisioned over a decade ago, only more reachable today, remains the translation of DEI to clinical utilization.
Zhong Zhong is the spokesperson for Beamline X17B1, a beamline specializing in high-energy x-ray diffraction. In addition, Zhong is also the local contact for Beamline X15A, specializing in Diffraction Enhanced Imaging and X-ray Standing Wave meassurements. Zhong’s research interests are medical imaging and diagnosis using monochromatic x-rays, x-ray phase contrast, and x-ray optics. As co-inventor of the Diffraction Enhanced Imaging (DEI) method, his recent research efforts have been on investigation of DEI on mammography and development of x-ray tube based DEI system. Unlike conventional x-ray imaging methods, DEI is sensitive to phase contrast and is thus more suitable for soft-tissue imaging. Zhong also pioneered a new class of crystal optics for sagittal focusing of high-energy x-rays produced by synchrotron radiation source. Past work include contrast agent imaging applied to angiography using K-edge subtraction and monochromatic x-rays, development of bent-crystal monochromator for conventional x-ray source.
Professor Renata Longo, University of TriesteClinical XPCi-based mammography with synchrotron radiation
The first clinical study in phase contrast mammography has been completed in Trieste (Italy): the study has involved 71 patients with questionable or suspicious breast abnormalities identified at the hospital by means of standard digital mammography together with ultrasonography. The final results of this study are now available and can be regarded as the starting point of further investigations. Moreover, this first clinical experience was characterized by the use of a screen-film system. As digital detectors with high spatial resolution (pixel size of ∼50μm) have recently become commercially available, they have been considered for future clinical experiments: a second clinical study, which utilizes a computed radiology system on a limited number of patients, has already been undertaken. Both qualitative and quantitative (diagnostic) analysis of the results will be presented and the possible role of the XPCi-based mammography will be discussed considering all the new imaging techniques available for breast imaging.
Renata Longo is Associate Professor of Medical Physics at the University of Trieste, Italy and associate researcher of the Italian National Institute of Nuclear Physics (INFN). Responsible of the University of Trieste for the program of mammography with synchotron radiation in cooperation with the synchrotron radiation laboratory Elettra and the Trieste university hospital. In this framework the first clinical study in free space propagarion phase contrast mammography is completed and new programs are going on. Present researchs: (a) Phase sensitive techniques for breast imaging and tomography with synchrotron radiation, including development of dedicated imaging detectors, (b) NMR medical imaging for human brain mapping. Reviewer for international journals of physics and radiology and for scientific institutions and laboratories. Author of more than 100 papers in international scientific journals.
Dr Maura Tonutti, Cattinara Hospital, ItalyClinical XPCi-based mammography with synchrotron radiation
Dr Maura Tonutti- • Graduated Medical School at the University of Trieste on 31st October 1990 with the following grade : 110/110 cum laude. • Completed Diagnostic Radiology residency programme in Trieste on 15 th December 1990 with the following grade : 70/70 cum laude. • Senology School certificate in 1993 • Working as Radiologist for the Radiology Department at the University of Trieste since 1st of July 1993 • Dealing with Senology and Ultrasound Imaging since 1991; and with Magnetic Resonance Imaging applied to breast since 2000. • Cooperating with SYRMEP (Synchrotron Radiation for medical Physics) project since 1991 focusing on Synchrotron Ray Mammography. • Actively working with multidisciplinary senology work group officially recognized by University Hospital since 2001. • Registered SIRM sections of Senology and Ultrasound Imaging Registered Italian School of Senology. • Head of Senology section at the Radiology Department of the University of Trieste since January 2006. • License for reading Breast Screening x-rays in 2006 after passing all the tests of the regional education programme at CSPO in Florence
Professor Marco Stampanoni, Swiss Light Source, Paul Scherrer Institute/ Institute for Biomedical Engineering, University and ETH ZürichPhase contrast X-ray imaging in the clinic: a first mammography study
Phase-contrast and scattering-based x-ray imaging are known to provide additional and complementary information to conventional, absorption-based methods. We present the results of a multicenter, international reader study aiming at the evaluation of the clinical relevance of phase contrast mammography. Freshly dissected whole breast specimens of 33 patients with histo-pathologically proven breast cancer were imaged using a Talbot-Lau interferometer equipped with a conventional x- ray tube (40 kVp, 28 keV, 25 mA). Absorption, differential phase and small-angle scattering signals were combined into novel, high-frequency-enhanced radiographic images and compared to digital mammography images. Six expert breast radiologists evaluated clinically relevant parameters such as general image quality, presence of artifacts, and visibility of diagnostic features (i.e. lesion conspicuity and skin infiltration) on a 5-point-scale. The study indicates that phase contrast enhanced mammograms show a better image quality concerning sharpness, lesions delineation, and visibility of microcalcifications, resulting in a general improvement of their clinical relevance.
Professor Marco Stampanoni studied physics at the Swiss Federal Institute of Technology Zürich (ETHZ) and obtained his MSc in Nov. 1998. He enrolled in a PhD program at the Institute for Biomedical Engineering (IBT) at the ETHZ and at the same time, he started a Master of Advanced Studies in Medical Physics, successfully concluded in October 2000. The subject of his physics PhD, defended in 2002, was the development of a novel approach towards X-ray computed tomography at the micron scale. In 2004 he was appointed beamline scientist and initiated the TOMCAT project, a beamline for TOmographic Microscopy and Coherent rAdiology experiments at the Swill Light Source. Stampanoni was appointed Head of the X-ray Tomographic Microscopy Group in 2005 and Assistant Professor (Tenure Track) for X-ray Microscopy at the Department for Information Technology and Electrical Engineering (D-ITET) of ETH Zürich in 2008. He is affiliated with the Institute for Biomedical Engineering (IBT) of the University and ETH Zürich and still heads his team at PSI.
Dr Han Wen, National Institute of Health, USABoosting phase contrast with two-arm interferometers using sub-micron period gratings
Grating interferometers of very high line density operate in the far field regime, where the incident beam is split into widely separated beams, which are then redirected to coherently interfere with each other. Because of the wide separation of the interfering beams, far field interferometers can provide high levels of phase contrast. They also provide absolute phase images in some cases. We report on imaging experiments using a symmetric three-grating interferometer of 200 nm period, operating at 22.5 keV and 1.5% spectral bandwidth on the 2-BM beamline of APS. The gratings consist of arrays of multi-layer stacks on a staircase substrate, which are fabricated in a thin-film deposition process. Using a slitted incident beam we acquired absolute phase images of lightly absorbing samples. Visible light versions of the interferometer have been shown to work with polychromatic sources. Our future aim is to adapt the method to compact x-ray sources.
Dr Wen obtained a B.S. in Physics from Peking University in Beijing, China, and graduated with a Ph.D. in Physics from the University of Maryland, College Park, Maryland, USA, through the CUSPEA Scholarship. He has been a Principle Investigator at the National Heart, Lung and Blood Institute of the National Institutes of Health since 1997. His research has been focused on imaging technologies for medical applications, including x-ray imaging and cardio-vascular MRI technologies.
Dr Peter Munro, The University of Western AustraliaMedicine, material science and security: the versatility of the coded-aperture approach
The principal limitation to the widespread deployment of X-ray phase imaging in a variety of applications is probably versatility. A versatile X-ray phase imaging system must be able to work with polychromatic and non-microfocus sources such as those currently used in medical and industrial applications, have physical dimensions sufficiently large to accommodate samples of interest, be insensitive to environmental disturbances such as vibrations and temperature variations, require only simple system setup and maintenance and be able to perform quantitative imaging. The coded aperture technique, based upon the edge illumination principle, satisfies each of these criteria. To date we have applied the technique to mammography, materials science, small animal imaging, non-destructive testing and security. In this talk we will outline the theory of coded aperture phase imaging and show several examples of where the technique has been applied to practical problems.
Peter Munro currently works in the Optical + Biomedical Engineering Laboratory and Centre for Microscopy, Characterisation and Analysis at the University of Western Australia where he is supported by an Australian Research Council discovery early career research award. He works on the development of models of light interaction with biological tissue with the objective of bringing innovation to biomedical imaging techniques. Prior to this, he worked in the Radiation Physics group at University College London where he developed a quantitative method for performing X-ray phase contrast imaging using incoherent sources. Dr Munro received a Commonwealth scholarship in 2002 and subsequently completed his PhD in the physics department at Imperial College London in 2006 on the use of numerical methods in the modelling of high numerical aperture optical imaging systems. He received a BSc and a BEng with honours, both from the University of Western Australia, in 1998 and 2000 respectively.
Dr Joseph Ferrara, Rigaku Woodlands Labs Rotating anode X-ray sources and their applications
Rigaku is a manufacturer of X-ray sources for the home laboratory and has been responsible for the introduction of many technologies used in such sources, for example the turbomolecular pump and the ferrofluidic vacuum seal. In this talk, Dr Ferrara will review the current state-of-the-art in X-ray generation and take a look forward to future technologies for X-ray generation in the home laboratory.
Dr. Ferrara received his B.S. in Chemistry from Case Institute of Technology in 1983 and his Ph.D. in Chemistry from Case Western Reserve University in 1988 under the tutelage of Wiley J. Youngs. Dr. Ferrara joined Molecular Structure Corporation in 1988, which became part of the Rigaku Group in 1996 and became Rigaku Americas Corporation in 2005. Dr. Ferrara is presently Chief Science Officer of RAC, Vice President, X-ray Research Laboratory, Rigaku Corp, and is a member of the board of directors for Rigaku Innovative Technologies. In the area of applied research, Dr. Ferrara participates in the development of X-ray generators, optics, goniometers, detectors and systems and software. In the area of basic research, Dr. Ferrara is working on the use of chromium radiation for extracting the anomalous scattering signal from sulfur and other weak scatterers for routine phasing of macromolecular diffraction data.
Professor Hans Hertz, KTH Royal Institute of Technology, StockholmLiquid-metal-jet sources for high-resolution phase-contrast bio-imaging
We have introduced a new anode concept for electron-impact sources, liquid-metal jets. This regenerative anode allows operation of microfocus tubes with an electron-beam power density several orders of magnitude higher than present stationary or rotating anodes. The source has been demonstrated for a wide range of liquid anodes and x-ray emission energies. Present systems rely on room-temperature liquid-metal alloys and typically operate with a 5-20 m spot size in the 10-50 kV range with up to one order of magnitude higher brightness than present state-of-the-art x-ray micro-focus tubes. The high brightness makes the source suitable for a wide range of diffraction, scattering, and imaging applications. For bio-imaging, in-line phase contrast with high spatial resolution is of particular interest. Present small-animal imaging applications include high-resolution CT, improved tumour demarcation, and micro-angiography. In the latter we employ CO2-gas as contrast agent and have demonstrated 3D tomography of rat-kidney blood-vessel network and 2D imaging of <8 m diam blood vessels in mouse ear, all at acceptable dose levels.
Hertz received his Ph.D. in optical physics 1988 at Lund University, Sweden. After post-doc research at Stanford University, he returned to Lund and started a research group on soft x-rays. In 1997 he was promoted to full professor in Biomedical Physics at the Royal Inst. of Technol. (KTH), Stockholm. Here he has built a cross-disciplinary research group in x-ray science, spanning from novel sources and optics to biomedical applications. The research covers both the soft and hard x-ray regimes and applications are primarily focused on micro- and nano-imaging. Other research interests include ultrasonic radiation pressure and its application to cell biology.
Professor Zulfikar Najmudin, Imperial College LondonPhase contrast imaging with compact plasma based accelerators
Ever increasing developments in x-ray brightness and usability are requested to satiate the demands of novel x-ray imaging techniques. The most sought after properties of these sources include high spatial resolution, high temporal resolution and both spatial and temporal coherence. Optical lasers excel in all of these properties but without the penetration of normal materials that makes x-rays ideal for investigating optically non-transparent materials. However high intensity optical lasers can be used produce x-ray beams with many of these sought after properties, and so can be used indirectly for imaging opaque matter. In this talk, we discuss methods of generating high quality x-ray beams derived from intense laser sources. In particular, we discuss our work in developing laser driven betatron sources. In this method, a high energy electron beam, similar to those used in conventional light sources, is generated by a high power laser beam but in a fraction of the distance as compared to a conventional accelerator. The same laser driven accelerating structure can also ‘wiggle’ the electrons to produce a bright, ultrashort pulse, collimated synchrotron x-ray beam that can be used for numerous x-ray applications. In particular, we highlight our recent work trialling this source for phase contrast imaging.
Professor Najmudin was born in Uganda, and educated at the Royal Grammar School Worcester, and Hertford College, Oxford. He came to Imperial College, as a postgraduate student, to work on plasma based acceleration of particles with the new class of super-intense lasers that have powers exceeding the power produced by the worlds power stations, at least, that is, for the briefest moment. Since then, the Plasma Physics Group at Imperial College has become one of the world’s leading groups in this exciting new area, and have made major breakthroughs in producing high energy and narrow energy spread beams of both electrons and ions. Recently Professor Najmudin has initiated a new program looking at using compact plasma based electron accelerators as a unique new light source, demonstrating that they can produce x-ray beams with several unique properties.
Poster Session- details to follow.
Dr Ewald Roessl, Philips Innovative Technologies, Research LaboratoriesClinical boundary conditions for differential phase contrast mammography
Research in gratings-based differential phase contrast imaging (DPCI) has gained increasing momentum in the past couple of years. First results on the potential clinical benefits of the technique for x-ray mammography are becoming available and indicate improvements in terms of general image quality, the delineation of lesions versus the background tissue, and the visibility of micro-calcifications. In this talk Dr Roessl will investigate some aspects related to the technical feasibility of DPCI for human x-ray mammography. After a short introduction to state-of-the-art full-field digital mammographic (FFDM) imaging in terms of technical aspects as well as clinical aspects, we put together boundary conditions within which a new DPCI modality would likely need to operate. He will then discuss the implications on system design in a comparative manner for systems with 2D detectors versus slit-scanning systems, stating advantages and disadvantages of the two designs. Finally, focusing on a slit-scan system, he will outline a possible concept for phase-acquisition.
Ewald Roessl graduated in theoretical physics in 1999 from the University of Technology, Graz, Austria. He received his PhD in cosmology and elementary particle physics from the École Polytechnique Fédérale de Lausanne (EPFL), Switzerland in 2004. His thesis entitled “Topological defects and gravity in theories of extra dimensions” was awarded best thesis at EPFL in 2004. Thereafter, Dr. Roessl joined the Philips research laboratories in Hamburg, where he is currently active in various fields of diagnostic imaging including direct-conversion, spectral imaging for computed tomography (CT), mammography and phase contrast imaging. From his nomination to senior scientist in 2008 on, Dr. Roessl leads the research within Philips on differential phase-contrast x-ray imaging to investigate the potential for clinical applications. Ewald Roessl is author or co-author of more than 25 peer-reviewed publications and about 17 US patent applications and reviewer for a number of journals including Physics in Medicine and Biology, Medical Physics, IEEE TMI, IEEE TNS, Journal of Physics D and NIMA.
Dr Kentaro Nagai, Canon IncPhase demodulation methods for two-dimensional grating-based X-ray interferometry
We present two new high spatial resolution approaches to the demodulation of images produced by a two-dimensional X-ray Talbot Imaging (2D XTI) system. Demodulation of XTI images is currently achieved either by phase stepping (PS) or Fourier transform (FT) methods. However, the PS method for 2D XTI requires more complicated control process than that of one-dimensional XTI. On the other hand, the FT method achieves lower spatial resolution than the PS method. For practical application of 2D XTI, a simpler exposure process with high spatial resolution is required. The first approach described is a hybrid of the PS method and the FT method. The exposure process is simpler than PS while the spatial resolution of the demodulated images is improved. The second approach is a spectral analysis process using a windowed Fourier transform. The process improves the spatial resolution of the FT method by isolating the required spectral term from other information carrying terms. The demonstration test results show that these proposed methods can achieve high spatial resolution for both the x- and y- differential phase components.
Dr Kentaro Nagai is a senior engineer at the Frontier Research Centre at Canon incorporation. He obtained his PhD degree in 2000 at Tsukuba University in Japan. He has worked as an engineer at Canon incorporation since 2004 after three years duty in another private company. His research focuses on developing novel X-ray phase imaging methodology and its applications. Especially, he is interested in phase demodulation methods from fringe patterns for X-ray phase interferometry.
Dr Rainer Raupach, Siemens HealthcareIs clinical grating-based CT possible?
The phase information provided by phase contrast CT (PCT) represents the local electron density which can also be obtained by multi-energy absorption measurements. In this sense, PCT visualizes material properties that are already accessible but based on an alternative physical effect and measurement principle. Standard CT and PCT show fundamentally different noise propagation implicating that spatial resolution plays an essential role. A clinically meaningful comparison has to evaluate the imaging performance per radiation dose. PCT outperforms CT only at high spatial resolution. The break-even spatial resolution at available x-ray source coherence of compact PCT setups is significantly higher than typically used in CT. The dose necessary in order to achieve a required CT contrast-to-noise ratio scales with resolution to the power of four. Although a relative advantage of PCT can be realized it will necessarily be related to increased radiation dose. PCT will not be beneficial for clinical CT as long as compact sources with much better spatial coherence are routinely available.
Rainer Raupach, born in 1972, graduated 1998 in physics (diploma) at the University of Cologne, Germany. He finished his PhD in theoretical physics in 2000 and started working for Siemens Healthcare in the business unit Computed Tomography, afterwards. His special topics are CT physics, image reconstruction and strategies for radiation dose reduction. He invented numerous improvements in the field of CT leading to more than 30 granted patents so far and was honored as ‘Inventor of the Year’ by Siemens in 2008. He holds a position as principle scientist since 2010. Starting in 2008, he investigated the signal and noise propagation in phase contrast CT (PCT) on a signal theory basis which has been published in the literature. The analytical approach allows for extrapolating the potential of PCT from laboratory scale to medical in-vivo application.
Mr Ian Haig, X-Tek, Nikon MetrologyInvestigation of the application of Phase Contrast Imaging using a point X-ray source to industrial Non Destructive Testing (NDT)
X-Tek Systems, a division of Nikon Metrology UK, designs, develops and manufactures microfocus X-ray radiography and CT systems for industrial non-destructive testing. The range of X-ray acceleration voltage of its current standard products is 130kV – 450kV. It is widely known that x-ray images can be created using phase contrast formed by the natural propagation of X-ray; results were reported in 1996. The short study which is the subject of this presentation, investigated the practical application of phase contrast imaging in an X-Tek tool which has a point X-ray source and has an acceleration voltage greater than 100kV. The study also included modeling and simulation Simulation of the natural propagation of x-ray through a cylindrical test sample predicted a small contrast peak at the boundary between the cylinder material and the air. Comparison data was obtained using a microfocus X-ray source with acceleration voltage above 100kV. The simulation results correlated well with the experimental data. A further practical example in which we detected intensity variation including the effect of phase contrast in the >100kV operating region is introduced and discussed In summary, phase contrast was observed in the radiographic images from a standard point X-ray source with acceleration voltages exceeding 100kV.
Ian Haig is Vice President Engineering at X-Tek Systems, part of Nikon Metrology based in Tring, UK. He graduated in 1974 from the University of Southampton, UK with an honours degree in Electrical Engineering. Subsequently he conducted research in the UoS Electrostatics group investigating hazards associated with the static electrification of fuel when pumped at high speed. In 1977 he began his working career working on the original development of X-Ray CT in the Central Research Labs of EMI specializing in x-ray source design. In 1983 he moved to the R&D group of Thorn EMI Varian developing advanced microwave tubes and high power electron guns. In 1991 he became Production Director and subsequently Technical Director. In 1995 he became a founding shareholder of TMD Technologies when it was formed as a result of an MBO. He joined X-Tek in 1999 to work with Roger Hadland on the development of advanced microfocus x-ray sources. Ian has held his current position under Nikon Metrology since April 2012. His primary expertise is in the field of high power and voltage vacuum devices and their associated power supplies and control systems. He is a member of the IET.
Mr Kazuaki Suzuki, Nikon MetrologyInvestigation of the application of Phase Contrast Imaging using a point X-ray source to industrial Non Destructive Testing (NDT)
Kazuaki Suzuki is Chief Strategy Officer of Nikon Metrology (Head Office locates in Leuven, Belgium). He received BS degree in plasma physics in 1981 and MS degree in X-ray astronomy in 1983 from University of Tokyo, Japan. He retired from a doctorate course and joined Nikon Corporation in 1984. For 25 years until 2009, he had led the development of high-end semiconductor exposure tools such as excimer laser stepper, excimer laser scanner, electron-beam projection lithography system and EUV scanner. He is a main editor of “Microlithography (second edition)” from CRC PRESS. He belonged to Core Technology Center at Nikon Corporation from 2009 to 2011 for research works of 3D measurement technologies. He has been the current position from autumn in 2011 and his location is Tring, Herts, UK.
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