Enabling 3D X-ray imaging at very low dose
  • European Union
  • VOXEL is Horizon2020 RIA-FET-OPEN Grant Number: 665207

VOXEL - Volumetric medical X-ray imaging at extremely low dose

Computerized Tomography (CT) has been one of the greatest achievements in medical imaging, but at the cost of a high, potentially harmful, X-ray irradiation dose. The ultimate goal of VOXEL is to provide an alternative to tomography with a disruptive technology enabling 3D X-ray imaging at very low dose. VOXEL aims at prototyping new cameras working either in the soft or hard X-rays that will combine the X-ray penetration and nanometre spatial resolution, easiness to use, afforded by avoiding the rotation of the source or the sample, and extremely low dose for maximum impact on medicine and biology.

VOXEL relies on the integration of trans-disciplinary fields in medical imaging, optics, X-ray physics, computational and applied mathematics. The VOXEL team members are experts in X-ray metrology, wavefront sensing, atomic physic, mathematical computing and 3D medical imaging. By basing the research lead in Portugal with a woman coordinator, VOXEL will be transformative for scientifically emerging countries.

VOXEL Project Team


VOXEL is an international project, with partners from Portugal, Spain, France, Italy, and the Netherlands. You can find a short description of all the VOXEL partners below.

Instituto Superior Técnico

The Association of Instituto Superior Técnico for Research and Development (IST-ID) is a private not-for-profit institution, which primarily aims at carrying out Science and Technology activities, fostering knowledge transfer and promoting the involvement of national and foreign researchers, internally and externally, in RD&I projects in their areas of expertise.

Laboratoire d'Optique Appliquée

Laboratoire d'Optique Appliquée (LOA) is a public French laboratory under three institutions CNRS, Ecole Nationale Supérieure des Techniques Avancées-ParisTech and Ecole Polytechnique. The LOA is composed of about 100 persons on which half have permanent positions.

Universidad Politecnica Madrid

The Universidad Politécnica de Madrid (UPM) celebrates its 33 anniversary this year 2014. Despite the recent foundation of this university, most of its centres are over hundred years old and were founded during the 18th and 19th century. They were independent schools until they were grouped to form the UPM. It is no exaggeration to state that over one and a half centuries great part of the history of Spanish technology has been written by the Schools of Architecture and Engineering.


The Laboratoire Interactions, Dymanique et Lasers (LIDYL) laboratory is dedicated to Ultrafast Science research. The laboratory belongs to the IRAMIS (Institut Rayonnement Matière de Saclay) institute devoted to fundamental research at the CEA (Commissariat à l'Energie Atomique) research agency. High-intensity laser-matter interaction, laser-driven ultra-short particle sources, femtosecond/attosecond coherent soft X-ray sources, free electron lasers, femtochemistry and development of ultrafast laser diagnostics are among the internationally recognized lines of research at LIDYL.

Centrum Wiskunde & Informatica

Centrum Wiskunde & Informatica (CWI) is the National Research Center for Mathematics and Computer Science in The Netherlands, located in Amsterdam. The Computational Imaging team headed by Prof. Batenburg currently consists of 8 researchers involved in large-scale inverse problems in 3D and 4D (time-resolved) imaging. The group covers all aspects of the computational imaging pipeline, including data pre-processing, mathematical inverse problems, advanced image reconstruction algorithms, and high performance computation.

Institute of Chemical and Physical Processes (IPCF)

The Rome Unit of the Institute of Chemical and Physical Processes (IPCF) of the Italian National Research Council (CNR) was established in 2010 and forms the IPCF's backbone together with the units located in Messina (IPCF's headquarters), Pisa, Bari and Cosenza. It is based in the Physics Department at Sapienza University, where most of its researchers are housed. Our members carry out experimental and theoretical research in different areas of active matter, soft matter, statistical mechanics and biophysics. The Unit is currently composed of 11 tenured researchers, about twenty research associates from different Italian universities, and three administrative assistants.

Imagine Optic

Imagine Optic is a French firm employing 26 persons full-time; 16 of the are working on R&D. The annual turnover is of 2.5 M€.


Articles in scientific journals
  • The impact of free electron degeneracy on collisional rates in plasmas, G. O. Williams et al. (2019), arXiv:1902.07052
  • Computed stereo lensless X-ray imaging, J. Duarte et al., Nature Photonics (2019) doi:10.1038/s41566-019-0419-1
  • 3D imaging of theranostic nanoparticles in mice organs by means of x-ray phase contrast tomography, E. Longo et al., Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 105734I (2018) doi:10.1117/12.2293090
  • 3D map of theranostic nanoparticles distribution in mice brain and liver by means of X-ray Phase Contrast Tomography, E. Longo et al., 2018 JINST 13 C01049 (2018) doi:10.1088/1748-0221/13/01/C01049
  • Elemental and Optical imaging evaluation of zwitterionic gold nanoclusters in glioblastoma mouse models, X. Le Guével et al., Nanoscale 39 (2018) doi:10.1039/C8NR05299A
  • Developments of EUV/x-ray wavefront sensors and adaptive optics at Imagine Optic, O. de La Rochefoucauld et al., Proceedings Volume 10761, Adaptive X-Ray Optics V; 107610E (2018) doi:10.1117/12.2320927
  • Interaction of hemispherical blast waves with inhomogeneous spheres: Probing the collision of a supernova ejecta with a nearby companion star in the laboratory, D. García-Senz et al., The Astrophysical Journal 871, 2 (2019) doi:10.3847/1538-4357/aaf894
  • Hydrodynamic evolution of plasma waveguides for soft-x-ray amplifiers, E. Oliva et al., Physical Review E 97 (2), 023203 (2018) doi:10.1103/PhysRevE.97.023203
  • Clocking femtosecond collisional dynamics via resonant x-ray spectroscopy, Q. van den Berg et al., Physical Review Letters 120, 055002 (2018) doi:10.1103/PhysRevLett.120.055002
  • Advanced light-field refocusing through tomographic modeling of the photographed scene, N. Viganò et al., Optics Express 27 (6), 7834-7856 (2019) doi:10.1364/OE.27.007834
  • Tomographic approach for the quantitative scene reconstruction from light field images, N. Viganò et al., Optics express 26 (18), 22574-22602 (2018) doi:10.1364/OE.26.022574
  • An improved ring removal procedure for in-line x-ray phase contrast tomography, T. Massimi et al., Phys. Med. Biol. 63 045007 (2018) doi:10.1088/1361-6560/aaa706
  • Assessment of the effects of different sample perfusion procedures on phase-contrast tomographic images of mouse spinal cord, E. Stefanutti et al., INST 13 C03027 (2018) doi:10.1088/1748-0221/13/03/C03027
  • Fractal Dimension Analysis of High-Resolution X-Ray Phase Contrast Micro-Tomography Images at Different Threshold Levels in a Mouse Spinal Cord, L. Maugeri et al., Condens. Matter 3(4), 48 (2018) doi:10.3390/condmat3040048
  • Exploring Alzheimer’s disease mouse brain through X-ray phase contrast tomography: From the cell to the organ, L. Massimi et al., NeuroImage 184, 490-495 (2018) doi:10.1016/j.neuroimage.2018.09.044
  • Investigation of Herculaneum Papyri by X-Ray Phase-Contrast Tomography, I. Bukreeva et al., Nanotechnologies and Nanomaterials for Diagnostic, Conservation and Restoration of Cultural Heritage (2019) doi:10.1016/B978-0-12-813910-3.00013-6
  • Synchrotron Radiation techniques boost the research in Bone Tissue Engineering, M. Mastrogiacomo et al., Acta biomaterialia (2019) doi:10.1016/j.actbio.2019.03.031
  • Comparison of reconstruction approaches for plenoptic imaging systems, C. Herzog et al., Proceedings Volume 10677, Unconventional Optical Imaging; 106772U (2018) doi:10.1117/12.2306800
  • DAGON: A 3D Maxwell–Bloch Code, C. Herzog et al., Springer Proceedings in Physics, vol 202. Springer, Cham (2018) doi:10.1007/978-3-319-73025-7_4
  • Physically corrected forward operators for induced emission tomography: a simulation study, N. Viganò et al., Meas. Sci. Technol. 29 034005 (2018) doi:0000-0003-1704-5574
  • Tracking the ultrafast XUV optical properties of x-ray free-electron-laser heated matter with high-order harmonics, G. O. Williams et al., Phys. Rev. A 97, 023414 (2018) doi:10.1103/PhysRevA.97.023414
  • 3D map of theranostic nanoparticles distribution in mice brain and liver by means of X-ray Phase Contrast Tomography, E. Longo et al., Journal of Instrumentation, 13 (2018) doi:10.1088/1748-0221/13/01/c01049
  • Investigating the origin of third harmonic generation from diabolo optical antennas, L. Shi et al., Appl. Phys. Lett. 111, 173102 (2017) doi:10.1063/1.5001005
  • Nano-plasmonic near field phase matching of attosecond pulses, T. Shaaran et al., Scientific Reports, 7 (2017) doi:10.1038/s41598-017-06491-7
  • Micro-Focusing of Broadband High-Order Harmonic Radiation by a Double Toroidal Mirror, H. Coudert-Alteirac et al., Appl. Sci., 7(11) 1159 (2017) doi:10.3390/app7111159
  • Optimization and Characterization of High-Harmonic Generation for Probing Solid Density Plasmas, J. Koliyadu et al., Photonics, 4(2), 25 (2017) doi:10.3390/photonics4020025
  • Nonadiabaticity of cavity-free neutral nitrogen lasing, P. Ding et al., Phys. Rev. A 96, 033810 (2017) doi:10.1103/physreva.96.033810
  • X-Ray Phase Contrast Tomography Reveals Early Vascular Alterations and Neuronal Loss in a Multiple Sclerosis Model, A. Cedola et al., Scientific Reports 7 5890 (2017) doi:10.1038/s41598-017-06251-7
  • Quantitative 3D investigation of Neuronal network in mouse spinal cord model, I. Bukreeva et al., Scientific Reports 7 41054 (2017) doi:10.1038/srep41054
  • SYRMEP Tomo Project: a graphical user interface for customizing CT reconstruction workflows, F. Brun et al., Advanced Structural and Chemical Imaging, 3:4 (2017) doi:10.1186/s40679-016-0036-8
  • New insights on the biomineralisation process developing in human lungs around inhaled asbestos fibres, F. Bardelli et al., Scientific Reports 7 44862 (2017) doi:10.1038/srep44862
  • Impact of noise in holography with extended references in the low signal regime, K. Boutu et al., Optics Expressm 24 (6), 6318-6327 (2016) doi:10.1364/OE.24.006318
  • Experimental demonstration of a collinear triple pulse grazing-incidence pumping scheme for a transient collisional pumped x-ray laser, S. Künzel et al., J. Phys. B: At. Mol. Opt. Phys. 49 215601 (2016) doi:10.1088/0953-4075/49/21/215601
  • A distributed ASTRA toolbox, W. J. Palenstijn et al., Advanced Structural and Chemical Imaging, 2:19 (2016) doi:10.1186/s40679-016-0032-z
  • Corrigendum: Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography, I. Bukreeva et al., Scientific Reports 6 30364 (2016) doi:10.1038/srep30364
  • Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography, I. Bukreeva et al., Scientific Reports 6 27227 (2016) doi:10.1038/srep27227
Books and book chapters
  • Overview on HHG High-Flux Sources in Optical Technologies for Extreme-Ultraviolet and Soft X-ray Coherent Sources, W. Boutu, M. Ducousso, J.-F. Hergott, H. Merdji, Springer Series in Optical Sciences, 63 (2015)
Conference / Workshop Proceedings
  • Harmonic generation in solids at near IR driving field, M. Hussain et al., 7th International Conference on Attosecond Science and Technology, Szeged, Hungary, July 1–5, 2019
  • Solid-state harmonic generation near IR driving field, M. Hussain et al., IV International conference on the applications of Optics and Photonics, Lisbon, Portugal, 1-5 June 2019
  • Ultrafast imaging the solid to plasma transition, M. Hussain et al., PhD Open Days, Instituto Superior Tecnico, Portugal, 9-10 April 2019
  • Applications of high harmonic generation: understanding ultrafast dynamics in solids and plasma, M. Hussain et al., PhD Open Days, Instituto Superior Tecnico, Portugal, 21-22 March 2018
  • Imaging the solid to plasma transition, G. O. Williams, 3rd European Conference on Plasma Diagnostics (ECPD), Instituto Superior Tecnico, Portugal, 6-9 May 2019
  • Digital in-line holography corrected from aberrations by resorting to wavefront measurements, T. Wodzinsky, Conference Face2Phase 2017, Delft, Netherlands, 9-11 October 2017
  • Impact of free-electron quantum effects on collisional rates in plasmas, G. O. Williams, 20th International Conference on Atomic Processes in Plasmas, Gaithersburg MD, USA, 9-12 April 2019
  • X-ray based plasma diagnostics, G. O. Williams, Visions on Future Laser-based X-ray Science and Technology Workshop, Barcelona, Spain, 19-20 November 2018
  • The impact of free electron degeneracy on collisional rates in plasmas, G. O. Williams, The 2018 International Workshop on Radiative Properties of Hot Dense Matter, Hamburg, Germany, Spain, 21-26 October 2018
  • Phase contrast imaging of high-intensity laser hole boring of solid-density wires at LCLS-MEC, G. O. Williams, 58th Annual Meeting of the APS Division of Plasma Physics, San Jose CA, USA, 31 October - 4 November 2016
  • Compact metrology beamline for EUV optic and test of adaptive optic, P. Zeitoun et al., SPIE Optics + Photonics, San Diego CA, USA, 19-23 August 2018
Thesis / Dissertations
  • Spatio-temporal characterization of high harmonic generation for plasma diagnostics, J. Koliyadu, Universidade de Lisboa—Instituto Superior Técnico, 2018
  • Characterization, optimization and applications of coherent XUV sources, S. Künzel, Universidade de Lisboa—Instituto Superior Técnico, 2017
  • X-Ray Optics, P. Estrela, Universidade de Lisboa—Instituto Superior Técnico, 2018
  • From X-ray tomography to the first X-ray plenoptic camera for nanoparticles bio-localization, E. Longo, Université Paris-Saclay, 2018


Recent news

APPLAuSE students learn high power laser science at VOXEL metrology station

November 24th 2017

The students of APPLaUSE (a PhD program hosted by Instituto de Plasmas e Fusão Nuclear at Instituto Superior Técnico) had the opportunity to visit the VOXEL metrology station and learn how to double the frequency of a high power laser to increase the efficiency of x-ray generation. APPLAuSE students are enrolled on a course on high energy density plasma diagnostics had a practical session at the VOXEL metrology station, where X-ray detectors were shown. The students had some hands on opportunity with the high power laser, competing in small teams for the maximum frequency doubling conversion efficiency.

Representatives of Indian Institutes of Technology visit VOXEL station

June 23rd 2017

On 23rd June 2017, the VOXEL station received an entourage of Presidents, Deans and Professor from the Indian Institutes of Technology of Gandhinagar, Madras and Roorkee, the aim of this visit is to establish a formal cooperation between these Institutes and Instituto Superior Técnico.

VOXEL project featured on euronews program

October 20, 2017

The VOXEL project has been recently featured on Futuris, a program by euronews that covers the latest news about the leading scientific and technological research projects in Europe. The video is available here.

VOXEL laboratory on Portuguese national TV

October 13, 2017

The VOXEL laboratory at Instituto Superior Técnico (IST) has been featured in the Portuguese prime time news of RTP1 on September 11, 2017. The news story (available here) covered the recent results of the application process to public universities in Portugal, where two courses of IST had the highest average admission grades at national level. Physics Engineering - one of the top-graded courses - students had the opportunity to visit the VOXEL laboratory at their first day at IST, as well as the new laser system supported by the European Commission under the FET program H2020 that will generate ultra-short and ultra-intense infrared light source that creates x-rays to test the VOXEL camera. They learned all about the research done at VOXEL from the European project coordinator Marta Fajardo and post-doctoral fellow Swen Künzel (in the picture).

Imagine Optic is a candidate for European Commission's Innovation Radar Prize

October 9, 2017

Imagine Optic, one of the partners in the VOXEL project, is running for the Innovation Radar Prize under the category of Best early stage innovation, with the project Disruptive 3D X-Ray imaging systems. The Innovation Radar Prize is a competition launched by the European Commission and has the ultimate goal of identifying Europe's top future innovators and their innovations. We invite everyone to vote for Imagine Optic for this prize until 15 October 2017 here.

The new VOXEL metrology station is ON

January 5, 2017

Around the beginning of 2017, IPFN received a new laser for the VOXEL program (Volumetric medical X-ray imaging at extremely low dose), thanks to the support of the European Commission under the program Horizon2020. The new laser will create an ultra-short and ultra-intense infrared light source, which focused on gases and solid targets like metals, creates x-rays to test the VOXEL camera. These tests will be crucial to calibrate the VOXEL camera prototype.

In a more technical basis, the GoLP team currently has a dual 800 nm laser providing 25 mJ - 40 fs - 10Hz and 7.5 mJ - 30 fs - 1kHz beams on a daily basis. With this configuration, the team hopes to build the X-ray beam lines, which will result toward nice experimental results.

As PI of the GoLP division of the VOXEL program, Marta Fajardo thanked all the involved in the effort, and welcomed all interested in booking a tour to the new facilities.

Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

October 24, 2016

More than 1800 carbonized Greek and Latin papyri, discovered at Herculaneum in 18th century, form the unique library survived from antiquity. This unique collection was charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. The goal is to read the text hidden inside unopened papyrus rolls without damaging them. We succeeded in reading the largest portion of Greek text ever detected inside Herculaneum-papyrus rolls using X-ray phase-contrast tomography combined with a set of numerical algorithms for  ‘virtual-unrolling’. We obtained precious information on their probable author, content, ink and on unexpected events historically experienced by them.

The work has been published in Scientific Reports 6, article number: 27227 (2016). The results have had an eco on the media, namely in italian news broadcast and in CNN, which filmed the presentation of this work during the 28th International Congress of Papyrology, (1-6 august 2016 Barcelona, Spain) and is preparing a report to be aired in November 2016.

VOXEL coordinator featured in Spirou

May 5th 2016

Marta Fajardo, coordinator of the VOXEL project, was recently featured in a special number of the Franco-Belgian comics magazine Spirou. In this number of Spirou, Marta Fajardo and some collaborators are seen in the Laser Laboratory L2I of the Institue of Plasmas and Nuclear Fusion (IPFN) @ Técnico Lisboa, Portugal.


May 14th-15th 2019
VOXEL Annual Meeting, LOA, Paris, France
March 4th 2019
1st COST TUMIEE WG, Porto, Portugal
November 20th 2018
COST TUMIEE 2nd MC Meeting, Madrid, Spain
November 19th-20th 2018
COST TUMIEE 1st General Meeting, Madrid, Spain
September 12th 2018
COST TUMIEE 1st MC meeting, Brussels, Belgium
May 24th 2018
VOXEL Annual Meeting, CEA Saclay, Paris, France
February 2nd 2018
VOXEL Review Meeting, IST, Lisbon, Portugal
December 14th-15th 2017
VOXEL Annual Meeting, UPM, Madrid, Spain
April 5th-7th 2017
ASTRA training school, Antwerp, Belgium >
February 6th-8th 2017
ESRF USER Meeting 2017, Grenoble, France
October 3rd-4th 2016
COST WG2 and WG5 meeting, Bucharest, Romania >
September 19th-21st 2016
COST general meeting, Athens, Greece >
June 16th-17th 2016
VOXEL MGT Meeting, CWI, Amsterdam, Netherlands
April 28th-29th 2016
COST WG1 and WG4 meeting, Tallin, Estonia >
April 11th-12th 2016
COST WG3 meeting, Amsterdam, Netherlands >
March 30th-31st 2016
COST WG2 and WG5 meeting, Barcelona, Spain >
January 29th-March 3rd 2016
VOXEL Experiment, CEA, Paris, France
December 15th-17th 2015
VOXEL MGT Meeting, LOA, Paris, France
November 19th 2015
Workshop on 3D Rec, CWI, Amsterdam, Netherlands
October 26th-27th 2015
Workshop on X&XUV optics, Prague, Czech Republic >
September 17th-18th 2015
COST meeting, Upsallla, Sweden >
July 11th-12th 2015
VOXEL MGT Meeting, LOA, Paris, France
July 2nd 2015
VOXEL Kickoff Meeting, Lisbon, Portugal
March 16th-17th 2015
VOXEL MGT Meeting, LOA, Paris, France