Keynote International Conference on Tomography of Materials & Structures

X-ray Ghost Imaging: Line Scans, Radiography and Tomography (85)

Andrew M Kingston 1 2 , Daniele Pelliccia 3 , David M Paganin 4 , Glenn R Myers 1 2 , Yin Cheng 5 , Imants D Svalbe 4 , Margie P Olbinado 5 , Alexander Rack 5
  1. Department of Applied Mathematics, Research School of Physics and Engineering, The Australian National University, Canberra, AUSTRALIAN CAPITAL TERRITORY, Australia
  2. CTLab: National Laboratory for Micro Computed-Tomography, Advanced Imaging Precinct, The Australian National University, Canberra, AUSTRALIAN CAPITAL TERRITORY, Australia
  3. Instruments and Data Tools Pty Ltd, Rowville, Victoria, Australia
  4. School of Physics and Astronomy, Monash University, Clayton, Victoria, Australia
  5. European Synchrotron Radiation Facility, Grenoble, CS 40220, France

We briefly describe the new field of x-ray ghost imaging, tracing it from first proofs-of-concept in 2016, through to the first application to ghost tomography in late 2018. In this method of imaging, only a small fraction of the x-rays pass through the object, yet all x-ray photons contribute to image formation. Avenues for reduced dose are a key driver for this exciting new tomographic field.

Ghost imaging is a new field of optics. Emerging from the field of quantum optics and initially believed to be underpinned by quantum-mechanical “spooky action at a distance”, the field has rapidly achieved prominence in studies using classical visible light [1].

This form of imaging is utterly counter-intuitive. Indeed, the method often seems confusing, if not impossible, when first encountered. In ghost imaging, photons from a source pass through a speckle-making mask, leading to a spatially random pattern “A” being measured over the surface of a position-sensitive detector. A beam-splitter then removes a very small fraction of the photons, which pass through an object and are then recorded by a single-pixel “bucket” detector that merely records the total number “B” of photons falling upon it. This process is repeated for a number of different mask positions. While no photon that ever passes through the object is ever registered by a position-sensitive detector, and no photons measured by the position sensitive detector ever pass through the object, the correlation between A and B can be used to reconstruct the object [1].

Ghost imaging using x-rays was only very recently achieved, with the first proofs of concept for one-dimensional x-ray ghost imaging being published by Yu et al. [2] and Pelliccia et al. [3] in 2016. This was soon extended to x-ray ghost imaging of two-dimensional objects, by Zhang et al. [4] and Pelliccia et al. [5]. Finally, based on the theory and computer modelling of Kingston et al. [6], the first experimental realisation of ghost tomography (using potentially any form of radiation, not just x-rays) was reported by Kingston et al. [7] with x rays. The experimental setup was schematically identical to that in the figure below, using the process as described above, but with the additional feature that the sample was rotated to a number of different angular orientations.

We discuss the origins of ghost imaging, explain the key principles underpinning the method, review the current state of art in x-ray ghost imaging in 1D (line scans), 2D (radiography) and 3D (tomography), consider some key drivers such as the quest for ever-reduced dose, and speculate regarding future developments. We attempt to reduce the counter-intuitive nature of the method to a retrospectively obvious simplicity, and address the obvious question of: “Why would one want to perform tomographic imaging in this peculiar manner?”

[1] O. Katz, Y. Bromberg & Y. Silberberg. Compressive ghost imaging, Applied Physics Letters, 95, 131110, 2009.

[2] H. Yu, R. Lu, S. Han, H. Xie, G. Du, T. Xiao & D. Zhu. Fourier-transform ghost imaging with hard X rays, Physical Review Letters, 117, 113901, 2016.

[3] D. Pelliccia, A. Rack, M. Scheel, V. Cantelli & D.M. Paganin. Experimental x-ray ghost imaging, Physical Review Letters, 117, 113902, 2016.

[4] A.-X. Zhang, Y.-H. He, L.-A. Wu, L.-M. Chen & B.-B. Wang. Tabletop x-ray ghost imaging with ultra-low radiation, Optica, 5, 374-377, 2018.

[5] D. Pelliccia, M.P. Olbinado, A. Rack, A.M. Kingston, G.R. Myers & D.M. Paganin. Towards a practical implementation of x-ray ghost imaging with synchrotron light, IUCrJ, 5, 428-438, 2018.

[6] A.M. Kingston, G.R. Myers, D. Pelliccia, I.D. Svalbe & D.M. Paganin. X-ray ghost-tomography: Artefacts, dose distribution and mask considerations, IEEE Transactions on Computational Imaging, 5, 136-149, 2019.

[7] A.M. Kingston, D. Pelliccia, A. Rack, M.P. Olbinado, Y. Cheng, G.R. Myers & D.M. Paganin. Ghost tomography, Optica, 5, 1516-1520, 2018.

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