New methods could improve, expand 3D imaging using X-rays

November 29, 2018

WASHINGTON -- Researchers report two new approaches to producing three-dimensional (3D) images using X-rays that could improve disease-screening, study of very fast processes and enable analysis of the properties of materials and structural information of opaque objects with unprecedented detail.

The researchers describe their approaches to 3D imaging with X-rays in two papers in Optica, The Optical Society's journal for high-impact research. One method might reduce X-ray doses needed in some types of preventative medical imaging, such as breast-cancer screening. The other method might allow 3D imaging of delicate biological samples or the study of very fast processes, such as the types of interactions that occur during space-debris impacts, to speed development of more durable materials.

Because of their high energy and short wavelength, X-rays can pass through materials that visible light cannot. Although it is possible to obtain 3D X-ray images, current approaches are limited in application because they require prolonged exposures to damaging X-rays.

In humans, too much radiation from medical X-ray imaging can increase cancer risk, which limits how often they can be screened with 3D mammography and other 3D X-ray technologies. Very high-energy X-rays used to study the detailed make-up of materials and biological samples often cannot be used because the samples would be destroyed after one exposure.

3D ghost tomography with X-rays

Researchers led by Andrew Kingston of the Australian National University together with a team at the European Synchrotron Radiation Facility (ESRF) in France have demonstrated for the first time that the unconventional imaging approach known as ghost imaging can be used to obtain 3D X-ray images of the interior of objects opaque to visible light.

"Because of the potential for significantly lower doses of X-rays with 3D ghost imaging, this approach could revolutionize medical imaging by making X-ray screening for early signs of disease much cheaper, more readily available and able to be undertaken much more often," said the paper's senior author, David Paganin, from Monash University, Australia. "This would greatly improve early detection of diseases including cancers."

Ghost imaging works by correlating two beams -- in this case, X-ray beams -- that do not individually carry any meaningful information about the object. One beam encodes a random pattern that acts as a reference and never directly probes the sample. The other beam passes through the sample.

The researchers created random X-ray patterns by shining a bright beam of X-ray light through a metal foam, which is like a sponge made of metal. They took a 2D image of this random beam, and then passed a very weak copy of it through the sample. A large-area single-pixel detector captured X-rays that passed through the sample. The process was repeated for multiple illuminating patterns and sample-object orientations to construct a 3D tomographic image of the object's internal structure.

As a proof-of-concept experiment, the researchers carried out ghost X-ray tomography on an aluminum cylinder with a diameter of 5.6 millimeters and containing two holes of less than 2.0 millimeters diameter. They were able to produce 3D images with 1.4 million "voxels"--a term for 3D pixels--with a resolution, or voxel side-length, of 48 millionths of a meter.

"X-ray ghost imaging, especially ghost tomography, is a completely new field that needs to be explored and developed much further," said Kingston. "With more development, we envision ghost X-ray tomography as a route to cheaper and, therefore, much more readily available 3D X-ray imaging machines for medical imaging, industrial imaging, security screening and surveillance."

3D images from a single exposure

A research team from the Paul Scherrer Institute in Switzerland, led by Marco Stampanoni, together with a team from the Deutsches Elektronen-Synchrotron (DESY) in Germany and the ESRF, acquired 3D images using high-brilliance X-ray sources. Their new approach uses a single exposure, or shot, to obtain 3D information from X-rays one hundred billion times brighter than a hospital X-ray source. The rays can only be produced at specialized synchrotron facilities.

"High-brilliance X-ray sources are quite useful for biology and materials science because they can probe faster processes and higher resolutions than other X-ray sources," said the paper's first author Pablo Villanueva-Perez from DESY. "Because the power of these sources can destroy the sample after a single pulse, current 3D imaging using the full power of these sources requires multiple identical copies of a sample."

The new technique can make the measurements necessary to form a 3-D image before destroying the sample, so it could be useful for studying the mechanics of delicate biological samples such as living insects or examining the internal 3-D structure of intact viruses or proteins.

The new single-shot approach uses a crystal to split one incoming X-ray beam into nine beams that simultaneously illuminate the sample. Using detectors oriented to record information from each beam allows researchers to acquire at once nine different 2D projections of a sample object before it is destroyed by the intense x-ray probe beams.

The researchers used the approach to image a moth, which demonstrated the potential for studying insect mechanics with 3D microscale resolution at speeds ranging from microseconds to femtoseconds. They also showed that they could achieve nanoscale resolution by imaging a gold nanostructure.

"We would like to combine our technique with the unique capabilities of the European X-Ray Free-Electron Laser Facility, the first facility to deliver X-ray pulses at a rate of one million pulses per second," said Villanueva-Perez. "This could allow 3D exploration of fast processes at speeds of millions of frames per second."

The researchers plan to use their single-shot multi-projection imaging technique to better understand insect biomechanics, which could inspire new engineering setups. They also want to study new, lighter materials that might lower fuel consumption for vehicles and plan to examine the fast processes that occur when space debris hits satellites, which could aid development of protective materials.
-end-
Papers:

A. M. Kingston, D. Pelliccia, A. Rack, M. P. Olbinado, Y. Cheng, G. R. Myers, D. M. Paganin. "Ghost Tomography," Optica, 5, 12, 1516-1520 (2018).

DOI: 10.1364/OPTICA.5.001516

P. Villanueva-Perez, B. Pedrini, R. Mokso, P. Vagovic, V.A. Guzenko, S. J. Leake, P.R. Willmott, P. Oberta, C. David, H. N. Chapman, M. Stampanoni. "Hard X-ray multi-projection imaging for single-shot approaches," Optica, 5, 12, 1521-1524 (2018).

DOI: 10.1364/OPTICA.5.001521

About Optica

Optica is an open-access, online-only journal dedicated to the rapid dissemination of high-impact peer-reviewed research across the entire spectrum of optics and photonics. Published monthly by The Optical Society (OSA), Optica provides a forum for pioneering research to be swiftly accessed by the international community, whether that research is theoretical or experimental, fundamental or applied. Optica maintains a distinguished editorial board of more than 50 associate editors from around the world and is overseen by Editor-in-Chief Alex Gaeta, Columbia University, USA. For more information, visit Optica.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.

Media Contact: mediarelations@osa.org

The Optical Society

Related Medical Imaging Articles from Brightsurf:

Improved medical imaging improves cancer staging
Prof. TIAN Chao's group improved the imaging quality and 3D construction of the photoacoustic imaging, and applied them to in vivo sentinel lymph node imaging.

AI techniques in medical imaging may lead to incorrect diagnoses
Machine learning and AI are highly unstable in medical image reconstruction, and may lead to false positives and false negatives, a new study suggests.

Tiny devices promise new horizon for security screening and medical imaging
Miniature devices that could be developed into safe, high-resolution imaging technology, with uses such as helping doctors identify potentially deadly cancers and treat them early, have been created in research involving the University of Strathclyde.

Advanced medical imaging combined with genomic analysis could help treat cancer patients
Melding the genetic and cellular analysis of tumors with how they appear in medical images could give physicians new insights into how to best treat patients, especially those with brain cancer, according to a new study led by TGen.

Low doses of radiation used in medical imaging lead to mutations in cell cultures
Common medical imaging procedures use low doses of radiation that are believed to be safe.

Use of medical imaging
This observational study looked at patterns of use for computed tomography (CT), magnetic resonance imaging (MRI), ultrasound and nuclear medicine imaging in the United States and in Ontario, Canada, from 2000 to 2016.

Medical imaging rates continue to rise despite push to reduce their use
The rates of use of CT, MRI and other scans have continued to increase in both the US and Ontario, Canada, according to a new study of more than 135 million imaging exams conducted by researchers at UC Davis, UC San Francisco and Kaiser Permanente.

Two-in-one contrast agent for medical imaging
Magnetic resonance imaging (MRI) visualizes internal body structures, often with the help of contrast agents to enhance sensitivity.

Medical imaging rates during pregnancy
Researchers looked at rates of medical imaging (CT, MRI, conventional x-rays, angiography, fluoroscopy and nuclear medicine) during pregnancy in this observational study that included nearly 3.5 million pregnant women in the United States and Canada from 1996 to 2016.

Scientists discover new method for developing tracers used for medical imaging
University of North Carolina researchers discovered a method for creating radioactive tracers to better track pharmaceuticals in the body as well as image diseases, such as cancer, and other medical conditions.

Read More: Medical Imaging News and Medical Imaging Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.