Researchers capture X-ray images with unprecedented speed and resolution
Ghost imaging approach could enable detailed movies of the heart with
low-dose x-rays

Date:
August 5, 2020
Source:
The Optical Society
Summary:
Researchers have demonstrated a new high-resolution x-ray imaging
technique that can capture the motion of rapidly moving objects
and quickly changing dynamics. The new method could be used for
non- destructive imaging of moving mechanical components and to
capture biological processes not previously available with medical
x-ray imaging.



FULL STORY ========================================================================== Researchers have demonstrated a new high-resolution x-ray imaging
technique that can capture the motion of rapidly moving objects
and quickly changing dynamics. The new method could be used for
non-destructive imaging of moving mechanical components and to capture biological processes not previously available with medical x-ray imaging.


==========================================================================
"The technique we demonstrated can be used with any x-ray source, plus
it is low cost, simple and robust," said research team leader Sharon
Shwartz from Bar-Ilan University in Israel. "Thus, it opens up the
possibility of using x- rays to measure fast dynamics outside the lab."
In The Optical Society (OSA) journal Optics Express, the researchers
describe their new x-ray imaging approach, which uses a non-traditional
imaging method known as ghost imaging to achieve fast imaging speeds with
high spatial resolution. They demonstrate the technique by creating an
x-ray movie of a blade rotating at 100,000 frames per second.

"Medical imaging systems based on this technique could offer a new
diagnostic tool for physicians," said Shwartz. "Our approach could,
for example, be used to acquire high-resolution movies of the heart
while greatly reducing the radiation dose for patients." Seeing through surfaces X-rays are useful for imaging because of their unique capability
to penetrate surfaces that are opaque to visible wavelengths. Traditional
x-ray imaging typically uses a pixelated camera with each pixel measuring
the intensity level of the x-ray beam at a specific position.



========================================================================== Capturing higher resolution x-ray images requires more pixels, which,
in turn, creates huge amounts of data that take time to transfer. This
creates a trade- off between imaging speed and spatial resolution
that makes it impossible to capture high-speed events with high
resolution. Although very specialized techniques involving extremely
powerful x-rays can overcome this trade-off, these x-ray sources are
only available at large synchrotrons found at a few facilities around
the world.

In the new work, the researchers turned to ghost imaging because it uses single-pixel detectors that can improve the imaging speed. 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. Because very little x-ray power comes into contact with the object being imaged, ghost imaging can also help reduce x-ray exposure when used for medical imaging.

"Although single-pixel detectors can be much faster than pixelated
detectors, they do not provide the spatial resolution necessary for
image reconstruction," said Shwartz. "We used ghost imaging to overcome
this problem and showed that we can image fast dynamics with spatial
resolution comparable to or even better than the state-of-the-art x-ray pixelated detectors." A simple solution To create the reference beam
needed for ghost imaging, the researchers used standard sandpaper mounted
on motorized stages to create a random pattern that was recorded with
a high-resolution, slow framerate pixelated x-ray camera. As the stage
was moved to each position, the x-ray beam hit a different area of the sandpaper, creating random x-ray transmissions, or intensity fluctuations.

They then removed the pixelated camera from the x-ray beam and inserted
the object to be imaged and a single-pixel detector. They moved the
motorized stages to irradiate the object with the intensity fluctuation patterns introduced at the various positions of the sandpaper and then
measured the total intensity after the beam hit the object by using the single-pixel detector.

To use this approach to image a fast-moving blade, the researchers
synchronized the measurements with the blade's movement. A final image
could then be reconstructed by correlating the reference pattern with
the intensity measured by the single-pixel detector for each position
of the blade.

The researchers created a movie of the moving blade by performing
image reconstruction frame-by-frame to capture the blade at different positions. The resulting movie clearly shows the motion with a spatial resolution of about 40 microns -- nearly an order of magnitude better
than the resolution of currently available medical imaging systems.

The researchers are continuing to make improvements to the overall system
as well as the image reconstruction algorithm to improve resolution and
shorten measurement times.


========================================================================== Story Source: Materials provided by The_Optical_Society. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. O. Sefi, Y. Klein, E. Strizhevsky, I. P. Dolbnya, S. Shwartz. X-ray
imaging of fast dynamics with single-pixel detector. Optics Express,
2020; 28 (17): 24568 DOI: 10.1364/OE.396497 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200805124032.htm

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