New simple setup for X-ray phase contrast

Jul 11, 2014
The scientists used a plastic flower as microscopic object. Credit: I. Zanette / TUM

X-ray phase-contrast imaging is a method that uses the refraction of X-rays through a specimen instead of attenuation resulting from absorption. The images produced with this method are often of much higher quality than those based on absorption. The scientists in the team of Prof. Franz Pfeiffer are particularly interested in developing new approaches for biomedical X-ray imaging and therapy – including X-ray phase-contrast imaging. One main goal is to make this method available for clinical applications such as diagnosis of cancer or osteoporosis in the future.

In their new study, the scientists have now developed an extremely simple setup to produce X-ray phase-contrast images. The solution to many of their difficulties may seem counter-intuitive: Scramble the X-rays to give them a random structure. These speckles, as they are called in the field, encode a wealth of information on the sample as they travel through it. The scrambled X-rays are collected with a high-resolution X-ray camera, and the information is then extracted in a post-measurement analysis step.

High accuracy and new X-ray source

Using their new technique, the researchers have demonstrated the efficiency and versatility of their approach. "From a single measurement, we obtain an attenuation image, the phase image, but also a dark-field image," explains Dr. Irene Zanette, lead author of the publication. "The phase image can be used to measure accurately the specimen's projected thickness. The dark-field image can be just as important because it maps structures in the specimen too small to be resolved, such as cracks or fibers in materials," she adds.

The source's high brightness is also key to these results. "In the source we used a liquid metal jet as the X-ray-producing target instead of the solid targets normally used in laboratory X-ray sources," says Tunhe Zhou from KTH Stockholm, project partner of the TUM. "This makes it possible to gain the high intensity needed for phase-contrast imaging without damaging the X-ray-producing target." To obtain all at once, an algorithm scans the speckles and analyzes the minute changes in their shape and position caused by the specimen.

But not all components of the new instrument are products of the latest cutting-edge technology. To scramble the X-rays, "we have found that a simple piece of sandpaper did the job perfectly well," adds Dr. Zanette.

The researchers are already working toward the next steps. "As a single-shot technique, speckle imaging is a perfect candidate for an efficient extension to phase-contrast tomography, which would give a three-dimensional insight into the microstructure of the investigated object," Zanette explains.

Explore further: Scientists make huge strides in imaging science

More information: I. Zanette, T. Zhou, A. Burvall, U. Lundström, D. H. Larsson, M. Zdora, P. Thibault, F. Pfeiffer, and H. M. Hertz. Speckle-based X-ray Phase-contrast and Dark-Field Imaging with a Laboratory Source. Phys. Rev. Lett., 2014. DOI: 10.1103/PhysRevLett.112.253903

Related Stories

Scientists make huge strides in imaging science

Jun 02, 2014

(Phys.org) —University scientists have developed a rapid new technique involving X-ray imaging that allows clear images to be obtained displaying the orientational properties of molecules in solid materials.

Phase contrast improves mammography

May 15, 2014

Phase contrast X-ray imaging has enabled researchers at ETH Zurich, the Paul Scherrer Institute (PSI) and the Kantonsspital Baden to perform mammographic imaging that allows greater precision in the assessment ...

Recommended for you

Researchers prove magnetism can control heat, sound

7 hours ago

Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by ...

How researchers listen for gravitational waves

16 hours ago

A century ago, Albert Einstein postulated the existence of gravitational waves in his General Theory of Relativity. But until now, these distortions of space-time have remained stubbornly hidden from direct ...

What's fair?: New theory on income inequality

May 27, 2015

The increasing inequality in income and wealth in recent years, together with excessive pay packages of CEOs in the U.S. and abroad, is of growing concern, especially to policy makers. Income inequality was ...

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.