Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laboratory breakthrough may lead to improved X-ray spectrometers

08.06.2016

Swiss researchers improve an interferometry technique by utilizing the interference fringe, an aspect previously viewed as a nuisance

Researchers at the Paul Scherrer Institute's Swiss Light Source in Villigen, Switzerland, have developed a new design for X-ray spectrometers that eschews a commonly utilized component to lowers overall production costs and increase the efficiency of x-ray flux, which may lead to faster acquisition times for sample imaging and increased efficiency for the system. This is essential for biological samples which may be damaged by continued x-ray exposure.


Directly resolved micro-meter interference fringes help reveal subtle phase contrast in the sample.

Credit: Kagias/PSI

X-ray grating interferometry is an extremely useful tool for investigating the compositions of unknown biological samples. In the traditional setup, a source of interference called the interference fringe necessitated the use of highly-sensitive detectors. In response to this, a method known as Talbot-Lau interferometry was developed and widely adopted. It renders the detector mostly inessential by decoupling the interferometer's sensitivity from the detector's resolution. However, a number of manufacturing costs and mechanical complexities ultimately complicate its implementation.

To remedy this, researchers at the Institute for Biomedical Engineering in Zurich and the Swiss Light Source (SLS) have developed an interferometer which does not use the traditional component, called a G2 grating, and instead directly exploits the fringe interference for higher resolution.

"We can perform differential phase contrast imaging with high sensitivity without the need for a G2 grating or a detector with small pixel size in order to resolve the fringe," said Matias Kagias. Kagias is a PhD student in the laboratory of Marco Stampanoni, the paper's primary investigator. Kagias and his colleagues present their work this week in Applied Physics Letters, from AIP Publishing.

X-ray interferometry works by firing X-rays at a downstream detector. When a biomedical sample or a piece of material is placed in the beam's path, the object modifies the observed interference pattern via absorption, refraction, and small-angle scattering. Once these signals are picked up by the detector, technicians can determine the sample's properties using an algorithm.

Along the way - either before or after the sample - the beams pass through a phase grating, which divides the beam into different diffraction orders based on their wavelength. The difference between these diffraction orders introduces an interference fringe - a problematic source of interference which needs to be in the micrometer range in order to achieve high sensitivity for the detector. Unfortunately, such fringes are challenging to record directly over a large field of view.

To work around this, the Talbot-Lau interferometry method utilizes an absorption grating, G2, placed right before the detector, and senses the distortions by a procedure known as phase stepping. Here, the absorption grating is scanned step by step for one or more periods of the interference fringe, each time recording an image which results in an intensity curve at each pixel. This allows the interference fringe to be sensed indirectly, while obtaining absorption, differential phase and small-angle scattering signals for each pixel.

However, this ultimately causes the system to be less efficient for each dose of x-rays due to photon absorption by G2. The required area and aspect ratio of the gratings, which are millimeter-sized, further complicate matters by driving up overall production costs.

The researchers' experimental setup consisted of an X-ray source, a single phase grating, and a GOTTHARD microstrip detector developed by the SLS detector group - a significantly simplified version of the traditional Talbot-Lau interferometer. The GOTTHARD detector uses a direct conversion sensor, in which X-ray photons are absorbed , the charge generated from one absorption event is collected by more than one channel for small channel sizes - charge sharing.

"The key point to resolving the fringe is to acquire single photon events and then interpolate their positions using the charge sharing effect, which is usually considered as a negative effect in photon counting detectors," Kagias said. By interpolating the position of many photons, a high resolution image can then be acquired.

When the researchers implemented the appropriate algorithm to analyze this recorded fringe, they found that the fringes of a few micrometers could be acquired successfully while still retrieving the differential phase signal.

According to Kagias, this ultimately increases the interferometer's flux efficiency by a factor of 2 compared to a standard Talbot-Lau interferometer. This may lead to faster acquisition times and a dose reduction, which is essential given X-rays' potential to damage biological structures.

Future work for Kagias and his colleagues involves moving to large area pixel detectors, and improving the resolution and sensitivity of their setup.

###

The article, "Single Shot X-Ray Phase Contrast Imaging Using a Direct Conversion Microstrip Detector with Single Photon Sensitivity" is authored by M. Kagias, S. Cartier, Z. Wang, A. Bergamaschi, R. Dinapoli, A. Mozzanica, B. Schmitt, and M. Stampanoni. It will appear in the journal Applied Physics Letters on June 7, 2016 (DOI: 10.1063/1.4948584). After that date, it can be accessed at: http://scitation.aip.org/content/aip/journal/apl/108/23/10.1063/1.4948584

About the journal:

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology.

http://apl.aip.org

Media Contact

John Arnst
jarnst@aip.org
301-209-3096

 @jasonbardi

http://www.aip.org 

John Arnst | EurekAlert!

Further reports about: Applied Physics G2 X-ray biological samples detector spectrometers

More articles from Physics and Astronomy:

nachricht New type of smart windows use liquid to switch from clear to reflective
14.12.2017 | The Optical Society

nachricht New ultra-thin diamond membrane is a radiobiologist's best friend
14.12.2017 | American Institute of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Plasmonic biosensors enable development of new easy-to-use health tests

14.12.2017 | Health and Medicine

New type of smart windows use liquid to switch from clear to reflective

14.12.2017 | Physics and Astronomy

BigH1 -- The key histone for male fertility

14.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>