Category Archives: Science

Compact light source improves CT scans

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The Compact Light Source by Palo Alto-based Lyncean Technologies Inc. generates X-rays suitable for advanced tomography. The car-sized device is a miniature version of football-field-sized X-ray generators known as synchrotrons and it emerged from basic research at SLAC in the late 1990s and early 2000s.
Credit: Lyncean Technologies Inc.

A new study shows that the recently developed Compact Light Source (CLS) — a commercial X-ray source with roots in research and development efforts at the Department of Energy’s SLAC National Accelerator Laboratory — enables computer tomography scans that reveal more detail than routine scans performed at hospitals today. The new technology could soon be used in preclinical studies and help researchers better understand cancer and other diseases.

With its ability to image cross sections of the human body, X-ray computer tomography (CT) has become an important diagnostic tool in medicine. Conventional CT scans are very detailed when it comes to bones and other dense body parts that strongly absorb X-rays. However, the technique struggles with the visualization and distinction of “soft tissues” such as organs, which are more transparent to X-rays.

“Our work demonstrates that we can achieve better results with the Compact Light Source,” says Professor for Biomedical Physics Franz Pfeiffer of the Technical University of Munich in Germany, who led the new study published April 20 in the Proceedings of the National Academy of Sciences. “The CLS allows us to do multimodal tomography scans — a more advanced approach to X-ray imaging.”

More than One Kind of Contrast

The amount of detail in a CT scan depends on the difference in brightness, or contrast, which makes one type of tissue distinguishable from another. The absorption of X-rays — the basis for standard CT — is only one way to create contrast.

Alternatively, contrast can be generated from differences in how tissues change the direction of incoming X-rays, either through bending or scattering X-ray light. These techniques are known as phase-contrast and dark-field CT, respectively.

“Organs and other soft tissues don’t have a large absorption contrast, but they become visible in phase-contrast tomography,” says the study’s lead author, Elena Eggl, a researcher at the Technical University of Munich. “The dark-field method, on the other hand, is particularly sensitive to structures like vertebrae and the lung’s alveoli.”

Shrinking the Synchrotron

However, these methods require X-ray light with a well-defined wavelength aligned in a particular way — properties that conventional CT scanners in hospitals do not deliver sufficiently.

For high-quality phase-contrast and dark-field imaging, researchers can use synchrotrons — dedicated facilities where electrons run laps in football-stadium-sized storage rings to produce the desired radiation — but these are large and expensive machines that cannot simply be implemented at every research institute and clinic.

Conversely, the CLS is a miniature version of a synchrotron that produces suitable X-rays by colliding laser light with electrons circulating in a desk-sized storage ring. Due to its small footprint and lower cost, it could be operated in almost any location.

“The Large Hadron Collider at CERN is the world’s largest colliding beam storage ring, and the CLS is the smallest,” says SLAC scientist Ronald Ruth, one of the study’s co-authors. Ruth is also chairman of the board of directors and co-founder of Palo Alto-based Lyncean Technologies Inc., which developed the X-ray source based on earlier fundamental research at SLAC. “It turns out that the properties of the CLS are perfect for applications like tomography.”

More Modes, Finer Detail

In the recent study, the researchers reported the first “multimodal” CT scan with the CLS: They recorded all three imaging modes — absorption, phase contrast and dark field — at the same time. Using a total of 361 two-dimensional X-ray images of an infant mouse taken from different directions, the scientists generated cross-section images of the animal.

“The absorption images only show bones and air-filled organs,” Eggl says. “However, the phase-contrast and dark-field images reveal much more detail, showing different organs such as the heart and liver. We can even distinguish different types of fat tissue, which is not possible with absorption-based CT scans.”

Using a standard sample of chemically well-defined liquids, the scientists also demonstrated that they could not only visualize but also quantify differences in their properties — information that can be applied to various body tissues and that is only obtained when combining all three tomography modes.

Implications for Cancer, Materials

The success of this research, which was done on a CLS prototype, has led to the commissioning of the first commercial device.

The researchers’ next goal is to use the CLS for phase-contrast and dark-field CT in preclinical studies — an approach that could help visualize cancer. “We work closely together with two clinics to study tumors,” Eggl says. “One of our plans is to image breast tissue samples and also entire breasts after mastectomy to better understand the clinical picture of breast cancer.”

Besides medical applications, multimodal tomography could also open up new possibilities in materials science, for instance, in studies of extremely durable and light-weight carbon fibers and other fibrous materials, where the X-ray absorption contrast provides little information.

Please follow this link to Science Daily for the original story.

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A New High-Speed MRI Technique Is Fast Enough To Record Someone Singing

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It’s a remarkable technology capable of looking inside a human being, but magnetic resonance imaging—or MRI—machines are finicky and require a patient to remain absolutely still while it does its thing. But researchers at the University of Illinois have found a way to capture up to 100 frames per second on an MRI machine allowing them to record patients in motion.

The need for a faster MRI technique arose when a faculty member at the University of Illinois’ Beckman Institute for Advanced Science and Technology wanted to study how the muscles of the larynx worked in elderly patients while singing, in an attempt to help give them more powerful and pronounced voices. The problem with using MRI machines was that they could only capture images at around ten frames per second which was far too slow to study what was going on with the 100 or so muscles required to sing.

So Zhi-Pei Liang, an electrical and computer engineering professor at the institute, worked with his team to develop a new methodology to extract more frames from an MRI machine—which is a far cheaper solution than trying to rebuild and redesign one of the incredibly expensive devices from the ground up. Here’s how the new technique they came up with is described in an issue of Magnetic Resonance in Medicine:

An imaging method is developed to enable high-speed dynamic speech imaging exploiting low-rank and sparsity of the dynamic images of articulatory motion during speech. The proposed method includes: (a) a novel data acquisition strategy that collects spiral navigators with high temporal frame rate and (b) an image reconstruction method that derives temporal subspaces from navigators and reconstructs high-resolution images from sparsely sampled data with joint low-rank and sparsity constraints.

To read the full story and for more information please follow this link to Gizmodo.

NASA Beams “Hello, World!” Video from Space via Laser

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NASA successfully beamed a high-definition video 260 miles from the International Space Station to Earth Thursday using a new laser communications instrument.

Transmission of “Hello, World!” as a video message was the first 175-megabit communication for the Optical Payload for Lasercomm Science (OPALS), a technology demonstration that allows NASA to test methods for communication with future spacecraft using higher bandwidth than radio waves.

“The International Space Station is a test bed for a host of technologies that are helping us increase our knowledge of how we operate in space and enable us to explore even farther into the solar system,” said Sam Scimemi, International Space Station division director at NASA Headquarters in Washington. “Using the space station to investigate ways we can improve communication rates with spacecraft beyond low-Earth orbit is another example of how the orbital complex serves as a stepping stone to human deep space exploration.”

Optical communication tools like OPALS use focused laser energy to reach data rates between 10 and 1,000 times higher than current space communications, which rely on radio portions of the electromagnetic spectrum.

Because the space station orbits Earth at 17,500 mph, transmitting data from the space station to Earth requires extremely precise targeting. The process can be equated to a person aiming a laser pointer at the end of a human hair 30 feet away and keeping it there while walking.

To achieve this extreme precision during Thursday’s demonstration, OPALS locked onto a laser beacon emitted by the Optical Communications Telescope Laboratory ground station at the Table Mountain Observatory in Wrightwood, California, and began to modulate the beam from its 2.5-watt, 1,550-nanometer laser to transmit the video. The entire transmission lasted 148 seconds and reached a maximum data transmission rate of 50 megabits per second. It took OPALS 3.5 seconds to transmit each copy of the “Hello World!” video message, which would have taken more than 10 minutes using traditional downlink methods.

“It’s incredible to see this magnificent beam of light arriving from our tiny payload on the space station,” said Matt Abrahamson, OPALS mission manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “We look forward to experimenting with OPALS over the coming months in hopes that our findings will lead to optical communications capabilities for future deep space exploration missions.”

The OPALS Project Office is based at JPL, where the instrument was built.  OPALS arrived to the space station April 20 aboard SpaceX’s Dragon cargo spacecraft and is slated to run for a prime mission of 90 days.

View the “Hello, World!” video transmission and animation of the transmission between OPALS and the ground station, at:

http://youtu.be/1efsA8PQmDA

For more information about OPALS, visit:

http://go.nasa.gov/10MMPDO

For more information about the International Space Station, visit:

http://www.nasa.gov/station

Source: NASA

Scientists discover how to turn light into matter after 80-year quest

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This shows theories describing light and matter interactions.
Credit: Oliver Pike, Imperial College London

Imperial College London physicists have discovered how to create matter from light — a feat thought impossible when the idea was first theorised 80 years ago.

In just one day over several cups of coffee in a tiny office in Imperial’s Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.

Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron — the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

The new research, published in Nature Photonics, shows for the first time how Breit and Wheeler’s theory could be proven in practice. This ‘photon-photon collider’, which would convert light directly into matter using technology that is already available, would be a new type of high-energy physics experiment. This experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts, which are the biggest explosions in the universe and one of physics’ greatest unsolved mysteries.

The scientists had been investigating unrelated problems in fusion energy when they realised what they were working on could be applied to the Breit-Wheeler theory. The breakthrough was achieved in collaboration with a fellow theoretical physicist from the Max Planck Institute for Nuclear Physics, who happened to be visiting Imperial.

Demonstrating the Breit-Wheeler theory would provide the final jigsaw piece of a physics puzzle which describes the simplest ways in which light and matter interact (see image in notes to editors). The six other pieces in that puzzle, including Dirac’s 1930 theory on the annihilation of electrons and positrons and Einstein’s 1905 theory on the photoelectric effect, are all associated with Nobel Prize-winning research (see image).

Professor Steve Rose from the Department of Physics at Imperial College London said: “Despite all physicists accepting the theory to be true, when Breit and Wheeler first proposed the theory, they said that they never expected it be shown in the laboratory. Today, nearly 80 years later, we prove them wrong. What was so surprising to us was the discovery of how we can create matter directly from light using the technology that we have today in the UK. As we are theorists we are now talking to others who can use our ideas to undertake this landmark experiment.”

The collider experiment that the scientists have proposed involves two key steps. First, the scientists would use an extremely powerful high-intensity laser to speed up electrons to just below the speed of light. They would then fire these electrons into a slab of gold to create a beam of photons a billion times more energetic than visible light.

The next stage of the experiment involves a tiny gold can called a hohlraum (German for ’empty room’). Scientists would fire a high-energy laser at the inner surface of this gold can, to create a thermal radiation field, generating light similar to the light emitted by stars.

They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can.

For more and the original story follow the link below.

Source: Science Daily