пятница, 26 июля 2019 г.

A Day in Our Lives With X-Ray Tech

On July 23, 1999, NASA’s Chandra X-ray Observatory, the most powerful X-ray telescope ever built, was launched into space. Since then, Chandra has made numerous amazing discoveries, giving us a view of the universe that is largely hidden from view through telescopes that observe in other types of light.


The technology behind X-ray astronomy has evolved at a rapid pace, producing and contributing to many spinoff applications you encounter in day-to-day life. It has helped make advancements in such wide-ranging fields as security monitoring, medicine and bio-medical research, materials processing, semi-conductor and microchip manufacturing and environmental monitoring.

7:00 am: Your hand has been bothering you ever since you caught that ball at the family reunion last weekend. Your doctor decides it would be a good idea for an X-ray to rule out any broken bones. X-rays are sent through your hand and their shadow is captured on a detector behind it. You’re relieved to hear nothing is broken, though your doctor follows up with an MRI to make sure the tendons and ligaments are OK.

Two major developments influenced by X-ray astronomy include the use of sensitive detectors to provide low dose but high-resolution images, and the linkage with digitizing and image processing systems. Because many diagnostic procedures, such as mammographies and osteoporosis scans, require multiple exposures, it is important that each dosage be as low as possible. Accurate diagnoses also depend on the ability to view the patient from many different angles. Image processing systems linked to detectors capable of recording single X-ray photons, like those developed for X-ray astronomy purposes, provide doctors with the required data manipulation and enhancement capabilities. Smaller hand-held imaging systems can be used in clinics and under field conditions to diagnose sports injuries, to conduct outpatient surgery and in the care of premature and newborn babies.


8:00 am: A technician places your hand in a large cylindrical machine that whirs and groans as the MRI is taken. Unlike X-rays that can look at bones and dense structures, MRIs use magnets and short bursts of radio waves to see everything from organs to muscles.

MRI systems are incredibly important for diagnosing a whole host of potential medical problems and conditions. X-ray technology has helped MRIs. For example, one of the instruments developed for use on Chandra was an X-ray spectrometer that would precisely measure the energy signatures over a key range of X-rays. In order to make these observations, this X-ray spectrometer had to be cooled to extremely low temperatures. Researchers at our Goddard Space Flight Center in Greenbelt, Maryland developed an innovative magnet that could achieve these very cold temperatures using a fraction of the helium that other similar magnets needed, thus extending the lifetime of the instrument’s use in space. These advancements have helped make MRIs safer and require less maintenance.


11:00 am:  There’s a pharmacy nearby so you head over to pick up allergy medicine on the way home from your doctor’s appointment.

X-ray diffraction is the technique where X-ray light changes its direction by amounts that depend on the X-ray energy, much like a prism separates light into its component colors. Scientists using Chandra take advantage of diffraction to reveal important information about distant cosmic sources using the observatory’s two gratings instruments, the High Energy Transmission Grating Spectrometer (HETGS) and the Low Energy Transmission Grating Spectrometer (LETGS).

X-ray diffraction is also used in biomedical and pharmaceutical fields to investigate complex molecular structures, including basic research with viruses, proteins, vaccines and drugs, as well as for cancer, AIDS and immunology studies. How does this work? In most applications, the subject molecule is crystallized and then irradiated. The resulting diffraction pattern establishes the composition of the material. X-rays are perfect for this work because of their ability to resolve small objects. Advances in detector sensitivity and focused beam optics have allowed for the development of systems where exposure times have been shortened from hours to seconds. Shorter exposures coupled with lower-intensity radiation have allowed researchers to prepare smaller crystals, avoid damage to samples and speed up their data runs.


12:00 pm: Don’t forget lunch. There’s not much time after your errands so you grab a bag of pretzels. Food safety procedures for packaged goods include the use of X-ray scans to make sure there is quality control while on the production line.

Advanced X-ray detectors with image displays inspect the quality of goods being produced or packaged on a production line. With these systems, the goods do not have to be brought to a special screening area and the production line does not have to be disrupted. The systems range from portable, hand-held models to large automated systems. They are used on such products as aircraft and rocket parts and structures, canned and packaged foods, electronics, semiconductors and microchips, thermal insulations and automobile tires.


2:00 pm: At work, you are busy multi-tasking across a number of projects, running webinar and presentation software, as well as applications for your calendar, spreadsheets, word processing, image editing and email (and perhaps some social media on the side). It’s helpful that your computer can so easily handle running many applications at once.

X-ray beam lithography can produce extremely fine lines and has applications for developing computer chips and other semiconductor related devices. Several companies are researching the use of focused X-ray synchrotron beams as the energy source for this process, since these powerful beams produce good pattern definition with relatively short exposure times. The grazing incidence optics — that is, the need to skip X-rays off a smooth mirror surface like a stone across a pond and then focus them elsewhere — developed for Chandra were the highest precision X-ray optics in the world and directly influenced this work.


7:00 pm: Dream vacation with your family. Finally!  You are on your way to the Bahamas to swim with the dolphins. In the line for airport security, carry-on bags in hand, you are hoping you’ve remembered sunscreen. Shoes off! All items placed in the tray. Thanks to X-ray technology, your bags will be inspected quickly and you WILL catch your plane…

The first X-ray baggage inspection system for airports used detectors nearly identical to those flown in the Apollo program to measure fluorescent X-rays from the Moon. Its design took advantage of the sensitivity of the detectors that enabled the size, power requirements and radiation exposure of the system to be reduced to limits practical for public use, while still providing adequate resolution to effectively screen baggage.  The company that developed the technology later developed a system that can simultaneously image, on two separate screens, materials of high atomic weight (e.g. metal hand guns) and materials of low atomic weight (e.g. plastic explosives) that pass through other systems undetected. Variations of these machines are used to screen visitors to public buildings around the world.

Check out Chandra’s 20th anniversary page to see how they are celebrating.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

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