News tagged with x rays

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Gov't says full-body scanners at airports are safe

(AP) -- They look a little like giant refrigerators and pack a radiation dose big enough to peer through clothing for bombs or weapons, yet too minuscule to be harmful, federal officials insist. As the government rolls out ...

Nov 18, 2010
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FDA clears Siemens' 2-in-1 medical scanner

(AP) -- The Food and Drug Administration says it has cleared the first medical imaging device to simultaneously perform two powerful scans used to diagnose a wide variety of diseases and ailments.

Jun 10, 2011
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Worried about a radioactive ocean? A reality check

(AP) -- This week, workers at the stricken Japanese nuclear plant dumped radioactive water into the ocean to make room for storing even more highly contaminated water on the site. The water dumping came after earlier leaks ...

Apr 06, 2011
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Americans get most radiation from medical scans

(AP) -- We fret about airport scanners, power lines, cell phones and even microwaves. It's true that we get too much radiation. But it's not from those sources - it's from too many medical tests.

Jun 14, 2010
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X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3 × 1016 Hz to 3 × 1019 Hz) and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays. In many languages, X-radiation is called Röntgen radiation after Wilhelm Conrad Röntgen, who is generally credited as their discoverer, and who had called them X-rays to signify an unknown type of radiation.:1-2

X-rays are primarily used for diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. X-rays are a form of ionizing radiation and as such can be dangerous.

X-rays from about 0.12 to 12 keV are classified as soft X-rays, and from about 12 to 120 keV as hard X-rays, due to their penetrating abilities.

The distinction between X-rays and gamma rays has changed in recent decades. Originally, the electromagnetic radiation emitted by X-ray tubes had a longer wavelength than the radiation emitted by radioactive nuclei (gamma rays). So older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m, defined as gamma rays. However, as shorter wavelength continuous spectrum "X-ray" sources such as linear accelerators and longer wavelength "gamma ray" emitters were discovered, the wavelength bands largely overlapped. The two types of radiation are now usually defined by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.

This text uses material from Wikipedia, licensed under CC BY-SA

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