Radiology & Imaging

Breakthrough X-ray technology goes from concept to medical standard

Detecting a deadly tumor as early as possible is vital to stopping its spread. However, creating the solution doesn't necessarily solve the problem—it needs to be widely adopted by medical professionals. That's why standards ...

Diseases, Conditions, Syndromes

How worried should we be about the pneumonia outbreak in China?

Reports of a surge in pneumonia-like illness primarily affecting children in northern China have captured our attention. The last time we heard about a mysterious respiratory outbreak leading to overcrowding in hospitals ...

Oncology & Cancer

Bendy X-ray detectors could revolutionize cancer treatment

New materials developed at the University of Surrey could pave the way for a new generation of flexible X-ray detectors, with potential applications ranging from cancer treatment to better airport scanners.

Oncology & Cancer

Canceling cancer with T cells

What if we could engineer our immune system to make the human body better at fighting cancer? Professor Roy Mariuzza is part of a major research effort aimed at doing just that. An expert in the structural biology of immune ...

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X-ray

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.

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