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.

They are longer than gamma rays but shorter than UV rays. In many languages, X-radiation is called Röntgen radiation after one of its first investigators, Wilhelm Conrad Röntgen.


X-rays are primarily used for diagnostic radiography and crystallography.

Radiographs obtained using X-rays can be used to identify a wide spectrum of pathologies. Due to their short wavelength, in medical applications, X-rays act more like a particle than a wave.

This is in contrast to their application in crystallography, where their wave-like nature is most important.

Differenet forms[]

X-rays span 3 decades in wavelength, frequency and energy. From about 0.12 to 12 keV they are classified as soft x-rays, and from about 12 to 120 keV as hard X-rays, due to their penetrating abilities.

Unit of measure and exposure[]

The rem is the traditional unit of dose equivalent.


Reported dosage due to dental X-rays seems to vary significantly. Depending on the source, a typical dental X-ray of a human results in an exposure of perhaps, 3, mrems (30 to 9,000 μSv).

How done-medical physics[]


When medical X-rays are being produced, a thin metallic sheet is placed between the emitter and the target, effectively filtering out the lower energy soft X-rays.


A thin metallic sheet is often placed close to the window of the X-ray tube. The resultant X-ray is said to be hard.


However the distinction between the two terms in medicine depends on the source of the radiation, not its wavelength.

Medical application[]

The basic production of X-rays is by accelerating electrons in order to collide with a metal target.

Metal used[]


In medical applications, this is usually tungsten or a more crack-resistant alloy of rhenium (5%) and tungsten (95%).


But sometimes molybdenum is used for more specialized applications, such as when soft X-rays are needed as in mammography.


In crystallography, a copper target is most common.


Photographic plate[]

The detection of X-rays is based on various methods. The most commonly known methods are a photographic plate, X-ray film in a cassette, and rare earth screens.

Before computers and before digital imaging, a photographic plate was used to produce radiographic images. Now computed & digital radiography has started to replace film in medicine, though film technology is still used in industrial radiography processes.

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