X rays

X-radiation (composed of X-rays) is a form of electromagnetic radiation.

Characetrsteics

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.

Uses

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.

Dosage

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

Soft

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.

Hard

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.

Distinction

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

Tungsten

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

Molibdenum

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

Copper

In crystallography, a copper target is most common.

Detectors

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.