X-Ray Imaging

The process of producing x-ray images

When a negatively charged electrode is heated, it causes the electrons to be emitted from it, which produces energy. In x-ray imaging, this energy is directed towards a metal plate at high velocity. When the energy collides with the atoms in the plate, x-rays are created.

An x-ray machine.

The process begins with the patient lying down on or standing up in front of a cassette. This cassette includes a film that is exposed to the x-ray wave. First, the x-ray wave enters the body, passing through organs, muscles, and bones. As the soft tissue cannot absorb the electromagnetic wave, it passes through and leaves the film under or behind the patient exposed, which leads to these areas appearing in black in the final image.

The bones and hard tissues absorb the electromagnetic x-ray wave so it cannot get through to the film as easily, which makes these areas appear in light grey or white in the image.

A neck x-ray scan.

What are the applications of X-ray imaging?

X-ray imaging has applications in medical, dental, and industrial fields. Most of these applications are based on the x-ray’s ability to pass through matter. In medical physics, x-ray imaging is used for a variety of purposes, such as getting an image of broken bones, swallowed objects, lung infections, or damage to bones from arthritis. X-rays are also used with CT scanners to help achieve a layer-by-layer image.

In industry, x-ray imaging can help to analyse paintings to reveal their age or underlying brushstroke methods to identify or verify the artist.

Another common use of x-ray imaging is to scan passengers or luggage at airports or malls. When used for luggage, the machine has a detector that detects the x-rays after they pass through the object. The x-rays are then sent through a filter, which filters out the lower-energy x-rays while the high-energy x-rays are detected by a second detector. A computer compares the data yielded by the two detectors to better depict low-energy items, such as most biological compounds.

Since different objects absorb different amounts of x-rays, these differences can be seen on the screen used by the operator. There are three primary categories depending on the spectrum of energy that passes through the object: organic, inorganic, and metal.

X-ray imaging being used in an airport luggage scanner.

Applications of x-rays in materials and chemistry sampling

There are three x-ray imaging techniques used for a variety of purposes. They are: x-ray fluorescence spectrometry, particle-induced x-ray emission (PIXE) spectrometry, and x-ray diffraction.

• X-ray fluorescence spectrometry is a non-lethal analytical method for identifying elements and their quantities in solid, powdered, and liquid samples.
• Particle-induced x-ray emission (PIXE) is an analytical approach based on the theory of x-ray emission. Also known as proton-induced x-ray emission, this is a strong, non-destructive analytical method that can identify all elements from sodium to uranium in solids, liquids, thin films, and aerosol filter materials.
• X-ray diffraction or XRD is a flexible, non-destructive analytical method for identifying and quantifying the many crystalline forms of chemicals found in powdered and solid samples, known as phases.