Plain film x-ray is the most common diagnostic radiological modality used in hospitals today. They were first discovered and used for imaging purposes by Wilhelm Röntgen on 8th November 1895, when he took an image of his wife’s hand.
Basic Principles
1.Ability to create to the electromagnetic radiation at the wavelength required.
2.Ability to focus the radiation on a particular area.
3.Ability to detect the radiation once it has passed through the patient.
This all happen due to thermionic emission
Interpreting an X-Ray
1.High density tissue (e.g. bone) – absorb x-rays to a greater degree, and appear white on the film.
2.Low density tissue (e.g the lungs) – absorb x-rays to a lesser degree, and appear black on the film.
3.Intermediate density tissue (e.g. muscle and fat) – appears as shades of grey on the x-ray film.
It is important to appreciate that x-rays only give a 2D superimposed view of the body part that has been imaged. Therefore, it may be necessary to take multiple views of the same area from different angle (e.g. in cases of suspected fracture), to gain a full understanding of the injury.
