Introduction
X–rays belong to a group of radiation called electromagnetic radiation which is essentially the transport of energy through space on a combination of electric and magnetic fields.

William Conrad Roentgen, a German physicist, discovered X–rays on November 8, 1895, through a series of fortunate coincidences while he was investigating the behavior of cathode rays (electrons) in high–energy cathode ray tubes.

By December 28, 1895 he had thoroughly investigated the properties of X–rays and prepared a manuscript which revolutionized the field of diagnosis. For this outstanding achievement, William C. Roentgen was awarded the first Nobel Prize for Physics in 1901.

Clinical applications of X–rays
Every part of the body, from head to toe, can be examined by X–rays. X–rays for certain parts of the body like the abdomen and lumbar spine need prior preparation (with bowel cleansing agents) and fasting to avoid misinterpretation. Other X–rays do not require any prior preparation.

Harmful Effects
All ionizing radiations are harmful hence, a radiation protection policy at all level is mandatory.

The harmful effects fall into two broad categories
Somatic effects
Harmful to the person being irradiated, for example, carcinogenesis

Genetic effects
Harmful to future generations. These are more frightening because they may not manifest for several generations and each new mutant constitutes a potential burden to society.

Mechanism
X–rays are produced by energy conversion when a fast–moving stream of electrons is suddenly decelerated in the target (usually tungsten or an alloy of tungsten) of an X–ray tube (a specially designed vacuum diode tube).

This energy is supplied to the tube by an X–ray generator connected to an incoming electric supply. X–rays pass through the body and carry information about the areas through which they have passed. The information is played on a special X–ray film/monitor for interpretation.

Radiological Procedures
These procedures include a vast spectrum of diagnostic examinations by administration of contrast material followed by radiological exposures.

• Oral (gastro intestinal tract).
• Intravenous/intraarterial/Intralymphatic.
• Per rectal (large intestine).
• Per urethral/vaginal (genitourinary system).
• Laryngo–tracheal (lungs and bronchial tree).
• Intraarticular (joints).
• Intraspinal (spine).

X–rays in Pregnancy
When a pregnant woman requires an X–ray and the primary beam irradiates the foetus, at the outset care shared be taken to ascertain whether the examination is really indicated.

X–rays should be avoided as far as possible in the first trimester, during the period of organogenesis. The number of exposures and absorbed dose per exposure must be kept to a minimum. Lead protection devices and proper collumation of the X–ray beam must be employed.