X-Rays are defined as a weightless package of pure energy (Photon) that are without electrical charge and that travel in waves along a straight line with a specific frequency and speed. X-rays were first produced by Sir William Morgan unknowingly while conducting one of his experiments. The first dentist to practice radiography in Dentistry was by Dr. C. Edmund Kells, who used it in a Root Canal procedure on May 10, 1899. 

X-Rays are pure energy having no mass and they transfer energy from one place to another in the form of photons. X-Rays do not have smell or sound and cannot be visible to the eye although they have the same wavelength as visible light. 

The Properties Of X-Ray are divided into 4 headings:

  1. Physical
  2. Chemical
  3. Biological
  4. Physiochemical

A) Physical Properties:

  1. X-Rays are electromagnetic radiations having a wavelength between 10A to 0.01A
  2. In Free Space, they travel in a straight line
  3. Speed – 1,86,000 miles/sec (same as that of visible light)
  4. X-rays Cannot be Focused on a Single Point
  5. They are Invisible to Eye.
  6. Cannot be Heard
  7. Cannot be Smelt
  8. They cannot be Reflected, Refracted or Deflected by magnetic or Electric Field
  9. They show properties of Interference, Diffraction and Refraction similar to Visible light
  10. They Produce an Electric field at right angles to their path of propagation
  11. They Produce an Magnetic Field at right angles to the electric field and path of propagation.
  12. They donot require any medium for propagation
  13. Penetration: X-Rays can penetrate liquids, solids and gases. The degree of penetration depends on Quality, intensity and wavelength of Xyray beam.
  14. Absorption: X-Rays are absorbed by matter, the absorption depends on the anatomic structure of the matter and the wavelength of the xray beam.
  15. Ionizing Capability: X-rays interact with materials they penetrate and cause ionization
  16. Fluorescence: when X-Rays fall upon certain materials visible light will be emitted called fluorescence.
  17. X-Rays have the property of Attenuation, Absorption and Scattering
  18. They also show Heating effect

B) Chemical Properties:

  1. X-Ray induces color changes of several substances or their solutions Ex: Methylene Blue gets Bleached
  2. X-Rays bring about chemical changes in solution because X-Rays produce highly active radical OH ions in water, which react with the solutes.
  3. X-Rays cause the destruction of the fermenting powers of Enzymes

C) Biological Properties:

  1. The excitation property of X-Rays is used in the treatment of malignant lesions.
  2. X-Rays also have a germicidal or bactericidal effect
  3. Somatic Effect: This ranges from simple Sun Burn to Severe dermatitis or to change in blood supply to malignancy
  4. Genetic Effect

D) Physiochemical Property:

  1. X-rays are capable of producing an image on a photographic film
  2. The surface of the photographic paper which is exposed to X-Rays will be developed and found blackened. The blackening is known as film density. 
  3. The amount of blackening of the film depends on various factors like – Amount of radiation, Quality of radiation, Characteristic of a film, length of developing time, use of intensifying screens or Concentration and age of developing solution


Oral Radiology – Principles & Interpretation (6th Edition) by While and Pharoah

Essential of Oral and Maxillofacial Radiology by Freny R. Karjodkar