Radiation is defined as a transmission or emission of energy in the form of waves or particles through space or through a material medium according to physics.
Radiation has dual nature photons (particles) and waves.
Types of radiation:
- Electromagnetic radiation: radio waves, microwaves, infrared, visible light, ultrasound, x-rays, & gamma radiation.
- Particle radiation: alpha radiation beta radiation, neutron radiation.
- Acoustic radiation: seismic waves and ultrasonic waves.
- Gravitational radiation: radiation that takes the gravitational waves formation.
Radiation is further categorized in ionizing radiation and non-ionizing radiation.
Ionizing radiation: The radiation which dissociate the matter into ions by breaking chemical bonds. The energy carried by ionizing radiation is very high i.e. >10eV, and able to ionize the molecule and atoms.
Non-ionizing radiation: The radiation which is not able to dissociate or ionize the atoms and molecules.
Sources of radiation
Natural source of ionizing radiation: We get natural radiation from the food we eat, the air we breathe, the water we drink ever the human body give off the radiation i.e. infrared radiation. The ionizing radiation produced from natural and man-made radioactive materials. At present the environment contain natural occurring radioactive elements like uranium, thorium, actinium and potassium-40. These elements exist in the material that makes the planet Earth. We also get radiation from the atmosphere this radiation comes from outer space and known as cosmic radiation.
There are the types of natural source of radiation:
- Terrestrial radiation: The radiation which comes from the soil, rocks or mountains in which the natural radioactive materials continuously dissociates and gives radiation.
- Sun: This source gives ultraviolet radiation which is very harmful to all living things.
- Internal radiation: This type of radiation is received within the body of the various mammals by the ingestion of the food particles and some ions present on their bodies like Ca2++ Mg2+ K+ Cl– etc.
- Cosmic radiation: They are the major natural source of radiation which is continuously providing external exposure to all the living beings. The major source of this radiation is Earth’s atmosphere and magnetic field originating from the gravitational force of the Earth. People living at sea levels receives an average dose of about 0.3milli sievert while the people living at high altitudes may receive a radiation does up to 0.02-0.08 milli sievert.
- Radon gas: It is a gas which is present in the form of a radio nuclei originates from the Earth’s crust. This gas is produced from the decay of uranium238, when this gas is inhaled by the living beings it causes respiratory system disorders with alpha particles. This gas causes cancer in both smokers and non-smokers.
- Sources from food and drinks: Food materials and water may contain radioactive particles which is easily transferred into the alimentary canal of living being. Many non-vegetarian food materials contain high amount of lead and polonium which gives high radiation dose to the internal structure and organs. For example: fish, red meat, lichen etc.
Artificial source of ionizing radiation: the artificial radiation is that radiation which is produced artificially for the various purpose. There are three main sources for artificial ionizing radiation:
- Medical devices: The use of radiation in hospital to diagnose various disease place an important role to provide high amount of radiation dose to the world population. Approximately 98% radiation is produced from the artificial sources.
- Diagnostic radiology: The diagnostic radiology produces the image of internal anatomical structures by using x-ray machines, CT scan machines and fluoroscopy machine. These imaging modalities using the ionizing radiation and contributes in radiation exposure. Interventional radiology or Cath lab department also uses radiation producing devices for the diagnosis and treatment of blood vessels.
- Nuclear medicine: In nuclear medicine department the radioactive materials or drugs are used. They are introduced into the body of humans and produce images of internal structures. The nuclear medicine department is mainly concern with the treatment of malignancy disorders.
- Radiotherapy/radiation therapy: The radiation therapy department use a very high amount of radiation for the treatment of the cancer and benign tumors. Radiation therapy machine uses the radioactive material cobalt 60.