Surgery and Radiology Section

IRRADIATION

• Sun light has a powerful germicidal action and exposure for sufficient time will produce sterilization.
• This action of sun light is mainly due to its contents of ultraviolet light having a wave length of 300–400 nm.
• The ultraviolet rays are absorbed by nucleic  acid and result in death of the cell.
• The ultraviolet rays are produced artificially by mercury vapour lamps and are used for sterilization of environment of the operating rooms and are not deep penetrating.
• They act on the surface only. Low pressure mercury vapour lamps, emitting 90% at 254nm, are widely used to decrease air borne infection. Eg. Surgical operation room, animal houses.
• It is important to protect eye by glasses, as excessive exposure of the cornea to the ultraviolet causes severe irritation.
• The shorter electromagnetic wavelength atomic rays (x-rays, gamma rays, beta rays) cause ionization of the living (or) non-living.
• These rays are deep penetrating and are used commercially for sterilization of heat sensitive material such as disposable poly ethylene (or) plastic catheters etc.