IZLUChENIYa (radiation)

From Big Medical Encyclopedia

Allocate three types I.: electromagnetic, corpuscular and wave movement of the environment.

Scheme of a scale of a range of different types of electromagnetic radiations.

1. Electromagnetic And. — these are the electromagnetic waves which are let out by charged particles, atoms, molecules, antennas and other radiating systems. Depending on the wavelength (frequency of fluctuation) and sources of radiation distinguish x-ray emission (see), gamma radiation (see), optical radiation (see. Infrared radiation , Light , Ultraviolet radiation ), radio emissions (fig.).

Range of electromagnetic waves is ranging from 10 - 13 m (radiation of atoms and atomic kernels) to 10 - 1 m and more. And. electromagnetic waves and the speed of their distribution depend on properties of the environment. In the heterogeneous environment such phenomena as reflection, refraction, diffraction and an interference of electromagnetic waves are observed. Sources of gamma radiation are the excited atomic kernels. X-ray results from braking of the accelerated electrons, and also upon transitions of external electrons to free levels in internal covers of heavy atoms. Radiations with the optical wave band result from processes of electronic excitement, oscillating and rotary motions of molecules. Radiations of radio waves arise at the movement of alternating electric currents on conductors of the radiating systems (antennas).

2. Corpuscular And. represents a flow of atomic particles: electrons, positrons, protons, neutrons, alpha particles, etc., the kernels accompanying natural and artificial disintegration. Many of these types And. received practical application in medicine (see. Alpha therapy , Beta diagnosis , Neutron therapy , Proton therapy , Electronic therapy ).

3. Wave And. results from the mechanical movement of any object causing consecutive compression or depression of the environment. Range of the sound waves perceived by an ear of the person occupies area of frequencies from 16 Hz to 20 kHz (see. Sound ). Lower than 16 Hz the area of infrasonic waves is located (see. Infrasound ), and it is higher than 20 kHz — area of ultrasonic waves (see. Ultrasound ). On a nek-eye to data, the range of the heard sounds extends also to ultrasonic area. In the heterogeneous environment there is a reflection, refraction, diffraction and an interference of sound waves that is the basis for various methods of defectoscopy which are widely used in medicine. Radiations in the sound range are widely applied at a wedge, researches of acoustical sensitivity (see. Audiometriya ), during the definition physical. conditions of various bodies (see. Auscultation ) etc. Ultrasonic And. use in clinic for the diagnostic, therapeutic and surgical purposes (see. Ultrasonic diagnosis , Ultrasonic therapy ).

Under natural conditions the human body is constantly subject to action various And., therefore knowledge of action And. various origin on a human body gives the chance of use And. as for treatment of a number of diseases (see. Radiation therapy ), and for development of preventive actions (see. Radioprotectors ).

It is known that X-ray has property to get through opaque bodies in visible light and to give the image on a photoemulsion or to cause a luminescence of the luminescing screens (see. X-ray analysis , Roentgenoscopy ). Therefore X-ray is used for various diagnostic purposes (see. Radiodiagnosis ).

At administration of the isotopes which are letting out gamma radiation in some cases it is possible to study patol, changes in bodies and fabrics (see. Radio isotope diagnosis ). E.g., at introduction of the radioiodine collecting in a thyroid gland it is possible to diagnose patol. changes of this gland. The telecobalt 60so is widely used at treatment of malignant tumors. The cobalt radiator giving intensive gamma radiation is called the gamma gun. The electrons accelerated in the special device — the betatron, at collision with a metal target give short-wave x-ray emission (see. Particle accelerators ). Therefore betatrons are used in medicine as a source of silnopronikayushchy x-ray emission.

Ultraviolet radiation is used for air sterilization in surgery, patrimonial blocks etc.

Visible radiation is widely used in medicine at microscopic examinations, at a research of a nasopharynx, bronchial tubes, went. - kish. path, urinary tract etc.

Solar And., containing both visible beams, and an ultraviolet and invisible heat, it is widely used in to lay down. and the preventive purposes (see. Heliation , Insolation ). Artificial sources of radiation — various filament lamps are applied to the same purposes (a lamp sollyuks, infraruzh, etc.).

Laser And., possessing a high orientation and energy density And., it is applied in diagnosis and to surgical treatment (see. Laser ).

Different types of radio waves are widely used in medicine. As the main action of radio waves on biol, fabrics is connected with heat effect, they are used in physical therapy along with infrared radiation (see. Diathermy , Inductothermy , UVCh-therapy ).

See also Ionizing radiation .

Bibliography: Remizov A. N. Course of physics, t. 1 — 2, M., 1976.

Yu. M. Petrusevich.