COLLIMATION (collimare — the distorted form of armor. to send collineare directly, to aim) — formation of the arranged flow of wave or corpuscular radiation in space by means of special devices. To. it is applied in astronomy, physics, medicine, etc.
In medicine it is used in spectrophotometers for receiving parallel beams of light (see. Spektrofotometriya ), in supermicroscopes — for creation of cathode rayss parallel to an optical axis of a lens for the purpose of reduction of errors in the image (see. Submicroscopy ), in radio isotope diagnosis (see. Radio isotope diagnostic units ) and radiation therapy (see) — for restriction of flow of ionizing radiation.
Collimation radio isotope — restriction of bunches of ionizing radiation with the collimator of the scintillation detector for the purpose of allocation from the general flow of radiation of a certain part of its range. The collimator represents the metal plate shielding the calculating surface of scintillator (see. Scintillation ), in a cut one or several through holes defining a space angle of the review are located.
Collimators happen the following types: single-channel, multichannel and slot-hole. Single-channel collimators (cylindrical and conical) are used at scanning (see), radio graphic and radiometric researches — gepato-and renografiya, a radio cardiography, a tserebrotsirkulografiya, a research of function of a thyroid gland, etc.; multichannel (focusing and not focusing) — during the scanning and gamma stsintigrafii (see. Stsintigrafiya ); slot-hole — at profile scanning.
For the characteristic of collimators use a number of parameters from which the greatest value have sensitivity of the collimator, its resolving power and a background. For the focusing collimators additional parameters are the focal length and depth of focus.
Bibliography: Zenkovich S. G. To a question of optimum collimation of the scintillation counter in radio isotope diagnosis of tumors, Medical radio-gramophones., t. 8, No. 3, page 77, 1963; Zubovsky G. A. and Pavlov of V. G. Skennirovaniye of internals, M., 1973, bibliogr.; Mai Intyre W. e. and. the lake of Sensitivity and resolution in radioisotope scanning, in book: Med. radioisotope scintigraphy, v. 1, p. 391, Vienna, 1969.
V. B. Sergienko.