in medicine, radium (cobalt)"gun", tele-radiotherapeutic
installation, apparatus for remote gamma therapy, mainly malignant
tumors. Operating principle G.- G.-u. (see fig.) -
the application directed, adjustable over the beam section of
gamma-radiation. G.- u. is supplied with the shielding container
(head) from lead, tungsten or uranium, that contain radiation source
(usually 60so, thinner than 137Cs; earlier used
radium). The window in the head, supplied with diaphragm, makes
it possible to obtain polyaoblucheniya of the necessary form and sizes
and to overlap beam in the off-position G.- g.-u. Distinguish
long- n short-focused G.- g.-u. In short-focused G.- u.
(distance from the radiation source to the skin sick less than 25 cm),
the intended for the irradiation tumors, located not deeper than 3-4
cm, are used usually sources by activity to 100 curies.
Long-focus G.- u. (distance between the source and the skin
70-100 cm) use for irradiating the deeply lying tumors; by
radiation source in them serves usually * °So as activity several
thousand curies; they create the advantageous distribution of
dose. Long-focus G.- u. for the static and mobile irradiation
are distinguished; in the latter the radiation source can either
revolve around one axis, accomplishing rotation (rotation) or rocking
to the preset angle (rotary G.- u.), or simultaneously to be moved
around three mutually perpendicular axes, describing in this case the
spherical surface (rotary- Convair -gentnye G.- u.). By mobile
irradiation is achieved the concentration of the absorbed dose in the
subject of lech. to action center with the retention from the damage
of healthy tissues. G.- u. place in the accomodation, whose the
walls are made from the special materials, which protect the
surrounding space from gamma-radiation.
the Rotary- convergent gamma ray source: 1
container with the radiation source; 2- table for positioning
the patient.
Lit.: Ruderman a. i. and Vaynberg M. sh., the
physical bases of the remote roentgen- and of gamma therapy, M., 1961;
The radiation therapy with the aid of high-energy radiations,
edited by I. Becker and G. Schubert, translated from the German, M.,
y9'ya.V. G. Videnskiy.
