ELECTRONIC THERAPY

From Big Medical Encyclopedia

ELECTRONIC THERAPY — the type of corpuscular radiation therapy consisting in radiation of the pathological center the electrons with energy from 1 to 45 Mev generated by means of linear accelerators, microtrons and betatrons. One of versions E. t. the beta-ray therapy is (see). Therapeutic effect E. t. it is based on development biol. reactions in the changed fabrics irradiated with electrons patholologically. Death of separate cells or loss of ability to division therefore E by them is result of such reactions. t. apply to treatment of malignant new growths, and also nek-ry nonspecific inflammatory diseases. AA. t. began to use in medicine from 50th 20 century when for the medical purposes the first dynamitrons were created (see Particle accelerators).

Space dozny distribution of electronic radiation (see) in environments is characterized by high value of a deep gradient of dosage rate (see Doses of ionizing radiation) at the end of the dozny plateau. It allows to improve conditions of radiation of a tumor due to reduction of the dose falling on the subject healthy fabrics (see Radiation). Depth of an arrangement of sharp recession of dozny distribution of electronic radiation expressed in centimeters is defined by energy of electrons and is approximately equal to a half of value of energy of electrons in megaelectron-volt. Thus, depending on a depth of a tumor select the optimum size of energy of electrons. During the scheduling E. t. it is necessary to consider the increased size of a skin dose and existence of the considerable side dispersion of electrons creating danger of emergence of so-called «hot» zones on site of joining of fields of radiation.

Due to the high skin dose E. t. it is shown at rather superficially located malignant new growths — a carcinoma cutaneum, a mucous membrane of an oral cavity, a vulva, a penis, a recurrence of a breast cancer, a lymphogranulomatosis, metastasises of a tumor in limf. nodes of a neck, parasternal area, axillary hollows, etc. Depending on the place of localization of tumors they are irradiated in the remote way or in the way of introduction of tubes to the perigastriums affected with a tumor. In some cases E. t. combine with photon megavoltny radiation therapy (see).

Technique E. t. depends on localization, volume and gistol. structures of a tumor. AA. t. it is possible to apply as independently (according to the radical plan or with the palliative purpose), and in a combination with surgical and chemotherapeutic methods of treatment. For the purpose of strengthening of therapeutic influence at E. t. use of various radio sensibilizing substances is possible (see).

During the carrying out E. t. development of local reactions in the form of an erythema, a wet epidermit and an epithelitis is observed. Intensity of local reactions is in direct dependence on the sizes of fields of radiation, size of a dose and fractionation of radiation. In cases of radiation of skin electrons with energy of 6 — 15 Mev at the mode of classical fractional irradiation the erythema arises at a total dose 2500 — 3000 is glad (25 — 30 Gr), and wet epidermit — at 4500 — 5000 is glad (45 — 50 Gr). Epidermit it is epithelized during 3 — 6 weeks. The general beam reactions at E. t. practically it is not observed. Beam damages (see) as a result of E. t. are possible at use of the doses exceeding limits of tolerance of normal fabrics (see Radiochuvstvitelnost).

Bibliography: Kozlov A. P., Akimov A. A. and Lukyanov V. P. Use of high-velocity electrons in radiation therapy of malignant new growths, Vopr. onkol., t. 20, No. 4, page 100, 1974; Panshin G. A., etc. The combined treatment of patients with cancer of a mammary gland with use of brake and electronic radiation. Medical radio-gramophones., t. 29, No. 10, page 23, 1984; Proceedings of Symposium on high-energy electrons, ed. by A. Zuppinger a. G. Poretti, V. a. o., 1965.

A.S. Pavlov, G. A. Panshin.

Яндекс.Метрика