radiotherapy


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.

radiotherapy

the treatment of disease, esp cancer, by means of alpha or beta particles emitted from an implanted or ingested radioisotope, or by means of a beam of high-energy radiation

Radiotherapy

 

the therapeutic use of several kinds of ionizing radiation of varying energies.

Radioactivity was found to have a biological effect on the body shortly after the discovery of radioactive substances by A. Becquerel in 1896 and the study of them by P. Curie. (Originally, radiotherapy was called curietherapy.) The French physicians E. Benier and H. Denlaut were the first to use irradiation with radium for therapeutic purposes (1897). Further research revealed that young, rapidly growing and multiplying cells were the most sensitive to the process; this became the basis for using radioactive radiation to destroy malignant tumors, which consist of such cells.

There are many kinds of radiotherapy, including alpha, beta, gamma, neutron, pi-meson, proton, X-ray, and electron. The use of radiotherapy is based on a number of factors. First, ionizing radiation induces functional and anatomical changes in tissues, organs, and the body as a whole. It suppresses the capacity of cells for growth and multiplication and causes the death of tissue elements of the irradiated organ. (The extent of injury to the irradiated tissues is directly proportional to the dose absorbed.) Second, pathologically altered tissues (tumorous, degenerative, or inflamed) are more sensitive to radiation than are normal tissues. Finally, the use of radiotherapy is based on the response of the body and of the individual organs and tissues to irradiation.

Slight radiation injury is reversible, and the response of irradiated tissue is manifested in compensation for or even intensification of the diminished or lost function. With deep anatomical injuries to irradiated tissues, however, the process is irreversible, and the dead elements are replaced by nonfunctional connective tissue. Therefore, in some cases, the purpose of radiotherapy is either to intensify or to suppress the function of the given organ. In other cases (for example, with such malignant tumors as cancer or sarcoma) the intention is to suppress vital activity completely and destroy the pathologically altered tissues.

An important prerequisite for effective radiotherapy is the choice of radiant energy and the dose to be absorbed by the tissues. Radioisotopes (60Co, 137Cs, 32P, 198Au, 137I, 192Ir), X-ray equipment, gamma-ray sources, and charged-particle accelerators (linear accelerators, cyclotrons, and betatrons) are used as sources of ionizing radiation.

Depending on the location of the source of radiation in relation to the irradiated organ, irradiation is described as internal or external. Internal irradiation is produced by introducing a radioactive substance orally or intravenously; the substance, which emits charged particles and gamma rays, gradually distributes itself in the various organs and tissues. External irradiation may be general (whole-body) or local. Whole-body irradiation is used only rarely; the local irradiation of an organ or a limited part thereof (with the other parts shielded) is the principal method of radiotherapy.

Remote irradiation (teletherapy) is used to treat deep-lying foci. The radiation source (gamma sources, X-ray machines, accelerators) is placed at a considerable distance from the skin (30-120 cm). Short-focus irradiation, in which the source (X-ray machines or devices with a 60Co or 192Ir charge) is kept no more than 3-7 cm from the skin, is the method generally used to treat skin diseases, especially malignant tumors. Skin diseases are also treated by contact irradiation or by the application to the skin or mucous membrane of radioactive preparations emitting alpha or beta particles.

Various methods are used for intracavitary irradiation. The small tube of a special close-focus X-ray machine is inserted directly into a body cavity, such as the mouth, vagina, or rectum. A rubber balloon filled with a solution of the radioactive substance, a metal case with tubes containing a radioisotope, or beads of 60Co are inserted into cavitary or tubular organs, such as the urinary bladder, uterus, or bronchus. A solution or suspension of a radioactive isotope can be injected into an organ or into the pleural or abdominal body cavity.

Interstitial irradiation is achieved by introducing needles or tubes containing 60Co or 192Ir into the tissues. Colloidal solutions containing 198Au or granules of 198Au can also be introduced into the tissues. Radiotherapy is commonly combined with surgery, drug therapy, hormonal preparations, dietary regulation, and other types of treatment, since a combination of methods is most effective.

REFERENCES

Domshlak, M. P. Ocherki klinicheskoi radiologii. Moscow, 1960.
Kozlova, A. V. Metodika primeneniia radioaktivnykh izotopov s lechebnoi tsel’iu. Moscow, 1960.
Kozlova, A. V. Luchevaia terapiia zlokachestvennykh opukholei. Moscow, 1971.
Luchevaia terapiia s pomoshch’iu izluchennii vysokoi energii. Moscow, 1964. (Translated from German.)
Fizicheskie osnovy luchevoi terapii i radiobiologii. Moscow, 1969. (Translated from French.)
Spravochnik po rentgenologii i radiologii. Edited by G. A. Zedgenidze. Moscow, 1972.

G. A. ZEDGENIDZE

radiotherapy

[¦rād·ē·ō′ther·ə·pē]
(medicine)
References in periodicals archive ?
1]] there are substantial health and economic benefits in using radiotherapy and huge investments need to be made to meet the world's needs.
Even in high income countries the numbers of radiotherapy facilities, equipment, and trained staff are inadequate.
The Albury Wodonga Regional Cancer Centre will feature 30 inpatient beds, 30 chemotherapy chairs, three radiotherapy bunkers, consulting suites, and a wellness centre.
In June, it was reported that Velindre, based in Whitchurch, Cardiff, was set to introduce the new cutting-edge radiotherapy technique so Welsh patients no longer have to travel to England to receive it.
In June, it was reported that Velindre, in Whitchurch, Cardiff, was set to introduce the new cutting-edge radiotherapy technique so patients who had previously travelled to England could now receive treatment in Wales.
SABR delivers high doses of radiation while causing less damage to surrounding healthy tissue than conventional radiotherapy.
This benefit from radiotherapy in women with one to three positive nodes held up when women also received chemotherapy and/or hormone treatment.
Receiving radiotherapy is a scary experience for anybody but it is especially frightening for children.
Two of Elekta's Versa HD Radiotherapy Systems are currently being installed in the hospital's Bexley Wing, in partnership with Medipass Healthcare, part of PFI partners St James' Oncology SPC.
Radiotherapy treatment sheets were photocopied and then abstracted centrally by a research radiation therapist with similar data quality strategies.
We believe that this study, the largest prospective trial in the world to test breast IMRT against standard two-dimensional radiotherapy, will be practice-changing at an international level," said Dr Charlottes Coles, from Addenbrooke's Hospital Oncology Centre, Cambridge, UK.
The centre's radiotherapy service is provided by three older generation linacs and a lower energy radiotherapy machine is used for treating superficial skin tumours.