| 单词 | radiotherapy | |||
| 释义 | radiotherapyra·di·o·ther·a·pyR0017200 (rā′dē-ō-thĕr′ə-pē)radiotherapy(ˌreɪdɪəʊˈθɛrəpɪ)ra•di•o•ther•a•py(ˌreɪ di oʊˈθɛr ə pi)n. radiotherapy
radiotherapy(reidiəuˈθerəpi) nounradiotherapyradiotherapyRadiotherapythe 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. REFERENCESDomshlak, 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]radiotherapyradiation therapyBecause of improvements in tumor localization, beam direction, planning and prescribing the field to be irradiated, and determining the precise dosage needed, radiation therapy is far more effective and less harmful now than when it was first introduced. Another form of internal radiation therapy is the administration of radioactive materials into the bloodstream or a body cavity. Iodine-131 is given orally in certain cases of hyperthyroidism and cancer of the thyroid; it is absorbed by the digestive system and concentrated in the thyroid. Phosphorus-32, a pure beta emitter, is injected intravenously for the treatment of various myeloproliferative diseases, leukemias, and lymphomas. Sources of radiation that may be of particular concern to health care personnel include: radioactive substances such as radium and cobalt-60 that are used as implants and serve as internal sources of radiation; external sources of radiation such as x-ray machines and cobalt-60 therapy units; and liquid radioisotopes such as iodine-131 and suspensions of radioactive gold or phosphorus. Generally speaking, the degree of exposure to radiation depends on three factors: (1) the distance between the source of radiation and the individual, (2) the amount of time an individual is exposed to radiation, and (3) the type of shielding provided. (See discussion at radiation.) When a patient receives radiation therapy from an external source, therapists must be aware of, and observe carefully, the policies and procedures established for personnel in and around x-ray rooms and the rooms that house teletherapy units. After the treatment is finished, the patient will not serve as a hazard of radiation. This type of radiation therapy is often done on an outpatient basis. Internal implants can present certain hazards for persons in contact with the patient for as long as the implant is in place. Visitors should sit at least six feet away from the patient and stay no longer than a total of one hour each day. Pregnant staff members and visitors should avoid all contact with the patient. When administering direct patient care, staff members should plan interventions so that each task can be accomplished as quickly as possible. Since distance is a factor in protection, it is advisable to position oneself as far as is feasible from the source of radiation. For example, if the radioactive implant is in the pelvis, the caregiver might stand at the head or foot, rather than the side, of the bed. Protective lead aprons or portable shields may or may not be recommended by hospital protocol. Whatever the policies, every person caring for the patient should know and follow the recommended policies and procedures. A film badge is worn on the outside of any protective devices worn by caregivers. The badge records the cumulative dose of radiation received by each person, and is used to monitor exposure over a period of time. It should be sent for monthly testing to be sure that no one is receiving more than the maximum allowable exposure. This amount should not exceed five rem per year. One should never lend one's badge to another staff member or borrow another staff member's badge. Another factor to be considered is accidental removal or dislodgment of a radioactive implant. Most patients are confined to bed and refused bathroom privileges, but it is still possible for a radium needle or radon seeds, for example, to be accidentally removed from the body. Should an implant become dislodged the physician or radiation safety officer must be notified immediately. Under no circumstances should a radioactive substance be handled with the bare hands. A lead container and long-handled forceps should be kept at the patient's bedside in the event an implant should become dislodged. It can then be picked up immediately and placed in the container. Dressings, bed linen, bedpans, and emesis basins should be checked with a radiation detection instrument after each use or before disposal. Liquid radioactive substances require additional precautions since these substances can enter the body of a worker through the skin, or by ingestion or inhalation. Not all types of radioactive materials require the same precautions. For example, iodine-131 is excreted in the urine for several days after it has been administered to the patient. In addition it appears in the patient's sweat, tears and saliva; thus all articles such as bed linens and toothbrush used by the patient must be considered a possible radiation hazard. Phosphorus-32 acts in the same way. Colloidal gold-98 usually is instilled into a body cavity and is not absorbed as are iodine and phosphorus. However, the radioactive gold emits gamma rays that penetrate beyond the patient's body and present a radiation hazard. Most people have a limited knowledge of radiation and how it affects cells, both normal and malignant. This lack of knowledge can add to the anxiety and stress already being felt by patients and significant others. The kinds of information they will need include how radiation works, whether or not patients present a hazard to others while undergoing treatment, when they will begin to experience its effects, and how long it will be before they begin to recover from the effects. Before treatment is initiated, the patient is told the expected therapeutic effects, what it is like to have a treatment, and what might be expected of the patient during the course of therapy. Most patients will receive external radiation therapy on an outpatient basis; hence, they will need to keep scheduled appointments or notify the clinic if they are unable to come when expected. They should be assured that the source of radiation is outside their bodies (if it is) and that they cannot serve as a source of radiation. Teaching patients and significant others how to recognize expected side effects and participate in their management is especially important when patients are not hospitalized. Written information that is easily comprehended should be available to them, as well as sufficient time and personnel to answer any questions they may have after reading the instructions and attempting to follow them at home. They should be encouraged to write down questions that have arisen between visits and to bring these questions with them on their next visit. In general, most side effects will not begin before a week to ten days after the first treatment. This allows time for patients to assimilate information given to them and to adjust to whatever changes they might experience. They can be told that side effects typically continue throughout the course of treatment and for several weeks after the last treatment. However, individual reactions can and do vary. Although all body systems can be affected by radiation, the skin is the system most at risk for injury. The reaction results from an inflammatory process caused by breakdown of cells in the epidermis and is similar to a sunburn. In preparation for radiation therapy the physician will mark the target area with indelible ink. Daily assessment of the skin for degree of reaction can be done by the patient or some other knowledgeable person. First-degree reactions resemble a sunburn and can destroy hair roots, causing the hair to fall out. Second-degree reactions, also called dry desquamation, produce bright red erythema. Sweat glands and hair follicles are damaged and the hair falls out. This change can be irreversible. Third-degree reactions, also called moist desquamation, are characterized by a dark purple color and possibly formation of blisters and ulcers. If the area is exposed to air, scabbing over the exposed area can occur. Fourth-degree reactions are very rare and are the result of radiation overdose. They are characterized by tissue necrosis. Effects of radiation on major systems of the body, healing time, and appropriate nursing interventions are summarized in the table at radiation. ra·di·a·tion on·col·o·gyradiotherapy(rā′dē-ō-thĕr′ə-pē)radiography episodeA regionally popular UK term for the treatment provided to a patient by a radiotherapist at a specific NHS site, which is usually comprised of a series of external beam therapy sessions. The episode is initiated by a clinician who prescribes a course of treatment and decides when to end the episode.ra·di·o·ther·a·py(rā'dē-ō-thār'ă-pē)radiotherapyThe medical specialty concerned with the treatment, almost exclusively of cancer, by ionizing radiation. Radiation affects cancerous cells more than normal cells and can be directed accurately by shielding, collimation and other means. The size and timing of the dosage is calculated to cause maximal damage to the tumour and the minimal damage to the patient. Radiotherapy sources include high voltage X-ray machines, linear accelerators and powerful radioactive isotopes such as cobalt 60. Isotopes may be inserted directly into tumours in tubes or needles or may be placed in close proximity.Radiotherapyra·di·o·ther·a·py(rā'dē-ō-thār'ă-pē)Patient discussion about radiotherapyQ. What is radiotherapy? My Grandfather had a surgery to remove a cancerous tumor on his cheek. He now needs to undergo radiotherapy. What is this? what are its side effects? Q. What problems my sister may face if radiation therapy is not given to her? My sister will have her radiation therapy by next week. Two weeks before she had her chemotherapy treatment. She is feeling good if not great. After her diagnosis of breast cancer she had her mastectomy and soon she was given chemotherapy treatment. I was wondering whether the radiation therapy has many serious side effects associated with it. So can we avoid this treatment? What problems my sister may face if radiation therapy is not given to her? Q. I am pregnant and my mother is having radiotherapy for breast cancer, Will it affect me or my unborn child? I married my close relative last month and there is a 8-year difference in our. I am healthy enough to take care of my family. Now I am pregnant and my mother is having radiotherapy for breast cancer, can I be around her? Will it affect me or my unborn child? radiotherapy
Synonyms for radiotherapy
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radiotherapy - (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance