radiation therapy

(redirected from 3-dimensional conformal radiation therapy)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

Radiation Therapy

 

Definition

Radiation therapy, sometimes called radiotherapy, x-ray therapy radiation treatment, cobalt therapy, electron beam therapy, or irradiation uses high energy, penetrating waves or particles such as x rays, gamma rays, proton rays, or neutron rays to destroy cancer cells or keep them from reproducing.

Purpose

The purpose of radiation therapy is to kill or damage cancer cells. Radiation therapy is a common form of cancer therapy. It is used in more than half of all cancer cases. Radiation therapy can be used:
  • alone to kill cancer
  • before surgery to shrink a tumor and make it easier to remove
  • during surgery to kill cancer cells that may remain in surrounding tissue after the surgery (called intraoperative radiation)
  • after surgery to kill cancer cells remaining in the body
  • to shrink an inoperable tumor in order to and reduce pain and improve quality of life.
  • in combination with chemotherapy
For some kinds of cancers such as early-stage Hodgkin's disease, non-Hodgkin's lymphoma, and certain types of prostate, or brain cancer, radiation therapy alone may cure the disease. In other cases, radiation therapy used in conjunction with surgery, chemotherapy, or both, increases survival rates over any of these therapies used alone.

Precautions

Radiation therapy does not make the person having the treatments radioactive. In almost all cases, the benefits of this therapy outweigh the risks. However radiation therapy can have has serious consequences, so anyone contemplating it should be sure understand why the treatment team believes it is the best possible treatment option for their cancer. Radiation therapy is often not appropriate for pregnant women, because the radiation can damage the cells of the developing baby. Women who think they might be pregnant should discuss this with their doctor.

Description

Radiation therapy is a local treatment. It is painless. The radiation acts only on the part of the body that is exposed to the radiation. This is very different from chemotherapy in which drugs circulate throughout the whole body. There are two main types of radiation therapy. In external radiation therapy a beam of radiation is directed from outside the body at the cancer. In internal radiation therapy, called brachytherapy or implant therapy, where a source of radioactivity is surgically placed inside the body near the cancer.

How radiation therapy works

The protein that carries the code controlling most activities in the cell is called deoxyribonucleic acid or DNA. When a cell divides, its DNA must also double and divide. High-energy radiation kills cells by damaging their DNA, thus blocking their ability to grow and increase in number.
One of the characteristics of cancer cells is that they grow and divide faster than normal cells. This makes them particularly vulnerable to radiation. Radiation also damages normal cells, but because normal cells are growing more slowly, they are better able to repair radiation damage than are cancer cells. In order to give normal cells time to heal and reduce side effects, radiation treatments are often given in small doses over a six or seven week period.

External radiation therapy

External radiation therapy is the most common kind of radiation therapy. It is usually done during outpatient visits to a hospital clinic and is usually covered by insurance.
Once a doctor, called a radiation oncologist, determines the proper dose of radiation for a particular cancer, the dose is divided into smaller doses called fractions. One fraction is usually given each day, five days a week for six to seven weeks. However, each radiation plan is individualized depending on the type and location of the cancer and what other treatments are also being used. The actual administration of the therapy usually takes about half an hour daily, although radiation is administered for only from one to five minutes at each session. It is important to attend every scheduled treatment to get the most benefit from radiation therapy.
Recently, trials have begun to determine if there are ways to deliver radiation fractions so that they kill more cancer cells or have fewer side effects. Some trials use smaller doses given more often. Up-to-date information on voluntary participation in clinical trials and where they are being held is available by entering the search term "radiation therapy" at the following web sites:
  • National Cancer Institute. 〈http://cancertrials.nci.nih.gov〉 or (800) 4-CANCER.
  • National Institutes of Health Clinical Trials. 〈http://clinicaltrials.gov〉
  • Center Watch: A Clinical Trials Listing. 〈http://www.centerwatch.com〉.
The type of machines used to administer external radiation therapy and the material that provides the radiation vary depending on the type and location of the cancer. Generally, the patient puts on a hospital gown and lies down or sits in a special chair. Parts of the body not receiving radiation are covered with special shields that block the rays. A technician then directs a beam of radiation to a pre-determined spot on the body where the cancer is located. The patient must stay still during the administration of the radiation so that no other parts of the body are affected. As an extra precaution in some treatments, special molds are made to make sure the body is in the same position for each treatment. However, the treatment itself is painless, like having a bone x-rayed.

Internal radiation therapy

Internal radiation therapy is called brachytherapy, implant therapy, interstitial radiation, or intracavitary radiation. With internal radiation therapy, a bit of radioactive material is sealed in an implant (sometimes called a seed or capsule). The implant is then placed very close to the cancer. The advantage of internal radiation therapy is that it concentrates the radiation near the cancer and lessens the chance of damage to normal cells. Many different types of radioactive materials can be used in the implant, including cesium, iridium, iodine, phosphorus, and palladium.
How the implant is put near the cancer depends on the size and location of the cancer. Internal radiation therapy is used for some cancers of the head, neck, thyroid, breast, female reproductive system, and prostate. Most people will have the radioactive capsule implanted by a surgeon while under either general or local anesthesia at a hospital or surgical clinic.
Patients receiving internal radiation therapy do become temporarily radioactive. They must remain in the hospital during the time that the implant stays in place. The length of time is determined by the type of cancer and the dose of radioactivity to be delivered. During the time the implant is in place, the patient will have to stay in bed and remain reasonably still.
While the implant is in place, the patient's contact with other people will be limited. Healthcare workers will make their visits as brief as possible to avoid exposure to radiation, and visitors, especially children and pregnant women, will be limited.
The implant usually can be removed in a simple procedure without an anesthetic. As soon as the implant is out of the body, the patient is no longer radioactive, and restrictions on being with other people are lifted. Generally people can return to a level of activity that feels comfortable to them as soon as the implant is removed. Occasionally the site of the implant is sore for some time afterwards. This discomfort may limit specific activities.
In some cases, an implant is left permanently inside the body. People who have permanent implants need to stay in the hospital and away from other people for the first few days. Gradually the radioactivity of the implant decreases, and it is safe to be around other people.

Radioimmunotherapy

Radioimmunotherapy is a promising way to treat cancer that has spread (metastasized) to multiple locations throughout the body. Antibodies are immune system proteins that specifically recognize and bind to only one type of cell. They can be designed to bind only with a certain type of cancer cell. To carry out radioimmunotherapy, antibodies with the ability to bind specifically to a patient's cancer cells are attached to radioactive material and injected into the patient's bloodstream. When these man-made antibodies find a cancer cell, they bind to it. Then the radiation kills the cancer cell. This process is still experimental, but because it can be used to selectively attack only cancer cells, it holds promise for eliminating cancers that have spread beyond the primary tumor.

Radiation used to treat cancer

PHOTON RADIATION. Early radiation therapy used x rays like those used to take pictures of bones, or gamma rays. X rays and gamma rays are high energy rays composed of massless particles of energy (like light) called photons. The distinction between the two is that gamma rays originate from the decay of radioacive substances (like radium and cobalt-60), while x rays are generated by devices that excite electrons (such as cathode ray tubes and linear accelerators). These high energy rays act on cells by disrupting the electrons of atoms within the molecules inside cells, disrupting cell functions, and most importantly stop their ability to divide and make new cells.
PARTICLE RADIATION. Particle radiation is radiation delivered by particles that have mass. Proton therapy has been used since the early 1990s. Proton rays consist of protons, a type of positively charged atomic particle, rather than photons, which have neither mass nor charge. Like x rays and gamma rays, proton rays disrupt cellular activity. The advantage of using proton rays is that they can be shaped to conform to the irregular shape of the tumor more precisely than x rays and gamma rays. They allow delivery of higher radiation doses to tumors without increasing damage to the surrounding tissue.
Neutron therapy is another type of particle radiation. Neutron rays are very high-energy rays. They are composed of neutrons, which are particles with mass but no charge. The type of damage they cause to cells is much less likely to be repaired than that caused by x rays, gamma rays, or proton rays.
Neutron therapy can treat larger tumors than conventional radiation therapy. Conventional radiation therapy depends on the presence of oxygen to work. The center of large tumors lack sufficient oxygen to be susceptible to damage from conventional radiation. Neutron radiation works in the absence of oxygen, making it especially effective for the treatment of inoperable salivary gland tumors, bone cancers, and some kinds of advanced cancers of the pancreas, bladder, lung, prostate, and uterus.

Recent advances in radiation therapy

A newer mode of treating brain cancers with radiation therapy is known as stereotactic radiosurgery. As of the early 2000s, this approach is limited to treating cancers of the head and neck because only these parts of the body can be held completely still throughout the procedure. Stereotactic radiosurgery allows the doctor to deliver a single high-level dose of precisely directed radiation to the tumor without damaging nearby healthy brain tissue. The treatment is planned with the help of three-dimensional computer-aided analysis of CT and MRI scans. The patient's head and neck are held steady in a skeletal fixation device during the actual treatment. Stereotactic radiosurgery can be used in addition to standard surgery to treat a recurrent brain tumor, or in place of surgery if the tumor cannot be reached by standard surgical techniques.
Two major forms of stereotactic radiosurgery are in use as of 2003. The gamma knife is a stationary machine that is most useful for small tumors, blood vessels, or similar targets. Because it does not move, it can deliver a small, highly localized and precise beam of radiation. Gamma knife treatment is done all at once in a single hospital stay. The second type of radiosurgery uses a movable linear accelerator-based machine that is preferred for larger tumors. This treatment is delivered in several small doses given over several weeks. Radiosurgery that is performed with divided doses is known as fractionated radiosurgery. The total dose of radiation is higher with a linear accelerator-based machine than with gamma knife treatment.
Another advance in intraoperative radiotherapy (IORT) is the introduction of mobile devices that allow the surgeon to use radiotherapy in early-stage disease and to operate in locations where it would be difficult to transport the patient during surgery for radiation treatment. Mobile IORT units have been used successfully as of 2003 in treating early-stage breast cancer and rectal cancer.
Radiation sensitizers are another recent innovation in radiation therapy. Sensitizers are medications that are given to make cancer cells easier to kill by radiation than normal calls. Gemcitabine (Gemzar) is one of the drugs most commonly used for this purpose.

Preparation

Before radiation therapy, the size and location of the patient's tumor are determined very precisely using magnetic resonance imaging (MRI) and/or computed tomography scans (CT scans). The correct radiation dose, the number of sessions, the interval between sessions, and the method of application are calculated by a radiation oncologist based on the tumor type, its size, and the sensitivity of the nearby tissues.
The patient's skin is be marked with a semipermanent ink to help the radiation technologist achieve correct positioning for each treatment. Molds may be built to hold tissues in exactly the right place each time.

Aftercare

Many patients experience skin burn, fatigue, nausea, and vomiting after radiation therapy regardless of the where radiation is applied. After treatment, the skin around the site of the treatment may also become sore. Affected skin should be kept clean and can be treated like sunburn, with skin lotion or vitamin A and D ointment. Patients should avoid perfume and scented skin products and protect affected areas from the sun.
Nausea and vomiting are most likely to occur when the radiation dose is high or if the abdomen or another part of the digestive tract is irradiated. Sometimes nausea and vomiting occur after radiation to other regions, but in these cases the symptoms usually disappear within a few hours after treatment. Nausea and vomiting can be treated with antacids, Compazine, Tigan, or Zofran.
Fatigue frequently starts after the second week of therapy and may continue until about two weeks after the therapy is finished. Patients may need to limit their activities, take naps, and get extra sleep at night.
Patients should see their oncologist (cancer doctor) at least once within the first few weeks after their final radiation treatment. They should also see an oncologist every six to twelve months for the rest of their lives so they can be checked to see if the tumor has reappeared or spread.

Key terms

Anemia — Insufficient red blood cells in the body.
Antibody — Protein molecule that recognizes and binds specifically to a foreign substance in the body in order to eliminate it.
Chemotherapy — Injecting drugs into the body where they circulate and kill cancer cells.
Computed tomography (CT or CAT) scan — —Using x rays taken from many angles and computer modeling, CT scans help locate and size tumors and provide information on whether they can be surgically removed.
Fractionation — A procedure for dividing a dose of radiation into smaller treatment doses.
Gamma rays — Short wavelength, high energy electromagnetic radiation emitted by radioactive substances.
Hodgkin's disease — Cancer of the lymphatic system, characterized by lymph node enlargement and the presence of a large polyploid cells called Reed-Sternberg cells.
Magnetic resonance imaging (MRI) — MRI uses magnets and radio waves to create detailed crosssectional pictures of the interior of the body.
Stereotactic — Characterized by precise positioning in space. When applied to radiosurgery, stereotactic refers to a system of three-dimensional coordinates for locating the target site.

Risks

Radiation therapy can cause anemia, nausea, vomiting, diarrhea, hair loss, skin burn, sterility, and rarely death. However, the benefits of radiation therapy almost always exceed the risks. Patients should discuss the risks with their doctor and get a second opinion about their treatment plan.

Normal results

The outcome of radiation treatment varies depending on the type, location, and stage of the cancer. For some cancers such as Hodgkin's disease, about 75% of the patients are cured. Prostate cancer also responds well to radiation therapy. Radiation to painful bony metastases is usually a dramatically effective form of pain control. Other cancers may be less sensitive to the benefits of radiation.

Resources

Periodicals

Goer, D. A., C. W. Musslewhite, and D. M. Jablons. "Potential of Mobile Intraoperative Radiotherapy Technology." Surgical Oncology Clinics of North America 12 (October 2003): 943-954.
Lawrence, T. S. "Radiation Sensitizers and Targeted Therapies." Oncology (Huntington) 17 (December 2003): 23-28.
Merrick, H. W. IIIrd, L. L. Gunderson, and F. A. Calvo. "Future Directions in Intraoperative Radiation Therapy." Surgical Oncology Clinics of North America 12 (October 2003): 1099-1105.
Nag, S., and K. S. Hu. "Intraoperative High-Dose-Rate Brachytherapy." Surgical Oncology Clinics of North America 12 (October 2003): 1079-1097.
Witt, M. E., M. Haas, M. A. Marrinan, and C. N. Brown. "Understanding Stereotactic Radiosurgery for Intracranial Tumors, Seed Implants for Prostate Cancer, and Intravascular Brachytherapy for Cardiac Restenosis" Cancer Nursing 26 (December 2003): 494-502.

Organizations

American Cancer Society. 1599 Clifton Rd. NE, Atlanta GA 30329-4251. (800) ACS-2345. http://www.cancer.org.
International Radiosurgery Support Association (IRSA). 3005 Hoffman Street, Harrisburg, PA 17110. (717) 260-9808. http://www.irsa.org.
National Association for Proton Therapy. 7910 Woodmont Ave., Suite 1303, Bethesda, MD 20814. (301) 913-9360. 〈http://www.proton-therapy.org/Default.htm〉.

Other

Radiation Therapy and You. A Guide to Self-Help During Treatment. National Cancer Institute CancerNet Information Service. http://cancernet.nci.nih.gov.

radiation therapy

 
the treatment of disease, usually cancer, by ionizing radiation in order to deliver an optimal dose of either particulate or electromagnetic radiation to a particular area of the body with minimal damage to normal tissues. The source of radiation may be outside the body of the patient (external beam irradiation) or it may be an isotope that has been implanted or instilled into abnormal tissue or a body cavity. Called also radiotherapy and irradiation. 

Because 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.
External Beam Irradiation. Modern radiation therapy primarily uses high-energy x-rays or gamma rays with peak photon energies above 1 megavolt; this is called megavoltage therapy. These high voltages are produced by linear accelerators or by cobalt-60 teletherapy units. Megavoltage radiation is more penetrating than lower energy radiation. It produces less damage to the skin at the entry port, is absorbed less in bone, and is scattered less, thus reducing the exposure to tissues outside the x-ray beam. Low-energy x-rays that do not penetrate are used for treatment of superficial skin lesions.
Internal Radiation Therapy (brachytherapy). This can involve the implantation of sealed radiation sources in or near cancerous tissue. Isotopes, such as radium-226, cesium-137, iridium-192, and iodine-125, are introduced either temporarily or permanently into body tissues (interstitial radiation therapy) or body cavities (intracavitary radiation therapy). Permanent sources have a short half-life so that the dose received by the patient is limited. 

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.
Protection from Radiation. Hospital personnel concerned with the care of patients receiving radiation therapy must be aware of the hazards of radiation and the protective policies and procedures established to reduce these hazards. Most institutions and clinics provide a safety program under the leadership of a radiation physicist or radiation safety officer. Since radiation cannot be seen or felt, it is extremely important to observe all rules outlined in the program. 

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.
Patient Care. Specific goals for the care of a patient receiving radiation thearapy will depend on the location of the irradiated site, the patient's medical diagnosis, and the source of radiation, i.e., whether it is internal or external. Special precautions in regard to handling radioactive material have been presented above. In addition to the goal of protecting patients and caregivers from unnecessary exposure, goals of patient care include familiarizing patients and significant others with the purpose and therapeutic effects of radiation therapy and helping them recognize and deal with its expected side effects. 

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 ther·a·py

treatment with x-rays or radionuclides. See: radiation oncology.

radiation therapy

radiation therapy

radiation therapy

Radiotherapy Administration of ionizing radiation to treat disease, usually malignant Types Local low energy radiation–brachytherapy or radioisotopes placed at or near the tumor or cancer cells–internal RT, implant radiation; high energy radiation delivered at a distance–teletherapy; most RT uses high-energy radiation from x-rays, neutrons, etc to kill CA and shrink tumors delivered as external-beam radiation; systemic RT includes use of radiolabeled monoclonal antibodies that circulate in the body, binding target cells, effecting therapy. See Conformal radiotherapy, Intracoronary radiotherapy, Intraoperative radiotherapy, Plaque radiotherapy, Radiation oncology, Stereotactic radiotherapy.

ra·di·a·tion ther·a·py

, radiotherapy (rā'dē-ā'shŭn thār'ă-pē, rādē-ō-thāră-pē)
Treatment with x-rays or radionuclides.

radiation therapy

See RADIOTHERAPY.

radiation therapy

radiant energy used in treatment of disease

ra·di·a·tion ther·a·py

, radiotherapy (rā'dē-ā'shŭn thār'ă-pē, rādē-ō-thāră-pē)
Treatment with x-rays or radionuclides.

radiation

1. divergence from a common center.
2. a structure made up of diverging elements, especially a tract of the central nervous system made up of diverging fibers.
3. energy carried by waves or a stream of particles. One type is electromagnetic radiation, which consists of wave motion of electric and magnetic fields. The quantum theory is based on the fact that electromagnetic waves consist of discrete particles, called photons, that have an energy inversely proportional to the wavelength of the wave. In order of increasing photon energy and decreasing wavelength, the electromagnetic spectrum is divided into radio waves, infrared light, visible light, ultraviolet light and x-rays.
Another type is the radiation emitted by radioactive materials. Alpha particles are high-energy helium-4 nuclei consisting of two protons and two neutrons, which are emitted by radioisotopes of heavy elements, such as uranium. Beta particles are high-energy electrons, which are emitted by radioisotopes of lighter elements. Gamma rays are high-energy photons, which are emitted along with alpha and beta particles and are also emitted alone by metastable radionuclides, such as technetium-99m. Gamma rays have energies in the x-ray region of the spectrum and differ from x-rays only in that they are produced by radioactive decay rather than by x-ray machines.
Radiation with enough energy to knock electrons out of atoms and produce ions is called ionizing radiation. This includes alpha and beta particles and x-rays and gamma rays.

radiation biology
study of the effects of ionizing radiation on living tissues.
corpuscular radiation
particles emitted in nuclear disintegration, including alpha and beta particles, protons, neutrons, positrons and deuterons.
radiation detection
special equipment, including Geiger-Müller tubes and a scintillation crystal, is available to detect radiation which may be accidental, or detect small amounts where this is expected but it needs to be measured in terms of accumulated dose.
electromagnetic radiation
energy, unassociated with matter, that is transmitted through space by means of waves (electromagnetic waves) traveling in all instances at 3 × 1010 cm or 186,284 miles per second, but ranging in length from 1011 cm (electrical waves) to 10−12 cm (cosmic rays) and including radio waves, infrared, visible light and ultraviolet, x-rays and gamma rays.
radiation exposure
means more than the patient being exposed intentionally to an x-ray beam. Technical persons in the vicinity will also be exposed to a much less dangerous but perniciously cumulative load of radiation.
infrared radiation
the portion of the spectrum of electromagnetic radiation of wavelengths ranging between 0.75 and 1000 μm. See also infrared.
radiation injury
is caused by exposure to radioactive material. High doses cause intense diarrhea and dehydration and extensive skin necrosis. Median doses cause initial anorexia, lethargy and vomiting then normality for several weeks followed by vomiting, nasal discharge, dysentery, recumbency, septicemia and a profound pancytopenia. Death is the most common outcome. Chronic doses cause cataract in a few. Congenital defects occur rarely.
interstitial radiation
energy emitted by radium or radon inserted directly into the tissue.
ionizing radiation
corpuscular or electromagnetic radiation that is capable of producing ions, directly or indirectly, in its passage through matter. Used in treatment of radiosensitive cancer, in sterilization of animal products and food for experimental use.
radiation necrosis
see radionecrosis.
radiation physicist
the person responsible for the administration of radiation therapy including estimating the dose required for a treatment, arranging for the dose to be delivered and making arrangements for safety of the patient and staff, and disposing of any residual radioactive material. Technical aspects of the work include computer estimations, preparation of isodose curves, preparation of wedge and compensating filters, and calibration of teletherapy equipment.
primary radiation
radiation emanating from the x-ray tube which is absorbed by the subject or passes on through the subject without any change in photon energy.
radiation protection
includes proper control of emissions from the x-ray machines, proper protective clothing for staff, keeping unnecessary people out of the way while the tube is actually generating its beam, the wearing and regular examination of a dosimeter and the proper storage of radioactive materials or residues.
pyramidal radiation
fibers extending from the pyramidal tract to the cortex.
radiation sensitivity
tissues vary in their sensitivity to the damaging effects of irradiation. The rapidly growing tissues are most susceptible, e.g. the embryo, rapidly growing cancer, gonads, alimentary tract, skin and blood-forming organs.
radiation sickness
see radiation injury (above).
solar radiation
see solar.
radiation striothalamica
a fiber system joining the thalamus and the hypothalamic region.
tegmental radiation
fibers radiating laterally from the nucleus ruber.
thalamic radiation
fibers streaming out through the lateral surface of the thalamus, through the internal capsule to the cerebral cortex.
radiation therapist
a person skilled in radiotherapy. See also radiation therapy (below).
radiation therapy
ultraviolet radiation
the portion of the spectrum of electromagnetic radiation of wavelengths ranging between 0.39 and 0.18 μm. See also ultraviolet rays.

therapy

the treatment of disease; therapeutics. See also treatment.

animal-assisted therapy
the treatment of humans, usually for mental or psychological illness, which incorporates familiarization with a companion or pleasure animal. Called also pet-facilitated or pet-assisted therapy. See also animal facilitated therapy.
anticoagulant therapy
the use of drugs to render the blood sufficiently incoagulable to discourage thrombosis.
heat therapy
see hyperthermia (2).
immunosuppressive therapy
treatment with agents, such as x-rays, corticosteroids and cytotoxic chemicals, which suppress the immune response to antigen(s); used in organ transplantation, autoimmune disease, allergy, multiple myeloma, etc.
inhalation therapy
see aerosol.
neoadjuvant therapy
given before the primary treatment, such as chemotherapy, hormone therapy, radiation therapy.
oxygen therapy
the administration of supplemental oxygen to relieve hypoxemia and prevent damage to the tissue cells as a result of oxygen lack (hypoxia). See also oxygen therapy.
physical therapy
use of physical agents and methods in rehabilitation and restoration of normal bodily function after illness or injury; it includes massage and manipulation, therapeutic exercises, hydrotherapy, and various forms of energy (electrotherapy, actinotherapy and ultrasound). See also physical therapist.
radiation therapy
treatment of disease by means of ionizing radiation. See also radiotherapy.
replacement therapy
treatment to replace deficient formation or loss of body products by administration of the natural body products or synthetic substitutes.
serum therapy
serotherapy; treatment of disease by injection of serum from immune animals.
substitution therapy
the administration of a hormone to compensate for glandular deficiency.
vaporization therapy
see aerosol.

Patient discussion about radiation therapy

Q. 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?

A. Generally, radiotherapy causes tiredness and sore, red skin in the area being treated. This is a bit like sunburn. Radiotherapy to the neck can damage the thyroid gland. Other side effects include: a sore throat- due to mouth ulcers, pain on swallowing,
a dry mouth- due to damage caused to the salivary glands (which are in charge of making the saliva), taste changes, a hoarse voice and effect on the sense of smell.

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?

A. Radiation therapy is used to clear the surgical area with any leftover cancer cells. These cancer cells can again return with the cancer if left inside the body. This can also pass through the blood to other areas of the body and can develop into a cancer in other areas of the body. To stop the chances of cancer reoccurrence this radiation therapy is helpful. Avoiding this treatment may be harmful as the future occurrence may be more serious. Hence it is better to go with the treatment.
http://www.youtube.com/watch?v=8mDWk0KV6jI&eurl=http://www.imedix.com/health_community/v8mDWk0KV6jI_breast_cancer_treatment_alternative_hyperthermia?q=radiation%20thera&feature=player_embedded

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?

A. Congrats! There is definitely no problem with radiotherapy for breast cancer. This is to with external high energy x-rays which pass straight through. People need to be careful with radioactive iodine for thyroid problems or treatment for similar diseases... hope this helps you. Take care of your mom. Have a healthy baby soon and let me know.
http://www.youtube.com/watch?v=JW6TDaotL_o&eurl=http://www.imedix.com/health_community/vJW6TDaotL%5Eo_breast_cancer?q=breast%20cancer&feature=player_embedded

More discussions about radiation therapy