Key Terms in Radiation Therapy

Remission

A decrease in or disappearance of signs and symptoms of cancer. In partial remission, some, but not all, signs and symptoms of cancer have disappeared. In complete remission, all signs and symptoms of cancer have disappeared, although cancer still may be in the body.

Radiologist

A doctor who specializes in creating and interpreting pictures of areas inside the body. The pictures are produced with x-rays, sound waves, or other types of energy.

Medical oncologist

A doctor who specializes in diagnosing and treating cancer using chemotherapy, hormonal therapy, and biological therapy. A medical oncologist often is the main health care provider for a person who has cancer. A medical oncologist also may coordinate treatment provided by other specialists.

Oncologist

A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer treatment. For example, a radiation oncologist specializes in treating cancer with radiation.

Radiation oncologist

A doctor who specializes in using radiation to treat cancer.

Radiation therapist

A health professional who gives radiation treatment.

Radiation nurse

A health professional who specializes in caring for people who are receiving radiation therapy.

Physical therapist

A health professional who teaches exercises and physical activities that help condition muscles and restore strength and movement.

Dietitian

A health professional with special training in nutrition who can offer help with the choice of foods a person eats and drinks. Also called a nutritionist.

Linear accelerator

A machine that creates high-energy radiation to treat cancer, using electricity to form a stream of fast-moving subatomic particles. Also called mega-voltage (MeV) linear accelerator or a linac.

Tumor

A mass of excess tissue that results from abnormal cell division. Tumors perform no useful body function. They may be benign (not cancerous) or malignant (cancerous).

Antiemetic

A medicine that prevents or relieves nausea or vomiting

Dosimetrist

A person who determines the proper radiation dose for treatment.

Radiation physicist

A person who makes sure that the radiation machine delivers the right amount of radiation to the correct site in the body. The physicist works with the radiation oncologist to choose the treatment schedule and dose that has the best chance of killing the most cancer cells.

Stereotactic injection

A procedure in which a computer and a 3-dimensional scanning device are used to inject anticancer drugs directly into a tumor.

Magnetic resonance imaging (MRI)

A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as CT or x-ray. MRI is especially useful for imaging the brain, spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging.

Internal radiation

A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called brachytherapy, implant radiation, or interstitial radiation therapy.

Interstitial radiation therapy

A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called brachytherapy, internal radiation, or implant radiation.

Implant radiation

A procedure in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. Also called brachytherapy, internal radiation, or interstitial radiation.

Social worker

A professional trained to talk with people and their families about emotional or physical needs, and to find them support services.

Stereotactic external-beam radiation

A radiation therapy technique for brain tumors that uses a rigid head frame attached to the skull. The frame is used to help aim high-dose radiation beams directly at the tumors and not at normal brain tissue. This procedure does not involve surgery. Also called stereotactic radiation therapy, stereotactic radiosurgery, and stereotaxic radiosurgery.

Stereotaxic radiosurgery

A radiation therapy technique for brain tumors that uses a rigid head frame that is attached to the skull. The frame is used to help aim high-dose radiation beams directly at the tumors and not at normal brain tissue. This procedure does not involve surgery. Also called stereotactic external-beam radiation, stereotactic radiation therapy, and stereotactic radiosurgery.

Stereotactic radiosurgery

A radiation therapy technique for brain tumors that uses a rigid head frame that is attached to the skull. The frame is used to help aim high-dose radiation beams directly at the tumors and not at normal brain tissue. This procedure does not involve surgery. Also called stereotactic external-beam radiation, stereotactic radiation therapy, and stereotaxic radiosurgery.

Stereotactic radiation therapy

A radiation therapy technique for brain tumors that uses a rigid head frame that is attached to the skull. The frame is used to help aim high-dose radiation beams directly at the tumors and not at normal brain tissue. This procedure does not involve surgery. Also called stereotactic external-beam radiation, stereotactic radiosurgery, and stereotaxic radiosurgery.

Radiation surgery

A radiation therapy technique that delivers radiation directly to the tumor while sparing the healthy tissue. Also called radiosurgery and stereotactic external beam irradiation.

Intracavitary radiation

A radioactive source (implant) placed in a body cavity such as the chest cavity or the vagina.

Lymph gland

A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph glands filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called a lymph node.

CAT scan

A series of detailed pictures of areas inside the body, taken from different angles; the pictures are created by a computer linked to an x-ray machine. Also called computerized axial tomography, computed tomography (CT scan), or computerized tomography.

Proton

A small, positively charged particle of matter found in the atoms of all elements. Streams of protons generated by special equipment can be used for radiation treatment.

Electron beam

A stream of electrons (small negatively charged particles found in atoms) that can be used for radiation therapy.

Implant

A substance or object that is put in the body as a prosthesis, or for treatment or diagnosis.

Cancer

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the bloodstream. Lymphoma is cancer that begins in the cells of the immune system.

Catheter

A thin, flexible, hollow tube through which fluids enter or leave the body. Radioactive materials may be placed in catheters that are placed near the cancer.

Neuroma

A tumor that arises in nerve cells.

Platelet

A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called a thrombocyte.

Neuron

A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called a nerve cell.

X-ray

A type of high-energy radiation. In low doses, x-rays are used to diagnose diseases by making pictures of the inside of the body. In high doses, x-rays are used to treat cancer.

Remote brachytherapy

A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote brachytherapy or high-dose-rate remote radiation therapy.

High-dose-rate remote radiation therapy

A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote brachytherapy or remote brachytherapy.

High-dose-rate remote brachytherapy

A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote radiation therapy or remote brachytherapy.

High-energy photon therapy

A type of radiation therapy that uses high-energy photons (units of light energy). High-energy photons penetrate deeply into tissues to reach tumors while giving less radiation to superficial tissues such as the skin.

Proton beam radiation therapy

A type of radiation therapy that uses protons generated by a special machine. A proton is a type of high-energy radiation that is different from an x-ray.

Clinical trial

A type of research study that uses volunteers to test new methods of screening, prevention, diagnosis, or treatment of a disease. The trial may be carried out in a clinic or other medical facility. Also called a clinical study.

Hyperfractionation

A way of giving radiation therapy in smaller-than-usual doses two or three times a day instead of once a day.

Neoplasm

An abnormal mass of tissue that results from excessive cell division. Neoplasms may be benign (not cancerous), or malignant (cancerous). Also called tumor.

Prosthesis

An artificial replacement of a part of the body.

Myeloma

Cancer that arises in plasma cells, a type of white blood cell.

Malignant

Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.

Palliative care

Care given to improve the quality of life of patients who have a serious or life-threatening disease. The goal of palliative care is to prevent or treat as early as possible the symptoms of the disease, side effects caused by treatment of the disease, and psychological, social, and spiritual problems related to the disease or its treatment. Also called comfort care, supportive care, and symptom management.

Calcification

Deposits of calcium in the tissues. Calcification in the breast can be seen on a mammogram, but cannot be detected by touch. There are two types of breast calcification, macrocalcification and microcalcification. Macrocalcifications are large deposits and are usually not related to cancer. Microcalcifications are specks of calcium that may be found in an area of rapidly dividing cells. Many microcalcifications clustered together may be a sign of cancer.

Radiation

Energy released in the form of particles or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, and medical x-rays.

Radioactive

Giving off radiation.

Alopecia

Hair loss

Gamma rays

High-energy rays that come from a radioactive source such as cobalt-60.

Intraoperative radiation therapy

IORT. Radiation treatment aimed directly at a tumor during surgery.

Simulation

In cancer treatment, a process used to plan radiation therapy so that the target area is precisely located and marked.

Treatment field

In radiation therapy, the place on the body where the radiation beam is aimed.

Brachytherapy

Internal radiation therapy using an implant of radioactive material sealed in needles, seeds, wires, or catheters placed directly into or near a tumor; also called internal radiation, implant radiation, or interstitial radiation therapy.

Anesthesia

Loss of feeling or sensation to prevent pain. Certain drugs or gases called 'anesthetics' are used to achieve anesthesia so that medical procedures may be performed without pain. A local anesthesia causes loss of feeling in part of the body. A general anesthetic puts the patient to sleep.

Red blood cell

RBC. A cell that carries oxygen to all parts of the body. Also called an erythrocyte.

Unsealed internal radiation therapy

Radiation therapy given by injecting a radioactive substance into the bloodstream or a body cavity, or by swallowing it. This substance is not sealed in a container.

Gamma knife

Radiation therapy in which high energy rays are aimed at a brain tumor from many angles in a single treatment session.

External radiation

Radiation therapy that uses a machine to aim high-energy rays at the cancer. Also called external-beam radiation.

Reconstructive surgery

Surgery that is done to reshape or rebuild (reconstruct) a part of the body changed by previous surgery.

Imaging

Tests that produce pictures of areas inside the body.

Lumen

The cavity or channel within a tube or tubular organ such as a blood vessel or the intestine.

Telangiectasia

The permanent enlargement of blood vessels, causing redness in the skin or mucous membranes.

Recurrence

The return of cancer, at the same site as the original (primary) tumor or in another location, after the tumor had disappeared.

X-ray therapy

The use of high-energy radiation from x-rays to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy) or from materials called radioisotopes. Radioisotopes produce radiation and can be placed in or near the tumor or in the area near cancer cells. This type of radiation treatment is called internal radiation therapy, implant radiation, interstitial radiation, or brachytherapy. Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. X-ray therapy is also called radiation therapy, radiotherapy, and irradiation.

Radiation therapy

The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy, implant radiation, or brachytherapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Also called radiotherapy.

Radiology

The use of radiation (such as x-rays) or other imaging technologies (such as ultrasound and magnetic resonance imaging) to diagnose or treat disease.

Adjuvant therapy

Treatment added to the primary treatment to enhance the effectiveness of the primary treatment. Radiation therapy often is used as an adjuvant to surgery.

Chemotherapy

Treatment with anticancer drugs.

Stereotaxis

Use of a computer and scanning devices to create three-dimensional pictures. This method can be used to direct a biopsy, external radiation, or the insertion of radiation implants.

White blood cell

WBC. Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.