Glossary of Radiation Terms

Adjuvant therapy - Radiation therapy, chemotherapy, or both, given as additional treatment for a cancer that has been or will be removed surgically.

Block - A thick piece of metal used to shield certain areas of the body from the X-ray or electron beam. Blocks are customized for each patient, but not all treatments require blocks.

Brachytherapy - A minimally invasive treatment in which tiny radioactive sources are permanently or temporarily implanted into the area needing treatment through hollow needles or catheters. This alternative to surgery concentrates radiation on the tumor site while minimizing exposure to surrounding healthy tissues. Brachytherapy has been proven successful in treating a variety of cancers, particularly prostate cancer and gynecological malignancies.

Cancer - A general term for more than 200 diseases characterized by abnormal and uncontrolled cell growth. The resulting mass, or tumor, can invade and destroy surrounding normal tissues.

CT Scanner - A computerized diagnostic X-ray machine that gives images of the inside of the body. Also known as a “Cat” scan, CT scans can be used during simulation (or planning).

Chemotherapy - Treatment with anticancer drugs. Chemotherapy is usually given intravenously, but some drugs are given orally. Concomitant chemotherapy is chemotherapy given at the same time as radiation. Sequential chemotherapy is chemotherapy given before or after radiation therapy.

Dosimetrist - A specially trained technologist who helps design external beam radiation treatments. The dosimetrist works closely with the radiation physicist.

Electron beam - A type of penetrating radiation generated by a linear accelerator, where electrons are accelerated to high energies. Electron beams can kill cancer cells.

External beam radiation - Radiation therapy using a machine that focuses radiation on a part of the body.

Field - The part of the body getting radiation. Also known as a port.

Fluoride therapy - Daily self-application of fluoride gel in a custom-fitted mouthpiece. This prevents excessive tooth decay in teeth that are in the radiation field.

Gamma rays - A type of penetrating radiation that is used to treat cancer. The source of the ray is a radioactive substance. Gamma rays can kill cancer cells.

Hormone - One of many naturally occurring chemical substances in the body that regulate body systems. For example, insulin is a hormone that regulates the sugar level in the body.

Hormone therapy - Also known as endocrine therapy, hormone therapy is the use of hormonelike drugs to control certain cancers. Prostate and breast cancer are examples of cancers that may be treated with hormone therapy.

Image guided radiation therapy (IGRT) - IGRT is the use of x-ray or ultrasound pictures, taken just prior to or during treatment, to guide treatment delivery. The tumor can be precisely located in 3D space immediately before treatment. The ability to correct for movement and setup errors allows smaller margins to be used, sparing healthy tissue and escalating the tumor dose.

Implant - A small container of radioactive material that is placed inside a tumor.

Intensity-modulated radiotherapy (IMRT) - IMRT is a recently developed technology that allows for even greater precision of radiation delivery using linear accelerators. With IMRT, the intensity of the radiation beam can be varied, allowing precise three-dimensional targeting of tumors. This technology is particularly useful in treating complex tumors that have spread close to sensitive structures, such as the spinal cord and salivary glands.

Internal radiation (interstitial and intracavitary radiation) - A type of radiation therapy, also called brachytherapy, in which a radioactive substance is implanted in the body in the area needing treatment.

Linear accelerator - A machine that creates and uses high-energy X-rays or electron beams to treat cancer.

Mask - A custom-made plastic mold of the patient’s head used to keep the head in the proper position during treatment of head and neck tumors.

Multileaf collimators - Each of Kaiser Permanente Santa Clara’s three linear accelerators, the devices most commonly used to deliver radiation treatments, is equipped with a Multileaf Collimator. This collimator technology enhances control of the radiation that is directed at a patient’s tumor site. It uses computer technology to control the shape and size of the radiation beam, a process formerly done manually..

Oncologist - A physician that specializes in diagnosing and treating cancers.

Port film - An X-ray picture taken at the start of and during treatment to make sure that the treatment beam is aimed correctly.

Radioactive - Giving off radiation.

Radiation oncologist A physician who has received specialized training in using radiation to treat cancer.

Radiation oncology nurse - A nurse who has received specialized training in the care of patients receiving radiation therapy.

Radiation oncology social worker - A social worker who has had special training to provide support and counseling to people with cancer.

Radiation therapist - A specially trained therapist who administers external radiation treatment using the individualized plans prepared by the radiation oncologist.

Radiation physicist - A person trained in the physics of radiation therapy. Radiation physicists prepare treatment plans, run treatment computers, and make sure the machines are running properly.

Radiation therapy - The use of high-energy penetrating rays to treat disease. Sources of radiation include linear accelerators and iridium.

Radiosurgery - See stereotactic radiation therapy.

Simulation - Also known as planning, simulation is the process of designing the treatment fields and calculating the details of treatment.

Stereotactic radiation therapy - Also known as radiosurgery. A technique of giving radiation therapy using multiple small beams that focus on a precise area. Most often used for treating brain tumors or abnormal arteries in the brain. Radiosurgery can also be used in other areas of the body.

Tamoxifen - A form of hormone therapy using an estrogen-like drug that blocks estrogen from reaching cancer cells.

Total body irradiation - Irradiation given to the whole body, typically to prepare for a bone marrow transplant.

X-rays - A type of penetrating radiation generated by a machine, usually a linear accelerator, but it can also be produced by orthovoltage machines. X-rays have the ability to kill cancer cells.

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