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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 through the vein, 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.

CyberknifeTM – A specialized linear accelerator mounted on a robotic arm for stereotactic radiosurgery (SRS). The Cyberknife can deliver radiation from almost any direction, track the target position during treatment and make adjustments based on any patient or target movement.

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.

Electronic portal imaging device (EPID) – digital imaging device used to monitor and manage target positioning during the course of treatment (“port films”).

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

Field – The projection of the radiation beam from the machine onto the patient. The shape and size of the field is based on the target and created by the collimators.

Fiducial Markers – Also called marker seeds or gold seeds, these are small markers implanted near your tumor to help with tracking the target in your body. These markers are usually placed during a separate outpatient appointment.

Fluoride therapy – Daily self-application of prescription strength fluoride. This prevents excessive tooth decay in teeth that are in the radiation field.

High Dose Rate (HDR) Brachytherapy – A type of internal radiation treatment in which the implanted radioactive source is removed between treatments. Because of the high dose rate, treatment times are relatively short. This procedure might require hospitalization.

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 hormone like 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, CT scan 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.

Immobilization Device – Customized equipment, such as masks and form fitting bean bags made at the time of planning and used with each treatment in order to increase accuracy and reproducibility.

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 (LINAC) – 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.

Medical Oncologist – A physician who has trained in internal medicine and received specialized training in using chemotherapy and other medications to treat cancer.

Multileaf collimator (MLC) – Device that helps shape the x ray beam produced by the LINAC. It consists of many computer controlled, metal leaves that move back and forth to focus the beam and better avoid your normal tissue. All of the LINACS at KP SSF Cancer Treatment Center are equipped with this device.

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

Port film – An X-ray picture taken at the start of and during treatment by the EPID 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.

Rapid ArcTM – IMRT technique allowing for complete daily treatment in a single rotation of the linear accelerator around the patient.

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

Stereotactic Radiosurgery (SRS) – SRS is a focused, high dose form of external beam radiation that is used to treat highly selected types of cancer and some benign diseases. The term radiosurgery is used to describe treatments with very high doses, typically given in 1 to 5 treatments. Stereotactic refers to the ability to localize the target with sub-millimeter accuracy during treatment.

Tattoos – Tiny, permanent ink dots placed on your skin in/near the treatment area during the planning phase. These are used each day before treatment to align your body in the accurate position.

Three Dimensional Conformal Radiotherapy (3D-CRT) – Radiation therapy treatment that creates a high dose volume that is shaped to “conform” to a three dimensional target.

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

Trilogy(TM) – A model of linear accelerator capable of 3-D CRT, IMRT, IGRT as well as Stereotactic radiosurgery (SRS) treatments.

X-rays – A type of penetrating radiation generated by a machine. Depending on the machine and the energy of the x ray, it can be used for imaging (chest X ray) or killing cancer cells. A Linear accelerator (LINAC) produces very high energy X rays that have the ability to kill cancer cells.