Oncology Terminology

Radiation therapy involves using many terms you may have never heard before. Below is a list of words you may hear during your treatment.


Adjuvant treatment

A treatment that is given in addition to the primary treatment to enhance its effectiveness and reduce the chance of the tumor recurring.


A device used to hold a radioactive source in place during brachytherapy.

Beam films

Another term for port films, beam films are pictures of the position of the radiation beams used to treat cancer. They are used to verify the position of the beams and confirm that treatment is delivered to the right place.


Pieces of metal alloy that can be used to shape the radiation beam.


An additional dose of radiation that is given after an initial course of radiation to enhance tumor control. A boost may be given to the tumor and areas to which the tumor may have spread.


Internal radiation therapy that involves placing radioactive sources inside or adjacent to the tumor. Learn more about brachytherapy


A group of diseases in which abnormal cells divide uncontrollably, forming a tumor or mass.


A tube inserted into the body that can be used to deliver radiation during brachytherapy.

Clinical trials

Studies that test new cancer therapies.

CT or CAT scan

A computer assisted tomography scan is an X-ray procedure that uses a computer to produce detailed pictures of the body.

High-dose-rate remote afterloading machine

A medical device that allows radiation to be delivered into a patient’s body through catheters during brachytherapy.

Hyperfractionated radiation therapy

A type of radiation therapy in which the radiation doses are divided into smaller amounts (hyperfractionation) and patients undergo radiation treatment more than once a day.

Hypofractionated radiation therapy

A type of radiation therapy in which patients undergo one or just a few treatments.

Immobilization device

A device that is used to help a patient remain in the same position during every treatment.


Another term for brachytherapy, internal radiation therapy involves placing radioactive sources inside the patient close to or in the tumor.

Intensity modulated radiation therapy or IMRT

IMRT is a specialized form of external beam therapy that allows radiation to be shaped to fit your tumor.

Interstitial brachytherapy

A form of seed implant where the radioactive sources are placed directly into the tumor, such as the prostate.

Intracavity brachytherapy

A type of brachytherapy where the radioactive seeds are put into a space where the tumor is located, such as the cervix or windpipe.

Linear accelerator

The most common type of machine used to deliver external radiation therapy. Sometimes called a “linac.”


Cancer that has spread from one part of the body to another, such as from the breast to the lymph nodes or bones.

Monoclonal antibody

A type of antibody that is created in the laboratory.

MR or MRI scan

A magnetic resonance imaging scan is a procedure that uses a magnetic field to create detailed pictures of the body.

Multileaf collimator or MLC

A part of a linear accelerator that is used to shape the radiation beam.

Neutron beam therapy

A specialized type of external beam radiation therapy similar to proton therapy.

Palliative care/palliation

Treatment that is intended to relieve symptoms, but not cure disease.

PET scan

A positron emission tomography scan uses a small dose of a chemical called a radionuclide combined with a sugar, which is injected into the patient. The radionuclide emits positrons. The PET scanner detects the positron emissions given off by the radionuclide.

Proton beam therapy

An external beam therapy that uses protons rather than X-rays to treat tumors.

Radiation oncologist

A doctor who specializes in treating cancer and other diseases with radiation therapy.

Radiation oncology

The medical specialty that deals with treating cancer and other diseases with radiation. Learn more about radiation oncology.

Radiation therapy

The careful use of various forms of radiation to treat cancer and other diseases.


The use of radiolabeled antibodies to deliver radiation directly to a tumor.

Radiolabeled antibodies

Monoclonal antibodies (antibodies produced in a laboratory) that have had a radioactive isotope attached to them in a process called radiolabeling.


A type of drug that protects normal tissues in the area being treated.


A term used to describe a tumor that does not respond well to radiation therapy.


A type of drug that can make a tumor respond better to radiation therapy.


The process of planning radiation therapy to allow the radiation to be delivered to the intended location.

Systemic radiation therapy

The use of radioactive isotopes that can travel throughout the body to treat certain cancers.

Treatment plan

A radiation oncologist’s prescription describing how a patient should be treated with radiation therapy. The radiation oncology team uses sophisticated treatment planning software to maximize radiation to the tumor while sparing healthy tissue.


An abnormal lump or mass of tissue.

file_downloadFree download

Skin Cancer eBook

Download our guide to learn how to protect and care for your skin, monitor moles, and understand the signs of skin cancer.

  • This field is for validation purposes and should be left unchanged.