Proton Therapy: Common Terms

When exploring cancer treatment options, it is important to understand the terminology. Here are definitions to some common terms you may hear throughout your proton therapy treatment.

• Brachytherapy: Radiation therapy that involves the insertion of radioactive material into the body, either directly into or near a tumor.
• Bragg Peak: The energy that is emitted from protons as they settle at the end of their path in the body. When proton therapy is used, this path ends at the tumor site. Radiation oncologists have the ability to place this rush of energy at a specific depth in the tissue in order to effectively target the tumor.
• Conventional radiation therapy: The most common type of cancer treatment, in which electrons or x-rays are used to target cancerous areas of the body.
• Entrance dose: The dose of radiation that is absorbed by healthy tissue before the radiation actually reaches its intended target, the tumor.
• Electron: The particles from an atom that are deposited during traditional radiation therapies, effective for tumors that lack depth.
• Exit dose: The dose of radiation that is absorbed by healthy tissues after the radiation actually reaches the tumor. With the use of proton therapy, protons enter the tumor and then stop, eliminating this exit dose.
• Local therapy: Cancer treatment that impacts the tumor itself and the area closely surrounding it (i.e. surgery)
• Metastasize: The result of cancer cells that split from a tumor, settle and form a new tumor in an additional location in the body.
• Pencil Beam: Feature of the proton therapy treatment unit from which the protons are administered. Allows for targeted, precise doses of radiation, minimizing negative side effects and providing a lower risk of damage to surrounding tissue.

• Protons: The particles from an atom that have a positive charge.
• Proton therapy: An advanced form of radiation therapy that uses a single beam of high-energy protons, rather than x-rays, to treat various forms of cancer, delivering precise treatment to tumors in a way that reduces negative side effects and cancer recurrence.
• Radiation therapy: Cancer treatment that involves the use of x-rays or radiation, including proton therapy.
• Simulation visit: the use of a computed tomography (CT) scan, a positron emission tomography (PET) scan or a magnetic resonance imaging (MRI) to determine the ideal treatment plan for proton therapy patients.
• Toxicity: Damage to normal, healthy tissue as a result of exposure to radiation during treatment.
• Tumor: Caused by a concentration of cells, it is a mass that may be benign, lacking the ability to metastasize and spread to other parts of the body, or malignant, able to spread and collect in additional areas of the body.