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There are two primary types of radiation therapy: external radiation and internal radiation.
External radiation This is delivered using machines outside the body. The radiation machine moves around your body without touching you. It does not cause pain, so you will not feel anything during your treatments.
This treatment, also called external beam radiation therapy (EBRT), does not make you radioactive. You can safely be around other people, including children.
External beam radiation is the most common approach to radiation treatment. It is produced by machines called linear accelerators. Some machines may have brand names, for example TrueBeam and CyberKnife.
Radiation therapy can be delivered in different ways:
3D (3-dimensional) conformal radiation therapy (3D-CRT) With this method, 3D images help the doctor better target the tumor. The images are created using a special machine — a computed tomography (CT) or magnetic resonance imaging (MRI) machine. The radiation beams can be aimed from many different angles to match the exact shape of the cancer.
Intensity-modulated radiation therapy (IMRT) This method is similar to the first method, but the doctor can adjust (“modulate”) how much radiation you get from each beam, which allows for better avoidance of nearby normal cells and reduces potential side effects.
Stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy (SABR) This method refers to radiation given in 5 or fewer treatments. Though these dose of radiation given is similar to standard radiation, when given in just a few treatments, the effectiveness is much greater, and this treatment is considered much more powerful in killing cancer cells. SBRT/SABR is a specialized treatment technique that is used in specific situations.
For each treatment, most of your appointment will be spent getting your body positioned correctly. The actual treatment lasts just a few minutes.
Internal radiation (Brachytherapy) This type of radiation therapy is offered only for certain gynecological and prostate cancers.
When giving internal radiation, called brachytherapy, your doctor positions small catheters or applicators in the treatment area to deliver radiation to where the cancer is. The applications are placed and removed with each treatment. You will receive sedation or anesthesia during the procedure, so the entire experience takes most of a full day. You will not be radioactive and can safely be around others when you return home. Most of the time, treatments can be done as an outpatient (no hospital stay).
The advantage of brachytherapy is that it can deliver higher doses of radiation to certain cancers, while limiting radiation exposure to normal tissue.