Different forms of External Beam Radiation Therapy (EBRT) and Brachytherapy (also known as Internal Radiation Therapy) can be used to treat brain tumors.
There are several types of EBRT, including Three-dimensional Conformal Radiation Therapy (3D-Conformal), Intensity-Modulated Radiation Therapy (IMRT) and Stereotactic Radiosurgery (SRS). Occasionally Low Dose- Rate (LDR) Brachytherapy, sometimes called seeds, is used to treat brain tumors. Which technology your oncology team recommends depends on the type, location and stage of your cancer.
3D-Conformal Radiation Therapy and Intensity Modulated Radiation Therapy (IMRT)
3D-Conformal Radiation Therapy and Intensity and Modulated Radiation Therapy are particularly effective on larger, less defined tumors of the brain and spinal cord. During 3D-Conformal treatments, a device called a "multi-leaf collimator" will shape the individual radiation beams to “conform” to your tumor according to the data and instructions it receives from the system computer. IMRT uses thousands of radiation “beamlets” from many different angles to deliver a single dose of radiation. The intensity of the “beamlets” can change during the treatment session to modulate the dose, so that the tumor receives a very precise high dose of radiation, while minimizing damage to surrounding, normal tissue.
Before each session, a Radiation Therapist will carefully position you on the treatment table using a body immobilizer for precise body placement. Image guidance will be used to confirm the location of the tumor before the therapy begins. During your treatment sessions, the radiation delivery system will revolve around you, delivering the radiation according to the plan set by your Radiation Oncologist. Each treatment session lasts from 10 to 30 minutes. Typically, you will be scheduled for five sessions a week for five to eight weeks. The sessions are pain-free and require no sedation so you can return to your normal activities right away.
Stereotactic Radiosurgery (SRS)
Stereotactic Radiosurgery combines extremely accurate image-guided tumor targeting with exact patient positioning, allowing higher doses of radiation to be delivered in fewer treatment sessions. SRS is only used for small, well-defined tumors in the brain. If you are a candidate for SRS, you will typically have one to five treatment sessions rather than the standard five to eight weeks of traditional EBRT treatment. During each session, a Radiation Therapist will carefully position you on the treatment table using a head immobilizer for precise head placement. Image guidance will be used to confirm the location of the tumor before the therapy begins. The machines are very quiet and you will feel no pain during the session.
Low Dose-Rate (LDR) Brachytherapy
LDR or Seed Brachytherapy is occasionally used a brain cancer treatment. Small radioactive seeds, each the size of a rice grain, are implanted into the brain and release radiation over the course of several months. Eventually, they no longer emit radiation and can remain in the brain.