Radiation may be performed externally or internally and can be an important step in treating most cancers.
External radiation treatment is called external beam radiotherapy.
Internal radiation treatment is called brachytherapy and uses radioisotopes delivered to the cancer in small “seed” implants.
Radiation works by damaging genetic DNA information in the cancer cell and stops cancer cells from being able to divide, grow, and multiply.
External Beam Radiotherapy is the most common form of radiation therapy and is used to treat most brain and spinal cord cancers. The radiation beam is directed toward the site of the cancer and given fives days a week for two to eight weeks, depending on the cancer location and type. Radiation treatment is performed using a machine called a linear accelerator or LINAC.
There are several important steps before radiation treatment begins. Your radiation oncologist will determine where your brain or spine requires radiation. Several different imaging techniques are used to help, like the MRI, CT scan, PET scan, Angiography, and SPECT scan.
The external beam radiation itself can be given in several ways:
- 3-D conformal radiation goes directly to and is shaped around each target area, typically the cancer and a small surrounding area. This technique is useful when the cancer target is located in the area near the bottom part of the skull (posterior fossa) or near critical brain structures.
- Intensity Modulated Radiation Therapy (IMRT) is a more sophisticated form of 3-D conformal therapy. Different doses of radiation can be given to different areas. Much higher doses of radiation can be given to the cancer and smaller doses to surrounding brain tissue. This system is useful to target cancers that are close to critical structures.
- Fractionated Stereotactic LINAC Radiotherapy (FSRT) is a sophisticated form of radiotherapy. A bite block (a custom-fit piece of plastic held in the mouth) is used to keep the patient positioned for treatment where cameras are also used. This is similar to a global positioning system (GPS). Patients are monitored during treatment for movement while the radiation is given.
- Stereotactic Radiosurgery is a very sophisticated, single, high-dose radiotherapy technique that can be given in several ways with the Leksell Gamma Knife®. A frame is temporarily attached to the patient’s head to prevent movement during the treatment. This frame allows for very accurate targeting of the cancer. If a patient moves during the treatment, the ability to accurately target the cancer is decreased.
- Brachytherapy involves placing radiation seeds or a balloon into the cancer bed during surgery. These implants are placed into the cancer to kill it from the inside out. A high dose of radiation can be delivered directly to the remaining cancer to destroy it.
- Proton therapy is a form of radiation treatment that targets protons at tumors to kill cancer cells. Learn more about proton therapy for brain and spinal cord cancer.