Radiation Therapy

During EBRT, a machine aims radiation at a specific part of your body to target the tumor. Most machines use photon beams, which can target tumors deep inside your body. Proton beams, which are made up of electrons (particles with a positive charge), can also be used.

A computer analyzes images of your body to calculate the precise dose and treatment path for the radiation, minimizing damage to nearby healthy cells. There are several different types of external beam radiation therapy:

• 3D conformal radiation therapy: MRI and CT images allow doctors to design radiation beams that conform to the size and shape of the tumor. Beams are delivered from many directions, allowing the machine to use high doses of radiation without harming nearby healthy tissue.
• Intensity-modulated radiation therapy (IMRT): IMRT is a type of 3D conformal radiation therapy that uses smaller beams of radiation. Their strength can be varied to give higher doses to parts of the tumor.
• Image-guided radiation therapy (IGRT): This is a type of IMRT where images are taken during treatment to detect changes in the tumor’s size and location. The radiation dose can be adjusted to improve accuracy.
• Stereotactic radiosurgery: This is often used to treat small tumors in your brain or spinal cord when surgery is not an option. Small beams aimed at the tumor from different directions deliver a precisely targeted dose of radiation to the tumor with less damage to nearby areas. 
• Stereotactic body radiation therapy (SBRT): Similar to stereotactic radiosurgery, radiation beams are used to target small tumors outside the brain, such as those in the liver and lungs.

Internal radiation therapy, also called brachytherapy, is often used to treat cancers of the prostate, breast or cervix. It involves the placement of a radioactive implant on or near a tumor. The implant is sealed inside a pellet, seed or other implant directly in your body using a small tube called a catheter or another application device. The radiation from the implant precisely targets the tumor, killing the cancer cells. Internal radiation therapy allows doctors to deliver a higher dose of radiation than external beam radiation therapy.

The implants can be temporary or permanent. The type of implant you receive will depend on your cancer type, its location and your general health.

Radiopharmaceuticals are a new class of drugs that target cancer cells, delivering radiation therapy directly. The Food and Drug Administration has approved radiopharmaceuticals to treat advanced prostate cancer that has not responded to other therapies.