External Beam Radiation Therapy
In the first category, external beam radiation therapy (EBRT), the radiation is usually delivered by a machine called a linear accelerator, or linac, which focuses a high-energy x-ray beam to the tumor site from outside the body. Whether you have had a lumpectomy or a mastectomy as part of your treatment, external beam radiation is the most common treatment post-surgery.
IMRT, or intensity modulated radiation therapy with image guidance, is the most commonly performed radiation treatment technique for breast cancer. IMRT technique uses 3-D scans of your body to guide the beams of radiation to the tumor from many different angles. At each of these angles, the intensity of the radiation is varied (modulated) and the shape of the beam is changed to match the shape of the tumor. These adjustments enable the prescribed amount of radiation to be delivered to each part of the tumor, while minimizing exposure to the surrounding healthy tissue. Treatments are typically given daily for 10 to 20 minutes over a six to eight week period.
IGRT, or image-guided radiation therapy, uses sophisticated computer software to analyze a series of image scans to create a detailed, three-dimensional picture of the target area and surrounding tissue, which enables your team to view the tumor and its position in your body before and during each treatment. The scans typically are produced by computed tomography (CT scan), magnetic resonance imaging (MRI), or positron emission tomography (PET scan).
APBI, which stands for accelerated partial breast irradiation, is a hyperfractionated regime performed in five to 10 sessions (usually 10 sessions in 5 days). Hyperfractionation is a technique in which the total dose of radiation prescribed for treatment is divided into smaller doses, and delivered over several sessions until the total dose received by the tumor is equal to the total dose prescribed. With APBI, the radiation is delivered at a higher overall dose rate over a shorter period of time compared to conventional radiation therapy.
Brachytherapy (Internal Radiation Therapy)
In the second treatment category, the radiation is delivered by placing tiny radioactive seeds each about the size of a grain of rice, inside the body near the cancer cells — a procedure called brachytherapy, internal radiation therapy, or implant radiation therapy.
Brachytherapy (from the Greek word "brachy," which means "close") is a less common approach, but may be appropriate for some women. The doctor places one or more thin tubes inside the breast through a tiny incision. A radioactive seed is then loaded into the tube. The treatment session typically takes a few minutes, and then the seeds are removed. Upon removal, no radioactivity remains in the body. This type of therapy is typically repeated every day for a week.