External Beam Radiation Therapy
External-beam radiation therapy refers to treatments in which the radiation is generated from a source outside your body, usually a machine called a linear accelerator, or linac. The radiation beams are then pointed precisely at your tumor. This is the most common type of radiation therapy that people receive to treat cancer.
Three-Dimensional Conformal Radiation Therapy (3D-CRT)
In 3D-CRT, the radiation treatment plan is specifically tailored to the patient’s anatomy. At the beginning of the planning process, the radiation therapists perform a computed tomography scan (CT scan) of the part of the body being treated. These images are loaded into a specialized computer and used to create the radiation treatment plan. The plan is designed to deliver a beam of radiation that conforms closely to the size, shape and contours of the tumor. This type of treatment is typically given five days a week (Monday through Friday) for two to eight weeks.
Intensity Modulated Radiation Therapy (IMRT)
IMRT is one kind of 3D-CRT. The basic idea is the same: The treatment plan is designed so that the beam of radiation conforms closely to the patient’s tumor. With IMRT, the beam can be split into smaller beams of different strengths. This helps the radiation oncology team deliver a higher dose of radiation to the tumor and lower doses to nearby healthy tissue.
Stereotactic radiosurgery delivers a high dose of radiation to a precise area from many angles, typically in one treatment session. Despite the name, it’s not like conventional surgery—it doesn’t involve any cutting. It’s usually used to treat tumors inside the head. The patient wears a head frame during treatment to keep their head still and help aim the radiation at the right spot. Gamma Knife is one form of radiosurgery.
Intraoperative Radiation Therapy (IORT)
When tumors can’t be removed completely from the pelvic or abdominal regions because they are attached to important organs or nerves, or if residual cells are left over after a tumor is resected, surgeons can move normal structures out of the way during surgery to expose the tumor for high-dose irradiation. UW Medical Center is the only hospital in the Pacific Northwest to offer this treatment. Treatment time is short and the radiation dose a patient receives is reduced compared to post-operative external radiation. (IORT can also be done using brachytherapy, a type of internal radiation therapy.)
Total Body Irradiation (TBI)
Radiation may be given to the whole body to prepare for a bone marrow transplant. This is part of conditioning; it’s described in the section on the transplant process.
This is a type of radiation that does not penetrate as deeply into the body as x-rays or photons, so it is best used to treat tumors on or near the surface of the body, like skin cancers.
Protons scatter less as they pass through healthy tissues to reach their target—the tumor—so they cause less damage along the way. Proton therapy allows physicians to deliver more targeted, higher-dose radiation with reduced side effects. In 2011, SCCA broke ground on a new proton therapy center—the first such center in the Pacific Northwest—slated to open in 2013. Bringing proton therapy here will greatly enhance cancer care for patients throughout the region.