External Radiation Therapies
External radiation therapy uses high-intensity beams of radiation, directed at a very specific area of the body, to kill cancer cells and shrink tumors. At our practice, we offer more than one type of external beam radiation therapy to treat cancer. The type that is used for each patient is dependent on the type of cancer and where it is located.
Types of External Beam Radiation Therapy
Intensity-Modulated Radiation Therapy (IMRT)
Intensity Modulated Radiation Therapy (IMRT) is an advanced form of external radiation treatment that allows precise targeting of tumor cells. It uses CT scans or other three-dimensional (3-D) images taken of the patient to build the treatment plan. 3-D modeling of the tumor cells and normal cells allows for very precise delivery of radiation. IMRT also allows the radiation oncologist to vary the intensity of some of the beams of radiation. By doing this, a maximum dose of radiation can be delivered to the tumor while minimizing the amount of radiation distributed to the surrounding healthy tissues.
Stereotactic Body Radiation Therapy (SBRT)
Stereotactic Body Radiotherapy (SBRT), also known as Stereotactic Ablative Body Radiation (SABR), is an advanced type of radiation therapy that delivers high doses of radiation using several beams of varying intensity. SBRT is used specifically for small, isolated tumors outside the brain and spinal cord, often in the liver or lung. This technique is sometimes used when surgery isn’t an option for the patient.
Due to the high intensity of the radiation dose, treatment may be delivered over short periods of time (1-5 treatments) rather than the standard 5-8 weeks found with IMRT.
Stereotactic Radiosurgery (SRS)
Stereotactic radiosurgery is actually a non-surgical technique that uses many small beams of radiation from different directions to precisely focus on a tumor in the brain or spine, especially if surgery would be difficult. Each beam has very little effect on the tissue it passes through, but delivers a precisely targeted dose of radiation to the site where all the beams come together.
The patient is carefully immobilized so that the radiation is aimed exactly where the tumor is located. Although often performed in a single treatment, it can be spread out amongst a few doses over the course of several days.
Image-Guided Radiation Therapy (IGRT)
Image-Guided Radiation Therapy (IGRT) combines three-dimensional images, such as CT scans, with the precise technology of Intensity Modulated Radiation Therapy (IMRT) to pinpoint and treat cancerous tumors. The images allow the cancer specialists to precisely localize the tumor each time radiation therapy is administered.
By using images, the radiation can be delivered more accurately, reducing the amount of radiation exposure to other areas of the body including nearby tissue and organs. IGRT is used to treat tumors in areas of the body that are prone to movement, such as the lungs, liver, and prostate gland, as well as tumors located close to critical organs and tissues. IGRT is used in all external treatments to improve accuracy.
Volumetric Modulated Arc Therapy (VMAT)
Volumetric Modulated Arc Therapy (VMAT) is a novel radiation therapy technique that delivers the radiation dose continuously as the treatment machine rotates. This technique accurately shapes the radiation dose to the tumor while minimizing the dose to the organs and areas surrounding the tumor. This treatment method is very accurate, shortens the treatment time, and uses a lower overall dose of radiation.