There are two broad categories of radiation therapy. Both are designed to target the tumor precisely while minimizing exposure to the healthy surrounding tissue. In the first category, external beam radiation therapy (EBRT), the radiation is delivered by a machine called a linear accelerator, or linac, which focuses a high-energy x-ray beam into the tumor site from outside the body. In the second treatment category, the radiation is delivered by radioactive material placed inside the body near the cancer cells — a procedure called brachytherapy (also called internal radiation therapy or implant radiation therapy).
External Beam Radiation Therapy
SBRT, or stereotactic body radiation therapy, is also known as radiosurgery. Despite the use of the word "surgery" in its name, radiosurgery does not involve removing the tumor with a surgical blade. Radiosurgery uses similar technology to other radiation treatment techniques but differs from conventional radiation therapy in one important way: rather than having treatment five days a week for several weeks, radiosurgery is delivered in a few very large radiation doses given in five or fewer sessions.
Until recently, radiosurgery was most often used when the patient could not undergo conventional surgery to remove the tumor(s) because of its size or location, or because the person's health was too poor for surgery. However, some hospitals consider radiosurgery as the first line of treatment for early stage lung cancer.
IG-VMAT, or image-guided volumetric modulated arc therapy, uses special software and an advanced linear accelerator to deliver treatments up to eight times faster than what was previously possible with standard radiation therapy. Unlike conventional treatments, during which the machine must rotate several times around the patient or make repeated stops to treat the tumor from a number of different angles, VMAT can deliver the dose to the entire tumor in a single rotation — in as little as two minutes.
Image-guidance technology 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).
IG-IMRT, or image-guided intensity modulated radiation therapy, is still being studied for the treatment of lung cancer. IG-IMRT 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. Although IG-IMRT is very effective for some cancer types, its use for lung cancer treatment is rare and currently there is limited data on its effectiveness for this purpose.
Brachytherapy (Internal Radiation Therapy)
Brachytherapy may be used to treat lung cancer if a tumor is found in the large airways, or major bronchi. It is most often used as a palliative therapy to relieve symptoms or pain when additional surgery and external beam radiation therapy are no longer good options for the patient. In this procedure, a thin plastic tube is inserted into the lung during a bronchoscopy. A small amount of radioactive material is then passed through the tube and left near a precise treatment area for about 30 minutes. The tube is removed after treatment. Due to its short treatment distance, brachytherapy minimizes the radiation dose given to sensitive nearby tissues, including the heart, esophagus, and spinal cord.