Stereotactic Body Radiation Therapy
Froedtert & The Medical College of Wisconsin have offered Stereotactic Body Radiation Therapy (SBRT) since 2006. SBRT is a treatment technique that uses special equipment to position a patient and precisely deliver external radiation therapy to tumors in the body (except the brain). When using SBRT, very high doses of radiation are delivered in one to five treatments.
SBRT is used to treat isolated tumors in the lung, liver and spinal column. This type of radiation therapy helps spare normal tissue while controlling tumor growth. In many cases, the control of cancer is as good as with surgery or better than invasive procedures. SBRT is associated with few side effects because the treatment area is generally very small and treatment is precisely delivered.
SBRT requires a high degree of precision when directing the radiation. For example, a tumor in the lung can be difficult to treat because the tumor can move during breathing. Technology such as gating can be used with SBRT to solve this problem and deliver precise doses of radiation to targeted areas.
SBRT may be used to treat:
Lung Cancer — 95 percent of lung tumors are controlled with SBRT.
Patients who may be considered for SBRT treatment:
- Primary lung cancer (tumors that begin in the lung)
- Patients with early stage lung cancer (tumors up to 5 cm)
- Patients who cannot tolerate surgery
- Patient who do not want surgery
- Secondary (metastatic) lung cancer (cancer that has spread to the lung from elsewhere in the body)
- Patients who have up to three lung nodules (or more in certain circumstances)
Liver Cancer — 92 percent to 100 percent of tumors are controlled with SBRT
Patients who may be considered for SBRT treatment:
- Primary liver cancer (tumors that begin in the liver)
- Secondary (metastatic) liver cancer (cancer that has spread to the liver from elsewhere in the body)
- Patients with up to three liver tumors (or more in certain circumstances)
- Patients with tumors less than 6 cm
- Patients with limited active disease (metastatic cancer) elsewhere in the body
Cancer of the Spine — 85 percent to 90 percent symptom response rate for paraspinal tumors (tumors adjacent to the spinal column)
The use of SBRT for spinal tumors is palliative. Patients who may be considered for SBRT treatment:
- Primary tumors
- Patients with primary tumors that cannot be removed with surgery
- Patients with metastatic tumors (tumors spread from other cancers) when there is limited spread elsewhere and surgery is not a good option
- Patients who require retreatment of tumors that have grown after previous radiation therapy
- Metastatic Cancer — SBRT is indicated for select patients with metastatic cancer in discrete, treatable locations that will result in complete clearance of tumors and decrease the overall burden of cancer.
Advanced Technology for SBRTAt Froedtert & The Medical College of Wisconsin, SBRT is delivered with advanced technologies that are highly customized to each patient’s specific situation. These technologies include:
- 4D (four-dimension) CT-based treatment planning — a technique that provides information to help plan when breathing impacts tumor motion. This allows us to conform the radiation dose to the tumor’s motion. By accounting for tumor motion during treatment, doses to critical organs can be limited while delivering higher doses to the tumor.
- TomoTherapy — a treatment unit designed to deliver intensity modulated radiation therapy (IMRT), TomoTherapy can treat small or large tumors in one region of the body or several regions, using a variety of doses. TomoTherapy can do a CT scan before each treatment to ensure the patient is perfectly aligned. A thin beam rotates around the patient from many directions. This results in hundreds of beams of different intensities converging on the tumor(s). A computer calculates the treatment plan and coordinates treatment delivery.
- Online CT guidance using either MV cone beam CT or kV CT-on-Rail for patient positioning — techniques to image a patient before each radiation treatment is delivered to verify that the patient is in the exact same position each day treatment is given.
- Body Frame — a device to prevent patient movement (except for breathing) to enhance precision during radiation treatment.
- Respiratory gating — in certain locations in the body, such as the lungs and abdomen, tumors can move as the patient breathes, making it difficult to accurately deliver radiation therapy to these tumors. Respiratory gating solves this problem. During respiratory gating, radiation treatment is timed to an individual's breathing pattern, targeting the tumor only when it is in the best breathing phase. This approach decreases amount of normal tissue receiving radiation, thus reducing complications and side effects, while using higher doses and achieving better outcomes.
- Treatment verification with online real-time fluoroscopy — the use of fluoroscopy imaging during treatment to detect patient and tumor movement in order to adjust treatment if needed.
Author: Marla Fraunfelder
Date: June 9, 2009
|Medical Reviewer: ||Elizabeth Gore, MD||