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Stereotactic Body Radiation Therapy (SBRT)
Stereotactic radiosurgery and stereotactic radiotherapy have been used successfully to treat tumors and benign conditions in the brain. The success of these two radiation therapy techniques led to the development of stereotactic body radiation therapy (SBRT) to extend precise radiotherapy treatment to targets outside of the brain. The development of SBRT required significant technical advances in the use of tumor imaging to guide patient immobilization and radiation administration. Although the term “stereotactic” implies the use of an external frame of reference, many current approaches to SBRT use frameless localization of the target.
Basically, SBRT is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors measuring 2 inches (5 cm) or smaller in parts of the body other than the brain. The total dose of radiation is divided into smaller doses (typically 1-5) given over one to several days. In contrast, with conventional radiotherapy treatment is typically given over several weeks. Conventional radiotherapy encompasses the tumor as well as a significant margin of normal tissue to avoid missing any part of the tumor. With SBRT, less normal tissue is irradiated.
SBRT is often used to treat tumors that have recurred in patients after prior radiotherapy or when a tumor is next to or within an organ that is very sensitive to radiation. Because SBRT is noninvasive, it also can be used as an alternative to surgery or other treatments for patients who are not healthy enough to undergo surgery.
Nearly all structures in the chest and abdomen move during normal respiration. This poses a significant problem for the radiation oncologist. The larger the respiratory motion, the greater the volume of normal tissue that receives irradiation. SBRT can be used to treat lung tumors, abdominal tumors such as pancreatic or kidney tumors or liver metastases, and spinal or paraspinal tumors while sparing more surrounding healthy tissue than as is possible with conventional radiotherapy.
TRILOGY SBRT Trilogy™ Stereotactic System from Varian Medical Systems is the most advanced, sophisticated machine of its type in the world. As the leading image-guided radiotherapy (IGRT) system, Trilogy marks the beginning of a new generation of cancer care. View a patient's guide to stereotactic radiosurgery.
The versatile Trilogy system combines imaging and treatment technologies, and can be used to deliver the widest range of external beam radiotherapies: 3D conformal radiotherapy, IMRT, stereotactic radiosurgery, fractionated stereotactic radiation therapy and intensity-modulated radiosurgery for cancer treatments.
Advanced imaging capabilities built into the system allow treatments with sub-millimeter accuracy. A respiratory gating system compensates for any tumor movement that occurs as a patient breathes allows for extreme precision in treatment delivery.
The Trilogy system is powerful, and it can deliver radiotherapy doses at least 60 percent faster than conventional accelerators. This shortens the length of time patients need to spend undergoing treatment. In addition, the radiation beam is highly precise, allowing clinicians to deliver treatments with unprecedented accuracy. This allows for least amount of damage to normal tissue, while eradicating the tumors.
How SBRT with Respiratory Gating works Planning begins with diagnostic imaging to help locate the tumor and determine the area that will be treated. This includes four-dimensional imaging that maps the target area as it moves over time with the patient’s breathing cycle. In the only invasive part of the treatment, gold seeds, called fiducials, may be implanted into the tumor before images are taken. Because the fiducials are visible in planning scans and at the time of treatment, that ensures the high-dose envelope of radiation is accurately overlying the tumor, while it ensures safe exposure of normal structures.
Who can benefit from Trilogy SBRT?
- Lung cancer tumors less than 5cm in patients who are not candidates for surgery.
- Lung Metastases
- Pancreatic and bile duct tumors
- Liver tumors (primary and metastatic)
- Kidney tumors
- Pelvic tumors (prostate, GYN)
- Spine metastases (sarcomas, previously radiated)
- Brain Tumors (those too large for Gamma knife; brainstem and optic tumors)
The Thomas and Dorothy Leavey Cancer Center at Northridge Hospital is located at 18300 Roscoe Boulevard, Northridge, CA 91328. To schedule an appointment in the Department of Radiation Oncology, call (818) 885-5331. |
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