Stereotactic Radiotherapy (SRT)

Stereotactic radiotherapy uses specialized, focused radiation beams targeting a well-defined tumor. Relying on detailed imaging, computerized 3-D technology and precise treatment set-up, stereotactic radiotherapy delivers the radiation dose with extreme accuracy.

There are two types of stereotactic radiotherapy:

• Stereotactic radiosurgery (SRS) refers to several stereotactic radiation treatments of the brain or spine. SRS is delivered by a team involving a radiation oncologist and a neurosurgeon.
• Stereotactic body radiation therapy (SBRT) refers to one or several stereotactic radiation treatments with the body, excluding the brain or spine.

SRS/SBRT is best for very small tumors. Dr. O'Connor and Dr. Montes use specialized scans to pinpoint exactly where within the body the tumor target is located. A customized holder may be used to keep the body perfectly still during treatment, or the treatment machine may have the ability to adjust for patient motion such as during breathing. These techniques allow doctors to give a high dose of radiation to the tumor in a short amount of time. SRS/SBRT is a type of external beam radiation therapy that can be completed in one to five days rather than over several weeks.

The advantage of SRS/SBRT is that it delivers the right amount of radiation to the cancer in a shorter amount of time than traditional treatments. Plus the treatment is delivered with extreme accuracy, minimizing the effect on nearby organs. A disadvantage to SRS/SBRT is that this technique is suitable only for small, well-defined tumors that can be seen on imaging such as CT or MR scans, thus the approach is not suitable for all situations. Also, the amount of radiation that may be safely delivered may be limited if the cancer is located close to a sensitive normal structure, such as the spinal cord or bowel.

Conditions Treated With Stereotactic Radiation

Stereotactic radiosurgery (SRS) is used to treat conditions involving the brain or spine including:

• Cancers that start in the brain (gliomas and other primary brain tumors).
• Cancers that spread to the brain (brain metastases).
• Benign tumors arising from the membranes covering the brain (meningiomas).
• Benign tumors of the inner ear (acoustic neuromas).
• Abnormal blood vessels in the brain (arteriovenous malformations).

Stereotactic body radiation therapy (SBRT) is used to treat small tumors in the chest, abdomen or pelvis that cannot be removed surgically or treated with conventional radiation therapy, including:

• Small lung cancers.
• Cancers that started elsewhere and spread to the lung (lung metastases).
• Cancers that started elsewhere and spread to the liver (liver metastases).

These lists cover commonly treated conditions but cannot include every possibility. Stereotactic radiation may be useful for other cancers not readily addressed with surgery or conventional radiation therapy. Patients with tumors that are small and few in number are the best candidates for stereotactic techniques. Not all patients can benefit from this type of treatment.

Dr. O'Connor and Dr. Montes can tell you whether this approach is an option for your specific condition as new research continues to broaden the use of this technology.

Who Is Qualified to Provide Radiation Therapy?

Radiation oncologists are highly trained, board-certified and licensed physicians who use radiation therapy in its various forms to care for patients with cancer and other conditions, and who oversee the care of each person undergoing stereotactic radiation. Radiation oncologists team up with neurosurgeons for stereotactic radiosurgery of the brain or spine.

Other members of the radiation therapy treatment team include medical physicists, dosimetrists,radiation therapists and radiation oncology nurses.