Stereotactic Radiosurgery (SRS)is a radiation technique that uses precise patient positioning and extremely accurate radiation delivery to treat brain lesions in one or up to five treatments.At Duke, SRS is delivered by a Novalis TX or Varian TrueBeam STX linear accelerator.These machines have state-of-the-art technology, which allows your radiation oncologist to give treatment with great precision, speed and patient comfort.SRS is used to treat many types of brain tumors. The use of SRS is limited by the size of tumors, which generally need to be less than 5 cm in maximum diameter (about 2 inches).Larger lesions up to approximately 3 cm (about 1.25 inches diameter) can often be treated in a single session, while larger tumors may require five, lower dose treatments. Treatable tumor types include metastatic lesions (meaning a brain tumor which develops as the result of spread from another primary site), such as breast, lung, melanoma or renal cell cancer. More recently, SRS has been used to treat malignant gliomas, such as glioblastoma (GBM) and anaplastic astrocytoma, that have recurred after previous treatment with surgery, radiation therapy and chemotherapy. SRS can also effectively treat small, non-malignant tumors, such as meningiomas, acoustic neuromas (also known as vestibular schwannomas) and glomus tumors.SRS is used to treat other brain abnormalities, including arteriovenous malformation (AVM) and trigeminal neuralgia (severe facial pain originating from the trigeminal nerve).
Stereotactic Body Radiotherapy (SBRT)uses the same precise techniques to treat tumors outside of the brain. This is most often used for small tumors in the lung, liver or spine.SBRTis used to treat metastatic tumors in the spine, lung, liver, abdominal or pelvis areas. There are limitations to using SBRT including the size and number of lesions.Early stage lung cancer can be treated with SBRT alone instead of undergoing lung surgery.Most often SBRT requires 3-5 treatments, but can be completed in one session if the lesion is small enough.
All radiosurgery procedures are performed by a multidisciplinary team consisting of a Radiation Oncologist, radiation physicist, radiation therapists, radiosurgery-specific treatment planners and, depending on the site of the body to be treated, a neurosurgeon, neurotologist or thoracic oncologist.Duke physicians, physicists, planners and therapists are actively involved in radiosurgery clinical trials, teaching, technology assessment and development of quality assurance systems.
WHAT IS THE BENEFIT?
At the time of the consultation visit with your radiation oncologist, the specific benefits of SRS vs. any other treatment options will be discussed in detail. In general, SRS for metastatic lesions is very well tolerated with few expected side effects.Since SRS can be completed in a short period of time, it allows the patient to move on quickly to other recommended treatments such as surgery or chemotherapy.For recurrent gliomas, the best option for safely delivering a second course of radiation therapy is using this highly precise SRS technique.
HOW OFTEN DOES A PATIENT NEED TREATMENT?
SRS can be completed in a relatively short timeframe.Every patient will have an initial consultation visit with a radiation oncologist specializing in their diagnosis.Once SRS is agreed upon,a customized plastic-mesh face mask will be made, which will maintain your head in the correct position for treatment planning and subsequent delivery.A CT scan is obtained while you are wearing the mask, whichwill be used to accurately position your head during the SRS treatment, as well as a new MRI scan.The SRS treatment is usually ready to be performed in about 4 working days after the planning procedures are done.For larger tumors, SRS may need to be done daily for 5 treatments.
SRS for treatment of trigeminal neuralgia requires a different method of head immobilization – alightweight metal stereotactic frame.The frame is placed and is followed shortly by a CT scan.An MRI scan is also used to plan the treatment, but this scan is performed one or more days before the day of SRS. The SRS procedure requires careful and precise planning and generally is ready to be performed by early afternoon.The head frame is removed as soon as the SRS procedure is done.
SBRT requires another type of immobilization device.This device would either be a foam-based mold or a cradle made via a vacuum.A CT scan is also performed while the patient is in the treatment device to begin the radiation planning.The first treatment will be scheduled in approximately one week.
HOW LONG DOES THE TREATMENT LAST?
SRS and SBRT treatments are outpatient procedures that take about 45 minutes to complete for one lesion, and somewhat longer for more than one lesion.The majority of the treatment time involves assuring your position is perfectly aligned before each x-ray beam is given. Your radiation therapist will keep you informed about your progress throughout the treatment process.Discharge instructions will be given to you at the SRS completion, including when to return for a checkup and MRI scan.
WHAT ARE THE SIDE EFFECTS?
Side effects from a SRS or SBRT procedure vary depending on the location, size and number of lesions that are treated.During the consultation appointment, any potential side effects will be discussed in detail with you by your radiation oncologist.
