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Stereotactic radiosurgery (SRS) uses precise patient positioning and extremely accurate radiation delivery to treat brain lesions with a single, high dose of x-rays. Because the radiation is tightly focused on the lesion to be treated, the surrounding normal brain tissue receives very little radiation. Lesions treated with SRS include acoustic neuromas, meningiomas, recurrent gliomas, glomus jugulare tumors, arteriovenous malformations, and many types of other cancer that have spread to the brain (brain metastases). SRS is typically limited to treating one to four lesions which are less than two inches in greatest dimension (See Answers to Radiation Therapy Questions).
At Duke, SRS is delivered by a Novalis TX® linear accelerator. This machine has state-of-the-art technology which allows your Radiation Oncologist to give treatment with the greatest precision, speed, and patient comfort that is currently available. (Watch a You Tube video about Novalis TX at Duke)
The first step in determining if SRS is the treatment of choice for you or your family member is a consultation appointment with the appropriate Radiation Oncologist. At the consultation visit, you will undergo a physical examination. In addition, you and your physician should provide the following information for the radiation oncologist: past medical history, x-rays and procedures related to your diagnosis, pathology (biopsy or surgery results), and records of any treatments already completed. Your Radiation Oncologist will then recommend appropriate treatment options, which may include SRS. You can expect a discussion of all treatment expectations, including any side effects or risks.
Two planning procedures are usually required before most SRS treatments, both of which can be done on the same day in the Radiation Oncology department. On the day of the planning procedures, you should eat, drink, and take medications on your regular schedule. The first step in the planning procedure is making a customized plastic-mesh headholder which will maintain your head in the correct position during treatment. A special plastic mesh is warmed to make it pliable and is then placed behind your head and over your face. Prior to this procedure, oral medicine for relaxation or pain is offered if needed. You must lie still on your back for 30 minutes while the mask cools to conform to the shape of your head. Although the mask is fairly tight, you will easily be able to breathe and see through the mesh. A CT scan is obtained while you are wearing the mask, and should only take about 10 more minutes. In addition, a new MRI scan may be needed for the SRS planning even if you recently had one elsewhere. The MRI is also performed in our department and will require an injection of dye into your vein. All of these immobilization and planning procedures may be done 24 hours or up to several days in advance of the SRS treatment.
Occasionally, SRS requires a different method of head immobilization such as when treating acoustic neuromas. Instead of a plastic headholder, a light-weight metal stereotactic frame is used. While you are under a local anesthetic, a Neurosurgeon or Neurosurgery Physician's Assistant will place a stereotactic headframe on your head and attach it to your skull with four pins. Most patients find the pressure from the headframe uncomfortable just for the first five minutes, but quickly grow used to it. The frame will be placed on your head early in the morning, followed by a planning CT scan and possibly another MRI. Based on the scans, a special SRS team consisting of your Radiation Oncologist, Dosimetrist, and Radiation Physicist will design a custom set of x-ray beams tailored to the exact size, shape, and location of your lesion(s). While the SRS treatment itself takes only a few minutes, the treatment planning and quality assurance processes take several hours to perform, so usually you will be treated in the afternoon.
Radiation Oncology has a private waiting area with television and lounge chairs for you to relax in until the planning is completed and you are ready for treatment. Free, convenient parking next to the clinic is also provided for your treatment day. You will be able to eat, drink, and take medications as needed. The headframe is removed as soon as the SRS is done.
The SRS treatment is an outpatient procedure that takes about 45 minutes to complete for one lesion and somewhat longer if more than one lesion is treated. The majority of the treatment time involves assuring your position is perfectly aligned before each x-ray beam is turned on. Your radiation therapist will keep you informed about your progress throughout the treatment process. Discharge instructions will be given to you at completion of your SRS treatment including when to come back for a follow-up MRI scan.
Feel free to contact us with any questions or concerns between appointments.
--Revised August 2009
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