Stereotactic Radiosurgery (SRS)

Stereotactic radiosurgery (SRS) is a technique to treat brain disorders. It uses a highly focused beam of radiation to target specific areas of the brain. The beam of radiation destroys the tissue that a doctor would otherwise have removed with a scalpel during an operation.

Treatment involves a team of specialists, including:

• Radiation oncologist—makes the treatment plan and ensures the dose delivered is appropriate
• Neurosurgeon—often places the head frame for brain treatment delivery, and assists with planning
• Medical radiation physicist—assists the radiation oncologist with dose prescription, maintains the actual radiation machine (gamma knife unit or linear accelerator)
• Dosimetrist—specifically works on the radiation dose prescription
• Radiation therapist—operates the machinery
• Radiation therapy nurse—assists the radiation oncologist with direct patient care
• Neurologist or neuro-oncologist—assists the neurosurgeon and radiation oncologist with the treatment of brain tumors, including seizure control and rehabilitation, may also coordinate overall treatment plan

SRS is used to:

• Stop cancerous and noncancerous tumor growth
• Shrink cancerous and noncancerous tumors
• Close off arteriovenous malformations (AVMs)—abnormal blood vessels that disrupt blood flow to the brain
• Treat disorders such as:
  • Trigeminal neuralgia —a condition that causes facial pain
  • Epilepsy —a disorder that causes seizures

Brain Tumor

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Possible Complications

If you are planning to have SRS, your doctor will review a list of possible complications, which may include:

• Headache
• Temporary swelling at the treatment site (may be associated with worsening of symptoms)
• Swelling, numbness, bleeding, or tingling around the sites where the head frame rests on the head
• Skin irritation
• Nausea
• Seizures
• Patchy hair loss from the radiation
• Permanent injury to the location in the brain being treated

Rare complications may include:

• Vision loss
• Deafness
• Bleeding
• Nerve problems

Although the risk for complications is low, advanced age, chronic medical conditions, previous surgeries, or previous radiation at or near the target site may increase the risk for complications.

What to Expect

Prior to Procedure

Your doctor may do the following:

• Perform a neurological exam to see how well your nervous system is functioning
• Review your x-rays, CT scans, MRI scans, or other diagnostic test results
• Order additional tests if necessary

Your doctor may ask if you:

• Take medicine or insulin to control diabetes
• Are allergic to intravenous contrast material—an injected substance that can make a tumor or other abnormality easier to see
• Are allergic to iodine or shellfish (iodine is present in both shellfish and contrast material)
• Have a pacemaker or any other medical device implanted in your body
• Have eye or ear implants
• Have had any previous surgeries
• Have ever had trauma to the skull
• Suffer from claustrophobia

Leading up to your procedure:

• Review your regular medicines with your doctor. You may be asked to stop taking some drugs.
• Arrange for someone to:
  • Drive you to the treatment facility
  • Drive you home afterward
  • Stay with you during treatment
  • Stay with you the following night
• If advised by your doctor, use a special shampoo.

The day before your procedure:

• Do not use any hair creams or hair spray.
• Do not eat or drink anything after midnight unless told otherwise by your doctor.

The day of your procedure:

• Bring your regular prescription medicines with you to the hospital.
• Do not wear jewelry, make-up, nail polish, a wig, or a hairpiece.
• Remove any contact lenses, eyeglasses, or dentures.
• An IV line will be inserted into your arm to deliver contrast material, medicines, and fluids.

Anesthesia

• You will receive a mild sedative to help you relax.
• A local anesthetic may be injected to numb your scalp.

Description of Procedure

There are a few types of SRS:

Cobalt-60-based Treatment (commonly called Gamma Knife Treatment)

The procedure will be done using 201 beams of highly focused gamma rays. It is used to treat smaller brain tumors and functional brain disorders. The Gamma Knife is the most well-known machine used for this procedure.

There are four phases to this treatment:

• Head frame placement—Local anesthesia will be injected into the front and back of your head to numb your scalp. A box-shaped, aluminum frame will be attached to your skull with special pins. This will keep your head from moving during treatment.
• Imaging—You will have a CT scan and/or MRI to pinpoint the exact location of the tumor. If you are being treated for an AVM, you may have a test called an angiography to locate the abnormal veins.
• Computerized dose planning—You will relax for about an hour while your doctors plan your treatment. When they are finished, you will lie down on a special couch. Your doctor will talk to you about the number of treatments you will receive and how long they will take. Your head frame will then be attached to a helmet full of small holes. Each hole will allow a single ray of radiation to target a specific part of your brain.
• Radiation delivery—The doctors and nurses will leave the room. Your couch will move into the treatment area. You might hear a click as the helmet locks into place. Your doctor will be able to see and hear you during the entire procedure, and you will be able to talk to her. You will remain still during the procedure and so will the machinery around you. You will not be able to see, feel, or hear the treatment being done. When treatment is complete, the couch will move back to its original position.

Linear accelerator (LINAC)-based Treatment

This treatment utilizes one large, powerful radiation beam. It is used to treat small and large brain tumors. You will go through the same phases listed above. During radiation delivery, however, part of the machine will move around you. The treatment couch will also be repositioned. Some newer systems can also deliver radiation to tumors of the spinal cord.

CyberKnife Treatment

CyberKnife treatment is given using a small linear accelerator mounted on a robotic arm. It is used to treat tumors and lesions of the brain and spine. No head frame is used.

There are three phases to treatment:

• Set-up—If you are being treated for a brain tumor, a special mask will be made to fit your head. No pins are needed to keep it in place. You will be given a CT scan, and possibly an MRI, with the mask in place. If you are being treated for a spinal tumor, a customized foam body cradle will be made, instead of a mask. You will most likely have some small metal markers, called fiducials, implanted near the tumor to help guide the radiation beams during treatment. The fiducials are implanted during a short outpatient procedure. After they are in place, you will be given a CT scan.
• Treatment planning—You may be allowed to go home while the doctors finalize your treatment plan. Actual treatment may take place that same day or several days after the set-up phase.
• Treatment delivery—You will be fitted with your mask or body cradle and then lie down on the treatment table. Before the treatment starts, x-rays will be taken to help the linear accelerator move into the proper position. Once treatment begins, the robotic arm will move around you and administer radiation beams from many different angles. Sometimes the arm will stop and more x-rays will be taken.

After Procedure

If you received Gamma Knife or LINAC-based treatment:

• The head frame and IV line will be removed.
• Your head will be wrapped in gauze, or small bandages will be placed at the pin sites, where the pins secured the frame to your head.

How Long Will It Take?

• Radiation delivery can take up to 2 hours for Gamma Knife and LINAC-based treatments. For CyberKnife treatments, it can take up to 3 hours.
• The total procedure usually takes 2-4 hours.

Will It Hurt?

• Anesthesia prevents pain at the pin sites if a head frame is used during treatment.
• You will feel some pressure as the head frame is attached.
• The treatment itself causes no pain.
• You may experience headaches or nausea a few hours after treatment. Your doctor will give you medicine to relieve any discomfort.

Post-procedure Care

When you return home after the procedure, do the following to help ensure a smooth recovery:

• You can typically return to your regular daily activities the day after the procedure.
• Resume your regular medicines, unless told otherwise by your doctor.
• Check with your doctor about performing any heavy lifting.
• For about a week, avoid scrubbing the pin sites when you wash your hair.
• Be sure to follow your doctor's instructions .

Call Your Doctor

After arriving home, contact your doctor if any of the following occurs:

• Signs of infection, including fever and chills
• Redness, swelling, increasing pain, excessive bleeding, or any discharge from the pin sites
• Nausea and/or vomiting that you cannot control with the medicines you were given after surgery, or which persist for more than two days after discharge from the hospital
• Pain that you cannot control with the medicines you have been given
• Cough, shortness of breath, heart palpitations, or chest pain
• You have a severe headache
• Weakness, loss of balance
• Vision problems
• Seizures
• Any new symptoms, including new onset of numbness

In case of an emergency, call for medical help right away.