(Gamma Knife Treatment; CyberKnife Treatment)
Stereotactic radiosurgery 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 elements of brain tumors]]>, such as seizure control and rehabilitation
Reasons for Procedure
Stereotactic radiosurgery 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:
If you are planning to have stereotactic radiosurgery, your doctor will review a list of possible complications, which may include:
- 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
- Patchy hair loss from the radiation
- Permanent injury to the location in the brain being treated
Rare complications may include:
- Vision loss
- 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.
- 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 three types of stereotactic radiosurgery:
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 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.
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.
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.
Stereotactic radiosurgery works over time. It may take several months to several years to see results.
- About one month after your procedure, your doctor will check your pin sites and perform a neurological exam.
- CT scans or MRIs will likely be performed sometime after the procedure to assess for treatment effect. The number of scans and frequency with which you get them depends on your doctor’s opinion and experience.
- If you were treated for an AVM, you will have a test called a cerebral angiogram two to three years after treatment to determine if treatment was successful.
- In many cases, stereotactic radiosurgery treatments can be performed again, if necessary.
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
- Any new symptoms, including new onset of numbness
In case of an emergency, CALL 911.
American Association of Neurological Surgeons
International Radiosurgical Association
The CyberKnife. University of Pittsburgh Department of Neurological Surgery website. Available at: http://www.neurosurgery.pitt.edu/spine/cyberknife.html. Accessed October 4, 2005.
CyberKnife stereotactic radiosurgery system. Georgetown University Hospital website. Available at: http://www.georgetownuniversityhospital.org/body.cfm?id=451. Accessed October 4, 2005.
CyberKnife stereotactic radiosurgery system overview. CyberKnife Society website. Available at: http://www.cksociety.org/PatientInfo/radiosurgery.asp#cyberknife_radiosugery. Accessed October 4, 2005.
Information for patients. Yale-New Haven Hospital Gamma Knife Center website. Available at: http://www.ynhh.org/gammaknife/infopatients.html#after. Accessed September 10, 2005.
Linear accelerator. RadilogyInfo website. Available at: http://www.radiologyinfo.org/pdf/linac.pdf. Accessed September 9, 2005.
Stereotactic radiosurgery. American Association of Neurological Surgeons website. Available at: http://www.neurosurgerytoday.org/what/patient_e/stereotactic.asp. Accessed September 9, 2005.
Stereotactic radiosurgery. Mayo Clinic website. Available at: http://mayoclinic.org/stereotactic-radiosurgery/index.html. Accessed September 9, 2005.
Stereotactic radiosurgery overview. International Radiosurgical Association website. Available at: http://www.irsa.org/radiosurgery.html. Accessed September 1, 2005.
Stereotactic radiosurgery questions and answers. International Radiosurgical Association website. Available at: http://www.irsa.org/qa.html. Accessed September 9, 2005.
What is stereotactic radiosurgery? University of Iowa Department of Radiation Oncology Virtual Hospital website. Available at: http://www.vh.org/adult/patient/radiationoncology/guide/04understanding.html. Accessed September 9, 2005.
What is stereotactic radiosurgery and how is it used? RadiologyInfo website. Available at: http://www.radiologyinfo.org/content/therapy/stereotactic.htm. Accessed September 1, 2005.
Last reviewed November 2009 by ]]> Rimas Lukas, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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