Gamma Knife radiosurgery has been used for decades to treat brain tumors and brain disorders without scalpels or blood. Thanks to constant advancements in technology, it remains the choice of neurosurgeons worldwide. In fact, approximately half a million people have been treated with Gamma Knife surgery.
“Surgery without a scalpel”
Gamma Knife is a very precise and effective instrument that uses radiation to treat the brain and is often called radiosurgery. Using this method, doctors are able to focus radiation directly, and very precisely, on the target in the brain without affecting surrounding healthy tissue.
Studies show strong treatment success rates; for example, local control (successful treatment of a specific site) of tumors in any brain location exceeds an average of 85%. And, despite the name, there is no blade or knife – it’s called Gamma Knife because radiosurgery (one-session treatment) has such a dramatic and precise effect in the target zone that the changes are considered ‘surgical.’ So there’s no incision or blood, and minimal risk of complications.
Through the use of three-dimensional, computer-aided planning and the high degree of immobilization of the patient, the treatment can minimize the amount of radiation to surrounding healthy brain tissue. There are approximately 200 sources of cobalt-60 loaded within the treatment unit. Thousands of radiation beams can be generated from these sources with a level of accuracy of more than 0.5mm, about the thickness of a strand of hair. Individually, each radiation beam is too weak to damage the normal tissues it crosses on the way to the target. But when focused precisely on that target, the beams intersect and the combined radiation is sufficient to treat the targeted area.
Because Gamma Knife radiosurgery is so accurate, the full dose of radiation can be delivered during a single session, compared with multiple visits for linear accelerator (linac) treatments, which use lower doses delivered in fractions (fractionated treatment).
The reduction of excess radiation is important to everyone, but particularly to cancer patients who are receiving other radiotherapy treatments. For these patients, treatment of a metastatic brain tumor – a cancer that has spread from the original site – might have to be delayed by up to six weeks if certain less precise treatments are used.
Gamma Knife surgery is “stereotactic radiosurgery”
Radiosurgery is the delivery of a single, large dose of radiation to a specific target in the brain with surgical precision. The radiation will react on a molecular level with the cancer cells and stop their reproduction, which kills the cancer.
Stereotactic refers to precise positioning in three-dimensional space. In Gamma Knife surgery, this means a 3-D reference frame is attached to the patient’s head during the procedure.
The stereotactic frame:
- provides a 3-D reference which can be seen on the imaging equipment to provide exact coordinates for the target
- totally immobilizes the patient’s head to ensure pinpoint accuracy when targeting and delivering radiation – it’s similar to placing a camera on a tripod rather than trying to hold it steady with just your hands
Concerns about excess radiation have been growing as new studies look at how much medical radiation Americans receive. A study conducted by the National Council on Radiation Protection and Measurement (NCRP) revealed Americans have experienced a six-fold increase in radiation from medical devices since 1980.
The study attributes much of the increase to CT scanning, which accounts for nearly half of the medical radiation dose delivered in the U.S., despite making up just 12% of all medical and radiation procedures in the country
Rather than dose-contributing CT scans, most neurosurgeons use a single MRI imaging scan to establish the treatment target for Gamma Knife surgery. Other linac-based systems that don’t use the head frame require constant imaging with CT scans during treatment, further contributing to excess dosage.
Standard of care
Gamma Knife surgery is what is known as “a standard of care” for its indications. In the last five years, the number of patients treated per year has increased by 300%. More than 30,000 patients every year worldwide are treated with Gamma Knife surgery.
Gamma Knife is a Swedish invention. In 1968 the first Gamma Knife was installed at the private hospital Sophiahemmet in Stockholm, Sweden. The first in the U.S. was installed in 1987 in Pittsburgh. Over the years, Gamma Knife has been refined and improved with advances in engineering radiation physics, robotic controls and computerized treatment planning.
Alternative to open surgery
Gamma Knife surgery is an alternative or can be complementary to open surgery. The procedure is normally performed by a neurosurgeon accompanied by a radiation oncologist and medical physicist.
Gamma Knife surgery provides lower complication rates than open surgery. Both mortality and morbidity rates are lower for radiosurgery. (Dheerendra Prasad, University of Virginia, USA Gamma Knife Surgery and Microsurgery, Clinical Review, 2002.)
Since no incision is made, the risk of surgical complications is low. The patient’s head does not have to be shaved and side effects are few. Treatment is much shorter than conventional surgery and causes only minor discomfort. Also, the patient can leave the day of surgery or stay overnight for observation, compared with several weeks for traditional surgery. The treatment is complete in one session and seldom takes more than a few hours. The full effects of Gamma Knife surgery may be realized over the course of several months following treatment.
Healthcare cost saving
Gamma Knife surgery is highly cost effective and generally fully reimbursed by insurance. The cost for Gamma Knife surgery is normally half the cost of open surgery, saving both the healthcare institution and patient money.
One reason for the lower cost is that the recovery period is extremely short compared to surgery, which can take several months. Generally, Gamma Knife is performed on an out-patient basis and the patient resumes normal activities almost immediately. Compared to other treatments, Gamma Knife surgery offers a more favorable quality of life before, during and after the procedure.
References : Electa / Sweden
Prof. Kılıç and the BAU School of Medicine Gamma Knife Team
HEAD FRAME & IMAGING
One of the key components of Gamma Knife – the tool that allows your doctor to precisely pinpoint your tumor or problem – is the special stereotactic head frame.
This lightweight frame, which is attached to your head with four small screws, ensures that the radiation beams are precisely targeted. The frame also prevents your head from moving during the treatment procedure, which ensures that only the target area in your brain receives radiation.
After your head frame is in place, a number of advanced imaging tests – such as an MRI or CT scan – will be required to precisely locate the size, shape and location of your tumor, lesion or abnormality.
If your physician is treating a blood vessel abnormality, an angiogram may also be required. As you may already know, an angiogram involves the injection of a dye into your bloodstream so that the imaging procedure clearly shows the blood vessels and arteries in the brain.
The coordinate markers on your head frame, which are part of the images taken, will help your physician develop an exact plan for your procedure.
Once your images have been taken, you can sleep, rest or relax while your physician develops your specialized treatment plan. First, your brain images are computerized. Then, using Gamma Knife 3-D planning software, a treatment protocol is planned.
No two treatment plans are alike; every patient’s plan is specifically designed to address his or her specific medical condition.
Because Gamma Knife includes a set of unique helmets that have 201 holes for the precise delivery of radiation to your brain, your plan will consist of one or more treatments using these helmets.
Once your treatment plan is complete, you’ll lay down on the treatment table and your head frame will be attached to the helmet for your first treatment. You’ll be awake during the procedure and able to communicate with your Gamma Knife team through a video and audio connection.
When Gamma Knife® S
urgery begins, the treatment table, which is much like the one you were on for your MRI or CT scan, will move into the dome section of the unit.
The team will be monitoring your procedure at all times. There may be several treatments lasting anywhere from two to forty-five minutes during your Gamma Knife session.
BACK TO YOUR NORMAL ROUTINE
Once your treatment is complete, the head frame will be removed. If you had an angiogram, you might have to lie quietly for several more hours. Some patients experience a mild headache or minor swelling where the head frame was attached, but most report no problems. Your doctor will tell you whether or not he wants you to stay overnight for observation or if you can go home immediately. Either way, you should be able to return to work or your normal routine in another day or so.
The effects of your Gamma Knife treatment will occur over time. Radiation treatments are designed to stop the growth of tumors or lesions, which means they won’t disappear immediately but over a period of weeks or months. Your physician and Leksell Gamma Knife® team will stay in contact with you to assess your progress, which will include follow-up MRI or CT images in the near future and periodic check-ups.