Friday, May 11, 2018
Gamma Knife: Treating brain tumors without doing brain surgery
It happens all the time on TV. A brain surgeon has to perform a risky, life-altering brain surgery on a patient with a brain tumor that most surgeons will not operate on.
What if that approach wasn't necessary – if you could stop a brain tumor from posing a threat without surgery? That treatment is possible with radiosurgery using the Gamma Knife.
The American Cancer Society estimates there will be 23,880 malignant tumors of the brain or spinal cord in 2018. The Gamma Knife at Marshfield Medical Center treated 106 brain tumors last year.
How Gamma Knife works
Before treatment, a frame with four pins is placed on the patient's head to restrict head movement. An MRI is then performed to find the location of the tumor(s), which is used by the cancer care team to map out the proper treatment.
Once the treatment plan is developed, the Gamma Knife uses 192 separate beams of radiation, which meet at one point to make a supercharged dose of radiation, killing the cancer cells at that location in the brain. The Gamma Knife then moves the patient's head so it can target another location.
At the point where the beams come together, three different sizes can be used to ensure the tumor is destroyed without actually affecting brain tissue.
"We can define volumes precisely enough to make sure we are hitting the tumor without including anything else within the 192-beam cluster," said Dr. Warren Olds, a Marshfield Clinic radiation oncologist. "Whole-brain radiation at doses that would have any chances of affecting the cancer in your brain will affect your memory and thinking."
Gamma Knife is non-invasive, which means the process doesn't include any cuts, anesthesia, bleeding, chance of infections, spinal fluid leaks, stroke, hair loss or any other problems that go along with other treatment options. It is also a relatively quick procedure with some treatments lasting less than an hour, while more complex procedures may take several hours.
"It is a way for our patients to get treatment for potentially very serious disorders with minimal risk, inconvenience and discomfort," said Dr. John Neal, a Marshfield Clinic neurosurgeon. "For the most part, our patients are happy with the experience because they can walk in and walk out."
Brain tumors Gamma Knife can treat
While the Gamma Knife doesn't treat all brain tumors, it can treat metastatic tumors, benign meningioma tumors and pituitary tumors. It also can treat other issues that are not cancer including acoustic neuromas, small vascular malformations and trigeminal neuralgia.
"For some of these conditions, like metastatic tumors, it is more effective than open surgery," Dr. Neal said. "It has been a huge advance in how we can treat patients."
Rare treatment with a long history
The Gamma Knife in Marshfield is one of only a few in the state. It has been in at the hospital since June of 2000 when it was the first one in the state, treating nearly 1,400 people in that time.
The procedure requires both a neurosurgeon and radiation oncologist to perform the procedure. The neurosurgeon will help create the plan, while the radiation oncologist sets the dosage and is the one that actually has to press the button.