PATIENT GUIDE TO THE GAMMA KNIFE
WHAT IS A GAMMA KNIFE?
The Gamma Knife is a machine that focuses a very large amount of
radiation on a very small part of the brain in order to shrink or
destroy that area. Although called radiosurgery, it is not surgery
in the usual sense of the word.
HOW DOES THE GAMMA
The best way to understand the Gamma Knife is to imagine an
entertainer on a stage in Las Vegas. When the entertainer first
comes on stage, the room is entirely dark. Then the spotlights are
turned on, and all intersect on the entertainer. He or she is brightly
illuminated, and all around is extremely dark and can barely be
seen. The Gamma Knife works on a similar principle except instead
of spotlights, there are 201 pencil-thin "spotlights"
of radiation. The spotlights are between 4 and 18 millimeters in
diameter, and all intersect precisely where we want in the brain
with a precision of 1 mm. The intent is to have these beams intersect
at the lesion in your brain that we want to treat; the normal brain
structures around the lesion receive an insignificant amount of
PREPARATION FOR THE
There is little you need to do to prepare for the Gamma Knife.
A few days before the treatment, you are invited to come to the
Gamma Knife Center, at which time you will be given a tour of the
unit. They will familiarize you with the surroundings so that on
the day treatment, all will go as comfortably and smoothly as possible.
THE DAY OF THE GAMMA
We usually ask that you arrive at 6 AM on the day of treatment
so that you can be admitted to the hospital, and fill out the usual
forms. You should not eat anything the day of the Gamma Knife, but
please take all your usual medications with a sip of water upon
leaving for the hospital.
are taken to the Gamma Knife unit. Beverly Ponte and I will put
a metal device on your head. This takes about 5 minutes, and is
called a Leksell frame. It allows us to treat your condition with
great precision. The Leksell frame attaches to your head with one-inch
metal posts. We start by injecting the scalp in the forehead and
behind the ears with Novocaine. We may put a small gauze pad over
your eyes to prevent any irritation should the Novocaine drip into
These metal posts advance to those anesthetized areas, and put pressure
against the scalp and head. Putting the Novocaine in is unpleasant,
but this only lasts for a few seconds. When the Leksell frame is
securely in position, you can expect to feel pressure for about
15 minutes, and then it should be comfortable and cause you little
discomfort. You will be transported over to the MRI unit that is
just down the corridor from the Gamma Knife Center.
The MRI study often takes as long as an hour, so sometimes we will
give you some sedation to enable you to sleep through it. After
this, you go to your room where you can read, watch television,
or take a nap.
PREPARATION OF THE
In the next several hours, the images from the studies are transferred
through the communications network to the Gamma Knife planning computer.
Dr. Saris and the physicist then make the treatment plan.
Once the treatment plan
has been finalized, you will be transported to the Gamma Knife unit.
You'll lie on the treatment table and the frame that we placed earlier
is secured to it. You have a microphone and can talk to us at all
times. There is music playing to help pass the time. You may bring
your own music, and we will be glad to play it for you.
The bed you are on will
slide into the Gamma Knife unit itself, and your entire body and
head move up a foot or so to engage with the unit. Undergoing the
gamma treatment is very much like undergoing an MRI. The table moves
you about, but nothing appears to be happening otherwise. The radiation
is odorless and colorless, and you will feel nothing at all as you
are treated. Each treatment lasts for a few minutes as the radiation
is directed to different parts of your lesion. We will tell you
what to expect for each one.
The typical treatment
takes between 15 minutes and two hours. When the last treatment
has been done, the Leksell frame is removed. The areas where the
metal rods posts have come in contact with the skin can be little
tender, but once they are removed should cause only a mild to moderate
ache. We will put Band-Aids on those areas, and may put a small
ACE wrap on your head for an hour or so.
When this has been completed,
you'll go back to your room for observation. You can have something
to eat that afternoon. Then you'll go home later that day. There
is no recovery. Anything you did the day before treatment you can
do the day after. The radiation is long gone by the time you get
to the recovery area after treatment.
My office will call you
in regard to being seen again, and we will arrange more MRIs as
needed. In general, the first MRI is six months after the treatment.
A helpful Web site to look at is www.elekta.com.
This is the company that makes the Gamma Knife. It will give you
helpful links to many other sites.
Stephen Saris M.D.