The Leksell Gamma Knife
What
to Expect - Step by Step Through Gamma Knife Surgery
The gamma knife is really not a knife at all. For this type of surgery,
201 highly-focused x-ray beams make up the “scalpel” that “cuts” through
diseased tissue.
The gamma knife surgery itself takes approximately
15 minutes to 1 hour, but pre-treatment preparation can take an hour or
more.
 Step
1 - Headpiece Frame Placement:
First, the head frame is secured with sterile pins. A local anesthetic,
or mild sedative are given to minimize discomfort and relax patients during
the placement of the frame. Once in place, the frame is used to localize
the target area and immobilize and position the patient’s head during
treatment with the gamma knife.
 Step
2 - Diagnostic Imaging:
Patients then undergo a series of advanced diagnostic tests to help physicians
determine the precise location and size of the tumor or abnormality. These
tests are painless and could include x-rays, computerized tomography (CT),
magnetic resonance imaging (MRI), and/or angiogram. These images will
guide the treatment team in determining the best radiation dosage and
treatment length.
 Step
3 – Treatment Planning:
Using the information obtained from diagnostic imaging, the gamma knife’s
computerized treatment-planning software creates a three-dimensional model
that matches the shape and size of the actual target. Dosage of radiation
and length of treatment are then determined.
 Step
4 – Gamma Knife Surgery: Individual x-rays beams of cobalt gamma radiation
are aimed through a helmet-like sphere called a collimator to the targeted
tumor or malformation. At the site of the tumor or abnormality, the separate
beams converge through the collimator into one beam delivering enough
radiation to cause damage to the diseased tissue while sparing surrounding
normal tissue.
The most current robotics and computer
technology are used in the Hopkins gamma knife to ensure accurate positioning
of the head and collimator. Gamma knife is non-invasive and painless,
so patients remain awake during treatment and, though physicians, technicians,
and nurses are in an adjoining room during delivery of the radiation,
they maintain constant visual and voice contact with patients.
 Step
5 – Recovery:
Patients are monitored for a few hours following treatment, and most return
home the same day. Some patients remain in the hospital overnight for
observation. The majority of patients resume normal activities within
one to two days of their gamma knife procedure. Patients will return to
their referring physician or Johns Hopkins for follow-up diagnostic tests
to monitor and assess the results of gamma knife surgery.
 Gamma
Knife Treatment for Children
Certain
brain lesions in children are ideally suited for treatment with gamma
knife. The non-invasive nature of the therapy and shorter treatment and
recovery periods are particularly attractive to parents of younger patients.
Treatment with gamma knife is essentially the same for adult and pediatric
patients, however, children may receive general anesthesia and typically
remain in the hospital overnight. Children treated at our gamma knife
center have the full expertise and resources of the world renowned Johns
Hopkins Children’s Center at their disposal.
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