the day of your scheduled CyberKnife treatment, you will need
to check in at the facility and go to the CyberKnife suite.
Wear loose, comfortable clothing as you will be treated wearing
your street clothing. Do not wear any jewelry. You may also
want to bring a newspaper/magazine to read or headphones and
a CD for any waiting time before your treatment. Try to relax
knowing this will be a painless procedure. Be sure to ask your
doctor or nurse beforehand about any medications you may be
taking and whether you should continue to take them on your
treatment day. Many patients find it very helpful to bring
a family member or other loved one to provide support during
will be asked to lie on the treatment table and will be fitted
with the facemask (for head lesions) or body cradle (for body
lesions) made earlier during the set-up process. Generally,
no sedation or anesthesia is used and you will be completely
awake throughout treatment. If you normally have pain while
lying on your back, you will need to take your pain medication
before being treated. Once you are positioned on the table,
the imaging system will acquire a set of digital x-rays to
identify the initial position of your lesion so the linear
accelerator can be positioned properly.
actual treatment, no one will be allowed to stay in the treatment
room with you (as live x-rays are being delivered). Family
members and friends may wait in the waiting area while you
are undergoing the actual treatment. The treatment usually
lasts 30-90 minutes depending on the complexity of your tumor.
You will be monitored throughout treatment by closed circuit
television so the treatment team will be able to observe and
hear you. If you need to temporarily halt treatment for any
reason, you may use verbal or physical cues instructed by your
you are positioned, the CyberKnife treatment begins. The computer-controlled
robot will move the linear accelerator to multiple, pre-calculated
positions around you as you lie on the table. At each of these
positions, the robot stops and the linear accelerator fires
a small beam of radiation at the tumor or lesion. Periodically,
digital x-ray images of the target will be captured by the
image-guidance system to verify the position of your lesion.
If you inadvertently move slightly, the change is detected
by this imaging system and it automatically re-positions the
robotic arm to immediately compensate for the change. This
ensures the radiation is delivered accurately to the target
throughout treatment. The process of checking target position
and delivering radiation is repeated until all beams of radiation
are delivered. The radiation beams are delivered from multiple,
different angles but all beams intersect at the tumor. Therefore,
the tumor receives a very high total radiation dose while the
surrounding tissue receives a much lower, non-injurious dose.
A typical treatment can be composed of 100 to 150 beams or
will not need to do anything during treatment except lie still
while the CyberKnife delivers the radiation. Some patients
even fall asleep while lying on the table. You will not feel
or smell anything as the radiation is being delivered. The
procedure is completely painless. You may see the robot moving
slowly around you as it moves the linear accelerator to deliver
each beam of radiation from different positions.
can go home immediately upon completion of treatment and resume
your normal routine. There is no recovery time. If the treatment
prescription is for staged (fractionated) radiosurgery, you
will return on a separate visit(s) (usually the next day) and
repeat the above process for treatment delivery. The decision
to fractionate treatment or divide the radiation dose into
2-5 smaller daily doses is determined by the CyberKnife team
on a case-by-case basis. Typically fractionation is beneficial
for larger tumors or lesions located in close proximity to
sensitive structures. The spacing of doses allows time for
the tissue to recover, reducing potential side effects such
as nerve damage, while still delivering a high total dose to
effectively kill or control the abnormal cells.
there are no side effects from treatment. Most patients feel
fine after treatment and are able to leave and return home
immediately. When there are rare side effects, they are usually
directly related to the area that was irradiated by the CyberKnife.
For example, you may experience temporary dizziness or headache
from treatment of tumors in the brain or mild nausea if your
tumor is located in the lower spine (as the radiation passes
through the intestines). In the majority of cases, no side
effects whatsoever are reported. Steroids or other medications
can be prescribed by your doctor if you do experience any temporary
the benefits nor the potential complications of radiosurgery
are immediate, and it may be several months before results
are known. Your doctors will tell you how often you will need
to be seen and when to obtain radiologic studies.
appointments are very important – be sure you do not miss any!
Your tumor or lesion will need to be monitored periodically
to follow its progress. It is important to understand that
the actual size of your tumor or lesion may not have changed
on follow-up scans, but this does not mean the treatment was
not effective or successful. Radiosurgery destroys the abnormal
cells which can leave behind scar tissue that visually looks
similar to the original tumor on MRI scans. Therefore, even
though the abnormal cells are dying or "dead", the
mass may not look any smaller. It may gradually shrink over
time; however it is not uncommon for successfully treated tumors
to appear unchanged, even after several years. The tumor or
lesion will not suddenly disappear after treatment.
important point is that the volume of the mass is measured
from the CT/MRI scan and that there is some variability depending
on which image slices were used to obtain the measurement.
The fact that the dimensions of your lesion changed by 1-2
millimeters, either on the larger or smaller side, is often
not considered significant and is considered routine measurement
variation. Thus, if the measured tumor size increased by 1
mm for example, this would not necessarily mean your tumor
actually grew 1 mm, but may be interpreted as unchanged.
of treatment may be defined by alleviation of symptoms, shrinking
or halting the growth of the tumor depending on your specific
condition. By routinely evaluating your symptoms and following
your post-operative MRI data, your doctor will be able to determine
more information on the CyberKnife related to a specific medical
indication, please visit CyberKnife Society at: www.cksociety.org and
click on a specific condition.