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What to Expect Before, During, and After CyberKnife Treatment

Being diagnosed with a tumor or other disease can often be frightening and overwhelming. Exploring all the treatment options available and choosing the one best suited to your individual condition is a very important decision that should be made in consultation with your physician and loved ones.

The patient process described below for CyberKnife radiosurgery may vary depending on the individual hospital and your specific medical condition. The following is provided to give you a general overview of what you might expect before, during, and after CyberKnife radiosurgery treatment. Patients who have previously undergone CyberKnife treatment have contributed their suggestions to this section on how to make the experience more comfortable and positive.

During the entire CyberKnife treatment process, several specialists will be involved in your care. They may include a surgeon, radiation oncologist, medical oncologist, physicist, radiation therapist, and nurse among other specialists. This team approach ensures that you receive the highest quality of care by benefiting from cross-disciplinary collaboration.

Finally, you can contact other patients who have undergone CyberKnife treatment here in our CyberKnife Patient Support Group community. Many patients are willing to speak to you about their own experiences and provide emotional support

For more information on the CyberKnife and the patient treatment process, please also visit


Initial Consult

It is best to consult a physician specializing in CyberKnife radiosurgery to determine if the CyberKnife is a potential treatment option for you. Many doctors may not be aware of the technology or may not understand exactly what it can and cannot treat. The best opinion on whether this technology can help you is obtained by consulting a CyberKnife center that has qualified physicians who can review your case. You can find a listing of CyberKnife sites around the world at

Some patients reported that they were not offered CyberKnife as a treatment option initially and had to do their own research and legwork in contacting CyberKnife sites to find out they were indeed candidates for the procedure. Be proactive in your research to find the best available treatment option for yourself or a loved one! Some CyberKnife sites may be able to review your CT/MRI films remotely (they may ask you send a copy of your films through the mail) and determine whether you would likely be a candidate and need to come out for an in-person consult. This can save travel costs and time for people who do not live near a CyberKnife center.

At your consult appointment, bring your CT/MRI films and any relevant medical test results you may have. During this visit with your specialist, you may want to bring a tape recorder to help you later recall information given to you by your doctor. Often there can be a large amount of information to digest and some patients have found it helpful to be able to replay exactly what was said verbatim. Also have a loved one present with you during this visit if possible to serve as a source of support. Writing out a list of questions ahead of time to bring with you will help ensure that you get all of your questions answered. Finally, be up front about your concerns – the more comfortable and knowledgeable you feel about what to expect, the less stressful the process will be. Following a diagnosis by your surgeon, radiation oncologist, or other medical specialist, you may be offered several treatment options. The decision on what the best treatment option is for you will be based on many factors and preferences.

CyberKnife radiosurgery is covered by Medicare and most private insurances. It is best to check with your insurance company and clear any pre-authorization requirements prior to treatment.

If you and your physician decide that CyberKnife treatment is right for you, you will be scheduled for the set-up process. The entire CyberKnife procedure consists of three main steps: set-up, treatment planning, and treatment delivery. These steps can be performed on the same or separate days, depending on the schedule preferences of you and the CyberKnife team. Patients may also go home after set-up and return on a separate day for treatment delivery. Unlike frame-based procedures, you do not need to be present during the treatment planning step.

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Step 1: Set-up

Fiducial Placement (for spine/body treatments only)

An initial fiducial placement step is required if your lesion is located outside of the head in the spine or body. This step is not needed for head or brain treatments.

3 to 6 small metal markers called fiducials will be implanted in a short, surgical procedure in the operating room. The markers provide an internal coordinate system that allows the CyberKnife system to track the exact position of the tumor in real-time throughout treatment. The fiducials, which are about 3-4 mm in length, are usually placed in an outpatient procedure with minimal pain associated with it. Typically injections of local anesthesia are used to numb the area, and the fiducials are placed near the tumor or lesion through small punctures in the skin. The markers do not need to be removed after treatment. For head/brain treatments, the CyberKnife uses the bony landmarks of the skull as the coordinate system to locate the tumor or lesion instead of fiducials, thus no markers are needed for these treatments. By using an image-guidance system to track the bony landmarks, the CyberKnife also eliminates the need for the painful stereotactic head frame, improving patient comfort.

Making a Face-Mask or Body Mold

For head treatments, a soft mesh mask will be custom-molded to your face to help stabilize your head/neck during treatment and ensure your comfort. This mask, unlike the stereotactic head frame, is non-invasive and painless. You will still be able to see and hear through the mask. For body treatments, a custom, foam body cradle will be fitted to your body instead.


You will next be scheduled for a computed tomography (CT) scan. If you had a face mask made, you will wear it during the CT scan. If needed, an IV may be inserted to inject contrast dye to enable physicians to better visualize the lesion. The CT scan provides detailed information on the exact size, shape, and location of your lesion. You are usually free to leave the hospital after the CT scan. In some instances, an MRI scan may also be necessary in order to fully visualize the tumor and nearby critical anatomy.

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Step 2: Treatment Planning

You do not need to be present during this step. The CT information is downloaded to the CyberKnife treatment planning computer where physicians and medical physicists will use the information to develop a customized radiation delivery plan. The treatment plan tells the CyberKnife robot the number, direction, and intensity of beams to deliver to the target. Using specialized software on the CyberKnife computer, physicians will outline the volume of the tumor or lesion to be irradiated, specify the dose to be delivered, and also mark areas near your lesion where radiation is to be minimized or avoided (e.g. sensitive areas of the brain, spinal cord, or organs). The high speed CyberKnife computer then performs millions of calculations to generate the optimal radiation delivery plan. The CyberKnife treatment planning system exploits the robot’s high degree of maneuverability to allow more even delivery of radiation throughout a tumor or lesion than can be achieved by older frame-based radiosurgery systems.

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Step 3: Treatment Delivery


On 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 the process.


You 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.


During 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 treatment team.

After 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 more.

You 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.

You 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.

Side Effects

Generally, 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 symptoms.

Neither 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.


Follow-up 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.

Another 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.

Success 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 your progress.

For more information on the CyberKnife related to a specific medical indication, please visit CyberKnife Society at: and click on a specific condition.

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