CyberKnife Treatment Process

Step #1: Initial Consultation

The initial consultation involves the radiation oncologist, a surgeon and other physicians if required. If you have a medical oncologist, we will also coordinate our plans with theirs. During your consultation, the procedure, as well as the risks and benefits, will be explained to you in detail. If treatment is to be done on soft tissue, small gold markers, known as fiducials, will need to be implanted into the tumor bearing region. Your doctor will discuss the fiducial placement procedure with you if it is a necessary part of your care.

Step #2: Treatment Preparation

Soft Tissue Fiducial Placement

Fiducials are small gold markers that are implanted into soft tissues in or near the tumor (lesion), to accurately guide the CyberKnife® radiation beams. These markers are typically required for tumors in the chest, abdomen, pelvis or other soft tissues, while they may or may not be required for tumors in the spine and are not required for tumors in the brain or skull.

If your treatment requires the placement of fiducial markers within the tumor or lesion area, that procedure will be done by a physician or surgeon and the San Diego CyberKnife® Center staff will make the arrangements for that procedure.

  • If fiducial placement is required, there are several things that you will want to keep in mind:
    • In most cases, fiducial placement will be done as an outpatient in a radiology facility, and you will be able to return home within an hour or two.
    • Prostate fiducials will typically be placed under ultrasound guidance, either by the urologist or by the radiation oncologist.
    • Placement of CT-guided lung fiducials may require a hospital-based radiology department, because some of these placements may result in a complication known as a pneumothorax (air trapped in the space between the lung and the chest wall – sometimes referred to as a “collapsed lung”). This complication occurs in about 1/3rd of lung fiducial patients. If a pneumothorax occurs, it may be minor, requiring no further treatment, or it may require a chest tube to remove this air pocket and reexpand the lung, potentially resulting in admission to the hospital overnight.
    • Other fiducial placement methods may also be used, such as placing them through a scope that passes through the bronchus or esophagus.
    • Our doctors will prescribe the best fiducial placement method for you and our staff will make the necessary arrangements.
    • You will not be allowed to eat or drink six to 12 hours prior to the fiducial placement procedure.
    • You will need someone to drive you that day.
    • You may experience some minor discomfort after fiducial placement.

Step #3: Treatment Planning

Making a Mask or Body Immobilizer

Prior to the treatment planning study (CT scan), the first step is to make a plastic mask (used with brain, head or neck tumors) or a comfortable foam body immobilizing system (for tumors everywhere else in the body). These devices are used to help minimize patient movement during treatment. The process is simple and painless.

Step #4: Treatment Planning

  • CT Scan
  • The surgeon and radiation oncologist will use a CT scan to identify the exact size, shape and location of the tumor, along with the surrounding healthy tissues to be avoided.
    • The time required for this step is variable, typically lasting from several minutes to several hours, depending upon the complexity of the planning process required.
    • When scheduling this appointment, you will receive instructions regarding the CT. You may be given IV contrast (dye). Please let the staff know immediately if you are allergic to the dye.
    • This is a painless procedure. We will discuss with you the need for any pre-medication for treatment such as sedatives or pain medications. Please make us aware of any particular concerns you may have.
    • In some cases, additional radiology studies such as a MRI scan or a PET scan will also be used in the treatment planning process. If we do this, these extra scans are three dimensionally fused with the planning CT-scan to provide the most detailed map possible of your treatment area.

Step #5: Tumor Mapping/Computer Programming

Once your CT studies are complete, your CyberKnife® team will review them in great detail in order to plan your treatment. Planning considerations include exact tumor or lesion configuration and its relationship to adjacent normal body structures, which in turn influences the number, intensity and direction of the radiation beams that the robotic arm will send to the tumor. This will help ensure that a sufficient dose is administered to the tumor in order to destroy it, while minimizing to the greatest degree possible, the radiation dose to the adjacent normal tissue.

When the physicians have completed their work, the physicists will finish the treatment planning. Be aware that this may take a day or longer depending upon the complexity. When the planning is complete, a date and time for treatment(s) will be scheduled. The nurse coordinator will be in touch with you during this time and will confirm with you the treatment date(s) and time(s).

Step #6: CyberKnife® Treatment

  • Arriving for Treatment
    • You may need to come with a family member or driver if you require sedation or relaxation for treatment. Our staff will review this with you prior to treatment.
    • Take any medications prescribed specifically for treatment according to directions on the prescription(s). You should also take your normal daily medications as usual with the exception of diuretics. Diuretics should be withheld until after treatment.
    • Wear comfortable clothing and no jewelry. A blanket will be provided for warmth if needed.
    • During treatment you will need to lay still. Generally no sedation is required because the treatment is painless, although this will be available depending upon your specific circumstance.
    • CyberKnife® treatment will be given 1-5 times depending upon your exact situation. Treatment times may vary from 30-120 minutes. We ask that you plan on spending two hours at the CyberKnife® center each day of the treatment to allow for variability of treatment time, though if more than one CyberKnife® treatment is given, this time estimate may be more exactly tuned after the first treatment.
    • You will receive written discharge instructions. Always ask questions if you do not understand a process or instructions!

The CyberKnife Treatment Process

When CyberKnife® treatment begins you will be lying on the treatment couch with your mask or body cradling system, while the imaging system acquires the first set of X-rays in the treatment position. The couch then adjusts to provide the necessary millimeter alignment, and the robotic arm then moves the linear accelerator to its first position and delivers the first treatment beam. This process is repeated many times as the X-ray system re-acquires the target and the robotic arm realigns the linear accelerator from multiple different positions – often greater than 100 times. At each angle, a precise radiation beam is delivered. The image-guidance system utilizes bony landmarks or implanted fiducial markers to track the exact location of the tumor during the entire treatment process, creating an extremely accurate and precise radiation treatment procedure.

If a lung or upper abdominal tumor is treated, the breathing cycle is also continuously tracked and correlated with tumor position, causing the robotic arm to assume a real time “breathing” pattern that tracks the tumor. This robotic breathing pattern exactly follows the tumor as it moves throughout the breathing cycle, keeping the radiation beam squarely on the tumor throughout the entire treatment.

The entire process is painless and usually lasts 30 to 120 minutes. Typically, you may return home and resume normal activities immediately following treatment. If the treatment plan calls for more than one treatment session (known as fractionated CyberKnife® treatment), the radiation therapists will schedule all of the appointment times with you.

Step #7: Follow Up

We will call you the day after treatment to see how you are doing and will arrange follow-up appointments to monitor your progress. Follow up imaging is generally performed to monitor the tumor’s response to treatment, though the exact study(ies) and their timing will vary with each situation as determined by your participating doctors. You will be given appointments to follow up with the radiation oncologist and surgeon. While waiting for your results, stay busy and maintain a positive state of mind.


Remember to always ask questions if you do not understand a process or instructions!

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