Step #1: Initial Consultation
The initial consultation involves the radiation oncologist reviewing your history, previous treatments, imaging, and pathology. If you have a medical oncologist or surgeon, 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 area is outside the brain, small gold markers, known as fiducials, might be needed 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 outside the brain or spine which include the chest, abdomen, pelvis. There are no fiducials or headframes for brain and spine sites.
If your treatment requires fiducial markers, our physicians will coordinate placement with referring physicians or radiologist at St. Luke’s Hospital as an outpatient procedure. Typically, we like the fiducials to stay in place for a minimum of 5 days prior to treatment planning to minimize migration of the fiducials.
- Prostate: Placed under ultrasound guidance similar to the prostate biopsy, by either the urologist or by the radiation oncologist.
- Lung: Placed under CT-guided or Super-dimension (brochoscopy). When placing fiducials in the lung, there is 30% chance of complication known as a pneumothorax (air trapped in the space between the lung and the chest wall – sometimes referred to as a “collapsed lung”). Other fiducial placement methods may also be used, such as placing them through a scope that passes through the bronchus or esophagus which has a lower incidence of pneumothorax. 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.
- Pancreas/Liver/Other Soft Tissues: Placed under CT-guided or endoscopy.
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 and allow for accurate repeatable setup. The process is simple and painless.
Once the immbolization devices is custom made for you, a CT Scan will be performed to determine the location, size, shape of the tumor and proximity of normal structures. Depending on the location of the tumor, IV contrast may be injected prior to the scan.
Step #4: Tumor Mapping/Beam Design
After CT studies are complete, your CyberKnife® team will review the images in order to plan your treatment. 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.
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. The treatment planning and beam design process can take a few days. When the planning is complete, a date and time for treatment(s) will be scheduled. The coordinator will be in touch with you during this time and will confirm with you the treatment date(s) and time(s).
Step #5: CyberKnife® Treatment
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 to allow setup and treatment.
The CyberKnife Treatment Process
When CyberKnife® treatment begins you will be lying on the treatment couch with your mask or body cradling system. We have the ability to play music of your choice to create an environment which is soothing. 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. Then 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 #6: Follow Up
Follow up imaging is generally performed to monitor the tumor’s response to treatment, though the exact studies 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.