1. Initial Consultation
CyberKnife treatments involve a team approach in which several clinicians and specialists participate. The initial consultation for any CK patient involves a meeting with the patient, a radiation oncologist, and a specialist physician depending on the location and type of tumor being treated. For example, with cranial and spinal tumors, the initial consultation would involve a radiation oncologist and neurosurgeon. Sometimes, physician assistants, nurses, and nurse practitioners are invited to participate.
During this initial meeting, the procedure, as well as its risks and benefits, will be explained to the patient. The patient should also expect to complete paperwork that is required to move forward with the treatment. Usually, the initial consultation is done days before the setup procedure; however, it may be done the same day.
2. Setup Procedure
Prior to the procedure, the patient is imaged using a CT scan, possibly combined with MRI or PET, to determine the size, shape and location of the tumor. This may be required even if you have had recent scans; the CyberKnife system requires that scans be obtained using specific protocols which are not normally used for standard diagnostic imaging.
3. Treatment Planning
With these new scans, treatment planning begins. The image data is digitally transferred to the CyberKnife treatment planning computer. Then, physicians and a medical physicist use the scans and sophisticated CyberKnife computer software to plan the details of the radiation delivery. The goal is to customize the treatment plan to match the desired radiation dose to the identified tumor location while limiting radiation exposure to the surrounding healthy tissue. The patient does not need to be present during this step.
4. Fiducial Placement
In some cases, patients may need a short, outpatient procedure to implant fiducials in or near the lesion prior to treatment with CyberKnife. Fiducials are small metal markers made out of gold or stainless steal that help track the progress that the CyberKnife is making on removing a tumor or lesion in the body. They are primarily used for soft tissue tumors in the body (non-head or spine). There are several different methods used to implant the fiducials depending on the location of the tumor, treatment plan, patient history, or physician decision.
5. Treatment Delivery
Once the treatment plan has been developed, the patient returns for treatment delivery. During treatment, the patient is fitted with a custom plastic mask (for cranial tumors) or body cradle (for spinal tumors/lesions or other extracranial tumors such as lung or pancreas) and lies comfortably on the treatment table. Generally, no sedation or anesthesia is required.
Then, the CyberKnife system’s computer-controlled robot will slowly move around the patient to the various locations from which it will deliver radiation to the tumor. The robotic arm will move to anywhere from 50 to more than 200 different positions around the patient to complete the treatment. At various intervals, the robot stops and additional x-ray images are obtained, thereby allowing the CyberKnife to track and compensate for small amounts of patient movement.
The entire process is painless and typically lasts 30 to 90 minutes depending on the type of tumor being treated. CyberKnife treatment is an outpatient procedure where the patient can usually go home immediately after and return to normal activities. Patients may experience some minimal side effects, but they often go away within the first week or two after treatment, and serious side effects are uncommon.
If treatment is being delivered in stages, patients will need to return for additional treatments over several days (typically no more than five), as determined by the patient’s doctor.
After CyberKnife treatment, the progress of the tumor or lesion must be monitored. Consultation with your physician and additional imaging with a CT and/or MRI will likely occur within 3 to 6 months of treatment.