What to Expect During CyberKnife Treatment

"Stereotactic Radiosurgery and Stereotactic Ablative Radiotherapy: What to Expect During Treatment and How to Manage Treatment Related Side Effects"

Initial Consultation

For cranial and spinal treatments, the initial consultation involves both the radiation oncologist and neurosurgeon, with the assistance of either the physician assistant, nurse practitioner or nurse.

For extracranial treatments, the initial consultation involves radiation oncologist and other physicians.

The procedure, as well as the risk and benefit, will be explained to the patients. The initial consultantion may be on the same day as the setup procedure. It is more often done days before the setup procedure. There are other paper work, such as insurance coverage, that has to be addressed before the rest of the treatment process can proceed.

Setup Procedure

The setup involves either a plastic mask or a foam body cradle. Either one will help a patient stay in a fixed position during treatment.

For a typical cranial tumor or lesion, a custom-fit plastic mask is made for each patient. With the mask in place, the patient undergoes a CT scan with contrast. In some instances, a MRI scan may be needed.

For extracranial tumor or lesion, a foam body cradle is custom-fit for the individual patient instead of the mask. Most extracranial cases require placement of small metal fiducials prior to treatment set-up. These implanted metal fiducials are 3 to 4mm long and are used to accurately target the tumor.

Although the procedure itself takes less than an hour, patients should expect to be at Stanford for about 8 hours. An example is 6:30am check-in, discharge at 3 pm with someone to drive the patient home. Patient receives moderate sedation for the fiducials implant procedure.

Treatment Planning

Treatment planning is the process through which physicians and the medical physicist plan the details of radiation delivery to a tumor or lesion.

During the CyberKnife treatment planning process, once the physician/physicist has determined the volume and dose of radiation, the CyberKnife computer determines the best radiation delivery plan.

Treatment Delivery

At some point after treatment planning, the patient returns for treatment delivery. During treatment, the patient is fitted with the custom plastic mask (for cranial tumors) or body cradle (for spinal tumors/lesions or other extracranial tumors such as lung or pancreas) and lies on the treatment table.

Prior to beginning of the actual radiation treatment, the imaging system acquires x-ray image of the patient position. This information, compared with the information gathered with the CT scan, is used to move the linear accelerator to the appropriate position by the robot.

This process is repeated at 50 to 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 it typically takes between 30 to 60 minutes to deliver all radiation beams for cranial treatments. Most typically a patient can go home immediately upon completion and return to normal activities. If the treatment prescription is for staged (fractionated) radiosurgery, the patient will return on a separate visit and repeat the above process for treatment delivery.

Followup

After the radiosurgery treatment, follow-up with MRI are usually done in 3 to 6 months. The physicians will explain to the patients such procedure at the end of the treatment.

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