Currently the CyberKnife Radiosurgery System is most frequently used by itself for patients with early stage prostate cancer confined to the prostate or in combination with another therapy, such as external beam radiation for patients with disease that extends beyond the prostate. In presentations at scientific meetings and peer-reviewed publications, CyberKnife researchers have reported reliable reductions in PSA levels with low rates of mild side effects during short-term follow-up after CyberKnife monotherapy. Depending on the stage of prostate cancer that is diagnosed, the doctor will recommend a treatment plan.
The CyberKnife treatment generally involves four steps:
Prior to CyberKnife treatment, patients will be scheduled for a short outpatient procedure in which three to five tiny gold seeds – called fiducial markers – are inserted into the prostate. The fiducials are placed through a needle, which is guided via an ultrasound. Patients may be asked to clean out their rectum with an enema the day of the fiducial placement.
The CyberKnife uses the fiducials as reference points to identify the exact location of the prostate. Doctors will wait approximately one week after insertion of the fiducials before CyberKnife treatment planning can begin to ensure that fiducial movement has stabilized.
Prior to the treatment, a special custom-fit body cradle will be made. The cradle is made of a soft material that molds to the patient’s body, ensuring that the patient is in the same position for each treatment session and is comfortable during the procedure.
While lying in the cradle, patients will undergo a CT scan. This CT data will be used by the CyberKnife team to determine the exact size, shape and location of the prostate. An MRI scan also may be necessary to fully visualize the prostate and nearby anatomy. Once the imaging is done, the body cradle will be stored and used during CyberKnife treatment.
A treatment plan will be specifically designed by a medical physicist in conjunction with the patient’s doctors. Patients will not need to be present at this time. During treatment planning, CT and/or MRI data will be downloaded into the CyberKnife’s treatment planning software. The medical team will determine the size of the area being targeted by radiation and the radiation dose, as well as identifying critical structures – such as the bladder and rectum – where radiation should be minimized.
At this time, the CyberKnife will be able to calculate the optimal radiation delivery plan to treat the prostate. Each patient’s unique treatment plan will take full advantage of the CyberKnife’s extreme maneuverability, allowing for a safe and accurate prostate cancer treatment. After the treatment plan is developed, patients return to the CyberKnife center for treatment. The treatment is usually delivered in one to five sessions.
For most patients, the CyberKnife treatment is a completely pain-free experience. They may dress comfortably in street clothes, and the CyberKnife center may allow patients to bring music to listen to during the treatment. Patients also may want to bring something to read or listen to during any waiting time, and have a friend or family member with them to provide support before and after treatment.
When it is time for treatment, patients will lie on their custom body cradle. The radiation therapist will ensure the body cradle is properly adjusted and that patients are appropriately positioned on the treatment couch. When patients are ready for treatment to begin, the location of the prostate will be tracked and detected. The medical team will be watching patients every step of the way as the CyberKnife tracks the patient’s prostate as it moves, and safely and precisely delivering radiation to it.
The CyberKnife’s computer-controlled robot will move around the patient’s body to various locations from which it will deliver radiation. At each position, the robot will stop. Then, special software will determine precisely where the radiation should be delivered. Nothing will be required of the patient during the treatment, except to relax and lie as still as possible.
For more information about CyberKnife, call 253-403-6399.