What to Expect During CyberKnife Stereotactic Radiosurgery Treatment

CyberKnife is one of the most advanced stereotactic radiosurgery systems in use today. Stereotactic radiosurgery relies on robotics and sophisticated image guidance technology to attack tumors with submillimeter accuracy. CyberKnife is an effective treatment for tumors in the prostate, lung, brain, liver, spine, kidney, pancreas and bone.

Anova Cancer Care (ACC) is nationally recognized as one of the most experienced CyberKnife prostate cancer treatment centers in the country. We see patients from all across the country as well as from other countries.

The ACC CyberKnife treatment involves a team approach in which several specialists participate. Our treatment protocol is structured into the following steps, so each patient knows what to expect.

  • Consultation
  • Placement of fiducial markers in the tumor if needed
  • CT and MRI imaging
  • Treatment planning
  • CyberKnife treatment (1-5 sessions)
  • Follow-up

Consultation for CyberKnife stereotactic radiosurgery

Many of our prostate cancer patients are referred by our partners at Urology Associates (UA) and other clinical specialists. Patients can also contact us directly and do not need a referral. Our patient coordinator talks with each patient to assure that ACC has all the needed information and any previous diagnostic CT or MRI scans to start the process.

Our initial consultation is unique to each patient. Anova’s doctors will review the patient’s medical history. With every patient, we discuss all possible treatment options, including CyberKnife treatment and other treatments they can receive from other cancer care providers.

Our doctors share published, peer-reviewed studies about stereotactic radiosurgery success and go over the pros and cons of CyberKnife. The patient then watches a brief educational video about the process, in which a patient receives the final CyberKnife treatment.

Fiducial placement

With soft tissues tumors (prostate, lung, liver, kidney and pancreas) a small gold fiducial marker is placed in the tumor prior to treatment. The fiducial markers (fiducial means “taken as a standard of reference”) are used to identify the location of the tumor. The fiducials are placed under ultrasound and allows the CyberKnife to locate the tumor during treatment. Tumors located in the brain, spine or bone do not require fiducial markers. With these tumors, the CyberKnife system uses the bony anatomy as a reference point for the tumor.

We refer our prostate and kidney patients to our partners at Urology Associates for the short outpatient procedure to place the fiducial markers. For patients with other soft tissue tumors, we coordinate with the appropriate clinical team for placement.

Setup and imaging

We wait a week for the minor swelling from the placement of the fiducial markers to subside before getting the CT scan. The clinical staff will perform a simulation of the treatment and put the patient in the same position on the CT/MRI scanner as he or she will be in on the CyberKnife system. If needed, they’ll create a custom “bean bag” that fits the patient’s anatomy and ensures he or she will always be in the same position during treatment.

At a nearby imaging center, patients get a high-resolution, thin-slice CT of the target area that provides us the best anatomical detail for use in the treatment planning process.

For a prostate tumor, a catheter will be placed to highlight the urethra in the treatment scans so we can avoid it during the treatment.

For brain cancer treatments, the patient will be fitted for a custom mask he or she will wear during treatment. The mask helps to prevent the head from moving during treatment.

Planning                                                                   

The physicists will fuse the CT and MRI scans so that they and the radiation oncologist can use both imaging sets to outline the exact location of the tumor/target area and critical anatomical structures. The images and contours are sent to the treatment planning software, and the radiation oncologist prescribes a radiation dose for the tumor, setting the allowable dose for healthy tissue.

A powerful algorithm is used to develop a deliverable treatment plan that meets all of the criteria set by the doctor and physicist team. The radiation plan and course goes through several rounds of calculations and algorithms to ensure the best case scenario for treatment. The software plots out the treatment plan, including all CyberKnife robot positions, appropriate angles and the diameter of the radiation field to be delivered. The process to evaluate the thousands of possible angles and beam sizes can take 4-8 hours to complete a plan before the doctor gives final approval. The patient is not present at this time.

Due to the many patients we’re helping, our scheduling team often allows 5-7 work days for this to be completed. If clinically necessary, the schedule will be adjusted.

Treatment with CyberKnife stereotactic radiosurgery

All treatments are completed in the Anova clinic on an out-patient basis. The process typically includes five 30- or 60-minute sessions, every other day. Patients receive a customized schedule for treatment with all of the details, from what they should/should not eat to the date and time of arrival.

Patients are encouraged to dress in comfortable clothes. Patients have a huge selection of music to enjoy during their treatment, and our radiation therapists are there to make it an easy experience for them.

In the treatment room the patient lies down on a table, and the radiation therapists will get him/her in the same position as during the CT and MRI scan. They have cameras and an intercom system so they can see and speak to the patient at any time.

Once the treatment starts, the CyberKnife robot moves and rotates around the patient to position the linear accelerator at the exact angle prescribed by the computer treatment plan. The patient will hear different clicks and mechanical sounds, which is the CyberKnife doing it’s thing. It’s moving into new positions, locking the robot’s joints and changing the size of the collimeter as instructed by the treatment plan.

During the treatment, the CyberKnife sytem takes periodic images to locate the fiducial markers or bony structure. It compares these orthogonal images to the CT and makes any adjustment necessary to ensure submillimeter accuracy.

Interesting fact, the CyberKnife robot that positions the linear acclerator is the same kind found on many manufacturing assembly lines, such as in the automobile industry. Although this robot has the capability to move very fast, the CyberKnife system uses a slower speed setting to not stress patients. Here is a video link to a Kuka robot, similar to the CyberKnife robot, making carbon fiber components.

Once the treatment is complete, patients can return to their daily activities with little to no interruptions. Most patients report that the CyberKnife treatment is completely pain free.

Follow-up

Follow-up will differ depending on the location of the patient’s tumor. For prostate cancer, there is a follow-up after one month, and no additional imaging is needed. Our doctors will ask how the patient is doing and ask about his prostate specific antigen (PSA) level, sexual health and urinary function.

For brain, lung or other cancers that require imaging, there will be a follow-up after six months. At that point, a new CT scan and/or MRI scan is needed to view the status of the tumor. It is important to remember that the tumor will not suddenly disappear; it takes three-six months for a tumor to show reduction in response to treatment.

Side effects

Most patients do not experience any side effects after CyberKnife treatment. Side effects that can occur include dizziness, nausea and fatigue. Most patients who do experience one of these side effects easily recover from them in a short time.

Patients being treated for a prostate tumor could also experience increased or decreased urination, burning with urination, more gas with bowel movements or increased frequency of stools.