What is Cyberknife Radiosurgery?
Cyberknife Radiosurgery is a non-invasive form of surgery that uses high doses of radiation to treat a broad range of non-cancerous and cancerous tumors throughout the body. This includes ailments in the prostate, lung, brain, spine, liver, pancreas, and kidney. Cyberknife delivers about 1400 highly pinpointed beams of radiation to control or kill the tumor. It has extremely high precision and accuracy.
Cyberknife system comprises of computer-controlled robot that slowly moves around the patient, delivering radiation to the tumor from various angles, which helps to spare surrounding healthy tissues. Each session of treatment lasts for between 30 to 90 minutes, for one to five days.
Cyberknife today is probably the most popular stereotactic radiosurgery. It is the best alternative for surgically complex or inoperable tumors. The location, shape, and size of the tumor determine the total dose and number of radiation treatments.
How does Cyberknife work?
Cyberknife does not require surgery & there is no cutting or anesthesia required. Cyberknife is comprised of a compact linear accelerator – a machine that generates a radiation beam- attached to a highly maneuverable robotic arm.
- The machine’s robotic arms move around you, aiming & firing targeted radiation beams from numerous angles.
- The imaging & tracking system continually updates the tumor location throughout the treatment procedure compensating for a patient movement like breathing.
- A treatment session typically lasts for 30-90 minutes.
During the CyberKnife procedure, the patient will lie on a treatment table while the machine’s robotic arm moves around his or her body delivering high doses of radiation directly to their tumor with pinpoint precision minimizing exposure to the surrounding healthy tissues.
Difference between SRS and SBRT
Stereotactic radiosurgery is a non-surgical therapy for treating small tumors and abnormalities of the brain. With its accurately targeted beams, it helps preserve healthy tissue by targeting radiation on the cancerous area.
When Stereotactic Radiosurgery is involved in the treatment of other body tumors rather than brain tumors, it is termed Stereotactic Body Radiation Therapy.
Reliability on the technology
The two types of treatment rely on different technologies that include:
- System for immobilizing and accurate positioning of the patient to maintain the same until the session lasts
- IGRT or image-guided radiation therapy uses imaging for localizing the tumor before the radiation treatment. The accuracy and precision of this procedure is through the IGRT
- 3-D imaging and other techniques for locating the tumor and determining the target coordinates
- Focused x-ray or gamma-ray beams converging on the abnormality or the tumor.
Why the Cyberknife surgery?
Cyberknife surgery is generally a preferred choice for patients who cannot opt for conventional surgery. The health problems and/or the age of such patients don’t allow them to go for a conventional surgery due to the involvement of associated risks. However, the SRS surgery is essential as the tumor is present in an area close to the vital structures. The tumors treated with this type of radiosurgery are:
- An acoustic neuroma (slow-growing nerve tumor connecting the brain and the ear)
- Spinal cord tumors
- Inaccessible abnormalities
- Metastasizing cancer or cancer that spreads from any area of the body to the brain
- Pituitary tumors
- Residual cells after a tumor removal surgery
- Cancers of kidney, lung, and prostate
- Cancers of breast, liver, and pancreas
- Melanoma of the eye (type of eye cancer)
- Arteriovenous malformations
- Shaking or tremors
- Tumors at the base of the skull
- Trigeminal neuralgia or pain in the nerve of the face
- Parkinson’s disease
- Orbital or intracranial tumors
Benefits of Cyberknife Radiosurgery
- No anesthesia is required.
- Exceptional accuracy, spares healthy tissues & organs.
- No invasive head or body frame.
- Immediate return to normal activity.
Preparing for the surgery
Both the types of procedures- whether SRS or SRBT are performed on an immediate basis. You can assume to spend around half of your day or even more at the hospital. The doctor will inform you if there’s a need for somebody to accompany you and/or take you home after the procedure. Your doctor will give an appointment within 1-2 days of your first visit to the hospital. You might need to do overnight fasting a night before the procedure is scheduled. You must ask your doctor if there’s a need for any kind of medication immediately before the treatment.
Alternatively, your doctor might also ask you to bring those particular medicines with you to consume the same minutes before the procedure starts. You must inform your doctor about anything that you are consuming or any other ailment that you are suffering from. If you are diabetic and/or under medications, inform the same to your doctor. If you have an allergy again anything, it is important to mention it too. Apart from this, if you have any kind of implants, pacemaker, or any stent, provide your doctor with the relevant details.
Who will perform the procedure?
A team of medical professionals performs the treatment who specialize in performing such procedures. The team may include a medical radiation physicist, a dosimetrist, a radiation therapy nurse, a radiation oncologist, a radiologist, a radiation therapist, and a neurooncologist.
- The medical radiation physicist adjusts the dose of radiation to be provided during the procedure.
- A dosimetrist or physicist will produce the treatment plan with the help of specialized software. He or she is also responsible for calculating the beam configuration and the exposure in the required dose for the treatment.
- A radiation therapy nurse will evaluate the patient and educate the patient about the entire treatment procedure. The nurse will also be responsible for monitoring the patient while undergoing the procedure and instructing him or her after the procedure is over.
- The radiation oncologist along with a neurosurgeon (in some cases) will lead the entire team. He or she will approve the treatment plan, locate the target area locate the tissues or organs adjacent to it that might be at risk, make a decision regarding the dose of the radiation for treatment, and finally infer the results of this procedure.
- A radiologist will interpret the images that helped identify the location of the tumor in the body.
- A radiation therapist is trained in positioning the patient accurately on the table and for operating the machine from the protected area. He or she will observe the patient through a closed-circuit television while communicating with the patient till the procedure gets over.
- A neurooncologist or neurologist will evaluate the various treatment possibilities available for the patient with the neurosurgeon and radiation oncologist. He or she will also decide if the radiosurgery will be beneficial for the particular case of the patient or the brain lesion that the patient is having.
Equipment for the procedure
The treatment procedure can be performed using any of the three types of equipment that involves the use of different sources of radiation as well as instruments.
- LINAC MACHINE: Linear Accelerator machines deliver photons or high-energy X-rays. These machines perform SRS in one or multiple sessions to destroy the bigger tumors. The procedure is fractionated stereotactic radiotherapy if it involves multiple sessions.
- GAMMA KNIFE: This machine uses 201 or 192 beams of gamma rays. These rays are highly directed towards the target tumor. The procedure is the best for tumors that are small or medium in size.
- PROTON BEAM RADIOSURGERY: It involves the use of heavily charged particles for performing the procedure and eliminating the intracranial lesions.
Performing the procedure
As there are three types of instruments used for the treatment procedure, there are three ways of performing the treatment.
- SRS USING LINAC: It involves four phases that are imaging, radiation delivery, head frame placement, and computerized dose planning. The machine has a gantry that moves around the patient to target the radiation beams towards the lesion. With the use of Cyberknife, the robotic arm is responsible for moving the LINAC at different angles surrounding the patient. A majority of LINAC-based SRS is now frameless allowing the procedure to be fractionated. This is beneficial in cases of large-sized tumors or tumors at risky locations.
- SRS USING GAMMA KNIFE: This procedure also involves four phases similar to LINAC-based SRS.
a. For the first phase, the nurse will position a needle in your arm for imaging and/or medications. The neurosurgeon will anesthetize two spots on the back portion of your head as well as your forehead using anesthesia. A frame will be connected to your head with the use of pins to prevent head movement during the procedure.
b. Next, an MRI will be taken in a separate room to locate the tumor concerning the frame. Alternatively, a CT scan might also be recorded.
c. The medical team will now assess the tumor and plan the treatment according to it. They will use special software to plan everything and ensure minimal radiation exposure to the surrounding normal tissues.
d. Finally, the team will move to the control area from where they will observe you and communicate with you through a microphone. The bed on which you are lying will move into the machine and undergo the treatment without any interruption. The treatment duration may vary between 1 hour to 4 hours. With a sound, the bed will get back to its original position when the procedure gets completed. The team will now remove the frame from your head and allow you to go home.
- SBRT: This type of treatment procedure involves one or multiple sessions over a week or two.
- For Cyberknife treatment, there will be the placement of a fiducial marker near the tumor in your head. The placement of the fiducial marker will be done by your radiation oncologist, gastroenterologist, pulmonologist, and radiologist.
- The radiation oncologist will choose the right method to bring your body and beams of the LINAC in alignment. This process is termed simulation to maintain precision during the treatment.
- The team will collectively decide upon the best beam arrangement for your case and may incorporate the use of some other imaging techniques also.
- The radiation delivery is finally done after placing you in the immobilization device. You will be positioned by the radiation therapist and the radiation oncologist followed by delivery of the treatment. The duration of the procedure will be around 1 hour or even more, in rare cases.
Pre-operative and post-operative instructions
The patient can neither hear nor feel the X-rays being recorded. However, one may experience flashes of light in some exceptional cases. One will not experience any kind of discomfort or pain during the entire procedure. In case of any pain, the patient must inform about the same to the doctor or radiologist. The team will bandage the pin sites upon removing the head frame to stop the minor bleeding. If you are suffering from a headache because of this, you can ask the team or any of them to prescribe you medications.
A majority of patients can get back to their routine activities within a day or two after the procedure. The doses of radiation you receive will determine the number of side effects. For the management of these side effects, you can talk to your doctor or the nurse. The side effects will go away within a few weeks post-treatment. These side effects may be but do not limit to:
- Skin problems
- Red and sensitive skin
- Swelling and irritation on the skin
- Dryness, peeling, or blistering of the skin
- Eating and digestion problems
- Nausea and/or vomiting
- Swelling and soreness in the area where treatment was performed
- Hair loss in the area of the treatment
- Difficulty in swallowing and mouth problems
- Urinary changes
In some cases, the side effects are quite late but may be permanent. This includes:
- Spinal cord changes
- Kidney changes
- Secondary cancer
- Brain changes
- Rectal and colon changes
- Fracture of bones
- Lung changes
- Joint changes
To avoid the chances of secondary cancer, you must regularly go for follow-ups and get yourself checked. Your radiation oncologist will assess you for any new or recurring cancer.
What makes cyberknife treatment accurate?
- Levels of the accuracy of Cyberknife are sub-millimetric and added with the benefits of real-time image guidance & tumor motion tracking, Cyberknife can aim at targets with pinpoint accuracy.
- Cyberknife has capabilities of automatic error correction. It continuously corrects for any changes in patient position during the treatment, thus allowing the patient to lie comfortably during the treatment.
- The availability of real-time image guidance & tumor motion tracking helps to treat tumors in moving areas with the greatest accuracy- by treating in synchrony.
- The use of a robotic arm in treatment helps in treatment from angles not easily accessible by conventional radiotherapy machines.
Precision for Cyberknife treatment
The cyberknife radiosurgery treatment is a desirable option for operating on varying kinds of tumors of the body. The accuracy and precision of this treatment are vital to destroy the cancerous cells with minimal exposure to the surrounding healthy tissues. This also minimizes the risk of side effects while offering the patient a better life quality before & after the treatment.
The patient might change his or her position while breathing or slightly move the head. Sometimes, the muscles of the patient tense or relax while coughing or sneezing. With Cyberknife treatment, motion management of the tumor as well as the patient is easy. The use of a cyberknife system eliminates the risk of irradiation to surrounding healthy tissues. This is because the cyberknife system has advanced technology to detect the location of tumors and keep the radiation doses restricted to the tumor.
Synchrony in the cyberknife system is the sole most real-time adaptive technology in the world. It precisely synchronizes the beam motion for treatment delivery towards the target and maintains the accuracy of radiation treatment to the body tumor. It has motion synchronization technology which makes it delivering treatment easier. The patient need not hold his or her breath for radiation treatment to the tumor.