Frequently Asked Questions

The CyberKnife System uses leading-edge robotics and advanced software, but it’s not new. The system has more than two decades of clinical evidence and is used to treat spine cancers and metastases at any point on the spine — including complicated neurosurgical cases, medically inoperable and other complicated cases — with a procedure called stereotactic radiosurgery (SRS) delivered in a single fraction or just a few sessions

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The CyberKnife System was cleared by the U.S. Food and Drug Administration in 1999 to treat tumors in the head and base of the skull, and in 2001 for treatment outside of the skull. Since then, thousands of patients have been treated with CyberKnife SRS for conditions within, near and adjacent to the spine.

CyberKnife treatment is available at hundreds of locations worldwide.

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The CyberKnife System offers many of the same benefits of precise surgical intervention. However, treatment with the CyberKnife System is not surgical at all. CyberKnife treatment is an outpatient procedure that does not require incision, general anesthesia, hospitalization stay or a long recovery period. The CyberKnife System provides an effective alternative for patients with spine tumors or metastases who cannot undergo surgery and/or whose tumors cannot be completely removed with surgery.

CyberKnife treatment is typically completed in just 1-5 treatment sessions in 1-2 weeks, compared to 10-15 sessions over 2-3 weeks with conventional radiation therapy.

Radiation therapy is a treatment that uses high-energy X-rays (photons) to kill, shrink or control the growth of tumors. Radiation therapy works by damaging cells, disabling them from growing and dividing. The goal of any radiation treatment is to destroy cancer cells while minimizing the dose delivered to surrounding healthy tissue. As imaging technologies have improved over the last several decades, radiation therapy has integrated those improvements to enhance dose delivery and minimize side effects.

Radiation may be recommended as an alternative to surgery or in addition to other therapies. There are several kinds of radiation therapy. The CyberKnife System delivers a type of radiation therapy called stereotactic radiosurgery (SRS) in a single fraction or just a few sessions.

Stereotactic radiosurgery (SRS) couples a high degree of targeting accuracy with very high doses of extremely precise, externally delivered radiation, thereby maximizing the cell-killing effect on the tumor(s) while minimizing radiation-related injury in adjacent normal tissues. The treatment is administered in 1-5 sessions to the brain or the spine, typically by a team involving a radiation oncologist and/or a neurosurgeon and a medical physicist. The treatment does not involve surgery.

The extreme, targeted precision of stereotactic radiosurgery (SRS) with the CyberKnife System can offer several powerful benefits, including:

  • Non-surgical and non-invasive
  • Very good local control of the tumor and pain relief
  • Minimal side effects
  • Treatments may typically be completed in 1-5 visits in 1-2 weeks
  • Most patients can continue normal activity throughout treatment
  • Does not typically interrupt chemotherapy cycles
  • Patients with previous spine radiation can receive CyberKnife SRS treatment
  • Could be done in addition to neurological surgery

Learn more about the advantages of non-surgical CyberKnife treatment

There are several options for treating spine cancer, and the right option depends on your specific tumor location, cancer type and cancer aggressiveness — as well as your overall health and treatment goals. The best way to determine if CyberKnife treatment is right for you is to find a CyberKnife treatment location and make an appointment to discuss your specific details.

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Initial side effects from SRS may occur early, during or after treatment and are typically gone within a few weeks. Side effects can, however, be severe. Late side effects can occur months or years later; such effects may require intervention. Discuss your specific case with your physician(s) to fully understand the potential risks associated with your treatment. Possible side effects include, but are not limited to:

  • Fatigue
  • Temporary skin changes such as redness, tenderness, itchiness, or rash
  • Dysphagia (inability to eat) for patients with upper spine treatments
  • Esophagitis (inflammation of the esophagus) for patients with upper spine treatments
  • Transient myelitis (may require corticosteroid treatment)
  • Spinal cord injury
  • Spinal cord (bone) injury
  • Exposure to nearby tissue

Click Here for More Information on Potential Side Effects

CyberKnife treatment is typically completed in 1-5 sessions in 1-2 weeks, compared to 10-15 sessions in 2-3 weeks with conventional radiation therapy.

Treatment with the CyberKnife System is a non-surgical and outpatient procedure that does not require general anesthesia, hospitalization, or a long recovery time. The majority of patients can continue normal activity during and immediately following treatment.

No anesthesia is required for CyberKnife treatment and treatment sessions are completed on an outpatient basis.

The majority of patients can continue normal activity during and immediately following CyberKnife treatment — compared to the typical requirement to limit normal activity for several weeks or more with traditional surgery.

The majority of patients can continue normal activity during and immediately following CyberKnife treatment — compared to the typical limitations that come with traditional surgical treatments.

The robotic design, combined with real-time imaging and automatic synchronization of the radiation beam with tumor movement, enables the CyberKnife System to deliver a maximum dose of radiation directly to the tumor from virtually any angle, with sub-millimeter precision through treatment delivery. The CyberKnife System does this by continually tracking, automatically adapting and synchronizing the radiation beam with the movement of the tumor in real-time. Greater precision helps minimize radiation dose to surrounding healthy tissues and the spinal cord and reduce the risk of common side effects and complications.

Despite being relatively rigid, spinal tumors can move during the treatment session even when immobilized.

Failing to synchronize the delivery of radiation dose with tumor movement can result in decreased dose delivered to the target — and increased dose delivered to the spinal cord and other surrounding healthy tissues. This can impact the overall effectiveness of the treatment and can potentially increase the incidence and severity of side effects and long-term complications.

Unlike any other radiation treatment, the CyberKnife System continually tracks, automatically adapts and synchronizes treatment delivery with movement of the tumor in real-time throughout the entire treatment session. This helps to ensure the radiation dose is delivered to the target — maximizing treatment effectiveness while minimizing radiation exposure to surrounding tissues to reduce the incidence of side effects.

The tissues and structures of the spinal cord are among the most delicate and important for maintaining the basic and complex functions of everyday life. The spinal cord relays messages from the brain to different parts of your body, allowing your organs to function and enabling you to control your movements, such as walking. So, when it comes to delivering radiation to a target in or near the spinal cord, accuracy matters. Precisely delivering the prescribed radiation dose to the target is essential for optimizing long-term cancer control — and minimizing the risk of potential side effects that can impact your ability to function and quality of life.

CyberKnife SRS treatment is a form of hypofractionated radiation therapy. Compared to traditional radiation therapy treatments – commonly called conventional fractionation, which uses a relatively lower dose of radiation, delivered in a dozen or more sessions across several weeks – hypofractionation entails delivering a higher dose per session (called a fraction) across fewer total fractions. Hypofractionated SRS treatment for spine cancer is typically completed in 1-5 sessions in 1-5 weeks.

Hypofractionated radiation therapy, such as spine SRS, has been proven to deliver clinical outcomes as good as conventional fractionation — while dramatically reducing both the number of treatments and the total cost of care for both patients and payers.

Despite the higher dose rate associated with SRS, multiple studies have validated that there are no worse side effects with CyberKnife SRS than with traditional radiation. The ability to deliver precise doses of radiation enables clinicians to decrease exposure to surrounding healthy tissue and minimize negative side-effects that can reduce a patient’s quality of life. Most patients resume normal activity immediately after treatment sessions. Nonetheless, side effects can and do occur — and can be severe — with any treatment option and should be discussed with your physician.

Compelling clinical evidence shows that the hypofractionated, high-dose SRS delivered by the CyberKnife System rapidly offers excellent tumor control, as well as reliable, long-lasting pain relief.1

  • A clinical study of 200 patients with spinal tumors receiving treatment with the CyberKnife System over multiple sessions found that patients experienced significant pain relief and improved quality of life following treatment1
  • A clinical study of 62 patients treated with the CyberKnife System for spinal metastases found treatments were very effective in providing lesion control and pain relief, with mild toxicity.2

Because it can precisely target tumors, the CyberKnife System may provide a safe and effective radiation treatment option for patients previously treated with the system who are diagnosed with a recurrent spine lesion.

Because the precise targeting of the CyberKnife System significantly reduces irradiation of surrounding healthy tissues. CyberKnife may provide a safe radiation treatment option even for patients who have previously received radiation therapy.

As of January 2020, SRS treatment for spine cancer is covered by Medicare in all 50 states and the District of Columbia. In addition, many private insurance payers cover SRS treatment for spine cancer. It is always best to check your insurance policy and if applicable, be sure to review your employee contract to determine if your insurance coverage benefits are limited. If you live outside of the United States, typically the CyberKnife Center that you would choose for treatment can answer coverage questions.

Just as surgery is not a one-size-fits-all solution, not every patient’s spine cancer can be effectively treated with CyberKnife SRS. Talk to your physician about your best options and come to a joint decision. If craniospinal irradiation is required (indicated for medulloblastoma as an example), Accuray’s Radixact® or TomoTherapy® System may be a good option: Radixact and the TomoTherapy Systems leverage CT-image guidance to ensure highly conformal dose delivery to the tumor with each treatment.


1 Degen JW, Gagnon GJ, Voyadzis JM, McRae DA, Lunsden M, Dieterich S, et al. CyberKnife stereotactic radiosurgical treatment of spinal tumors for pain control and quality of life. J Neurosurg Spine 2005;2(5):540-9.

2 Gagnon GJ, Nasr NM, Liao JJ, et al. Treatment of spinal tumors using cyberknife fractionated stereotactic radiosurgery: pain and quality-of-life assessment after treatment in 200 patients. Neurosurgery 2009;64:297-306; discussion 306-297.

3 Wang Q, Song Y, Zhuang H, et al. Robotic stereotactic irradiation and reirradiation for spinal metastases: safety and efficacy assessment. Chin Med J (Engl) 2014;127:232-238.

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Important Safety Statement: Most side effects of radiotherapy, including radiotherapy delivered with Accuray systems, are mild and temporary, often involving fatigue, nausea, and skin irritation. Side effects can be severe, however, leading to pain, alterations in normal body functions (for example, urinary or salivary function), deterioration of quality of life, permanent injury and even death. Side effects can occur during or shortly after radiation treatment or in the months and years following radiation. The nature and severity of side effects depend on many factors, including the size and location of the treated tumor, the treatment technique (for example, the radiation dose), the patient’s general medical condition, to name a few. For more details about the side effects of your radiation therapy, and if treatment with an Accuray product is right for you, ask your doctor.