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CyberKnife FAQs

What can the CyberKnife System treat?
The CyberKnife System is a non-invasive alternative to surgery for the treatment of both cancerous and non-cancerous tumors anywhere in the body, including the head, spine, lung, prostate, liver and pancreas. Click here for a list of some, but not all intracranial (head and brain) and extracranial tumors and lesions that can be treated by the CyberKnife System.

How many patients have been treated with the CyberKnife System? 
As of July 2008 more than 50,000 patients have been treated worldwide by the CyberKnife System. More than half of those patients were treated with lesions or tumors outside of the brain and head.

How is a CyberKnife "radiosurgery" treatment different from traditional radiation therapy treatment? 
Traditional radiation therapy typically delivers radiation to a wide field of tissue in the body resulting in the treatment of both the tumor and a large amount of surrounding healthy tissue.  This is necessary because traditional radiation therapy systems did not account for tumor motion and were therefore much less accurate.  These wide radiation fields increased the possibility of damage to normal tissue, increasing the risk of side effects following the radiation treatment. To reduce the number of side effects, clinicians were forced to rethink the way traditional radiation therapy was delivered.  As a result, the overall radiation dose was reduced and the number of treatments was divided into 30 to 40 sessions, delivered over a period of weeks. 

Radiosurgery devices, such as the CyberKnife Robotic Radiosurgery System, were designed to deliver radiation with extreme accuracy, targeting the tumor with minimal damage to the surrounding healthy tissue. The accuracy of the CyberKnife System allows clinicians to deliver very high doses of radiation safely because the size of the radiation field is smaller and only includes the tumor and a small amount of surrounding tissue.  This allows for less damage to surrounding healthy tissue and for clinicians to complete treatment in 1 to 5 days vs. the weeks it takes traditional radiation therapy.

How does the CyberKnife System differ from other radiosurgery systems?

  • Unprecedented Targeting Accuracy - Many tumors, even when their movement has been restricted, have been proven to move during treatment delivery. Using advanced robotic technology and the ability to track the tumor's movement throughout the treatment, the CyberKnife System can deliver radiation with extreme accuracy while automatically correcting for tumor movement without interrupting the treatment or having to reposition the patient.
  • Unrivaled Conformality and Dose Gradient - Unconstrained by the clockwise / counterclockwise gantry rotations of conventional radiotherapy systems, the robotic mobility of the CyberKnife System enables it to treat from a variety of angles without clinician intervention or treatment interruption.
  • Unparalleled Healthy Tissue Sparing - Without the limitations of conventional respiratory gating and breath-holding techniques, the CyberKnife System delivers radiation beams that adjust in real-time with a patients breathing cycle. By dramatically reducing the planning margins to only that which are clinically relevant, the CyberKnife System's ability to minimize damage to the surrounding healthy tissue is unmatched.

What are the different treatment options for treating cancer or benign lesions? 
The treatment options available vary according to the specific cancer and its location. In general, the treatments can be divided into the following categories:

A) Radiosurgery: Radiosurgery, also known as stereotactic radiosurgery, is a form of radiation and despite its name, is not surgery. It is designed to precisely destroy a tumor or lesion by delivering a very high dose of radiation to the tumor in 1 to 5 treatments over a treatment course of 1 to 5 days. Patients are not required to be hospitalized during treatment and the procedure is almost always performed on an outpatient basis.

B) Radiation therapy: Radiation therapy is a form of radiation that is usually delivered 5 days a week over a treatment course of 6 to 8 weeks. Radiation therapy, (as opposed to stereotactic radiosurgery), usually treats larger areas that include not only the tumor, but large amounts of healthy tissue, increasing the risk of possible complications. Patients are not required to be hospitalized during treatment and the procedure is almost always performed on an outpatient basis.

C) Brachytherapy: Brachytherapy is a specialized form of radiation therapy that requires the surgical placement of small radioactive sources in and around a tumor. The radioactive sources can be implanted either temporarily or permanently, depending on the nature of the source used. Low dose rate brachytherapy (LDR) delivers a prescribed dose over a longer period of time. Radioactive sources are usually implanted permanently. High dose rate brachytherapy (HDR) uses a different source type that delivers dose over a shorter period of time, therefore HDR sources are usually implanted temporarily. Brachytherapy has been used to treat a wide variety of cancers including prostate, breast, lung, head and neck cancers.

D) Cryoablation: With Cyroablation, which is also called cryotherapy, a probe is inserted through the skin and into the tumor to freeze the tumor and kill its cells. Placement of the probe requires an incision and can be performed either on an inpatient or outpatient basis depending on the tumor being treated.

E) High Intensity Focused Ultrasound (HIFU): HIFU uses a focused ultrasound beam to kill tissue containing cancer cells. It is not FDA approved in the United States, but has been used to treat prostate cancer in Europe.

F) Surgery: Surgery or surgical resection is an invasive procedure that requires an incision to remove or cut the tumor out of the body.   Surgery can be performed on an inpatient or outpatient basis depending on the tumor being treated.  Because of the invasiveness of some types of surgery, some patients may be excluded from receiving this type of treatment.

Has the CyberKnife System been cleared by the FDA?
Yes, the Food and Drug Administration (FDA) cleared the CyberKnife System to treat tumors in the head, neck and upper spine in 1999 and tumors anywhere in the body in 2001.

Are CyberKnife treatments covered by private insurance companies and Medicare? 
While Accuray cannot guarantee reimbursement from any third-party payer, data collected from US-based CyberKnife centers indicate that Medicare has covered the CyberKnife treatment, and over 100 unique commercial, private payers are reimbursing the related codes, and any or all portions of CyberKnife services. Patients should always consult with a physician in connection with any and all treatment options, and if required, obtain prior authorization from their insurance companies once a treatment option is determined.

Accuray offers assistance to those patients that may experience challenges with their insurance carriers. If you need special assistance, please contact Accuray Patient Relations at (888) 522-3740 ext 4301, (408) 789-4301 or

What is the difference between a lesion and a tumor?
A lesion can refer to any focused abnormality in the body, such as a tumor, a blood clot, a cyst, an aneurysm or an inflammatory mass. A tumor is an abnormal collection of cells that has grown due to a change in the cells. Tumors can be either malignant or benign and are a type of lesion.

How is cancer "staged" and what does this mean? 
Staging describes the extent or severity of an individual's cancer. Knowing the stage of the disease helps the physician plan treatment and estimate prognosis. Staging systems for cancer have evolved over time and continue to change as scientists learn more about cancer. There are many staging systems and some are specific to certain cancer types. The TNM staging system, for example, is used for lung cancer and is based on the extent of the tumor (T), its spread to lymph nodes (N) and its metastasis (spread to other parts of the body) (M). Most cancers can be described as stage 0, stage I, stage II, stage III or stage IV. Physical exams, imaging procedures, laboratory tests, pathology reports, and surgical reports provide information to determine the stage of each cancer.

I am currently on or have been on chemotherapy. Am I eligible for a CyberKnife treatment? 
The CyberKnife System can treat patients that have either gone through chemotherapy or are currently undergoing chemotherapy. It is important for the patient to provide their physician with a complete medical history, so to the physician can prescribe the appropriate treatment course.

I have had radiation or proton therapy. Am I still eligible for a CyberKnife treatment?
The CyberKnife System can treat patients that have either gone through radiation therapy or are currently undergoing radiation therapy. It is important for the patient to provide their physician with a complete medical history, so the physician can prescribe the appropriate treatment course.

How much does a CyberKnife treatment cost? 
During the consultation process, the CyberKnife staff will tell the patient how much the CyberKnife treatment costs.

What side effects can I expect after a CyberKnife treatment? 
Most patients experience minimal to no short-term side effects and often recover quickly. Depending on the treatment site, some patient's may experience different side effects such as mild fatigue or nausea. The CyberKnife physician will disclose all possible side effects prior to treatment.

After treatment, when will my tumor or lesion disappear? 
The effects of radiosurgery vary and may occur gradually and over time. The timeframe can range from days, months or years depending on the medical condition targeted. Some tumors may disappear slower than others or may simply stop growing and present no further cell activity. After treatment, patients typically are asked to get periodic images (CAT scan or MRI) of their tumor(s) and additional tests may be required, so the physician can monitor the effectiveness of the treatment.

How many times can I receive a CyberKnife treatment?
The frequency of treatments depend on where the tumor is located and what type of tumor is being treated. Most cases can receive multi-treatments or can be re-treated with the CyberKnife System.

What is a linear accelerator? 
A linear accelerator or LINAC is a device that uses an extremely high voltage power supply to produce high energy radiation.