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ROBOTIC PRECISION, PERSONALIZED RADIATION THERAPY.

Oncology is an ever-evolving field. Thanks to research and advancements in technique and technology, we are able to continue honing our skills and provide the most leading-edge care to our patients who need it most. 

One such technological advancement in radiation oncology was the creation of Cyberknife. First debuted in 1994, Cyberknife is a precision robotic radiation treatment machine designed for and dedicated to stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatment. With its robotic delivery system and built-in real-time image tracking, this established technology provides extreme accuracy over a minimum number of treatment sessions, without an invasive frame.

Despite its name, Cyberknife treatment is completely non-invasive, like traditional radiation treatment. The unique method of radiation delivery and high level of precision is ideal for some of the more complicated and high-dose treatments, commonly known as “stereotactic” treatments. These shorter course treatments are the future of radiation oncology, either by themselves as a curative treatment, or in combination with the growing number of targeted chemotherapy and immunotherapy options. These treatments are highly effective and safe, using robotic delivery and precision to spare nearby normal tissues. 

Cyberknife makes use of robotics technology and artificial intelligence, coupled with well-established radiation therapy techniques in order to provide the best treatment accuracy and efficiency. At the most basic level, the Cyberknife system is composed of a compact and lightweight linear accelerator linked to the arm of a precision robotic manipulator. The robotic manipulator allows for independent targeting of lesions in all six dimensions with sub-millimeter accuracy. The unsurpassed maneuverability of this system provides effective ablative treatments that are delivered safely and fast.

Patient and lesion motion has always been a challenge in radiotherapy. If a patient’s lesion was stationary, targeting the lesion would be a simple matter. However, especially in the case of lung cancers, lesion motion induced by internal anatomic motion such as respiration complicate the process. Some lung lesions can move as much as 5 cm due to respiration. In traditional radiotherapy, this internal motion is often managed by including margins around the lesion along with the use of patient immobilization. Immobilization techniques are used to control and limit respiration, thereby reducing lesion motion. Other techniques for managing this motion have been to simply stop the treatment when the lesion deviates from the intended position, which prolongs the treatment.

The Cyberknife tracking system referred to as “Synchrony”, is designed to continuously compensate for internal anatomic and patient motion in real-time. By doing this, it minimizes the need for excessive margins, the sometimes uncomfortable motion limiting devices or prolonged treatment times. The system monitors the patient closely prior to the treatment and models the patient’s respiratory pattern accurately predicting the lesion’s location. During treatment, real-time x-ray images allow the system to monitor a lesion’s actual location and adjust the respiratory model using artificial intelligence. The system uses the updated location information to make minute adjustments to the robot, thus compensating for lesion motion and precisely delivering the prescribed dose to the intended area.

The Accuray “Precision” treatment planning system that designs a patient’s treatment uses the most accurate calculation engine available; Monte Carlo. Aided by “Precision”, the radiation oncologist can accurately develop the optimal treatment plan accounting for each patient’s unique anatomy. Each treatment plan is customized for each patient, taking advantage of Cyberknife’s one-of-a-kind technology.

With these technologies, Cyberknife is ideally suited to treat a host of central nervous system (CNS) diseases with stereotactic radiosurgery (SRS) and fractionated stereotactic radiation therapy (FSRT). The thousands of unique treatment beam angles allow for the treatment of simple and complex brain metastases, skull base lesions, as well as certain functional disorders, like trigeminal neuralgia, while sparing normal brain tissue. Similarly, aggressive treatment of spine lesions can be performed safely while sparing the adjacent spinal cord by tracking spine position in real-time and adjusting the treatment beam appropriately.

Using real-time tumor and fiducial tracking, Cyberknife also allows for highly effective and safe treatment with stereotactic body radiotherapy (SBRT) to a number of tumor sites throughout the body. For some sites like lung cancer, Cyberknife is able to track lung tumors during the respiratory cycle and continually adapt the treatment beam to target the tumor as it moves during normal breathing. This results in smaller required margins and less dose to a multitude of nearby critical structures, such as normal lung, heart, blood vessels and spine. For other tumor sites, such as the prostate, liver and pancreas, Cyberknife is able to detect and track implanted fiducial metal markers and automatically adapt the treatment accordingly. For liver and pancreatic tumors, motion is largely due to respiratory motion, while for prostate cancer, it is largely due to bowel and bladder filling. Additionally, despite traditionally used devices to limit patient motion during treatment, inevitably there is always some small amount of patient movement during treatment. This allows another layer of quality assurance that this motion is accounted for and it will not cause inadvertent treatment of normal structures, or missing the target altogether.

The concept of stereotactic treatments (SBRT, SRS and FSRT) is not new, but they have attracted more attention recently. Traditional treatments for lung cancer could be as long as six to seven weeks, but for some early-stage lung cancer, treatment with SBRT can be performed in as few as three to five treatments over approximately a week and a half. Not only is the treatment course shorter, but these treatments are also tolerated very well with patients typically experience minimal side effects and have success rates greater than 90 percent. Similarly, traditional radiation treatment courses for prostate cancer are among the longest of any treated tumor site, sometimes approaching nine weeks and 45 treatments. While we have been able to moderately shorten this for most patients – so-called moderate hypofractionation that is four to five weeks of 20 to 28 treatments – some patients are able to be treated with prostate SBRT in as few as four to five treatments with excellent biochemical control and few side effects. 

The publication of multiple clinical trials demonstrating survival benefits with the addition of SBRT to the standard of care chemotherapy in patients with oligometastatic disease (limited number of metastatic sites of disease) has shifted the way we approach these patients. Instead of a one-size-fits-all approach to metastatic disease, we know that these patients will live longer on average. Additionally, data shows that aggressive local treatment to sites of disease in addition to systemic treatment improves it even more. In addition, in patients with more widespread metastatic disease, the proliferation of targeted chemotherapy and immunotherapy options means patients are living longer, making the need for durable local control with treatments such as SRS and SBRT more important, as well.

These types of treatments result in life-changing benefits for patients. Fewer treatments mean fewer visits and more time at home with family. Additionally, real-time tumor tracking and robotic precision delivery mean fewer side effects and potentially higher control rates.