CyberKnife: Robotic Stereotactic Radiosurgery Without Surgical Incisions

CyberKnife is a robotic stereotactic radiosurgery (SRS/SBRT) system capable of delivering high-dose radiation to tumors and certain benign lesions with sub-millimeter precision, without requiring any surgical incision. Thanks to its intelligent imaging and robotic arm, which can track movement and make real-time adjustments, it can safely treat targets in many parts of the body, including the brain.

What is CyberKnife and How Does It Work?

  • Robotic Arm: Delivers radiation beams from over 100 different angles, concentrating the dose on the tumor while protecting surrounding healthy tissue.
  • Real-Time Imaging: Monitors the position of the tumor and organs during treatment, adapting instantly to movements such as breathing or swallowing.
  • Frameless Comfort: No need for a rigid head frame fixed to the skull; comfortable immobilization is achieved with a mask or body molds.
  • Hypofractionation: High doses are typically given in 1–5 sessions; total treatment time is limited to a few days.

When is CyberKnife Used?

Indications are personalized according to tumor type, size, location, and the patient’s clinical condition. Common applications include:

Brain and Skull Base

  • Metastases, meningioma, acoustic neuroma (vestibular schwannoma)
  • Pituitary adenomas, trigeminal neuralgia
  • Arteriovenous malformations (selected cases)

Body (SBRT)

  • Lung nodules (early-stage or oligometastatic)
  • Liver, pancreas, kidney, adrenal gland lesions
  • Spinal and bone metastases
  • Prostate cancer (primary or salvage treatment)

CyberKnife can be an alternative for patients who are not suitable for or do not prefer surgery; however, the decision is made in a multidisciplinary tumor board.

Advantages

  • Non-invasive and painless: No anesthesia required; most patients go home the same day.
  • High precision: Motion tracking and multi-angle dose concentration protect healthy tissue.
  • Short duration: Usually 1–5 sessions; each session lasts about 30–60 minutes.
  • Repeatable: In selected cases, re-irradiation can be offered to previously treated areas.
  • Quality of life: Most patients quickly return to daily activities.

Treatment Process: Step by Step

  1. Evaluation and Planning: Imaging (CT/MRI/PET), lab tests, and clinical examination clarify the indication. Masks or vacuum cushions may be prepared if necessary.
  2. Simulation and Imaging Record: Planning CT with thin slices is performed; MRI/PET scans may be fused. Gold markers may be placed beforehand in organs such as the prostate for motion tracking.
  3. Dose Planning: Targets and organs at risk are contoured; a personalized radiation dose and fraction schedule are determined.
  4. Treatment Delivery: During the session, frequent imaging verifies target position; the robotic arm makes automatic corrections. Pain is not expected.
  5. Follow-Up: Clinical check-ups and imaging (usually at 6–12 weeks) monitor response and possible late effects.

Preparation and Session Day Recommendations

  • Take daily medications as instructed unless told otherwise by your medical team.
  • Wear comfortable clothing; remove metal accessories.
  • For lung/abdominal targets, breathing motion training may be given—follow instructions carefully.
  • For prostate treatments, bladder filling and bowel emptying protocols may be applied.

Possible Side Effects

As CyberKnife is highly targeted, side effects are usually mild and temporary, depending on the treatment area:

  • General: Fatigue, mild skin sensitivity
  • Brain: Temporary headache, rarely swelling (steroids if needed)
  • Lung: Cough, rarely radiation pneumonitis
  • Spine/Bone: Temporary pain flare, rarely fracture risk
  • Prostate: Frequent urination, reduced urinary flow, mild rectal irritation

If significant symptoms occur, the care team is informed and supportive treatment is tailored to the patient.

CyberKnife vs. Other Radiosurgery Systems

  • Gamma Knife: Especially effective for intracranial lesions; usually single session and requires a rigid head frame. CyberKnife also covers extracranial targets and is frameless.
  • LINAC-Based SRS/SBRT: Modern LINACs offer high performance. CyberKnife’s robotic multi-angle approach and real-time motion tracking can offer advantages, especially for moving targets.

Who is Eligible?

Tumor size, location, previous treatments, and overall health are considered. Pacemakers, active infections, uncontrolled comorbidities, or large-volume targets require careful evaluation. The final decision is made by a multidisciplinary board.

Quality, Safety, and Team

  • Teamwork between a radiation oncologist, medical physicist, radiation therapist, and relevant specialists
  • Independent physical quality assurance (QA) checks before and after planning
  • Evidence-based, guideline-compliant personalized protocols
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