Stereotactic Radiosurgery (Gamma Knife / CyberKnife)
Stereotactic radiosurgery (SRS) is an incision-free treatment in which a high dose of radiation is focused on a target in the brain or spine with millimetric accuracy in a single session or a small number of sessions. Gamma Knife and CyberKnife are two typical systems that deliver this approach.
最終更新: 2026-06-09
Definition
Stereotactic radiosurgery is a radiation therapy method in which many thin radiation beams are focused to intersect at a defined target, delivering a high dose to a small volume. Despite the name 'surgery', no incision is made; the effect relies on the radiation dose delivered to the target tissue. Gamma Knife uses gamma rays from cobalt-60 sources, while CyberKnife steers the beam with a robotic-arm linear accelerator (linac). Treatment may be given in a single session (radiosurgery) or divided into a few sessions (fractionated stereotactic).
Indications
SRS is considered for selected intracranial targets whose borders can be clearly defined on imaging. Typical uses include brain metastases, acoustic neuroma (vestibular schwannoma), meningioma, pituitary adenomas, arteriovenous malformations, and functional conditions such as trigeminal neuralgia. Suitability is assessed according to lesion size, location, distance from critical structures, and the patient's overall status. Not every lesion is suitable; other treatments may be preferred for large-volume or diffuse targets.
Procedure
Before treatment, high-resolution MRI and/or CT images are obtained and the target and surrounding organs at risk are defined in detail. To ensure targeting accuracy, fixation methods such as a stereotactic frame (frame-based) or a thermoplastic mask are used. The treatment plan is created to deliver the intended dose to the target while sparing surrounding healthy tissue. The patient is positioned on the treatment couch and the system focuses beams onto the target from the planned angles; the procedure is usually completed on an outpatient basis without anesthesia.
Advantages and Limitations
Reported potential advantages include avoiding an incision, not requiring general anesthesia in most cases, and the ability to deliver a relatively low dose to surrounding tissue. However, the effect appears over time rather than immediately; tumor shrinkage or control may take months. Open surgery may be more appropriate for large-volume lesions, marked mass effect, or when tissue diagnosis is needed. Outcomes depend on the type and size of the target and on patient selection.
Recovery and Risks
After treatment, many patients return to daily activity quickly; the recovery process varies with the target and the dose delivered. Possible risks include transient fatigue, headache, edema related to the treated area, late radiation necrosis, and neurological effects for targets located near critical structures. No outcome is guaranteed; the decision is made individually by considering the patient's clinical status together with imaging findings.
参考文献
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:1903-1907.
- Winn HR, ed. Youmans Neurological Surgery. 6th ed. Saunders; 2011:1788-1794.
- Quiñones-Hinojosa A, ed. Schmidek and Sweet: Operative Neurosurgical Techniques. 7th ed. Elsevier; 2021:1055-1061.
- Leksell L. The stereotaxic method and radiosurgery of the brain. Acta Chir Scand. 1951.
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