Stereotactic Radiosurgery (SRS)

The term “radiosurgery” can be confusing because no incision is made. Stereotactic radiosurgery (SRS) is a highly precise form of radiation therapy that delivers a concentrated dose of radiation to a carefully defined target without traditional surgery.

Hundreds of radiation beams are delivered from different angles, all converging on the tumor or treatment target. Each individual beam carries a relatively low dose of radiation too low to significantly affect the healthy tissue it passes through. Where the beams intersect, however, the combined dose is high enough to damage tumor cells, stop tumor growth, or close off abnormal blood vessels such as arteriovenous malformations (AVMs). Because the radiation is concentrated within a small treatment area, the surrounding brain and spinal cord receive much lower doses.

The precision of SRS depends on advanced imaging and computerized treatment planning. Before treatment, high-resolution MRI and CT scans and for some conditions, cerebral angiography are used to define the target with sub-millimeter accuracy. These images are combined in sophisticated planning software that calculates the optimal beam angles and radiation dose to maximize treatment of the target while minimizing exposure to nearby healthy brain, spinal cord, cranial nerves, and other critical structures.

CyberKnife®

CyberKnife® is a robotic stereotactic radiosurgery (SRS) system that delivers radiation from hundreds of different angles using a compact linear accelerator mounted on a robotic arm. Its defining feature is real-time image guidance. During treatment, X-ray cameras continuously monitor the patient’s position, allowing the robotic arm to automatically adjust for even small movements and maintain exceptional accuracy.

Unlike older radiosurgery systems that required a rigid head frame secured to the skull, CyberKnife is frameless, making treatment more comfortable while also allowing radiation to be delivered over multiple sessions when clinically beneficial.

TrueBeam™

TrueBeam™ is a state-of-the-art linear accelerator used for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). Its advanced beam-shaping technology allows highly conformal radiation delivery while minimizing dose to nearby healthy tissues.

TrueBeam is particularly well suited for treating larger or more complex targets, as well as situations where shorter treatment times are advantageous. It can be used for both brain and spine tumors and provides another highly precise treatment option within the Atlantic Brain and Spine radiosurgery program.

Choosing the right platform

Atlantic Brain and Spine offers both CyberKnife® and TrueBeam™, allowing the multidisciplinary treatment team to select the technology best suited to each patient’s diagnosis. The decision is based on several factors, including the size and location of the target, its proximity to critical structures, the type of condition being treated, and whether treatment is best delivered in a single session or over multiple sessions.

The Atlantic Brain and Spine stereotactic radiosurgery (SRS) program treats a wide range of brain and spinal conditions, including:

• Brain metastases — Highly targeted treatment of one or more metastatic brain tumors, often allowing patients to avoid or delay whole-brain radiation therapy while preserving healthy brain tissue.
• Glioblastoma (GBM) and other high-grade gliomas — SRS may be used as part of a comprehensive treatment plan for selected patients, including treatment of recurrent tumors or carefully selected residual disease.
• Meningiomas — Treatment of small- to medium-sized meningiomas that are not suitable for surgery, as well as residual or recurrent tumors following surgical removal.
• Acoustic neuromas (vestibular schwannomas) — Excellent long-term tumor control while preserving facial nerve function and, in appropriately selected patients, hearing.
• Pituitary adenomas — Treatment of residual or recurrent pituitary tumors after surgery or functioning adenomas that are not adequately controlled with medication.
• Arteriovenous malformations (AVMs) — Focused radiation gradually closes the abnormal blood vessels over time. See AVM Treatment.
• Trigeminal neuralgia — Highly focused radiation directed at the trigeminal nerve for patients who are not candidates for, or prefer to avoid, microvascular decompression (MVD).
• Spinal tumors and spinal metastases — Stereotactic body radiation therapy (SBRT) delivers highly targeted radiation to spinal tumors while minimizing radiation exposure to the spinal cord.

Not every brain tumor or neurological condition is best treated with stereotactic radiosurgery. Depending on the diagnosis, size and location of the lesion, symptoms, and overall treatment goals, surgery, conventional radiation therapy, systemic treatment, or a combination of therapies may provide the best outcome. Every case is reviewed individually by the multidisciplinary team to determine the most appropriate treatment strategy.

Every stereotactic radiosurgery (SRS) treatment plan is developed collaboratively by neurosurgeons, radiation oncologists, neuroradiologists, and other specialists to ensure each patient receives the most appropriate treatment approach. Every case is reviewed by the multidisciplinary Neuro-Oncology Tumor Board, where imaging, diagnosis, and treatment options are discussed before therapy begins.

Together, the team determines the most appropriate radiosurgery platform (CyberKnife® or TrueBeam™), radiation dose, number of treatment sessions, and overall treatment strategy based on the patient’s diagnosis, tumor size, location, and proximity to critical brain or spinal structures. Just as importantly, the team determines whether stereotactic radiosurgery is the most appropriate treatment—or whether surgery, conventional radiation therapy, systemic therapy, or observation would provide a better outcome.