Stereotactic Radiosurgery (SRS) is a non-surgical treatment for various brain conditions. This advanced radiation therapy delivers highly focused energy to a specific target, precisely addressing abnormalities while minimizing exposure to healthy brain tissue. It offers a targeted alternative to traditional surgical interventions.
What is Stereotactic Radiosurgery?
Stereotactic radiosurgery is a specialized radiation therapy using three-dimensional imaging to deliver a precisely focused, high dose of radiation. The term “stereotactic” refers to pinpointing an exact brain location. This precision is achieved by converging multiple radiation beams at a single target, delivering a powerful dose to the abnormality while minimizing exposure to healthy tissue.
This technique treats various brain conditions, including malignant and benign brain tumors, arteriovenous malformations (AVMs), and trigeminal neuralgia. SRS aims to damage the DNA of targeted cells, preventing reproduction and leading to gradual shrinking or inactivation of the treated area.
Unlike conventional surgery, SRS involves no incisions. It uses sophisticated technology to direct X-ray or gamma ray beams from multiple angles through the skin to the target. While often a single session, some cases use fractionated stereotactic radiosurgery (FSR), dividing the total dose into smaller doses over multiple days.
How SRS is Performed
SRS begins with detailed brain imaging to precisely locate the target. This typically involves MRI, CT scans, and sometimes angiography, providing a three-dimensional view of the abnormality. A specialized medical team then uses these images to create a treatment plan.
During planning, a team of experts—including radiation oncologists, neurosurgeons, physicists, and dosimetrists—designs the radiation dose and trajectory. They determine how beams will be directed to maximize the dose to the target while protecting healthy brain tissue. This involves calculating the exact angles and intensity for precise convergence at the abnormal area.
For radiation delivery, patient immobilization prevents movement. This may involve a head frame secured with sterile pins under local anesthetic, or a custom-fitted mesh mask for multi-session treatments. The patient is positioned on a treatment couch, and a radiation machine (e.g., Linear Accelerator or Gamma Knife) delivers focused beams. The machine may rotate or the couch adjust to deliver radiation from various angles, a process taking less than an hour to a few hours depending on target complexity.
The Patient Journey Through SRS
The patient journey begins with an initial consultation where the medical team reviews history and explains the procedure. If SRS is appropriate, preparation for immobilization follows. This may involve a head frame secured with pins under local anesthetic, or a custom-molded mask.
During the treatment session, patients lie still on a treatment couch. The procedure is not painful, and patients do not feel the radiation. They may hear a slight buzzing sound from the machine or observe its movement as it delivers beams from different angles. Sessions typically last 15 to 60 minutes.
After treatment, the immobilization device is removed. Patients are monitored briefly in a recovery area before discharge. Most individuals go home the same day. Some immediate, short-term effects, such as mild fatigue or a sensation of pressure in the head, may occur but are temporary.
Monitoring and Managing Outcomes
After SRS, regular follow-up appointments and imaging scans monitor the treated area. These appointments allow the medical team to assess radiation effectiveness and tissue response over time. Imaging, often using MRI, tracks changes in the size and characteristics of the treated abnormality.
Patients may experience short-term effects in the days or weeks following SRS, including headache, nausea, or fatigue. These effects are managed with medications and typically resolve within a few weeks. The medical team provides guidance on managing discomfort and advises when to seek further attention if symptoms persist or worsen.
Longer-term outcomes vary by condition. Benign tumors may gradually shrink over 18 months to two years, with the goal to prevent future growth. Malignant tumors may show more rapid shrinkage, sometimes within a few months. For arteriovenous malformations, radiation causes blood vessels to thicken and close off, a process that can take two years or longer. Regular follow-up identifies and manages any complications, such as radiation necrosis.