Stereotactic Radiosurgery

 

Gamma Knife surgery represents one of the most advanced and precise means available to manage brain tumors and metastases, arteriovenous malformations, and pain or movement disorders. Requiring no surgical incision to treat the target, the Gamma Knife is one of the primary means of delivering focused radiation called stereotactic radiosurgery. It can also reduce or eliminate pain conditions, such as trigeminal neuralgia, and certain movement disorders, such as tremor, as well as silence malfunctioning areas of the brain precisely that have not responded to other management strategies.

Gamma Knife Technical Overview

Houston Methodist Hospital houses the newest Leksell Gamma Knife system, the ICON. This system uses an internal collimator system with 4, 8, or 16 mm isocenters and 192 Cobalt 60 sources for radiation. Movement of the patient and opening of the shielding door is performed with high prevision. The patient's head is moved into the focus point with very high precision robotics. The mechanical accuracy as dictated by the manufacturer should be less than 0.3 mm. The ICON system is equipped with an on-board CT scanner and microradiosurgery capabilities for extremely precise treatments.

A significant advantage of the Gamma Knife over other available radiosurgical systems is the ability to create conformal and irregular dose plans using multiple target points. Highly conformal and selective radiosurgery is crucial to maintain low side effect rates by tailoring the effect to the irregular 3D geometry of the target volume. In addition, Gamma Knife has high selectivity, meaning that the radiation dose falls off outside of the target very steeply, thereby reducing the risk of injury to adjacent structures.

Finally, patients do not need to undergo general anesthesia and only require mild sedation for placement of the guidance Leksell frame before treatment begins. This further reduces the risk profile compared to an open surgical procedure. Patients usually leave the hospital the same day of the procedure.