Gamma Knife and RapidArc Radiosurgery Equally Effective

Researchers at Thomas Jefferson University (TJU; Philadelphia, PA, USA) conducted a study involving six patients with three or four small brain metastases that varied from 0.1–10.5 cm³ in size. Stereotactic radiosurgery (SRS) modalities for multiple brain metastases were made using both the Gamma Knife (GK) Perfexion system and a single-isocenter, multiple non-coplanar RapidArc device, as determined according to the size of the target.

The results showed that the Gamma Knife system was slightly more effective than RapidArc at focusing the beam of radiation at a very low-dose (<3 Gy), thus limiting spread to normal tissue. On the other hand, the RapidArc system offered much quicker treatment; compared to GK treatment, which typically takes 60–100 minutes, RapidArc was about 3-5 times faster. The study was published on January 25, 2016, in Frontiers in Oncology.

“Understanding the benefits of advanced radiosurgery technology is essential because there has been, and will continue to be, an increase in cases of brain metastases,” said study coauthor Adam Dicker, MD, PhD, of the TJU Sidney Kimmel Medical College. “Chemotherapies and targeted agents can't reach the brain and the central nervous system because of the blood-brain barrier. The results are that a number of different cancers are now showing up in the brain.”

The Gamma Knife, a product of Elekta (Stockholm, Sweden), features a circular array of 201 beams of gamma radiation that meet at a single point. The downside of the treatment, although very accurate, is that patients need to be protected with a helmet. The RapidArc Radiosurgery system, a product of Varian Medical Systems (Palo Alto, CA, USA), emits very small, high-energy X-ray photons with varying intensities aimed at a tumor and then rotated around the patient, resulting in complete three-dimensional (3D) dose delivery at a rate at least three times faster than GK. Advantages include the ability to treat multiple metastases simultaneously, rather than sequentially, and frameless immobilization.

Related Links:
Thomas Jefferson University
Elekta
Varian Medical Systems