Thanks to advances in motion tracking technologies used for years on nonbrain-related cancers, such as lung and liver, precision radiosurgery for treatment of malignant brain tumors can now be performed using a flexible, removable mask placed over the face, instead of the anchored stereotactic headframe, previously required. Penn State Health Milton S. Hershey Medical Center is one of the first in the country to have the new Leksell GammaKnife® upgrade, called the Icon™ (Elekta, Sweden), which offers the motion-tracking mask, as well as the conventional headframe.
The radiation sources and beam technology are unchanged. According to James McInerney, MD, professor of neurosurgery, “Eliminating the need for a stereotactic headframe anchored to the skull opens up treatment possibilities that weren’t feasible in the past. This translates into hope for patients who had certain types of brain tumors that might have had fewer treatment options.”
With the Icon unit, the tracking mask is integrated with a real-time on-board CT scan and software that continually accounts for movement in the three rotational axes, as well as the three translational axes, without the need for mechanical adjustments or having to halt the radiation treatment. Dr. McInerney adds, “Perhaps the biggest change, in terms of treatment options, is the ability to conduct hypofractionated radiotherapy. We can now treat larger tumors and tumors located in sensitive areas, like the brain stem or optic chiasm, more aggressively, over multiple sessions. The level of precision has also improved; smaller tumors can be targeted. With hypofractionated treatment, sessions are shorter, so patients are more comfortable.”
The Icon system is also likely better at treating metastatic disease. With the older versions of this system (Perfexion™), Dr. McInerney adds, “It took a lot of time to target just three small tumors. Now it’s possible to target up to 15 smaller tumors during a single session.” The Icon system achieves ultra-high precision (±0.15 mm), within the context of several hypofractionated treatment sessions. Other tumors involving vascular malformation may also be more amenable to treatment with this newer system. It allows for hypofractionated therapy to help decrease the risk of bleeding secondary to treatment, which can lower the risks associated with management.
Dr. McInerney adds, “Treatment planning and radiation delivery can be performed over several days or a week with the mask. This will likely make the entire process much more flexible and convenient for patients, family members and care providers.”
James McInerney, MD
Professor of Neurosurgery
RESIDENCY: Neurological surgery, Dartmouth Hitchcock Medical
Center, Lebanon, N.H.
INTERNSHIP: General surgery, National Naval Medical Center,
MEDICAL SCHOOL: Georgetown University, School of Medicine,