TILBURG, the Netherlands, March 15, 2016 /PRNewswire/ -- On January 11, the Gamma Knife Center at Elisabeth Tweesteden Ziekenhuis (ETZ, Tilburg) launched a new frameless option for its advanced cranial radiosurgery program with the treatment of a 74-year-old male patient with a large, recurrent vestibular schwannoma, a slow-growing tumor of the inner ear. Using its new Leksell Gamma Knife® Icon™ system, clinicians used a frameless (mask-based) approach to immobilize the patient's head and deliver the therapy over multiple sessions (fractions).

Gamma Knife Icon is the latest advance in Elekta's industry-leading stereotactic radiosurgery (SRS) technology, delivering industry-leading accuracy and the lowest dose to normal tissue. With the option to use frameless or traditional frame-based treatments, Icon offers greatly enhanced flexibility in how clinicians deliver stereotactic radiosurgery. Frameless therapy provides the opportunity to treat patients with large or critically located lesions over several sessions, thereby expanding the range of patients who could benefit from Gamma Knife radiosurgery.

"The patient's tumor was 21.5 cm in volume, which was too large to treat in single session," says Guus Beute, MD, ETZ neurosurgeon. With the Icon system's frameless head immobilization we were able to divide the therapy into five treatments and be assured of precise repositioning for each session."
To date, ETZ has treated 146 patients on Icon using frame-based immobilization, in addition to two more patients who received multisession, frameless treatments. One of these, a female patient with 11 meningiomas, received "staged" therapy in which six lesions were treated in one session and five in a second session.

"We could have treated her in one two-hour session with the frame, but we recommended that she have a frameless treatment and stage the therapy in two shorter sessions," Dr. Beute notes. "It was more convenient and comfortable for the patient, so we were pleased we could offer her that as an option."

Precise repositioning critical for multisession therapy

Multisession, frameless radiosurgery demands management of differences in the patient's repositioning from session to session. The cone beam CT (CBCT) imaging technology and advances in Gamma Knife treatment planning system enables automatic online adaptation of the dose delivery to correct for patient repositioning differences session to session.

"The ability to accurately reposition the patient with Icon gives us a lot of confidence, and offers a very smooth and quick workflow," he says. "Leksell GammaPlan® software automatically adapts the plan if there are any changes in patient position. These are usually so small that the corrected plan looks identical to the original plan. We simply review and accept the corrected plan and then treat."

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