AbstractID: 8833 Title: A Leksell-BRW Adapter for Linac Radiosurgery as an
Adjunct to Gamma Knife Treatment
The situation occasionally arises during a Gamma Knife procedure in which a lesion that
is intended to be irradiated cannot be placed at the focus of the beams. In some instances
the lesion may be too far lateral or too far inferior to be reached. Another instance of an
unreachable lesion occurs when a patient has two widely spaced metastases, both of
which need to be treated. Often the unreachable lesion can be treated by a linear
accelerator radiosurgery system, but this normally requires a second frame placement.
We have investigated an adapter, available from Zmed, Inc., that permits a patient with a
Leksell coordinate frame to be planned and treated with a linear accelerator stereotactic
radiosurgery system based on the BRW design. Targeting accuracy has been tested using
a head shaped phantom with an insert that accepts Gafchromic film. CT scans of the
phantom with the Leksell frame and localizer attached were processed through the Zmed
FastPlan planning system from which the target coordinates were determined. We have
found that with the Leksell-BRW adapter objects within a head phantom can be targeted
by the linear accelerator to within an accuracy of approximately 1 mm.