Gamma Knife of Spokane
Physician Inquiry - Physics: How does it Work?
We just wanted to thank you for making our experience with you as comfortable as possible. We know that you go through this process on a regular basis with many different people. Yet you still look each one of us in the eye offering compassion,...
The gamma knife has 201 Co-60 sources of equal activity totalling 2.2X10 GBq. They are positioned to emanate gamma rays through a primary and a secondary collimator such that the gamma rays focus to an oblate spheroid of from 4 - 18mm average diameter. The 4mm focal ellipsoid has a penumbre of 1mm from the 50%-10% of its maximum profile. With careful positioning and weighting of the 4,8,14, and 18mm focal spheroids, extremely sharp dose volume histograms can be attained for the target and nearby critical structures. Blocking of up to half of the 201 sources affords even tighter control of dose shaping to the target and adjacent critical structures.
-- Courtesy of NASA |
