Καλώς όρισες @giotap5
It is great that you found us and a pleasure to help you. By the way, never apologise for your English because it is better than my Greek by many thousands of words!
My understanding of gamma knife versus cyber knife is the method used to deliver the radiotherapy: principally, the targeting method. We have a couple of older articles from former members that I will share with you. These members are likely not active on the forum these days.
This article talks about gamma versus cyber. If there is anything you don’t understand about it, please ask. Gamma Knife vs Cyber-Knife My two dimes worth
It references a more general article about radiotherapy though I don’t think that helps to distinguish between gamma v cyber. Photons vs Protons, What´s the difference?
I hope these references help,
Very best wishes,
Richard