Hi Jerry and welcome... wow, your treatment was quite a number of years ago! Good for you!
I rechecked the thread here and did not see a reference to "CM", unless you are noting:
CK = Cyberknife radio-surgery (a newer form of radiation treatment)
cm = centimeter, which I'm sure you already know.
If it is CK (Cyberknife), here is a great website to help you understand what exactly it is....www.accuray.com
(the manufacturer of Cyberknife)
I hope that helps.. .and again, welcome