Beverly, the first post you wrote about markers being suggested I thought right away oh now that's interesting as markers are used as guidelines for radiation therapy, but I couldn't figure out why they would be used for an An as with Gk or Novalis or whatever name the machine has, plus Ck, there already is a way of stabilizing the head for an An......ie with a mask or a mouthpiece or a Halo as for GK.....at which point in my thinking I thought hmmmmm are they trying to do this super, super, super accurately, with less margins receiving doses, (and maybe that changes the total dose received or something), or is this a new way where even the mask can be dispensed with, or what? I even wondered if this is part of new research we don't know about yet lol.....
I know that during the weeks of treatment the tumour can change slightly as you go along which is why image guided pics each day (some machines now have that capability at the same time as one has treatment) can help with aiming the target and add even more precision to the miniscule mm figures out there ... i figured markers would maybe do the same thing too I don't know....you are the first I have heard here who has mentioned this as a possibility with an An...
In any case, stats show the variation between different radiation machines used for Ans as far as mm accuracy isn't all that variable plus as i understand it, the dosage given each time enters into the picture too..... i dont think you can look at one aspect only really...but if he says you can go without the markers, great.
Ct scans and mris show different things sharper so when they overlay one over the other,(to help them plan the treatment) it gives them an even better picture... (it's why they are moving to the machines that give the dose each day and
also take pics
each day ) so having an MRI and a Ct scan pre treatment is par for the course and good.
here's a site i found after i wrote the above that is about ck generally....
http://www.cyber-knife.net/fileadmin/Menubilder/Cyberknife_radiosurgery_en01.pdfAll the best,
W.