jemcmac,
I'll add my welcome to the forum to Phyl's as well. I also think the GK is a good choice for treating the AN, particularly if you are comfortable with the one dose protocol outcomes on nerve preservation as opposed to the fractionated radiosurgery approach. So I would certainly support your choice in that context.
That being said, Everyone needs to be careful in basing conclusions or opinions of different machines on the propaganda pieces published by the hospitals that have a vested interest in them. I would make that statement about any of the machines. Peer reviewed clinical studies are a much more reliable and relevant reference point.
The Wake Forest link you referenced as been posted by others in the past and the misrepresentations made in it regarding CK addressed definitively. The ability to navigate the archives on this site is challenging, but they are there if you want to read them. it is a pretty safe bet this piece was written by elektra , the manufacturer of the GK since the Univ of VA web site has the same information practically verbatim. It should also be noted that the primary radiation oncologist at Wake Forest is the son of an executive at Elektra, although that conflict of interest is not disclosed. In my personal opinion, in reflects poorly on the credibility of an institution like Wake Forest to allow distortions like these to be on this web site. If they want to advertise the positive attributes of the GK that's fine, but to essentially slander a competitive machine is clearly an unprofessional thing to do and probably refelcts the fact that CK placements are eroding their market share.
Specific to the accuracy statistics that were quoted, it is important to recognize the difference between total error and machine error. the GK .3 mm is essentially machine error while the .89 mm error shown in clinical study for CK is total error. It's apples and oranges and I would suggest only total error is ultimately relevant. The other elements of targeting error are 1) the inherent error variance of the CT scan and in the case of GK only as Phyl pointed out is 2) the error as part of the frame itself. In point of fact, the total error of GK is typically shown to be between 1 to 1.3 mm. The variation is how old the frame is , how much it has been "torked" in usage and how often it has been calibrated. Again, as Phyl indicated both machines provide a very equivalent accuracy for treating AN's. However, GK is also not the definitive "gold standard" anymore in the area of accuracy.
I would still say GK and CK as true radiosurgery machines are better in some capabilities than others but choosing between two comes down to two criteria
If one wants a one dose treatment then both are equally good and it comes down to how big a deal having the frame screwed into the head is as a source of discomfort
If one wants a fractionated approach, then the choice is CK since GK isn't typically used that way given no one wants to endure the frame for 2-3 days.
Again, I think your choice of GK for treatment is great, but hospitals (or manufacturers) putting out distorted information to patients is a real sore spot for me.
Best
Mark
