just when i though all was in order. . .
in-person MD visits, MRI and CT and mask creation on july 31st
five dose regimen cyberknife scheduled for august 6th through 9th
beachhouse rented and paid for for the entire week (whole family coming to charleston, S.C.)
feeling good about modality, duration, and location for my hypo-fractionated cyberknife treatment
then a medical school buddy, (who is a general-purpose oncologist) gets back to me today, (literally 30" after paying for the beach house rental)
he had been kind enough to take my case, and MRI, and his partner who is a radiation oncologist, who presented my case before their multidisciplinary tumor panel. this process was initiated a few weeks ago, while i was still torn cyber vs gamma, and how many treatments to seek if i CHOSE cyber. after having finally DECIDED 5-dose cyber, i had really thought i ought just have him/them take me off the list for discussion.
along with the MRI, i sent both a short, and a long version, of the play-by-play of my "SCHWANNoma SONG", and at the end i pointed out that i had already essentially decided on five-dose cyber. i had told my friend i had decided, and was comfortable, but he wanted to proceed, so i guessed (wrongly?) it wouldn't hurt. it was even free.
so while waiting to hear back, i was really expecting a noncommittal "that sounds like a fine option, that you'v chosen there" [my 5 dose cyber], instead, they said "go for gamma!!" - reason being it is more accurate.
with gamma, the treatment plan is directly mapped onto the tumor, on an MRI
with cyber, they essentially COPY the tumor image from an MRI to a CT, and the treatment plan is mapped on the CT, (which is now a second-generation image of the tumor) potentially introducing room for error/decreasing accuracy.
up till a week or so ago, i was under the impression that gamma was slightly more accurate/precise, because the frame is SCREWED to ones SKULL, and since there si only one dose, no chance for INTER-dose variability.
a week ago, i heard back from another radiation oncologist who tends to be pretty "forum-friendly" in answering patients with acoustic neuromas, interestingly he uses (has used both cyber and gamma) and said he thinks cyber is more accurate - so this helped make my decision, as above. he wrote :
Gamma Knife is emphatically NOT more accurate. I don't know why they tell people that. The MECHANICAL accuracy of the Gamma Knife is 0.3 mm. But in addition, there is frame torsion, the possibility that screws will not be tightened sufficiently, the accuracy of the automatic positioning system, and the inherent inaccuracy of MRI (used for targeting for Gamma Knife) versus CT (used for targeting for CyberKnife). The overall accuracy is 1-2 mm, and in better centers is probably closer to 1 mm.
The verifiable accuracy of the CyberKnife in this situation is o.5 mm, and that is overall accuracy. Therefore, if there is a difference, it favors Cyberknife.
I have done thousands of cases with both machines, and am very familiar with the characteristics of each. But I think that is unimportant. What is more important is the soil in contouring and the dose selection. Either center should be able to do this competently, and unless they are just not even trying to get it right either should be fine.
The real question is whether fractionation spares normal tissues in this situation, and that is unknown. We thought that fractionation was better at preserving hearing, but I am no longer certain. It certainly does not hurt.
i was really kinda surprised to hear what i heard from the panel, as i don't really think either treatment is "wrong", i just want to choose what i think will be best for me, in preparation for living with the potential sequelae of the treatment down the road (if any), and being to handle the "buyer's remorse", should there be any.
i really felt good, settled, and at peace with my decision on 5 dose cyberknife, - till a few hours ago
i felt and still feel good about the decision to operate, 2 years ago, KNOWING WHAT WE KNEW THEN. so no regrets.
had we known then what we know now, (that it is a facial nerve and not an acoustic). . . i'd have probably nuked away 2 years ago.
thoughts?
thanks,
jesse
