Live Webcast: Gamma Knife Radiosurgery a Treatment for an Acoustic Neuroma

[or-live.com]

During the webcast, Marshfield Clinic physicians Benjamin Lawler, MD, neurologist; Warren Olds, MD, Radiation Oncologist; John Neal, MD, Neurosurgeon; and David Loshek, PhD, Radiation Physicist  at Saint Joseph's Hospital will discuss the sophisticated treatment option for acoustic neuroma. The program will feature a pre-taped surgical video of the Gamma Knife procedure as well as a real-time panel discussion and analysis of the procedure. The webcast is set for Wednesday, January 17, 2007 at  4 PM CST on www.OR-Live.com. Viewers will have to opportunity to send questions directly to the OR for a live on camera response from the doctors. 

[Derek]

Hi all...

Unfortunately I missed the opportunity to participate in this webcast and wondered if anyone could provide a brief overview of how successful it was re any new innovations revealed  etc?

Regards

Derek

[Sefra22]

Hi Derek,
I think you can still view the webcast. Go to the site, find the "archives" box on the left, then click "other specialties", then scroll to "Neurology/Neurosurgery". I watched it last night, and found it to be very informative, although they did talk quite a bit about conditions other than AN.
Lisa

[Derek]

Hi Lisa...

Many thanks for your post...I have now accessed the item which, being a prospective GK patient, I found most informative. Albeit biased in favour of GK, I  particularly noted the following points from the stats:-

+ By the year 2010 there will be more GK treatments than microsurgery for AN and will be more than doubled by 2020

+ GK is more accurate than CK

+ 98% of all GK treatments  are successful and require no further treatment

+ Microsurgery is only necessary in 2% of all cases following GK treatment

+ GK treatment does not preclude future necessary microsurgery from being successfully accomplished

+ After 4 years have elapsed following GK treatment an MRI is normally only necessary every 4th year thereafter

+ The risks of morbidity with GK are substantially less than with microsurgery and therefore a greater degree of  preservation of quality of life with GK can be anticipated

Regards

Derek

[Mark]

Derek did a great job of highlighting the key points of the webcast in terms of radiosurgery in general and GK in specific. I would agree with all of the points made with the exception of:

+ GK is more accurate than CK

Understanding that this webcast was put on by docs who only use GK, that assertion is simply not true. Both machines are equally effective in treating an AN and I wouldn't split hairs over a person utilizing one over the other, but studies of total machine error previously discussed in this forum suggest otherwise. I'm not sure why they felt a comparison to any other machine was even necessary for the purpose of the webcast, but I suspect it was part of a "selling" element.

Other than that issue, I thought it was a pretty effective discussion of the GK process

Mark

[Derek]

Hi there Mark..

Just clarifying re the comment on the live webcast by Warren Olds MD, Radiation Oncologist, relevant to his claim that GK is more accurate than CK.

 In essence (my synopsis follows in layman terms) he stated that GK utilises 201 stationary beams whereby nothing moves whereas in his opinion CK uses a single pencil beam with an element of movement which  affects ultimate accuracy.

He also stated that the CK collimator is larger than that used with GK which affects accuracy and thus the smaller GK collimator has the ability to treat smaller lesions with greater accuracy.

 He also stated that GK was only suitable for skull based procedures and praised CK for its ability to afford treatment to areas of the body other than the skull.

Regards

Derek

[Mark]

Hi Derek,

Thanks for clarifying the specific comments by Dr. Olds. I'm not sure I understand his logic on the stationary nature of GK vs. the robotic function of CK. CK moves to a predetermined spot in the computer program, visually verifies the tumor is in the right position, then fires it's pencil beam whereas GK fires at a spot determined by the CT scan which makes the frame placement critical. I've never heard of the size of the collinator being different and effecting the accuracy, so I don't have any thoughts on that issue.

It would seem that he also left out a discussion of the frame error of GK which CK which is a signifcant factor I've been told in total error determination. I think at the end of the day there are probably certain design elemnets that favor one over another, but it is the total error or accuracy ( depends on how you look at it  ) that matters. Given the last published data had CK at around .89 mm and GK at 1.2-1.5 mm I would still hang my hat on that. The collinator issue is intriguing though, so I posed it over on the CPSG board to see what Drs Medbery or Spunberg think about it since they use both.

It's not a big issue either way, I just get bugged when doctors make ( what I believe to be  ) errant comments. Both the CK and GK are equal from all I've read for one dose treatments. CK becomes the better choice if you have a problem with the head frame or want a fractionated treatment plan, other wise it's a wash in my mind

Mark

[Derek]

Hi again Mark...

I entirely agree with your analogy, particularly with regard to your earlier reference to a probable 'selling element' favouring GK re St Josephs not undertaking the CK treatment process. I certainly would be most interested to hear what the views of Drs. Medbury and Spunberg are on the collinator issue.

On a personal stance it does not affect my decision to eventually opt for GK as the CK procedure is not yet available within the UK.

Regards

Derek

[Mark]

Hi Derek,

Here's the response from the always colorful Dr. Medbery on the two issues Dr. Olds raised in the webcast relative to 1) stationary vs. motion and 2) collinator size.

Horse puckey.

It is true that the robot moves the CK. It does so with a reproducibility of <0.2 mm in 5000 cycles of a repetitive motion.

CK uses a variety of collimator sizes ranging from 5 mm to 6 cm. GK uses collimators of 4, 8 14, and 18 mm. With a special tracking we sometimes use for small intracranial targets, the effective smallest collimator size is about 4 mm with the CK.

Clinton A. Medbery, III, M.D.
St. Anthony Hospital Cyberknife Center
(405) 272-7311
buddy@swrads.org or cmedbery@coxinet.net


At any rate, as was said before, both machines will very effectively treat an AN.

Cheers,

Mark

[pearchica]

Thanks guys for the further discussion of GK versus CK.  I found the GK podcast very helpful as a beginner AK'er- I thought it was interesting that out of all the GK applications at St. Joes, only 12% were for ANs- Ironically, it made me feel really lucky to have a benign tumor and it helped me put this condition in perspective- it could be so much worse!  I talk with Stanford on 1/23 about various options including ck. take care, Annie