I've made my decision!

[sloxana]

Hi Craig

I made an appointment with Dr. Cmelak at Vandy.  Wow...he was hard to make an appointment with!  I was just about to give up until I found a sympathetic person on the phone at his office who was willing to make an appointment for me.  Did you have that much trouble getting an appointment?  I do feel I should research all the radiation treatments available though, including Trilogy.  After that, I'll check out CK.

My balance issues have calmed down considerably after making my treatment decision.  I guess stress was playing a big part in making it worse.  Does anyone else feel their balance is worse under stress?  Well anyway, who knows?  I'm just glad it's better.

Have a great day, everyone!
Susan

[sgerrard]

I think stress is a huge contributor to AN symptoms. I notice the difference every day, as the stress builds up, so does the "fullness" feeling, in my case. I don't know what the mechanism is, but it seems like the AN is a little barometer that reacts to everything.

Trilogy vs GK vs CK? The good news is that all three are well developed systems, based on research and clinical results of radiation treatments over the last 20 years or so. The theoretical accuracies are just that - the optimum level of accuracy attainable if everything is perfect. In practice, I doubt any of them ever reach that level of accuracy, there are just too many variables going in to get a perfect result every time.

The question of multiple fractions vs 1 shot is interesting; there are lots of arguments about it, but not much clear evidence one way or the other. The best I have found is phrases like "suggestive", meaning that fractionating may have a small advantage. For me, a possible 10% extra chance of saving hearing is worth pursuing, even if the evidence for it is only suggestive, but it is just a chance.

The trade-off is that repeating the setup every day can never be done perfectly, so there is more spreading of the radiation when you do multiple fractions. As said in another debate on surgery vs. radiation, it is a "tastes great, less filling" kind of question. Small doses to minimize side effects, but with more spread, versus one big dose on target, with a risk of zapping something nearby.

Maybe that's how I wound up picking CK, a compromise "tastes pretty good, not too filling" choice. 3 smaller doses, so a smaller risk of zapping something nearby, but only 3 doses, so not much spread in hitting the target.

If I were going by how the machines look, though, I would pick Trilogy for having the coolest looking machine.

Steve

[Mark]

I think Steve articulates all the aspects of the discussion very well. Only differentiator in the consistency of placement in a fractionated protocol is that all the machines "shoot" from a preloaded CT image and rely solely on that for targeting except CK which actively "sees' the tumor during the treatment and compares it to the CT planning image.

As far as making a choice on looks, I guess I'm still partial to the Preying Mantis look of CK. It looks more menacing to the tumor to me 

mark

[Mark]

Windsong,

very interesting information on Trilogy, thanks for passing it on. Admittedly, it is a PR piece by a hospital which I somewhat discount as a source of information for any of the machines.

The one item listed that caught my eye was the ability to do real time tracking of the tumor. If that is correct, then it certainly moves trilogy into CK's category and I stand corrected on my earlier comment. I thought CK had patented the active imaging process so I'm not sure how Varian got around that.

The respiratory gating would obviously apply to extra cranial tumors ( liver, Lung, prostrate,etc) and would be the equivalent of the fiducials that are placed next for the tumor when CK treats it. The fiducials allow CK to track the tumor as it moves since it can "see" it , so I'm curious how the respiratory gating works but it sounds like it's some kind of timing of the breathing and anticipating where the tumor will be. The technology for both machines gets way over my head but it is fascinating to see what some of these machines can do for health care.

I still think we need to see clinical studies on the machine to quantify and validate some of the claims, but if they are substantiated then Trilogy will have certainly stepped up from the levels of other machines to equal CK or possibility establish a newer generation standard which would be exciting to see.

Mark

[sgerrard]

There was a video posted somewhere showing a Trilogy machine in action. I believe they use the image system to align the machine at the beginning of each treatment - once a day, in other words. That is also the wording used on the Trilogy web site. They also have an infra-red beam for monitoring a block placed on the patient's chest, for cases where breathing movement is an issue.

So my impression is that while they line it up with images at the start of each day, which is an improvement, they are not shooting images "real time" during the actual treatment, as happens with the CK machine. Only the infra-red tracking is real time.

Steve

[BeJoi]

Yes, Steve.  I just went through 28 days of it.  They took pictures and aligned them with the most recent MRI and CT scans (which were taken a few days before my treatment started).  It was not real-time tracking of my tumor.  I used the same mask as I think they do in CK.  With an An, I suppose that's enough, since I don't think it would be changing that significantly day to day for a month.   And it doesn't move like a tumor in soft tissue.   Since they are using the daily imaging to align to the MRI, then any changes in my head placement would be accounted for daily after they clamped me in.  As long as it's lining up with the MRI and CT images, it should be okay.

I have had no odd side effects so far.  No balance problems, same hearing in the AN ear, no numb spots, metal tastes, or twitches in my face.  I get eyelid twitchess when I'm really tired, which has been the case my whole life.  I don't know how much damage was done to surrounding tissue, or what side effects may still appear later.   But I do know that the 28 smaller doses daily five days a week helped the surrounding tissue heal from each day's exposure to radiation.   And I ended up with over 50 gy total radiation. 

Beverly

[Mark]

The last part of Beverly's most recent post raises a question about radiation dosing that I must admit I don't totally understand.

Setting aside the issue of machine capabilities for a minute, the basic protocols are one shot which is typically done by the GK or FSR which is typically done in 3 stages for the Radiosurgery machines and 25-30 for radiotherapy or whatever the doctors preference.

The theory on one dose is that you hit it with a sledgehammer and put the nerves at a higher level of toxicity risk. Some of the GK folks can help me , but I think the standard GK dose is somewhere around 12 GY or so.

The theory of fractionating is that you hit the tumor more times with a smaller hammer on the assumption that the healthy DNA of the nerves recover between treatments while the abnormal DNA of the tumor doesn't. In the case of CK, let's say you use a mallet and in my case I had 7 GY treatments on 3 consecutive days for a total of 21 GY ( I think they are using 6 Gy in today) . In Beverly's case Trilogy , let's say it used a ball pin hammer over 28 days for an average daily dose of around 1.75 GY, but a total dose of 50 GY.

Anybody hear the tune "if I had a hammer" playing in their head yet? 

So, if that makes sense so far, and as Steve pointed out the FSR protocols still need long term studies, here are my questions:

1) How do the oncologists balance what the right balance is to generate enough lethal dose for the AN while enhancing the preservation stats (usually hearing since facial nerve results tend to be good even with one dose)?

2) The preliminary studies on all FSR show somewhat  better preservation percentages, but I've never seen anything that suggests there is a difference or advantage of 25-30 day protocols over 3-5 days. Has anyone ever seen such a comparison? If clinical studies show there is not a difference in efficacy defined as tumor death and nerve preservation, what would be the reason for using the longer protocol?

3) From a radiation oncologist perspective, is there any concern of total dose delivered to the patient i.e. 50>21>12? One would assume all of these represent safe levels, but I'm curious if anyone has ever had a doctor explain their rationale for treatment plan as it relates to total dose?

These questions have bounced in an out of my head over the years and Beverly's comment just prompted it again. I'll probably pose these to the doctors on the CPSG board to see what they say, but are there any potential radiation oncologists out there who can set me straight on these issues? 

Mark

[sgerrard]

Beverly, I think you are right, aligning the setup before each treatment should be enough. The "real time" tracking of CK is really meant for body treatments, and it probably does not make much difference for a head treatment, since you have the mask holding your head in place anyway.

Mark, you raise some interesting questions. First, why do they do GK with 12 Gy, CK with 18 Gy, and FSR/Trilogy with 50 Gy? Dr. Chang said in an email to me "We would use a dose of 18 Gy total delivered over three 6 Gy treatments. This has the same biologic effect on the tumor as 12 Gy delivered in a single shot, which is typically what the gamma knife centers use." I went to an oncologist at a GK center, and his report said 12-13 Gy. I know that in earlier days, the GK dose was higher, and they dialed it down to bring up the nerve preservation numbers, once it was established that you could still get good tumor control at a lower dose.

So how does 18 Gy in three treatments equal 12 Gy in one treatment, or 56 Gy in 28 treatments? I saw somewhere that at 12 Gy, you are at the level of "cooking" the tumor, and can get some immediate die off from blasting it, rather than just disturbing its DNA. The Wikipedia entry said that 10-20 Gy delivered to the whole body is a lethal dose. So maybe lowering the individual dose means you need more in total, since you are relying more on the biological effect of disturbing the DNA. I'm not sure that expains why Trilogy has to go up to 50 Gy though.

I'm not sure that the "safe level" issue enters in, other than making sure that the spill-over dose to surrounding tissue is below hazardous levels. In theory, the only tissue getting the full dose is the tumor, and that is supposed to get a high lethal dose. You don't have any other tissue in your body that has been exposed to those high levels. The amount of surrounding tissue exposure can be an issue, I guess, if you ever needed a second treatment, but it is certainly much lower.

I have not seen anything either, that has determined whether the CK approach of 3 x 6, or the Trilogy approach of 28 x 2, is any better or worse at preserving hearing. As far as I know, they both report good high tumor control rates and facial nerve preservation. It may be that both are being used, to see if one or the other proves to be better in the long run, since no one really knows yet. 2 Gy a day is no doubt gentler, but 56 total is no doubt more total, so who is to say?

I appreciate the discussion, it is fascinating to me, as well as directly relevant to many of us.

Steve

[ceeceek]

Wow, what a discussion!
So far I have to say, it has been fascinating...
I will be treated with CK with Dr. Spunberg....in W Palm Beach..
Reasons I chose CK??
Similar to treatment of Gamma the "golden standard in radiation treatment of brain tumors" without the head frame. Gamma has been the most studied of all the treatments as it has been around the longest...does it make if the best? not necessarily but there is more info on long term study....
CK uses the same type doses of radiation,,,but fractionated....sounds okay,,why not have fractionated if it reduces the chance of injury to surrounding tissue...
Do other treatments fractionate even more so? Sure,,,are they as effective in the long term? probably, but still sort of unknown as they are of course newer..
No head frame...big bonus as I also had surgery and still have problems in my skull where I had pin markers..not even as severe as the head frame for GK....
Love my Dr who did surgery,,he is head of Gamma board at his hospital,,and wanted me to do either Gamma or CK...which I found interesting that he felt the CK was as effective as Gamma...a strange thing since he is in charge of the gamma center there...and really had no preference..said either would be just fine....
Main reason...
Dr. Medbery, Dr. Spunberg and all the other Dr's whom participate on the CK site...they volunteer thier time, answer all sorts of questions and actually care about the patients whom ask questions....Dr. Spunberg immediately took on my case, and has held my hand from the beginning....gave me personal contact info, encouraged my well being even with my endo surgery (he wanted the biopsy before proceeding with any type of radiation) has never encouragad me to try one form of radiation over another even though of course he personally uses CK...
So all being said....
CK with a Dr whom actually cares what happens to me, and is not going to forget me five minutes after treatment .....
That is what ruled important to me..Overall, I think CK is a well studied and safe proceedure,,,does it have risks? yes,,so do all of them. Are the risks of CK higher than other types? they are all so close, it is almost impossible to determine. So it came down to, whom would be treating me,,,,not what.
Good luck and glad to see you made a decsion...I certainly think that it is always worth trying the least invasice approach first...and if it doesnt for some really strange reason,,with fractionated you can a; try a second time and b; always attempt surgery with its much higher risk later...(this is dispite the bad rumor that radiation affects the tumor making it harder to remove...a bad myth do not believe it)
So keep us informed and good luck
Ceeceek

[sgerrard]

Ceeceek,

I totally agree, the response from the CK doctors does the trick. I had been doing research, and finding I could only talk to a doctor if I went through the whole appointment process, which is never very satisfying, I would always think of one more thing I should have asked about an hour later.

Then I sent an email to Dr. Chang, on a Saturday, and got a reply within the hour. Later I sent one on a Sunday, with a list of questions, and got a detailed response the same day as well. The sense that these doctors actually care about patient outcomes, understand what it is like, and are willing to interact with patients as much as they need, is a huge plus to me.

Steve

[Mark]

OK, for those of you radiosurgery geeks or newbies following this discussion about radiation doses and machine comparisons, specifically Trilogy vs. CK or GK, here is a response from Dr. Medbery who was vacationing in Santa Fe, when he responded 

The entire discussion link is:

http://www.cyberknifesupport.org/forum/default.aspx?f=16&m=14240&p=1

But I'll copy the gist of his response. I think it does a pretty extensive job of covering some of the discussion points, particularly a comparison of Trilogy and CK, but like anything else it is information that everyone can interpret as they see fit.

Mark

All right, let us start from the top and work our way through this morass...and by the way, don't believe ANY hospital PR pieces.

THere are a number of factors that go into successful treatment of tumors, particularly small tumors near critical structures as is the case with acoustic neuromas. These include:

Tumor characteristics: size, shape, location, previoius treatment if any, etc. To the best of my knowledge, no one has invented a way for us to change these things prior to treatment, so we can assume that all systems fact the same obstacles.

Team characteristics: treatment philosophy, experience, knowledge etc. These factors are intertwined inextricably with the selection of treatment machine except in the centers such as Oklahoma, Baylor, Phoenix, and a few others that have access to Gk, Ck and other methods of treatment. In general, team experience is important only up to a point. That is, once a team gets sufficient early experience, only small gains come from additional experience, at least in terms of actually performing the treatment. That said, if you have a choice of two teams that have experience with multiple delivery systems and are in close proximity, choose the one that has treeated a lot of cases rather than just a very few.

Imaging characteristics: MRI is inherently less accurate than CT, and the accuracy is more dependent on proper machine maintenance and calibration. It is beyond the scope of this piece to talk about why, but please accept that it is true. That is not the reason that CK uses the CT dataset for targeting, but it does produce a slight advantage. Data from Accuray suggests that if you use the best fusion package available to fuse CT and MRI datasets, there will be about a 0.5 mm difference. This is one reason we insist on CT cisternograms whenever we are really worried about critical structures around the base of the brain (brainstem, cranial nerves etc)

Machine characteristics: accuracy is only part of the issue. FIrst of all, if any radiation oncologist has a machine of any type that is accurate to 0.02mm and can measure that accuracy, he needs to be reporting it. That is simply untrue. Even Varian does not claim that. They claim a best case scenario of 0.5 mm accuracy in the three cardinal axes (x,y,z) and 0.7 mm when you include rotational accuracy. To that you must add imaging inaccuracy meaning that under the most perfect of conditions you may be able to get to somewhere around 1.2 mm. As you might guess, perfect conditions are rarely achieved in clinical practice. Second, any claim that Trilogy images during treatment is simply untrue. It images before treatment, or perhaps before every arc. Third, there is the issue of solid angle. Imagine the head of the CK traveling around not he surface of a large invisible sphere centered around the patient's tumor. The more of that sphere is available, the more angles from which the planning system can choose beams in order to avoid critical structures. Even the CK cannot use the entire sphrere (we are unable to treat the patient from directly underneat for instance), but we use a VERY large fraction of the sphere, and therefore have a better chance of treating the tumor and avoiding things such as the brainstem, cochlea, etc. Fourth, there is the issue of isocentric treatment versus non-isocentric. With isocentric treatment, you aim a number of beams at a particular point in the tumor. With Trilogy, you use beam arcs, and the entire arc is aimed at that same isocenter, and you simply have to live with any adverse effects. With CK, treatment is non-isocentric. This means that you can aim anywhere that is best in order to achieve the desired result. You may use a small number of isocenters with Trilogy, but CK directs beams from 100-300 or more directions that can come from anywhere and go anywhere.

Some statements in this thread are true:
Trilogy can deliver a higher dose rate (up to 1000 mu/min in stereotactic mode) than CK (400 mu/min on G3 machines, 600 mu/min for g$ machines. Henry Kissinger once famously told the chief Vietnamese negotiator at the Paris peace talks "You never beat us on the field of battle". THe Vietnamese responded, " That is true. It is also irrelevant." Dose rate is irrelevant.

Trilogy has respiratory gating. CK does not because it is unnecessary. Rather than use a gating technique that has been shown in studies at MD Anderson to be little better than no gating, CK actually images and tracks a tumor during respiration, making it unnecessary to turn the beam off and on during the respiratory cycle.

Trilogy can do several things: true, but do you want treatment with a machine that is being used 95% of the time to treat lung and breast and prostate, where stereotactic treatments are an afterthought? Or do you want treatment by a machine that is dedicated to your type of problem. Here's an interesting exercise: tell the Trilogy folks that you would prefer to be treated at 9:30 in the morning and see their response. They will not want to interrupt their busy day with your treatment in all probability.

The rest of the statements are all fluff and nonsense.

As for doses, GK uses 12 GY in a single fraction, we use 18-21 Gy in three fractins, and higher total doses are used by units treating with small daily fractions. The GK and CK treatments are probably nearly identical, the other possibly so as well. When you give a higher daily dose, you give a lower total dose.

There is not published Trilogy data on AN's of which I am aware. Older data from accelerators adopted to stereotactic treatment showed good 9but perhaps lower) control but higher complication rates. It is impossible to say whether the same would be true with Trilogy.

Gads.. I should have stayed in Santa Fe.

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

Clinton A. Medbery, III, M.D.
Southwest Radiation Oncology
1011 N. Dewey Ave.
Oklahoma City, OK 73102

[sgerrard]

So is Medbery basically saying "give it a rest, you huge techno-geeks" ? 

Lots of good info there, plus a little editorializing, as in, re. Trilogy, "stereotactic treatments are an afterthought." That's stretching it a little, I think. Can't get enough of the non-isocentric treatments and solid angle stuff, though.

I still don't really get how 12 = 18 = 50, but I will leave it to the radiation oncologists to do the math on that. Medbery's explanation was just "When you give a higher daily dose, you give a lower total dose." Well okay.

Thanks for all the info and discussion.

Steve