has anyone seen this, re Uni of Michigan?

[Alison]

Hi,
just wondered if anyone's seen this on the UMHS ( university of Michigan health systems) radiology oncolgy site:

http://www.med.umich.edu/radonc/pat_fam/LINAC.htm

In my pursuit of information about Linacs (which is the only available option for SRS and FRS at my local treatment centre in the Uk, where we have limited choice of treatment centres) I was surprised to find a US site advocating Linac as opposed to Cyberknife.

Is the Uni of Michigan a respected treatment centre in the US? Would be interesting to know if this is a valid opinion to throw into the mix!

Also do Linacs come under various names/brandnames?

Any information would be very welcome,

thanks, Alison

[JWW]

Linac Systems:
1. Novalis (This is what was used for my SRS on July 31, 2012) most preferred over CK
2. Varian Triology
3. Elekta
4. TomoTherapy

[Alison]

Thanks JW,

thats really useful to know. It's all a bit of a minefield trying to distinguish between different names for treatments and types of machines and brandnames! I've only been looking into this for a few weeks and I'm learning so much.

I read some of your previous posts and was glad to hear you had a good experience. I hope that is ongoing.

Alison

[PaulW]

All radiation treatments will kill the tumour, regardless of the machine or the technology.

What is important to the patient is which machine will do the least amount of damage.
For AN Patients thats damage to the Brainstem, nerves and hearing


The answer to that depends on a number of things.
Large odd shaped tumours maybe better suited to a LINAC with a multileaf collimator which can shape the beam to be the same shape as the tumour, like the machine at Michigan.
But the smallest beam they can make is a 5mm x 5mm square, and the accuracy is not as good.. So this machine is not great for a round 4mm AN. The accuracy argument becomes less important as the tumour gets larger, and the advantage of shaping the beam comes into play.. If you have a large odd shaped tumour this could be the machine for you.

Really small targets that have no bony structure near them could be better served with Gammaknife
As the Gamma knife beam at its smallest is 4mm and it uses MRI to postion the tumour

Cyberknife with its robotic arm is very good at avoiding critical structures like the cochlear and the brainstem.
It positions itself using bony structures in the skull via realtime 3d Xrays, and with many Acoustic Neuromas living in the bony IAC,
it makes Cyberknife very accurate for AN's and a good fit for avoiding the cochlear and brainstem.. There is also the option of fractionating the dose which may help in Acoustic Neuromas.
The smallest beam is 5mm in diameter.
   
No one machine is best, and each machine, it can be argued is better than the other at certain things.
And as nobody can afford all the machines , you tend to get the one that can do most things OK and make the biggest return on investment. That machine is the tradional gantry based LINAC.

[Alison]

Thanks Paul for providing very interesting and useful information. You really have researched all this!

Alison

[leapyrtwins]

Is the Uni of Michigan a respected treatment centre in the US?

The University of Michigan is a very reputable center for treating ANs.

Some excellent doctors there.

Jan

[JWW]

PaulW, it is my understanding that ALL procedures for radiosurgery use an extra MRI called a Stereostatic MRI (extra slices/pics of the tumor) for the planning stage. I had this along with the CT scan for making my mask and the actual procedure, SRS, using the Novalis.
My radiation oncologist, Dr. Teh in Houston, Texas (The Methodist Hospital) said: "The Novalis has 1mm or less accuracy!" The Novalis takes in account movement. He avoided my cochlea and the AN was confined to the IAC. I had excellent hearing before and I still do.....2 months later. Procedure done on July, 31, 2012.
Mild dizziness and mild balance issues GONE!!! I do have mild tinnitus now which I tune out!

JW

[PaulW]

You are correct JW.
I guess my point is that every machine is the best and the worst at something.

If the Cyberknife was a ferrari, Novalis TX a Rolls Royce and Gamma Knife the Toyota Prius.

All 3 of them can take you from A to B up the freeway, and if you drive at the speed limit the end result will be the same.

If you have a need to get their quickly you would use the Ferrari.
If you need to get there in utmost comfort for an elderly millionaire you would take the Rolls Royce
If you need to use as little fuel as possible you take the Prius
 
The same problems arise in Radiosurgery. Each machine was designed to be good at something, but it can never be great at everything.

What you should not do is attempt to travel in a model T Ford on a 100 degree day at 65mph, with somebody who just got their license.. That is bound to be trouble.

I guess my point is that if you could give a medical team any machine they wanted to perform Radiosurgery, they will probably use all 3.
Each machine has its advantages and disadvantages depending on the size, shape, and the location of the tumour.

Novalis TX is a Varian Linear Accelerator fitted with a Brainlab Multileaf Collimator
I found this research paper comparing BrainLab and Cyberknife for Acoustic Neuromas
It should be noted that the tumours in this study were quite small, which would favour Cyberknife.
Larger odd shaped tumours, may have given a totally different result.


http://www.researchgate.net/publication/51619115_Dosimetric_comparison_of_Linac-based_(BrainLAB)_and_robotic_radiosurgery_(CyberKnife_)_stereotactic_system_plans_for_acoustic_schwannoma/file/d912f4fa035f9af4d4.pdf?ev=pub_ext_doc_dl&docViewer=true

It should be noted that the latest machines, with the best operators, are producing very similar results for AN's
So while in theory one machine maybe better than the other, its not really showing up in the published results so far.

It could be that the latest versions of all machines in the hands of the best teams, the differences are becoming more academic and theoretical than practical.

[Alison]

Thanks to JW and Paul for their input.

Paul, the link didn't work for me but I have read that paper in abstract on the pubmed site. The debate goes on!

Alison