This also belongs in the after treament category.

From my experience is appears that PET scans are done differently depending on where you get them.

My initial pet scan was done with a head rest and "THE" mask. For the follow up PET scan my insurance company insited that I go to another place. This is in principle no problem, except for the following:
they did not have a head rest and no setup to affix a mask. The fact that they were not set up for the mask is probably ok if not optimal but that they did not even have a head rest was troublesome. i.e. Head on a board! Needless to say that I was not impressed! However since the radioactivity was injected already there was no point in terminating this.

You want proper and symmetric positioning of the specimen and you also do not want the patient to move. Both of which may increase false positives, especially in the head and neck region. There are structures that have show a moderate uptake for normal tissue.


Any experiences with PET scan setups?

Markus

PS while looking into this, I came across a review which stated that chewing/grindig and talking resulted in visible uptake.

Hey Markus

I did not have "the mask" for any of my PET's, only for the IMRT treatments and the initial x-ray & CT setups.

KC

Marcus,

I have had several PET scans and none of those were given using a mask. In fact I have not heard of this before.

Judy

Ditto - no mask for the PET

Markus,
I have heard of this. There are two routes of administration for the radioactive substance that is needed for the scan. It is given either via intravenous injection ( the most common route) or by inhaled gas. "The Mask". There is no statistically significant difference in the accuracy of the scan in either case. The choice is dependant on operator choice.

Hope this is usefull.

Cheers.

Mike

Mike
thanks.... the gas method used 15-O and is used to study oxygen metabolism. This is more of a research tool. The half life of 15O is just a tad more than 2 minutes, which means that you need cyclotron next to the facility.
For cancer, FDG is generally used to assess glucose uptake.

I checked some more and it appears that if the masks are used at all then only for the initial PET/CT scan for IMRT planning.
And then the PET/CT and IMRT setup should be compatible.... which was why the RO was pretty adamant as to where to get the PET scan. The same RO also suggest to take the mask for the post TX PET. The idea is to minimise head movements which may lead to artifacts. This is most likely overkill.
However, I do think that you DO need a proper head/neck rest. Since there is a moderate uptake in the mouth/neck region anyway, everything should be done to preserve the integrity of the scan. (i.e. excessive talking, chewing etc before the scan) Note that this is not first hand knowledge. I am not quite crazy enough to provoke a positive scan by trying this.

Markus

As someone that had a horrible, frightening week because of a false read on a PET scan, I agree with you that people who are having them need to know more about how to "behave" before and during their scan. For instance, no one told me that I should be very inactive the day before my scan and for the hour before my scan. I spent that hour talking to the guy in the chair beside me, and I can talk anyones head off. I am also a nervous "sitter", I hate to just sit without anything to do. So I have a habit of kicking and wiggling my legs, I'm never still. These things can affect a scan. The test is new and it's useful so I'm sure they'll get more particular about it as time goes on.

I also have never had "The Mask" for any of my PET scans, nor have I heard of it. That doesn't mean there was not an indication for it in your case, however.