Any MEG source analysis is only as good as the underlying stability of the subject, give and take some improvements from motion correction algorithms. Hence, minimising subject movement is of utmost importance for good source reconstruction.
While each MEG device comes with its own set of cushions or inflatable caps, Sofie Meyer and Gareth Barnes have developed a new solution using 3D printing of individual foam caps, or head casts. Here's what they say:
"We have now been using head-casts to position subjects in the MEG system for some time. We realise that some of you are interested in following along these lines but thought that we should share some of our important safety guidelines with you."
See also a short video here:
To sum it up:
We advise that you should never move the MEG chair or dewar if the head-cast is on the subject’s head.