In medicine they actually use fidelity film holders! I have picked up seven of it in size 8x10 for a $100 in the other day! They are film holders for photography, so dont believe anything else! They are feet into any cameras with out any problem!
So, why they are using it and where?
There is one examination method called for ultrasound and there is a very low intensity X-ray too!
In regular X-ray we using intensifying screen also called salted screens and they can be blue or red or neutral! It gives certain speed for x-ray films so exposing time can be reduced as those rays is dangerous for your health! So its just because to eliminating risks! But those look totally different so its impossible to mistaking its aluminium and when you open it up its white inside!
Than there is a so called soft X-rays. Now, when using soft X-rays usually film can not be put in any type of intensifier holders as in that case the aluminium would filtrate all X-rays so they using 8x10 holder instead of plastic just to cover the film rather than have in it lying free!
Thats it guys!