http://www.mri-roentgen.ch/standorte/mri-bahnhofplatz/
http://www.mri-roentgen.ch/angebot/osteodensitometrie/
Going back over my bills, it looks like the cost was only ca. 110. (At least I can't find any other charges related to that.) Now - that does not include interpretation or consultation. A technician does the scan and results are sent to your doctor who then discusses them with you. So figure in the doctor's time on top of that.
My endocrinologist ordered the scan, but it was not covered under my basic insurance. At ca 110, though, a relative bargain, can't complain.
If I understand correctly, in some cases insurance will cover it, such as specific previous or ongoing disease/medication/treatment that affects bone density.
I have no idea if a doctor's referral is needed, I imagine it is because you could not otherwise get the results - but you could always call and ask.
ETA:
Googling around, given that you are in ZG, I see that the Zuger Kantonspital does the DXA scan with a referral from your doctor:
https://www.zgks.ch/Rheumatologie%20...osezentrum.php
But a couple of pharmacies offer bone density measurement - not sure what method is used. For instance the Zug Bahnhof Apotheke:
http://www.apotheke-zug.ch/wir.asp?angebot=Messungen
Depending on what you need and why, this might be an option without a doctor's referral.
But honestly - first step should be to talk to your GP.
Having checked out the cost for the scan in the fitness context, prices start at 180, going up to 250. So I was thinking it may be cheaper to have it done in a medical environment, even if I pay for it myself.
My oncologist told me that a rheumatologist in private practice is less expensive than a hospital scan. I've never checked.