@Geoff ******
when that DTV came out they were handing that 5 year visa out to anyone who had an appt for a hangnail from a doc,
Then consulates got harder and started wanting treatment plans, proof of treatment, appt schedule,
SO whether you can or can't do a DTV based on medical reasons would come down to why you are having medical treatment here and how good your documentation is about the treatment.
If you apply and they want more documentation they'll email you, but worst case you apply and they reject the application and you are out the fee