I think you are referring to the one which is the serpent and the staff, but I have no idea how that came to be a medical insignia.
That is an interesting insignia. This insignia has an eagle.
Insignia
INSIGNIA You are correct.
From a medical professional
A medical license may be used for practicing as a medical professional. The exact title of the medical professional and requirements for license vary by state and are mandated by the AMA.
Which insignia did you have in mind, since there's a few different insignia worn? There's rank insignia, branch insignia, and regimental crests.
How do I delete on my Insignia camcorder
Insignia is a noun.
professional
The plural noun is insignia.The singular noun is insigne.
The title "Dr." should be used when addressing a medical professional.
The caduceus is the traditional doctor's symbol.