There is no particular sign for doctor on hand lines but you can an idea about it from few indications on hand.
But in India you need to be careful because there are so many fake doctors and fake healers.
Mostly you will find these indications on hands of surgeon, social worker, Indian ayurvedic doctor, magician, etc.
Medical Stigmata (Chikitsak Rekha): Vertical lines on Mount of mercury, healer. No need to confuse by children line versus medical stigmata because children line always found over marriage line underneath little finger.
A line from headline goes to Mount of mercury. This is clear indication of doctor and sportsman, etc.
Mars Line ends on bracelets (manibandh) or long mars line. You will find this type of indication on hand of astrologer, doctor, nurse, magician, healer, etc but do not confuse by double life line or long mars line.
