Hi, doctor should be accepted. At least Collins dic seems to translate salve! as "Hello! or Hi!" https://www.collinsdictionary.com/dictionary/italian-english/salve
I would appreciate a response from a native speaker on these: Is it typical that an established patient would refer to their doctor using the formal? Would a nurse always address a doctor formally? Salve is more formal than ciao, but is it more or less formal than buongiorno?