Patients can be referred by their own GP, by any specialist, by friend or relative, or they can be self-referred.
A letter from their own doctor would be helpful (but not necessary) for the purposes of medical communication. At completion of treatment, and with the patient's permission, I would like to report back to the referring doctor.
Although I consider this a "specialist" service, under Medicare I am still classed as a GP, and therefore only GP rates will apply. (Thus there is no need for a referral under Medicare.)