A psychiatrist is a physician who specializes in psychiatry. The translation from Greek and Latin origin is as follows: "Psych"-Greek transliterated meaning breath, life, soul, spirit or mind; "Iatro" is Greek for physician and -ist in Latin comes from "ista or iste" and the pronoun means "that one" or "specialist". A psychiatrist specializes in the diagnosis and treatment of mental disorders. Psychiatrists are medical doctors who must evaluate patients to determine whether their symptoms are the result of a physical illness, a combination of physical and mental, or a strictly psychiatric one. As part of the clinical assessment process they may employ a mental status examination, a physical examination, brain imaging such as computerized tomography (CT/CAT scan), magnetic resonance imaging (MRI), and positron emission tomography (PET) scanning, and blood testing. Psychiatrists prescribe medicine, and may also use psychotherapy, although the vast majority do medical management and refer to a psychologist or another specialized therapist for weekly to bi-monthly psychotherapy.