Ted Bell knew his portrayal of a depressed, elderly patient was convincing when the medical student who was examining him broke down in tears. Her instructors had to call a timeout because his flat monotone and unkempt appearance reminded her too much of her father, who had similar symptoms. Sad personas are part of Bell's new career. He plays the part of a patient. It's a big change for the retired civil engineer who spent more than three decades managing construction projects for the Army Corps of Engineers. Emotion was hardly part of the job description. Bell, 62, of Greenbelt, is one of hundreds of people in the Washington area whose day jobs are to realistically portray patients in medical cases. They are poked and prodded. They occasionally take off their clothes. Some even undergo breast and pelvic exams. They come under the direction of medical school clinical directors, who act as casting directors, stage managers and dialect coaches rolled into one. With six major medical schools in the region annually training tens of thousands of students seeking to be doctors, nurses, pharmacists, social workers and other health-care professionals, demand for "patients" is high.