How many scanners are enough?
D001927:Brain Diseases / Q000175:diagnosis*; D001932:Brain Neoplasms / Q000175:diagnosis; D004865:Equipment and Supplies, Hospital / Q000600:supply & distribution*; D006801:Humans; D012040:Regional Health Planning; D014056:Tomography, X-Ray / Q000295:instrumentation*; D014481:United States