abrasion accuracy algorithm arm atrial beam bladder breast breath bruit catheter cerebrovascular chest coil cosmetic ct design detector digital drive echo emg ercp esophageal exoskeleton femur gadolinium gait gamma hand haptic hardware impedance implantable impulse instrument jet laparoscope mesothelioma microphone motion optical phantom posture power proton pyretic resolution resorption shadow sign simulation sleep sound spina stethoscope stirring thermal ultrasound variate