諸橋 侃, 飯塚 理八

Tsuyoshi MOROHASHI, Rihachi IIZUKA

慶応義塾大学医学部産婦人科学教室

Department of Obstetrics and Gynecology, Faculty of Medicine, Keio-Gijuku University

キーワード : diagnostic ultrasound, low intensity, fetus, heart beat, continuous record

Fetal or embryonic heart beat can be detected theoretically with the acoustic intensity of pulsed ultrasonic diagnostic equipment as low as 0.001 W/cm². The level is estimated from the echo level of fetal (embryonic) heart beat, attenuation of ultrasound intensity due to the spread of ultrasonic beam, efficiency of ultrasound transducer, electric power of noise and the lowest S/N ratio which enables fetal heart detection. A real-time B-mode electronic scan equipment is developed in this study with clinically low acoustic intensity as low as 0.01 W/cm² (SAPA). Furthermore, a unique system for continuous recording of fetal heart movement is developed with optical fiber CRT. The system records a real-time B-mode picture and then continuous M-mode subsequently at B-mode marker line which corresponds fetal heart.