Study On The Sensor Of Diagnosing Osteoporosis By Quantitative Ultrasound

Quantitative ultrasound (QUS) measurement is an economical and effective method of measuring bone mineral density (BMD) in recent years. At present, quantitative ultrasound instruments are imported mostly in our country. Some key technology must be solved to develop quantitative ultrasound instruments with wholly independent intellective property right. Ultrasonic transducer is the key unit in the whole quantitative ultrasound diagnosis system whose performance relates to the transducer closely. The design of high-powered ultrasonic transducer is very urgently important to the design of the whole quantitative ultrasound diagnosis system.On the basis of analyzing the basic theory and the measuring principle of quantitative ultrasound, the ultrasonic transducer of measuring BMD is designed. The relation between the design parameter and the performance of the transducer is obtained through experiment. The experiment indicates that when the proportion of tungsten in damp block is increased, the peak to peak value of respond wave decreases gradually and the number of oscillations decreases too. When the number of matching layer is increased, the same phenomenon is discovered. The circuit is simulated by Pspice and the suited circuit of meeting the need of measurement is gained. The ultrasound transmitting circuit can generates a high voltage trigger pulse to power the ultrasound transducer. The circuit does not need a high voltage direct current source compared with the traditional circuit. The ultrasound receiving circuit transforms the ultrasound calcaneus test signal to the corresponding electric signal, then the electric signal is amplified and filtered to provide the later circuit. Through the experiment in vitro, ultrasound transmitting power is continually adjusted to obtain the standard that calcaneus is safely measured. Finally, through the experiment in vivo, calcaneus test signal is acquired to be used to diagnose bone status for the tested. The transducer and the suited circuit designed through theoretic analysis and test result are successful, it lays the foundation for the study of the whole quantitative ultrasound diagnosis system.