Study On Multi-Frequency Ultrasound For Non-Invasive Measurement Method In Vivo

Hyperthermia is an efficient therapeutics for cancer. Its sticking point is whether the temperature is able to be measured and controled correctly or not. In current thermometry, temperature is measured by inserting the temperature transducer into the tissue to be measured. Owning to its disadvantages such as invasive etc, this thermometry will influence the curative effect greatly and limit the clinical application of this hyperthermia. Therefore, non-invasive thermometry is increasingly becoming the people's investigation focus. The advantages of ultrasonic non-invasive thermometry include low cost, able to gather and process data in real-time, relative deeper penetrate ability and higher space-time resolving power, so we adopted this thermometry.This subject research mainly put forward an ultrasonic non-invasive thermometry, using ultrasonic nonlinear parameter to measure the temperature in media. An advanced ultrasonic pulse-echo method is developed which uses a new kind of BI-frequency ultrasonic focused piezoelectric transducer to precisely measure the nonlinear parameter B/A without being effected by the scattering characteristics of the media. It was proved to be a practical method of non-invasive in-vivo thermometry in hyperthermia. Corresponding to this ultrasonic non-invasive thermometry, a signal gathering equipment and signal processing system has been established, a series of system experiments have been done so as to testify the practically feasibility of this thermometry.Where, design of the hardware of this signal gathering equipment used for this thermometry was discussed in detail, and the reliability of this signal gathering equipment has been testified by experiments. An echo-wave signal processing system was designed for gaining the ultrasound non-linear parameter B/A. At last, through two system experiments, temperature relativity of the ultrasound non-linear parameter B/A has been got, and temperature distribution of the sample has been measured non-invasively using the temperature relativity of B/A, which testified the feasibility of this thermometry, that using ultrasonic nonlinear parameter B/A to measure the temperature in sample.