Research And Realization On The Key Technologies Of Noninvasive Temperature Estimation Using Backscattered Ultrasound Equipment

Noninvasive temperature estimation using ultrasound is an advancedinterdisciplinary topic, which involves ultrasonics, biomedicine, thermology,electronics, computer science, image processing and analysis, mathematics, etc. It hasnot only great application requirement but also much more technology advantagesthan EIT, X-CT, MRI, Microwave, and other technologies of noninvasive temperatureestimation. This thesis is based on WBPH (Whole Body Perfusion Hyperthermia), andaimed at noninvasive temperature estimation using backscattered ultrasound. Itdeveloped a suit of effective scheme of noninvasive temperature estimation usingultrasound, through the aspects of ultrasound temperature model and algorithm,design and realization of ultrasound diagnostic apparatus, in vitro and in vivoexperiments, and etc. It points out that those tissue whose Km is smaller will beclinical used firstly in the noninvasive temperature estimation, if we have highperformance ultrasonic temperature measurement apparatus and excellent time-shiftalgorithm based on prior knowledge. This thesis fully analyzed ultrasound backscattered time-shift andfrequency-shift models for noninvasive temperature estimation, which are based onthe discrete random medium model of biotissue. We select the better model oftime-shift, and invent a new BIFT (Binary Image Fuzzy Tracking) algorithm from theview of image processing and analysis, present its theoretical basis, and compare itwith CCA (Cross Correlation Algorithm) and AR-PSD (Autoregressive PowerSpectrum Density). Comparing to conventional CCA, BIFT has better performancesat several aspects of spatial resolution and memory capacity, computationalcomplexity, algorithm convergence and anti-noise ability. BIFT has been usedsuccessfully in the simulation and in vitro tissue experiments of the time-shift modelfor noninvasive temperature estimation. For getting original ultrasonic RF echoes, the conventional ultrasonic diagnostic - III -英 文 摘 要apparatus can't meet the requirements of high sampling frequency and highsignal-noise ratio for the ultrasound temperature estimation models and algorithm. Sothis thesis researched and developed the full-digital A/B mode ultrasonic temperaturemeasurement apparatus based on PC, including several key technologies such as theselection of ultrasound probe, overall consideration of diasonograph, full-digitalultrasound, the amplifying circuit with high sampling-frequency, high gain and highsignal-noise ratio, frequency self-adaptation circuit, and etc. At last this thesis givestwo designing examples based on the A/B mode probe respectively, which meet therequirements of any temperature measurement systems using ultrasonic pulse echoes,such as time-shift, frequency-shift, and power models. This thesis developed a suit of effective clinic scheme of noninvasivetemperature estimation using backscattered ultrasound, through data simulation, watertemperature experiments, in vitro tissue experiments, tissue characterization, clinicalresearch, and etc. It were found that the time-shift fitting order associated with theprior knowledge of heat mode and object size, the sampling frequency andsignal-noise ratio of the ultrasonic temperature measurement apparatus, tissuecharacterization parameter Km are the three major factors which directly affect thetemperature estimation precision. This thesis developed the clinical token method ofultrasound temperature estimation, considering the motion compensation, humanbody thermal model and anatomical model. It also gives the minimal ultrasonicsampling frame rate criterion, and the Km of the poker liver.