Research On Adaptive Dynamically Filtering Of High-frequency Ultrasonic Ddiagnostic Aapparatus

In the situation of the continuous development of ultrasound diagnostic techniques, various types of specialist ultrasonic diagnostic equipment has also been greatly developed, and ophthalmic ultrasonic diagnostic apparatus is one of the fastest growing specialist ultrasound diagnostic equipment. With the development of modern science and technology, medical ultrasound equipment is constantly updated and improved in aspects of the probe, signal detection and processing, computer applications. In order to meet the needs of the clinical diagnosis and improve the system performance further and comprehensively, some indicators such as the exploration depth, spatial resolution, imaging speed and sensitivity are the research objectives of the engineer. In this paper, the design of adaptive dynamic filter is researched.Firstly, the theoretical significance of the algorithm of automatically matching the dynamic filter is analyzed, and then the principle of the algorithm and hardware architecture are described. Secondly, the basic principles of FIR filter module and the FFT processor system and their several hardware architecture are described in detail, and the FFT processor hardware optimization measures and methods are given. In addition, The realization scheme of each module is given, which combined with FPGA technology using in ultrasound system widely. In this paper, FPGA realization scheme of two key modules is elaborated particularly, which are the cascaded FIR filter module based on the parallel distributed algorithm and the high speed parallel iterative FFT processor module based on radix-2-DIF. Simulation results show that this algorithm is feasible. Finally, based on the previously selected suitable sub-module, adaptive dynamic filter is achieved, which can be applied to existing ophthalmic high frequency of B ultrasound diagnosis system. The image collected from tissue mimicking ultrasonic body module performs better than traditional filter. The probing depth is increased and image sensitivity is improved. The auto-matched dynamic filter designed in this paper is able to give a real-time analysis of the spectral characteristics of the echo signal, and adjust the center frequency of dynamic filter when necessary. which achieved the desired requirements. In addition, the FFT processor module can be used as an independent tool, and lay a foundation for further research of Doppler flow measurement system.