Research On Front-end Transmission Circuit And Beamforming In The Medical Ultrasound Machine

With the rapid development of computer science and electronic science, modern medical imaging technology has witnessed an unexpected increase. Among such medical imaging technologies as ultrasound imaging, X-CT tomography, radioisotope scanning and magnetic resonance imaging, ultrasound imaging has the advantages of real-time imaging, noninvasiveness, and low cost and therefore it has been widely applied in the field of diagnosis, treatment and surgical navigation.This paper is partly focused on the design of the front-end of medical ultrasonic transmission and receiving circuit, which involves designing ultrasonic pulse transmission circuit, preamplifier, TGC and its control circuit, the filter circuit, PCB and so on. Experimentally, thickness measurement has been conducted using ultrasonic transmission and receiving circuit. The delay time of each channel in the array elements is determined using the focus formula and it is quantified into the minimum delay of 5ns. The design of beamfoming and digital beam synthesizer are realized based on QuartusⅡ.Thickness measurement experiments show that measurement accuracy can reach about 2-4mm, which basically meets the criteria of medical ultrasound machine. Simulation results of beamforming and receiving beam synthesis demonstrate that the emitting pulse time sequence of the predefined focal point (5cm, 10cm or 15cm in the scan line) can be produced using transmission focusing and such operations as delaying superimposition and apodization can be implemented using receiving focusing . The research work involved in this paper will be of great reference significance for the technical personnel who are engaged in the development of all digital ultrasound machine.