The development of a novel push-type ultrasonic endoscope is described in which probe rotation is accomplished by a small motor situated near the transducer. A digital FPGA-based ultrasound imaging system is implemented which uses coded excitation to increase the SNR and penetration depth, with probe rotation accomplished by a small motor situated near the transducer replacing the external motor and the long steel wire used in other ultrasonic endoscopes. The apparatus is tested continuously for 300 hours with no obvious problems. The coded excitation, digital quadrature demodulation imaging system can obtain ultrasonic images of higher quality and more information of the echo is preserved compared with the analog imaging system, because the analog digital conversion is moved to the first step of the signal processing.The digital imaging system possesses a higher SNR resulting in a sharp image. Locating the motor near the probe improves the consistency of rotational speed in comparison with external guide-wire rotation, and increases the image quality and life-span of these devices.
为了提高医学超声内窥镜系统的探测深度和成像质量,将广泛应用于雷达系统的编码激励技术引入到超声成像系统中,采用编码脉冲信号激励超声换能器,以增加超声发射功率,提高回波信号信噪比。在分析编码激励原理和超声换能器暂态工作特性的基础上,设计并实现了超声信号的4 bit Barker编码脉冲发射。实验中,激发电路输出的编码激励信号与超声换能器的暂态工作特性吻合;玻璃杯壁的反射超声回波信号,具备编码特征,与Matlab仿真结果相同,且幅度较强。
