医用超声内窥镜探头驱动控制电路的设计
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摘要
医用超声内窥镜是电子内窥镜技术与超声传感技术、微机电技术、现代计算机技术等高新技术的不断发展和融合的产物,是当前应用前景非常广阔的医疗仪器。内窥镜超声成像系统以电子内窥镜系统为基础,将超声探头经由电子内窥镜活检通道伸入体腔、接近目标器官,由微型电动机驱动超声探头实现扇面扫描,获得消化器官管壁各个断层的组织学特征。与电子内窥镜相比,提高了早期病变诊断的能力。与体外超声比较,探头与器官间距离短,避免了脂肪、体腔内气体对成像的影响,获得的图像信息要比体表上获得的扫描信息准确详细。
内窥镜超声成像系统关键技术的研究主要包括:超声探头激励电路、回波信号接收处理电路、同步控制电路三个部分的内容。本文根据超声成像系统的要求完成了三个部分电路的设计与实现;同时,根据对医用内窥镜超声成像的清晰度、分辨率和保真度的要求进行分析,并提出了新的提高超声图像质量的数字化方法。
超声波的发射是由压电换能器完成的。激发电路的功能即是产生瞬时高压脉冲,激励超声换能器发射超声波。激发电路包括同步控制脉冲产生电路、激发主电路和换能器的调谐匹配电路,这三部分电路控制超声换能器按照一定的频率高效的发射超声波。
回波处理电路用于检测由人体组织反射的超声信息,对转换成的电信号进行解调输出。回波处理电路包括放大电路、增益补偿电路、检波、滤波及A/D转换电路。解调出的信号进行A/D转换,输出图像的扫描线数字信号,经FIFO缓存后,数字信号由PCI图像采集卡进入计算机内存。
现场可编程逻辑阵列(FPGA)作为核心控制模块完成对数据传输和相关电路及芯片的控制,主要实现了对超声波激发、A/D转换以及成像部分同步控制。根据各部分电路在系统中的功能,详细地介绍了FPGA产生外部电路控制逻辑和数字信号处理的方法,并给出了相关的实验波形图和硬件系统的整体调试结果。
系统的各电路性能均得到实验验证,达到了医用超声内窥镜探头驱动控制系统的各项指标要求,并实现了显示512×512大小的超声扫描图像的要求。最后,分析了系统的噪声来源,总结了系统的特点,并提出了改善超声成像质量的措施和方法。
Endoscopic Ultrasonography System (EUS) is a nonsurgical medical evaluation that has been proven effective for diagnosing gastrointestinal diseases. EUS will be a widely used and reliable endosonography instruments in the world. Endoscopic Ultrasonography, or EUS, combines the medical technique of endoscopies with ultrasound technology and modern computer technology. EUS uses a flexible tube called an endoscope, which works like a periscope. The doctor inserts this tube into the digestive tract through the mouth or the rectum. This state-of-the-art combination allows the doctor to examine internal organs not only by the tissue surface, but also by ultrasonic tomography images which can show the pathological changes under tissue surface, and photograph and videotape the findings.
The key technologies of ultrasonic imaging system are emission circuit, receiving circuit and synchronous control circuit. On the basis of ultrasonic imaging system, we have concretely complemented the circuits design and implementation. In addition, according to the definition, resolution factor and fidelity factor requirements of ultrasonic imaging system, I put forward new methods for increasing the SNR of ultrasonic images.
The ultrasonic is emitted from a piezoelectric sensor. The function of emission circuits is to produce instantaneous high voltage plus, inspiriting piezoelectric sensor to transmit ultrasonic. Emission circuits include a creation circuit of synchronous pulse, the basic circuit for emission and tuned coupled circuit, which control the piezoelectric sensor transmitting ultrasonic according to a certain frequency.
Receiving circuits detect the wave reflected by human tissue and output electric signal that has been demodulated. The receiving circuit is composed of amplification circuit, variable gain amplification circuit, demodulation circuit, filter circuit and A/D translation circuit. The output of emission circuit is digital signal of scanning line. After buffer storage, the digital signal is send into the computer through PCI card.
A FPGA is used as the kernel module to control the data transferring、related circuit and chips working, accomplishing the synchronous control among the ultrasonic emission、receiving、analog-to-digital conversion and ultrasonic imaging. On the basis of different functions of these circuits, I concretely introduce the methods of digital processing and how the FPGA implements the control logic. In addition, the correlative experimental oscillogram and the debugging results of hardware system are offered.
The performance of each circuit has been verified by experiments and has been achieved the norms for Endoscopic Ultrasonography System. The image size is 512×512, which meets the demand of this system. In the end, noises of the whole system are summarized and further work for improving the imaging quality is indicated.
内窥镜超声成像系统关键技术的研究主要包括:超声探头激励电路、回波信号接收处理电路、同步控制电路三个部分的内容。本文根据超声成像系统的要求完成了三个部分电路的设计与实现;同时,根据对医用内窥镜超声成像的清晰度、分辨率和保真度的要求进行分析,并提出了新的提高超声图像质量的数字化方法。
超声波的发射是由压电换能器完成的。激发电路的功能即是产生瞬时高压脉冲,激励超声换能器发射超声波。激发电路包括同步控制脉冲产生电路、激发主电路和换能器的调谐匹配电路,这三部分电路控制超声换能器按照一定的频率高效的发射超声波。
回波处理电路用于检测由人体组织反射的超声信息,对转换成的电信号进行解调输出。回波处理电路包括放大电路、增益补偿电路、检波、滤波及A/D转换电路。解调出的信号进行A/D转换,输出图像的扫描线数字信号,经FIFO缓存后,数字信号由PCI图像采集卡进入计算机内存。
现场可编程逻辑阵列(FPGA)作为核心控制模块完成对数据传输和相关电路及芯片的控制,主要实现了对超声波激发、A/D转换以及成像部分同步控制。根据各部分电路在系统中的功能,详细地介绍了FPGA产生外部电路控制逻辑和数字信号处理的方法,并给出了相关的实验波形图和硬件系统的整体调试结果。
系统的各电路性能均得到实验验证,达到了医用超声内窥镜探头驱动控制系统的各项指标要求,并实现了显示512×512大小的超声扫描图像的要求。最后,分析了系统的噪声来源,总结了系统的特点,并提出了改善超声成像质量的措施和方法。
Endoscopic Ultrasonography System (EUS) is a nonsurgical medical evaluation that has been proven effective for diagnosing gastrointestinal diseases. EUS will be a widely used and reliable endosonography instruments in the world. Endoscopic Ultrasonography, or EUS, combines the medical technique of endoscopies with ultrasound technology and modern computer technology. EUS uses a flexible tube called an endoscope, which works like a periscope. The doctor inserts this tube into the digestive tract through the mouth or the rectum. This state-of-the-art combination allows the doctor to examine internal organs not only by the tissue surface, but also by ultrasonic tomography images which can show the pathological changes under tissue surface, and photograph and videotape the findings.
The key technologies of ultrasonic imaging system are emission circuit, receiving circuit and synchronous control circuit. On the basis of ultrasonic imaging system, we have concretely complemented the circuits design and implementation. In addition, according to the definition, resolution factor and fidelity factor requirements of ultrasonic imaging system, I put forward new methods for increasing the SNR of ultrasonic images.
The ultrasonic is emitted from a piezoelectric sensor. The function of emission circuits is to produce instantaneous high voltage plus, inspiriting piezoelectric sensor to transmit ultrasonic. Emission circuits include a creation circuit of synchronous pulse, the basic circuit for emission and tuned coupled circuit, which control the piezoelectric sensor transmitting ultrasonic according to a certain frequency.
Receiving circuits detect the wave reflected by human tissue and output electric signal that has been demodulated. The receiving circuit is composed of amplification circuit, variable gain amplification circuit, demodulation circuit, filter circuit and A/D translation circuit. The output of emission circuit is digital signal of scanning line. After buffer storage, the digital signal is send into the computer through PCI card.
A FPGA is used as the kernel module to control the data transferring、related circuit and chips working, accomplishing the synchronous control among the ultrasonic emission、receiving、analog-to-digital conversion and ultrasonic imaging. On the basis of different functions of these circuits, I concretely introduce the methods of digital processing and how the FPGA implements the control logic. In addition, the correlative experimental oscillogram and the debugging results of hardware system are offered.
The performance of each circuit has been verified by experiments and has been achieved the norms for Endoscopic Ultrasonography System. The image size is 512×512, which meets the demand of this system. In the end, noises of the whole system are summarized and further work for improving the imaging quality is indicated.
引文
[1]. 高立明,林良明等,全方向蠕动机器人驱动内窥镜系统的研究[J],中国生物医学工程学报,1998.3,Vol.17(17):54～64
[2]. M.V Statva,etc.al.,Current Generation Video Endoscopes[J]. A Cirtical Evolution, Am.Surg., 1988, Vol.54: 73~77
[3]. 李德印,电子内窥镜的构成及主要功能探讨[J],医疗装备,1996,Vol10:15～16
[4]. 李励,医用内窥镜的发展历程[J],医疗设备信息,1999
[5]. AD Keet,Ch.B.,The Pyloric Sphincteric Cylinder in Health and Disease [M], Spring-Verlag, 1993
[6]. 张凯,周铁英,三种弯曲旋转超声电机的原理及研究[J],压电与声光,2002,Vol.24(3):191～195
[7]. 金震东,消化系统腔内超声临床应用进展[J],中华超声影像学杂志,2001,Vol.10(7):389
[8]. 金震东,刘枫,超声内窥镜检查术临床应用进展[J],世界医疗器械,2003,Vol.9(4):26～29
[9]. 冯若,超声诊断设备原理与设计[M],中国医学科技出版社,1993
[10]. 万明习等, 医学超声学原理与技术[M],西安交通大学出版社 1992.10
[11]. S.Holm, “Bessel and conical beams and approximation with annular arrays”[J] IEEE Trans. Ultrason. Ferroelect, Freq. Cont. 1998.9, Vol.45(3): 712~718,
[12]. 会长善,超声工程[M],哈尔滨工业大学出版社,1989
[13]. 高上凯, 医学成像系统[M],清华大学出版社,2000
[14]. 孙军华,董名利. 钢轨高速探伤系统超声发射/接收装置的设计[J],2002,Vol.36(12):51-53
[15]. 谢嘉奎,电子线路—线性部分[M],高等教育出版社,1999
[16]. 关立勋,雷纪胜,超声诊断仪原理与维护[M],人民卫生出版社,1983
[17]. 应崇福,超声学[M],科学出版社,1990
[18]. ANALOG DEVICES 8-Bit40MSPS/50 MSPS/80 MSPS Conerter AD9057 Data Sheet,2001
[19]. Benso, S. Cataldo, S. Chirusano and P. Prinetto, A High-Level EDA Environment for the Automatic Insertion of HD-BIST Structures, Proceedings of the 1999 IEEE European Test Workshop
[20]. 王金明,Verilog HDL 程序设计教程[M],人民邮电出版社 2004
[21]. 沈绪榜等,超大规模集成系统设计[M],科学出版社,1992
[22]. 吴继华,王诚,Altera FPGA/CPLD 设计[M],人民邮电出版社,2005
[23]. 赵雅兴,FPGA 原理、设计与应用[M],天津大学出版社,1999
[24]. 刘铁兵,汤黎明.基于可编程逻辑器件的便携式心电监护仪的设计与实现[J],医疗卫生装备,2001,Vol.22(4):9—10
[25]. ECRI,Video Colonoscope System(Evaluation) [J], Health Device, 1994,Vol.25:151～205
[26]. 孙正,基于 PCI 总线的医用电子内窥镜实时采集和显示系统的研究,[硕士学位论文],天津;天津大学,2002
[27]. 余浩,詹志强,武威等,Protel98 详解[M],电子工业出版社,1992
[28]. 高鹏,安涛,电路设计与制版 Protel 99 入门与提高[M],人民邮电出版社,2000
[29]. 曾峰,侯亚宁,曾凡雨,印刷电路板 (PCB) 设计与制作[M],电子工业出版社 2002
[30]. 彭旗宇, 数字化医学超声成像方法的研究,[硕士学位论文],北京;清华大学电机工程与应用电子技术系生物医学工程,2003
[31]. 王毓银,数字电路逻辑设计[M],高等教育出版社,1999
[32]. 童诗白,华成英,模拟电子技术基础[M],高等教育出版社,2002;
[33]. 吴迎娟,医用内窥镜安全有效性要点探讨[J],中国医疗器械杂志,2003,Vol.27(3)
[34]. L.D.Picciano & J.M. Taylor, Color Technology in Video Endoscopy[J], Journal of Clinical Engineering, 1994,Vol.19:490～496
[35]. M.V.Sivak, Electronic Endoscopy[J], Endoscopy, 1992,Vol.24:154～158
[36]. 李晴辉,彭承琳,一种用于超声医学测量的增益补偿电路的设计[J],医疗卫生装备,2002.3
[37]. 孙军华,董明利,祝连庆,钢轨高速探伤系统超声发射/接收装置的设计[J],工具技术,2002,Vol36.(12):51~53
[38]. 孙颖,李醒飞,张国雄,生物软组织特性测定仪的研究[J],航空精密制造技术,2002.12,Vol.38(6):34~36
[39]. Chebli, R.; Kassem, A; Sawan, M. Integrated front-end preamplifier dedicated to ultrasonic receivers. Electronics, Circuits and Systems[C], 2001.ICES 2001. The 8th IEEE International Conference on, 2001,(3):1103~1106
[40]. Dual, Ultralow Noise Variable Gain Amplifier AD604 Data Sheet, 2004
[41]. Singh VR, et al. Non-invasive measurement in ultrasonic hyperthermia[J]. IEEE Engineering in Medicine & Biology Society 10th Annual International Conference.1988:850~851
[42]. Sehgal MC, et al. Measurement of the acoustic nonlinearity parameter B/A in human tissues by a thermodynamic method[J]. J. Acoustic. Soc. Am. 1984,Vol.76(4):1023~1029
[43]. Gong X F, et al. Ultrasonic investigation of the nonlinearity parameter B/in biological media[J]. J. Acoustic. Soc. Am. 1984,Vol.76(3):949~950
[44]. 夏雅琴,贾丽芹,彭见曙等,一种用于超声测温的双超声脉冲发射接收电路的设计[J],中国医疗器械杂志,2002,Vol.26(4):245~249
[45]. Ueno S I, Furuya N, et al. Application of nonlinear ultrasonic pulse reflection method. Measurement of acoustic parameters[J]. Japanese Journal of Applied Physics. 1989,Vol.28:191~193
[2]. M.V Statva,etc.al.,Current Generation Video Endoscopes[J]. A Cirtical Evolution, Am.Surg., 1988, Vol.54: 73~77
[3]. 李德印,电子内窥镜的构成及主要功能探讨[J],医疗装备,1996,Vol10:15～16
[4]. 李励,医用内窥镜的发展历程[J],医疗设备信息,1999
[5]. AD Keet,Ch.B.,The Pyloric Sphincteric Cylinder in Health and Disease [M], Spring-Verlag, 1993
[6]. 张凯,周铁英,三种弯曲旋转超声电机的原理及研究[J],压电与声光,2002,Vol.24(3):191～195
[7]. 金震东,消化系统腔内超声临床应用进展[J],中华超声影像学杂志,2001,Vol.10(7):389
[8]. 金震东,刘枫,超声内窥镜检查术临床应用进展[J],世界医疗器械,2003,Vol.9(4):26～29
[9]. 冯若,超声诊断设备原理与设计[M],中国医学科技出版社,1993
[10]. 万明习等, 医学超声学原理与技术[M],西安交通大学出版社 1992.10
[11]. S.Holm, “Bessel and conical beams and approximation with annular arrays”[J] IEEE Trans. Ultrason. Ferroelect, Freq. Cont. 1998.9, Vol.45(3): 712~718,
[12]. 会长善,超声工程[M],哈尔滨工业大学出版社,1989
[13]. 高上凯, 医学成像系统[M],清华大学出版社,2000
[14]. 孙军华,董名利. 钢轨高速探伤系统超声发射/接收装置的设计[J],2002,Vol.36(12):51-53
[15]. 谢嘉奎,电子线路—线性部分[M],高等教育出版社,1999
[16]. 关立勋,雷纪胜,超声诊断仪原理与维护[M],人民卫生出版社,1983
[17]. 应崇福,超声学[M],科学出版社,1990
[18]. ANALOG DEVICES 8-Bit40MSPS/50 MSPS/80 MSPS Conerter AD9057 Data Sheet,2001
[19]. Benso, S. Cataldo, S. Chirusano and P. Prinetto, A High-Level EDA Environment for the Automatic Insertion of HD-BIST Structures, Proceedings of the 1999 IEEE European Test Workshop
[20]. 王金明,Verilog HDL 程序设计教程[M],人民邮电出版社 2004
[21]. 沈绪榜等,超大规模集成系统设计[M],科学出版社,1992
[22]. 吴继华,王诚,Altera FPGA/CPLD 设计[M],人民邮电出版社,2005
[23]. 赵雅兴,FPGA 原理、设计与应用[M],天津大学出版社,1999
[24]. 刘铁兵,汤黎明.基于可编程逻辑器件的便携式心电监护仪的设计与实现[J],医疗卫生装备,2001,Vol.22(4):9—10
[25]. ECRI,Video Colonoscope System(Evaluation) [J], Health Device, 1994,Vol.25:151～205
[26]. 孙正,基于 PCI 总线的医用电子内窥镜实时采集和显示系统的研究,[硕士学位论文],天津;天津大学,2002
[27]. 余浩,詹志强,武威等,Protel98 详解[M],电子工业出版社,1992
[28]. 高鹏,安涛,电路设计与制版 Protel 99 入门与提高[M],人民邮电出版社,2000
[29]. 曾峰,侯亚宁,曾凡雨,印刷电路板 (PCB) 设计与制作[M],电子工业出版社 2002
[30]. 彭旗宇, 数字化医学超声成像方法的研究,[硕士学位论文],北京;清华大学电机工程与应用电子技术系生物医学工程,2003
[31]. 王毓银,数字电路逻辑设计[M],高等教育出版社,1999
[32]. 童诗白,华成英,模拟电子技术基础[M],高等教育出版社,2002;
[33]. 吴迎娟,医用内窥镜安全有效性要点探讨[J],中国医疗器械杂志,2003,Vol.27(3)
[34]. L.D.Picciano & J.M. Taylor, Color Technology in Video Endoscopy[J], Journal of Clinical Engineering, 1994,Vol.19:490～496
[35]. M.V.Sivak, Electronic Endoscopy[J], Endoscopy, 1992,Vol.24:154～158
[36]. 李晴辉,彭承琳,一种用于超声医学测量的增益补偿电路的设计[J],医疗卫生装备,2002.3
[37]. 孙军华,董明利,祝连庆,钢轨高速探伤系统超声发射/接收装置的设计[J],工具技术,2002,Vol36.(12):51~53
[38]. 孙颖,李醒飞,张国雄,生物软组织特性测定仪的研究[J],航空精密制造技术,2002.12,Vol.38(6):34~36
[39]. Chebli, R.; Kassem, A; Sawan, M. Integrated front-end preamplifier dedicated to ultrasonic receivers. Electronics, Circuits and Systems[C], 2001.ICES 2001. The 8th IEEE International Conference on, 2001,(3):1103~1106
[40]. Dual, Ultralow Noise Variable Gain Amplifier AD604 Data Sheet, 2004
[41]. Singh VR, et al. Non-invasive measurement in ultrasonic hyperthermia[J]. IEEE Engineering in Medicine & Biology Society 10th Annual International Conference.1988:850~851
[42]. Sehgal MC, et al. Measurement of the acoustic nonlinearity parameter B/A in human tissues by a thermodynamic method[J]. J. Acoustic. Soc. Am. 1984,Vol.76(4):1023~1029
[43]. Gong X F, et al. Ultrasonic investigation of the nonlinearity parameter B/in biological media[J]. J. Acoustic. Soc. Am. 1984,Vol.76(3):949~950
[44]. 夏雅琴,贾丽芹,彭见曙等,一种用于超声测温的双超声脉冲发射接收电路的设计[J],中国医疗器械杂志,2002,Vol.26(4):245~249
[45]. Ueno S I, Furuya N, et al. Application of nonlinear ultrasonic pulse reflection method. Measurement of acoustic parameters[J]. Japanese Journal of Applied Physics. 1989,Vol.28:191~193
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