眼科高频环阵超声波数字化成像技术的研究

目的设计眼科高频环阵B超平台,实现超声波全程数字化处理。方法设计环阵换能器发射接收电路,将高频的超声回波信号经过前级放大后直接引出进行高分辨率、高速的模拟数字采样。信号数字化后,通过高速的现场可编程门阵列（field-programmable gatearray,FPGA）完成波束形成、动态聚焦、滤波、检波及对数放大等一系列信号处理。结果通过临床验证,眼科高频环阵B超平台图像横向分辨率0．2mm,侧向分辨率0．4mm,满足临床要求。结论环阵超声波数字化成像技术可提高图像分辨率和疾病检出率。     

超声多探头联合检测对椎基底动脉供血不足的诊断价值

目的探讨椎动脉超声应用多探头联合检测对椎基底动脉供血不足(VBI)的诊断价值。方法 89例VBI患者(VBI组),其中男性49例,女性40例,平均年龄58.0岁;40例正常人(对照组),其中男性21例,女性19例,平均年龄53.0岁。采用小凸阵探头(6.0～10.0 MHz)、线阵探头(5.0～10.0 MHz)及凸阵探头(2.0 MHz)对VBI组和对照组患者的椎动脉起始段、颈段及颅内段的走行、结构和血流动力学参数进行检测分析。结果高频小凸阵探头诊断VBI的灵敏度为65.6%;高频线阵探头诊断VBI灵敏度为81.8%;低频凸阵探头诊断VBI灵敏度为89.2%;三者联合检查,灵敏度达94.2%。结论多探头联合应用检查椎动脉,可以较全面观察椎动脉的走行和结构,获得血流动力学参数,提高超声对VBI诊断的灵敏度。     

脐尿管囊肿伴感染的超声诊断价值

目的探讨超声在脐尿管囊肿伴感染的诊断价值.方法应用频率3.5MHz凸阵探头、7.5MHz高频线阵探头及彩色多普勒血流显像进行观察.结果 3.5MHz凸阵探头显示病变区为一液性包块 ;7.5MHz高频线阵探头显示病变区为一混合性包块;彩色多普勒示包块周边及内部未探及明显血流信号.超声诊断被手术、病理证实.结论超声等影像可评估其部位、形态、范围、大小、内部构成及与邻近组织的关系.高频探头探查及彩色多普勒血流显像为脐尿管囊肿伴感染的首选检查方法之一.     

全数字化乳腺X线、高频超声联合MRI对乳腺癌的早期诊断价值分析

目的探讨全数字化乳腺X线、高频超声联合MRI对乳腺癌的早期诊断价值。方法选择我院2014年12月到2018年5月就诊收治的行全数字化乳腺X线、高频超声、MRI检查的94例乳腺癌患者作为研究对象,比较全数字化乳腺X线、高频超声、MRI检查及三者联合检查的符合率及诊断乳腺癌的敏感性、特异性。结果全数字化乳腺X线、高频超声联合MRI检查乳腺癌符合率高于全数字化乳腺X线、高频超声、MRI检查任意单一检查的符合率(P0.05);单一检查乳腺癌符合率由高到低顺序为MRI、全数字化乳腺X线、高频超声(P0.05);全数字化乳腺X线、高频超声联合MRI检查敏感性、特异性、阳性预测值、阴性预测值均高于全数字化乳腺X线、高频超声、MRI任意单一检查的敏感性、特异性、阳性预测值、阴性预测值(P0.05)。结论全数字化乳腺X线、高频超声联合MRI检查对于乳腺癌患者有较好的早期诊断价值,可有效提高早期诊断率及敏感性。     

脐尿管囊肿伴感染的超声诊断价值

目的：探讨超声在脐尿管囊肿伴感染的诊断价值．方法：应用频率3．5MHz凸阵探头、7.5MHz高频线阵探头及彩色多普勒血流显像进行观察．结果：3．5MHz凸阵探头显示病变区为一液性包块；7．5MHz高频线阵探头显示病变区为一混合性包块；彩色多普勒示包块周边及内部未探及明显血流信号．超声诊断被手术、病理证实．结论：超声等影像可评估其部位、形态、范围、大小、内部构成及与邻近组织的关系．高频探头探查及彩色多普勒血流显像为脐尿管囊肿伴感染的首选检查方法之一。     

高频超声检查在乳腺肿块诊断中的应用及与病理对照分析

目的探讨高频超声检查对乳腺肿块的诊断价值。方法对我院70例乳腺肿块患者采用高频超声进行诊断。结果 70例乳腺肿块经高频超声检出65例,检出率为92.9%,检出良性肿块36例,恶性肿块29例。结论高频超声在乳腺肿块的诊断及鉴别诊断中有着重要的价值,对肿块数目、大小的测定有独到之处。且无放射性、操作简单、无痛、可复性强等,对临床治疗有重要的指导价值。     

医学超声关键技术研究和进展(一) 超声换能器与超声编码技术

医学超声技术的发展使得超声成像成为临床诊断领域的重要组成部分。许多新的医学超声技术仍然在不断涌现。医疗换能器及阵列,不仅直接影响到医学超声图像的质量,同时也决定了系统设备的应用。宽频带、多维高密度、高频、微型化腔内集成探头是未来超声换能器发展的主要方向。该文对国内外医疗超声换能器材料发展、结构创新、应用三个方面作了简要综述。超声编码技术具有可以提高医学超声成像系统的信噪比、帧频和探查深度等优点,目前仍是超声成像技术的研究热点之一。该文介绍了超声编码检测原理、超声编码检测研究现状、技术难点,并对超声编码技术的前景进行了展望。     

高频超声检查在乳腺肿块诊断中的应用及与病理对照分析

目的 探讨高频超声检查对乳腺肿块的诊断价值.方法 对我院70例乳腺肿块患者采用高频超声进行诊断.结果 70例乳腺肿块经高频超声检出65例,检出率为92.9%,检出良性肿块36例,恶性肿块29例.结论 高频超声在乳腺肿块的诊断及鉴别诊断中有着重要的价值,对肿块数目、大小的测定有独到之处.且无放射性、操作简单、无痛、可复性强等,时临床治疗有重要的指导价值.     

高频超声在急诊肋骨及肋软骨骨折中的临床应用

目的:研究高频超声在急诊肋骨与肋软骨骨折中的临床应用,为临床应用提供数据基础。方法:回顾性分析中南大学湘雅三医院就诊的90例肋骨或肋软骨骨折患者,对比高频超声与X线肋骨的肋软骨骨折、不同损伤肋骨骨折、不同错位幅度肋骨骨折的检出率,分析两者的优缺点,总结高频超声在急诊肋骨及肋软骨骨折中的诊断价值和优势。结果:高频超声的肋骨骨折、肋软骨骨折的检出率高于X线检查,差异有统计学意义(P0.05);在直接暴力损伤中两者肋骨骨折的检出率比较无统计学意义(P0.05),在间接暴力损伤中两者肋骨骨折的检出率高频超声优于X线检查,差异有统计学意义(P0.05);在骨折断端错位小于0.5 mm及0.5~2.0 mm时高频超声检出率优于X线检查,差异有统计学意义(P0.05),在骨折断端错位大于2.0 mm时,X线检查检出率与高频超声检查比较无统计学意义(P0.05)。结论:高频超声适用于急诊胸外伤受力较小、骨折错位较轻的肋骨骨折及肋软骨骨折的早期确诊,检出率高,价格便宜,值得临床广泛应用。     

钼靶X线联合高频彩超在乳腺癌早期筛查中的应用价值

目的 探讨钼靶X线联合高频彩超在乳腺癌早期筛查中的应用价值。方法 选取2016年1月~2018年12月于什邡市人民医院就诊的126例早期乳腺癌患者（直径＜2 cm）作为研究对象。所有患者均被序贯予以钼靶X线和高频彩超检查,比较钼靶X线、高频彩超及联合检测早期乳腺癌筛查的血流信号检出率、微钙化灶检出率及诊断准确率。结果 高频彩超血流信号检出率为80.16%,高于钼靶X线的21.43%;高频彩超微细钙化检出率为33.33%,低于钼靶X线的59.52%,差异有统计学意义(P＜0.05)。高频超声诊断准确率为82.54%,高于钼靶X线的80.16%,差异无统计学意义(P＞0.05);而联合检查诊断准确率为96.83%,高于单用高频超声和单用钼靶X线,差异有统计学意义(P＜0.05)。结论 钼靶X线、高频彩超应用于乳腺癌的早期筛查各有优劣,联合应用能提高诊断乳腺癌的准确率,具有较高的临床价值。     

应用于超声成像的数据采集系统设计

数据采集系统在全数字医用超声成像设备中占有重要地位.本文介绍了应用于超声成像的数据采集系统的设计方案.系统采用AD9228芯片（Analog Devices Inc）作为模数转换芯片,使用现场可编程门阵列（FPGA）与静态随机存储器（SRAM）构成相关控制、缓存等数字电路模块,使用ISE组件Chipscope对采样结果进行测试.测试结果表明：系统采集样本正确;FPGA准确接收采样数据的输出,并完成串并联转换、缓存等处理;系统可以稳定地工作在40MHz的数据采集与存储速率下,符合医用超声成像系统的使用要求.     

数字双波束合成孔径超声成像方法的研究与实现

以提高超声诊断系统的性／价比为目标,提出了一种数字化超声图像合成的新方法,利用双波束合成技术将帧频加倍和利用合成孔径技术将接收通道个数减半。在分析和仿真的基础上,详细地讨论了其硬件设计的要点,并进行了实验验证。实验结果表明,该方法且不损失帧频和图像质量,可显著降低系统成本。     

Signal detectability in digital radiography: spatial domain figures of merit

The usefulness of Fourier-based measures of imaging performance has come into question for the evaluation of digital imaging systems. Figures of merit such as detective quantum efficiency (DQE) based on Fourier domain parameters are relevant for linear, shift-invariant systems with stationary noise. However, no digital imaging system is shift invariant, and realistic images do not satisfy the stationarity condition. Our methods for the task-based evaluation of imaging systems, based on signal detectability in the spatial domain, do not require such assumptions. We have computed the performance of ideal and quasi-ideal observers for the task of signal detection in digital radiography. Signal detectability in terms of an observer signal-to-noise-ratio (SNR) has been compared to results obtained from a Monte Carlo simulation of the digital image-acquisition process. The simulation incorporates the effects of random amplification and secondary quantum blur, integration over pixel area, and electronic noise. The observer figures of merit that have been previously shown to bracket human performance directly specify the usefulness of the images for the stated diagnostic task. In addition, the observer figures of merit give a task-dependent measure of imaging system efficiency in terms of the ratio of an output SNR2 to an input SNR2. Thus, the concept of "detective quantum efficiency" reappears in a natural way but based in the spatial domain and not dependent on shift invariance and stationarity assumptions. With respect to the optimum amount of system blur, our simulations indicate that under certain task-dependent conditions, large signals are fairly insensitive to blur in the x-ray transducer, while an optimum blur is found for small signals.     

基于线性调频信号的高帧率超声成像系统

基于有限衍射波束的高帧率超声成像系统能实现快速成像，但由于仅通过一次发射事件成像，信噪比较低，本研究针对该问题提出一种改进方案。它采用合成孔径雷达中所使用的线性调频信号作为激励信号，在接收端则利用线性调频信号的脉冲压缩比等于信号的时间带宽积的特征，将接收信号通过匹配滤波器处理。结果表明该方案不仅能显著提高成像系统的信噪比，改善重构图像的质量，增加成像深度，而且不损失分辨率。     

二维数字化超声软组织应变成像系统的研制

利用超声散射回波测量生物组织在静态压缩情况下弹性系数的超声弹性成像方法得到了很大的发展.利用国产高速数据采集卡以及商业线阵B型超声诊断仪,建立了一套二维数字化超声软组织应变成像系统.应用这一系统获得了数字化的射频组织超声散射回波信号,并对组织内的应变分布进行成像.实验结果表明,该应变成像系统在获得传统B型超声图像的同时,可以获得组织内部的应变分布图像,从而获取在B超图像上无法得到的组织弹性变化.这一系统的研制成功,不仅为超声弹性成像技术在医学临床上的应用研究打下了基础,同时也为扩宽普通商业B超的应用范围提供了途径.     

Measured performance characteristics of a solid-state linear detector array

Experimental studies of a solid-state linear detector array developed for a prototype scanning slit digital chest radiographic unit have been completed. The detector consists of a strip of scintillating material, optically coupled to a linear silicon photodiode array. Measured performance characteristics of the detector, such as sensitivity, modulation transfer function, and detective quantum efficiency, are presented for several different scintillators. Results indicate that direct x-ray absorption events in the silicon photodiode can degrade detective quantum efficiency. Results also indicate that the inexpensive preamplifier circuits used in the digital chest prototype contribute negligible noise at diagnostic x-ray photon fluence rates.     

功率M模式经颅多普勒超声测量系统的设计

经颅多普勒（TCD）是研究颅内大血管中血流动力学的常用技术,但传统TCD中依然存在着对大脑血管定位困难和对微栓子检测不确定等缺点。为了克服这些弊端,本研究设计了一种功率M模式TCD测量系统。该系统通过FPGA设计、USB固件驱动以及PC数据后处理等模块共同实现。数字电路模块以FPGA为核心进行状态机设计,并采用高速AD采样和双FIFO乒乓工作模式来确保良好的实时性;硬件电路部分和PC之间的数据传输依靠高速USB实现;软件模块结合功率M模式多普勒成像技术、短时傅里叶变换和伪彩色图像处理,对超声波束发射方向上整体深度的血流状态进行监测,方便定位血管深度,并为临床医生提供选通深度的声谱图信息。     

A quantitative investigation of additive noise reduction for active matrix flat-panel imagers using compensation lines

A quantitative investigation of a technique for reducing correlated noise in indirect detection active matrix flat-panel imagers has been reported. Correlated noise in such systems arises from the coupling of electronic noise, originating from fluctuations in external sources such as power supplies and ambient electromagnetic sources, to the imaging array via its address lines. The noise reduction technique involves the use of signals from columns of compensation line pixels located in relatively close proximity to the columns of normal imaging pixels on the array. Compensation line pixels are designed to be as sensitive to externally-coupled noise as columns of normal imaging pixels but are insensitive to incident radiation. For each imaging pixel, correlated noise is removed by subtracting from the imaging pixel signal a signal derived from compensation line pixels located on the same row. The effectiveness of various implementations of this correction has been examined through measurements of signal and noise from individual pixels as well as of noise power spectra. These measurements were performed both in the absence of radiation as well as with x rays. The effectiveness of the correction was also demonstrated qualitatively by means of an image of a hand phantom. It was found that the use of a single compensation line dramatically reduces external noise through removal of the correlated noise component. While this form of the correction increases non-radiation-related uncorrelated noise, the effect can be largely reduced through the introduction of multiple compensation lines. Finally, a position-dependent correction based on compensation lines on both sides of the array was found to be effective when the magnitude of the correlated noise varied linearly across the array.     

A fast low-noise line scan x-ray detector

A fast, low-noise line scan detector (NIKOS) for digital radiography has been developed. It consists of an input x-ray phosphor screen that is coupled to a modified Reticon photodiode array by means of fiber optics with incorporated image intensifier. In its current version the detector can be operated with a maximum 500 Hz image acquisition rate for interlaced readout of two lines of 128 pixels each. Using a Gd2O2S:Tb x-ray input phosphor, an afterglow of 25% in the first subsequent readout was observed. We also conducted afterglow measurements on several other powder and single-crystal phosphors and the photodiode array. Using CdWO4, the afterglow of the detector is limited by the lag of the photodiode array of 4.5%. By modifying the readout electronics the noise of the photodiode array was reduced to below 1 Graylevel, corresponding to a signal-to-noise ratio of 5200. The detective quantum efficiency (DQE) of the detector ranged from 0.18 to 0.4 for typical signal levels. The sensitivity was 10% saturation per 1.9 mR entrance dose. The modular design of the NIKOS detector allows for individual selection of each component to optimize performance for a given application.