CT快速二维反投影算法

CT图像重建过程中，标准的二维反投影运算计算量为D(N^3)。本研究提出一种快速二维反投影算法，其计算量仅为D(N^2log2^N)。该快速算法可以并行实现，处理器阵列规模为D(N^2)时，计算量为D(log2^x)。本研究还分析得到快速算法的误差上界，并提出一种改进的快速二维反投影算法以获得更高的计算精度。最后，对算法进行了仿真实验。理论分析及仿真实验结果都表明，本研究的二维反投影算法在CT图像重建过程中有着更高的计算效率，并且具有良好的计算精度。     

磁共振成像系列讲座之三磁共振成像方法和原理

磁共振成像系列讲座之三磁共振成像方法和原理林意群（第一军医大学生物医学工程系广州５１０５１５）本讲将重点地介绍二维付里叶成像的基本原理和临床常用的成像脉冲序列。磁共振成像方法除了二维付里叶成像方法外，还有点成像、线成像和二维投影成像等方法，但是现在临...     

二维超声及彩色多普勒血流显像诊断下肢深静脉瓣功能不全

目的：探讨下肢深静脉瓣功能不全的二维声像图及彩色多普勒血流的特点。方法：对14例17条静脉瓣功能不全的下肢静脉进行了二维超声及彩色多普勒血流显像的检查。结果：17条下肢静脉瓣功能不全，根据二维超声表现分为原发性13条静脉，继发性4条静脉；根据血流反流时间的不同，可分为I组（9条静脉），Ⅱ级（5条静脉），Ⅲ级（3条静脉）。结论：二维超声及彩色多普勒血流显像能观察静脉管腔，管壁的结构及实时状况，并能明确瓣膜的反流部位及反流程度。以此标准诊断下肢深静脉瓣功能不全，对外科合理的选择手术部位及方式提供有效的依据。     

线扫描磁共振成像方法

目的：在磁共振成像领域，线扫描是最早的一种傅立叶成像方法，后逐渐被二维傅立叶成像方法取代，近年来线扫描方法又重新引起了人们的兴趣，本文介绍磁共振线扫描方法，并分析其优缺点；方法：从线扫描与二维傅立叶成像方法的原理人手，在多个方面比较两种方法的差异；结果：线扫描方法在成像速度及图像信噪比方面不如二维傅立叶成像方法。但在克服运动伪影、金属伪影及手术过程中实时磁共振检查等方面优于二维傅立叶成像方法；结论：线扫描方法是一种适用于中低场永磁型磁共振设备的成像方法，在术中磁共振成像方面有广泛的应用前景。     

高频二维超声及彩色多普勒对乳腺肿瘤的诊断价值

对284例乳腺肿瘤进行了二维及彩色多普勒检查。总结各自的二维声像图及彩色多普勒血流特征,分析了二维超声及彩色多普勒在乳腺肿瘤疾病的诊断价值。结果显示：二维超声彩色多普勒是诊断及鉴别诊断乳腺肿瘤的首选方法。     

扩张型心肌病二尖瓣声像图分析

扩张型心肌病二尖瓣声像图分析周素怀，谢丽萍，刘秉乾邵阳市中心医院心脏Ｂ超室关键词ＤＣＭ，多普勤二维超声心动图近年来，二维超声心动图已广泛用于心血管疾病的超声诊断。我院自１９９２年～１９９４年共检出ＤＣＭ６０例，为该病确诊提供了诊断依据。１对象和方法６...     

胎儿畸形的超声诊断效果及对优生优育指导的临床价值

目的分析应用四维、二维超声诊断胎儿畸形的特异度、敏感度和准确度,探讨其在优生优育指导中的临床价值。方法选择2015年1月-2017年1月在我院行孕检并生产的孕妇1360例作为研究对象,所有孕妇在每次检查中均平行采用二维超声和四维超声检查,根据胎儿畸形严重程度选择终止妊娠或继续妊娠。对终止妊娠的胎儿行病理检查,正常妊娠并生产的胎儿出生后行全面检查,诊断新生儿是否出现先天性畸形。以病理检测结果和出生后全面检查结果为金标准,分别计算二维超声、四维超声、四维超声联合二维超声诊断胎儿畸形的特异度、灵敏度和准确度并比较。随访产检中二维超声、四维超声及二维超声联合四维超声诊断出胎儿畸形但符合继续妊娠孕妇的妊娠结局,并比较不同方法诊断结果指导继续妊娠后的妊娠结局差异。结果引产后病理诊断和出生后全面检查共检出畸形儿88例,畸形率6.47%。二维超声3次检查共计检出胎儿畸形78例(首次检查出胎儿畸形后,未引产者后续再次检出不计算在内),四维超声检查出86例。二维超声联合四维超声诊断出129例。四维超声联合二维超声诊断胎儿畸形的灵敏度明显高于单纯二维超声和四维超声,四维超声诊断胎儿畸形的特异度明显高于二维超声和二维超声联合四维超声诊断,四维超声联合二维超声诊断胎儿畸形的准确率明显低于单纯二维超声和四维超声。四维超声联合二维超声诊断确诊为胎儿畸形并继续妊娠者,妊娠结局明显优于其它两种诊断方法(P0.05)。结论四维超声联合二维超声诊断胎儿畸形,可有效提高胎儿畸形的诊断灵敏度,但同时也增大了误诊率,指导患者继续妊娠后妊娠结局总体良好,临床应综合二维超声、四维超声及二者联合诊断结果,谨慎决策,指导优生优育,提高妊娠结局质量。     

斑点追踪技术的应用前景分析

1 M型和二维Simpson法测量LVEF的不足
　　冠心病是常见心血管疾病之一，是导致心血管事件的主要原因，尤其在急性心肌缺血或发生心肌梗死的患者中，节段性室壁运动异常是早期的特征性表现，且均伴有不同程度的收缩功能减低。对于左室整体收缩功能的评价，目前常用的是M型和二维Simpson法测量的LVEF，二者均有一定的局限性，M型测量以局部功能代表了整体功能，而二维Simp原son法测量左心功能时二维图像的两个切面（心尖两腔、四腔切面）分别取自两个不同的心动周期，会产生人为误差。     

大鼠附睾液蛋白质组二维液相色谱分离的实验研究

目的：建立一种利用二维液相色谱分离和质谱鉴定大鼠附睾液蛋白质组的实验方法,为以后研究其它哺乳动物附睾蛋白质组提供实验基础。方法：分离提取大鼠附睾头体尾部官腔蛋白,样品经脱盐、浓缩,利用起始缓冲液置换,进行一维色谱聚焦分离,收集pH8.5-4.0之间的组份进行二维反相色谱分离,并通过自动馏分收集器收集分离组份;最后将获得的二维UV图通过ProteoVue软件转换成二维PI/UV图谱;选择含高丰度蛋白的馏份经冷冻干燥浓缩后进行质谱鉴定。结果：通过二维液相色谱成功分离了大鼠头体尾部附睾液蛋白并建立了二维PI/UV图谱;对二维获得的含高丰度蛋白的馏分进行了质谱鉴定,获得大鼠附睾头体尾部主要蛋白。结论：为进一步利用二维液相色谱全面分离附睾蛋白和研究附睾功能奠定了基础。     

基于CT图象的髓关节三维图象表面重建

本文介绍了ＣＴ断层图象重建髋关节三维表面的系统。详细介绍了实现重建的方法和算法，并对开发过程中所尝试的多种方法进行了比较．作者开发了一个二维光标系统，并与二值化等图象牌技术相结合，找到了一种采集髋关节二维边界线数据的方便而有效的途径，并成功地完成了三维表面的重建工作。这一方法不仅适合髋关节，也可以用于其它形态复杂的脏器的三维表面重建工作。利用该系统可以定量地描述髋关节的二、三维几何形态，从而为进一步研究病理髋关节、临床诊断以及人工髋关节的设计奠定了基础。     

Image data compression using a new floating-point digital signal processor

A new dual-ported, floating-point, digital signal processor has been evaluated for compressing 512 and 1,024 digital radiographic images using a full-frame, two-dimensional, discrete cosine transform (2D-DCT). The floating point digital signal processor operates at 49.5 million floating point instructions per second (MFLOPS). The level of compression can be changed by varying four parameters in the lossy compression algorithm. Throughput times were measured for both 2D-DCT compression and decompression. For a 1,024 x 1,024 x 10-bit image with a compression ratio of 316:1, the throughput was 75.73 seconds (compression plus decompression throughput). For a digital fluorography 1,024 x 1,024 x 8-bit image and a compression ratio of 26:1, the total throughput time was 63.23 seconds. For a computed tomography image of 512 x 512 x 12 bits and a compression ratio of 10:1 the throughput time was 19.65 seconds.     

基于NIOSⅡ软核处理器和USB2．0的医学图像压缩和传输

目的：为了进一步探讨医学图像的压缩与高速传输的问题。本文在NIOSⅡ软核处理器下进行医学图像压缩与传输的软硬件协同设计的研究。方法：采用Altera公司开发的基于SOPC技术的NIOSⅡ嵌入式处理器，完成一个医学图像压缩以及高速传输系统。整个系统硬件部分主要包括大容量FPGA芯片、Cypress公司的EZ-USB FX2 Cy7C68013芯片以及外围存储器。采用适合FPGA实现的行列分解的方法，将复杂度高、消耗时间多的2D-DCT部分实做成IP核形式即硬件实现，并根据硬件电路实现的特点进行优化；通过NIOSⅡ定制指令的方法来调用此硬件加速部分提高整个算法的运行速度：采用USB2．0接口来完成图像数据的高速传输。结果：通过对照，我们发现系统取得良好的压缩效果，基本上不影响医学诊断。结论：该系统性价比高且能在短时间内以较低的成本实现，其使用新的技术新的方法给医学仪器设计领域带来一个新的亮点。     

基于AVR的高精度医用激光功率密度计

目的 设计一种高精度的医用激光功率密度计,用于测量激光在临床医学上的功率密度,以便更好地将激光应用于临床.方法 采用热释电探测器将激光信号转换为可处理的电信号,设计与探测器相匹配的前级放大滤波电路及控制显示电路;采用C语言进行软件编程,软硬件相结合,研制一种基于AVR单片机控制的高精度医用激光功率密度计.结果 功率密度计可测量的最小功率密度为1 mW/cm2,误差为2％,可满足临床上医用激光功率密度测量的参数要求.结论 功率密度计精度高、误差小、稳定性好,能够精确测量激光功率密度大小.     

Incentive moderates the impact of implicit anger vs. sadness cues on effort-related cardiac response

This experiment investigated the combined effect of implicit affect and monetary success incentive on effort-related cardiac response in a 2 (Affect Prime: anger vs. sadness)×2 (Incentive: low vs. high) between-person design. Sixty-two participants were exposed to affect primes during an objectively difficult short-term memory task. As predicted, by our theorizing about affect primes' systematic impact on subjectively experienced task demand and corresponding effort mobilization, sadness primes led to a weak cardiac pre-ejection period (PEP) response when incentive was low (disengagement), but to a very strong PEP response when incentive was high (high effort). PEP responses were moderate in the anger-prime conditions (low effort). HR responses largely corresponded to those of PEP. The results demonstrate for the first time that high incentive can compensate the effort mobilization deficit of individuals who process sadness primes during a difficult task.     

基于FPGA设计的呼吸机控制系统

FPGA和VHDL是当今嵌入式系统设计的两个重要工具。本文详细介绍了基于FPGA的呼吸机控制系统的设计和实现，包括原理和电路结构图。通过仿真和测试验让了设计的正确性。结果表明，利用FPGA和VHDL设计的控制系统具有体积小、重量轻、功耗低和稳定性高等优点。     

Effects of varying physical parameters of a PET system on the accuracy of radioactivity quantitation in vivo.

The accuracy of quantitation of radioactivity by positron emission tomography (PET) is dependent on design parameters which differ among the PET-cameras in use today. Using a high resolution PET camera (Scanditronix PC 4096-15WB) we have simulated various of these parametric design differences such as xy- and z-resolution, slice thickness, methods of scatter and attenuation correction. The quantitation of actual patient data differed by up to 40% for both static and dynamic data when single parameters were varied to fit cameras of preexisting and recent design. For example, we found that cortical FDG data are 15% lower for 11 mm image resolution than for 5.5 mm image resolution, and striatal uptake of a D2-receptor-ligand decreases by 25% when the slice thickness is 14 mm instead of 7 mm. In general, the errors due to the single effects studied here are expected to be cumulative, leading to an even greater discrepancy in the overall performance of older PET cameras when compared to those of recent design.     

Analysis of resonant coupled coils in the design of radio frequency transcutaneous links

A theory of coupled resonant coils has been developed which makes possible the design of radio frequency transcutaneous links of simultaneously high overall efficiency and good displacement tolerance while keeping circuitry simple (particularly in the implanted receiver). Series-tuned transmitter coils were used, obtaining high efficiency. In the first example a stimulator which has excellent displacement tolerance because it works at critical coupling is designed. The second example shows how the theory was used when the voltage in the implant was regulated. The design process involvesad hoc compromises between disparate quantities (e.g. efficiency against voltage transfer ratio), rendering a standard design procedure unsuitable. Fortunately, the derived theoretical formulae are simple enough for every design to be considered from fundamentals, based on coil parameters. Extensive coil loss data are presented here for the frequency band 0·2 to 20 MHz.     

An experimental study on the determinants to the effects of self-affirmation]

The purpose is twofold: first to examine whether an experience that affirms a valued aspect of the self eliminates the negativity of failure and second, to identify what is the most effective condition of self-affirmation. A 2 x 3 factorial design was employed: Immediately after having failed and prior to rating the beneficialness of failure experience, 72 subjects were allowed to affirm the real-self that they had built up, or the pseudo-self made by the experimenter. The situation of self-affirmation was (1) that subjects affirmed the self in private or (2) that the experimenter also affirmed the subject's self or (3) that the experimenter added information of another one who had the same aspect of self the subjects had affirmed. The self-affirmation effect was most clear-cut, when the real-self was affirmed, and was also affirmed by the experimenter. This effect was especially pronounced for high self-esteem subjects. Joint effects of high self-esteem, clearer real-self, and its publicity elevated level of self-affirmation.     

基于AD9228的超声数据采集电路的设计

介绍了数字超声成像系统中数据采集电路的设计方案和功能特性。该电路以ADI公司的高速A/D转换芯片AD9228为基础,可以实现最高达65MSPS的模数转换速率,并使用FPGA实现LVDS信号的电平转换,以及串并转换,最后实现数字信号的并行输出。测试结果表明:该系统的12位数字化输出只在最后1位有抖动,可满足实际设计要求。     

Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: a novel direct-conversion design and its feasibility

Most electronic portal imaging devices (EPIDs) developed to date, including recently developed flat panel systems, have low x-ray absorption, i.e., low quantum efficiency (QE) of 2%-4% as compared to the theoretical limit of 100%. A significant increase of QE is desirable for applications such as a megavoltage cone-beam computed tomography (MVCT) and megavoltage fluoroscopy. However, the spatial resolution of an imaging system usually decreases significantly with an increase of QE. The key to the success in the design of a high QE detector is therefore to maintain the spatial resolution. Recently, we demonstrated theoretically that it is possible to design a portal imaging detector with both high QE and high resolution [see Pang and Rowlands, Med. Phys. 29, 2274 (2002)]. In this paper, we introduce such a novel design consisting of a large number of microstructured plates (made by, e.g., photolithographic patterning of evaporated or electroplated layers) packed together and aligned with the incident x rays. On each plate, microstrip charge collectors are focused toward the x-ray source to collect charges generated in the ionization medium (e.g., air or gas) surrounded by high-density materials that act as x-ray converters. The collected charges represent the x-ray image and can be read out by various means, including a two-dimensional (2-D) active readout matrix. The QE, spatial resolution, and sensitivity of the detector have been calculated. It has been shown that the new design will have a QE of more than an order of magnitude higher and a spatial resolution equivalent to that of flat panel systems currently used for portal imaging. The new design is also quantum noise limited down to very low doses (approximately 1-2 radiation pulses of the linear accelerator).