CBCT转化头颅侧位片与传统的头颅侧位片一致性的研究

目的:对比研究锥形束CT(cone-beamcomputedtomography,CBCT)转化头颅侧位片与传统X线头颅侧位片定点的一致性.方法:53名(男24名,女29名)正畸患治疗前拍摄头颅侧位片和锥形束CT扫描.选取22个常用标记点,由同一操作对所有侧位片进行定点,间隔进行三次.采用HotellingT2检验两种类型头颅侧位片定点的一致性.结果:绝大多数的定点差异无统计学意义.有4个点,耳点(t=0.50,P=0.006)、前鼻棘点(t=0.49,P=0.008)、下颌角点(t=0.39,P=0.039)和颅底点(t=0.64,P=0.006),定点差异有统计学意义(P<0.05).结论:锥形束CT转化的头颅侧位片定点更加精确,可以代替传统的X线头颅侧位片.     

基于CMOS高清医用电子内镜图像处理器的设计

目的设计一种基于互补金属氧化物半导体(CMOS)的高清医用电子内镜图像处理器,以便满足医院对高清电子内镜的需求。方法设计高清图像处理器,包括高清摄像模组、高清采集和处理板、主控制板和机箱。采用微型高清CMOS图像传感器进行图像采集,使用1/11寸高清1 280×720 (简称HD720P)、1/6寸全高清1 920×1 080 (简称FHD1080P)两种分辨率宽屏技术;图像处理采用Xilinx公司的XC3S200系列快速现场可编程门阵列(FPGA)芯片结合复杂图像处理算法;还采用多屏、电子染色和放大技术。高清图像处理器与高清医用电子内镜、冷光源、高清显示屏、台车组装成高清医用电子内镜系统,并进行体外测试和试用。结果体外测试内镜系统符合临床使用的要求。高清内镜图像处理器可提供两种高清宽屏图像,即HD720P、FHD1080P高清图像。图像分辨率可以分别达到100万像素和200万像素。试用结果,咽部、人肺模型、手掌图像清晰,颜色不失真。结论高清医用电子内镜图像处理器可以克服现有图像处理器的缺陷,达到了高清、微型的效果,能够更加细腻地显示病灶图像。     

AFT024-SCF细胞系的构建及其生物学功能鉴定

 目的: 构建AFT024-SCF和HPC-Lhx2细胞系,并用HPC-Lhx2细胞系鉴定AFT024-SCF细胞系的生物学功能。方法: 采用逆转录病毒感染法构建干细胞因子(stem cell factor,SCF)依赖的永生化造血干/祖细胞(hematopoietic stem/progenitor cell,HPC)-Lhx2细胞系和小鼠胎肝基质细胞系AFT024-SCF及其不含目的基因的对照组细胞系AFT024-GFP。采用real-time PCR法及Western blot法鉴定此AFT024-SCF细胞系中SCF的表达。ELISA法鉴定AFT024-SCF上清液中SCF的表达。收集AFT024-SCF及AFT024-GFP细胞培养上清液并以1:10与IMDM基础培养基混合备用。以AFT024-SCF组上清液为实验组,AFT024-GFP组上清液为内源性阴性对照组,无任何添加的IMDM基础培养基为外源性阴性对照组,添加重组SCF的IMDM培养基为阳性对照组,分别与HPC-Lhx2细胞系共培养72 h。MTT法检测各组HPC-Lhx2细胞增殖活性,集落形成实验鉴定HPC-Lhx2细胞系扩增后的细胞干性。结果: 构建的AFT024-SCF细胞系表达SCF;HPC-Lhx2细胞系体外培养72 h后,外源性及内源性阴性对照组未能维持HPC-Lhx2细胞增殖;而阳性对照组及实验组均可促进HPC-Lhx2细胞增殖;阳性对照组及实验组细胞均有集落形成单位,且差异无统计学意义,阴性对照组无集落形成单位。结论: 成功构建表达SCF的AFT024-SCF细胞系,其培养上清液能够替代重组SCF用于HPC-Lhx2细胞系的体外扩增。     

PCR定点突变法构建人抗菌肽FALL-39基因突变体及其功能的研究

目的 :用PCR定点突变法构建人抗菌肽FALL 39基因突变体 ,并比较研究FALL 39及其突变肽的功能。方法 :采用PCR体外定点突变技术 (PCR SDM ) ,设计一对方向相反的引物 ,其中一个引物引入一个突变点 ,应用高保真的PolybestDNA多聚酶进行含FALL 39肽的PGEXλ1T质粒的PCR扩增 ,使FALL 39第 2 2位密码子由CAG突变为AAG ,将扩增片段自身连接后克隆入工程菌JM1 0 9中使其表达其突变肽 (FALL 39 lys2 2 ) ,纯化后与FALL 39进行抗菌活性比较。结果 :DNA测序结果表明在预期位点发生突变 ,突变后FALL 39 lys2 2抗菌活性…     

基于T波最大值的T波电交替分析法

提出了一种基于T波最大值T波电交替(T-wave alternans,TWA)的快速傅氏变换(Fast fouriertransform,FFT)分析法。该方法能在减少抽样频率的条件下,保证计算精度。基于T波最大值的方法还解决了固定T波的取样点随着心率的变化而变化问题。该方法对连续128个正常心跳周期的ST-T结构中的T波最大值进行FFT变换,进而可以得到其功率谱曲线图。该功率谱图可反映TWA。     

PCR定点突变法构建人抗菌肽FALL-39基因突变体及其功能的研究

目的 :用PCR定点突变法构建人抗菌肽FALL - 39基因突变体 ,并比较研究FALL - 39及其突变肽的功能。方法 :采用PCR体外定点突变技术 (PCR -SDM) ,设计一对方向相反的引物 ,其中一个引物引入一个突变点 ,应用高保真的PolybestDNA多聚酶进行含FALL - 39肽的PGEXλ1T质粒的PCR扩增 ,使FALL - 39第 2 2位密码子由CAG突变为AAG ,将扩增片段自身连接后克隆入工程菌JM10 9中使其表达其突变肽 (FALL - 39-lys2 2 ) ,纯化后与FALL - 39进行抗菌活性比较。结果 :DNA测序结果表明在预期位点发生突变 ,突变后FALL - 39-lys2 2…     

湖南大学生活体测量

身高和体型是衡量个体发育和人群形态特征的重要指标。由于遗传、生活环境[1]和南北差异以及城乡的差别,身高和体型也表现出个体差异性[2-5]。有关湖南地区汉族学生的人体测量报道很少。通过对250名大学生(男125名,女125名)的14项指标的测量及分析其相关性,为临床美容医学、医疗保健及营养评价标准提供基础资料。1材料和方法1.1对象于2006年测本校就读大学生250名(男125名,女125名),汉族,籍贯湖南,年龄18~24岁,身体健康,无畸形。1.2测量工具圆杆直角规、磅秤、卷尺。1.3定点髂嵴点(ic)、髂前上棘点(is)、大转子点(tro)、会阴点(pe)、胫骨点(…     

一体化多电极电阻抗断层成像数据采集系统设计

非均匀与均匀介质电场的空间分布在边界条件上的关系是影响旋转电极EIT成像分辨率的因素之一。为此设计了一种8层共1 024电极的电阻抗断层成像数据采集系统。该系统采用一体化设计方案,8层PCB层叠结构,用排针、排母进行物理支撑和电气连接,最大限度地减少了引线对信号采集的影响。PCB工艺形成的电极具有数量多,分布均匀,在不同旋转方向上形成的电场一致性较好的特点。系统采用在FPGA中构建NIOS II软核处理器进行整体控制。结果表明,系统物理模型所形成的介质电场均匀,从不同旋转角度上实测的电场分布的其一致性较好;电场分布和数据采集的结果达到设计要求。     

现代医学仪器中的光栅扫描显示技术

四、光栅扫描字符及汉字显示原理 1.字符库的构成光栅扫描显示字符一般采用5×7点阵(或7×9点阵)。在监护仪中,还常用4倍(或更大)于一般字符大小的大字符显示平均心率及血压等参数值。字符点阵的设计方法如图28所示。字符采用5×7点阵,在屏幕上每个字符占8点×10     

磁共振谱成像(MRSI)技术的研究进展

磁共振谱成像 (MRSI)在临床诊断中的作用越来越大。目前 ,最有效的快速谱成像法有回波平面法、螺旋轨迹法和阵列采集法。但是 ,这些 MRSI方法的数据采集时间仍然很长 ,速度有待于进一步提高。抑水抑脂脉冲序列基本定型 ,改进的余地不大。在定量的谱分析方面 ,已经实现分析自动化。谱参数估计方法基本完善 ,但在强基线信号时参数估计方法有待于深入研究。目前 ,磁共振谱的图像重建方法局限在 FFT或网格化后的 FFT,这些方法比较简单、快速 ,但也局限了采样脉冲序列 (采样轨迹 )的大胆设计。期望研究出速度更快的 MRSI数据采集脉冲序列。     

Fast dedicated microprocessor for real-time frequency analysis of ultrasonic blood-velocity measurements

A signal processor has been designed using bit-slice microprocessor techniques. The processor has two data bases for input/output, a central processing unit and a memory. The microprogram in the processor can be changed to suit individual needs. The analysis which is performed at present is a fast Fourier transform (FFT) of ultrasonic blood-velocity signals with graphic display of the results. The FFT operates on 256 sampled points, thus giving 128 frequency components of the signal. Each transform is calculated in less than 4·5 ms. The algorithm of the FFT uses base 2, and the real-valued signal is transformed into a complex sequence to simplify the program. The microprocessor has been interfaced to an ultrasound doppler blood-velocity meter. Results from measurements on arteries are shown.     

一种新型自适应动态滤波器在超声成像中的应用

目的 为使动态滤波器的中心频率可实时匹配回波信号中心频率,本文设计了一种新型的自适应动态滤波器.方法 本文自适应机制是以快速傅里叶变换（fast Fourier transform,FFT）算法实时分析真实回波信号的频率特性,根据频率编号自适应匹配动态滤波器的系数.该滤波器的所有模块基于现场可编程门阵列（field programmable gate array,FPGA）硬件实现,最后将加入白噪声的正弦信号使用Modelsim时序仿真工具进行仿真.结果 仿真结果表明,这种滤波器能良好匹配回波信号中心频率,消除噪声.结论 本文提出的自适应动态滤波器满足高速实时系统的要求,为超声系统中滤波器的设计提供了可靠依据.     

Dedicated hardware processor and corresponding system-on-chip design for real-time laser speckle imaging

Laser speckle imaging (LSI) is a noninvasive and full-field optical imaging technique which produces two-dimensional blood flow maps of tissues from the raw laser speckle images captured by a CCD camera without scanning. We present a hardware-friendly algorithm for the real-time processing of laser speckle imaging. The algorithm is developed and optimized specifically for LSI processing in the field programmable gate array (FPGA). Based on this algorithm, we designed a dedicated hardware processor for real-time LSI in FPGA. The pipeline processing scheme and parallel computing architecture are introduced into the design of this LSI hardware processor. When the LSI hardware processor is implemented in the FPGA running at the maximum frequency of 130 MHz, up to 85 raw images with the resolution of 640×480 pixels can be processed per second. Meanwhile, we also present a system on chip (SOC) solution for LSI processing by integrating the CCD controller, memory controller, LSI hardware processor, and LCD display controller into a single FPGA chip. This SOC solution also can be used to produce an application specific integrated circuit for LSI processing.     

Time domain algorithm for accelerated determination of the first order moment of photo current fluctuations in high speed laser Doppler perfusion imaging

Advances in optical array sensor technology allow for the real time acquisition of dynamic laser speckle patterns generated by tissue perfusion, which, in principle, allows for real time laser Doppler perfusion imaging (LDPI). Exploitation of these developments is enhanced with the introduction of faster algorithms to transform photo currents into perfusion estimates using the first moment of the power spectrum. A time domain (TD) algorithm is presented for determining the first-order spectral moment. Experiments are performed to compare this algorithm with the widely used Fast Fourier Transform (FFT). This study shows that the TD-algorithm is twice as fast as the FFT-algorithm without loss of accuracy. Compared to FFT, the TD-algorithm is efficient in terms of processor time, memory usage and data transport.     

A GPU implementation of a track-repeating algorithm for proton radiotherapy dose calculations

An essential component in proton radiotherapy is the algorithm to calculate the radiation dose to be delivered to the patient. The most common dose algorithms are fast but they are approximate analytical approaches. However their level of accuracy is not always satisfactory, especially for heterogeneous anatomical areas, like the thorax. Monte Carlo techniques provide superior accuracy; however, they often require large computation resources, which render them impractical for routine clinical use. Track-repeating algorithms, for example the fast dose calculator, have shown promise for achieving the accuracy of Monte Carlo simulations for proton radiotherapy dose calculations in a fraction of the computation time. We report on the implementation of the fast dose calculator for proton radiotherapy on a card equipped with graphics processor units (GPUs) rather than on a central processing unit architecture. This implementation reproduces the full Monte Carlo and CPU-based track-repeating dose calculations within 2%, while achieving a statistical uncertainty of 2% in less than 1 min utilizing one single GPU card, which should allow real-time accurate dose calculations.     

A field-programmable gate array based system for high frame rate laser Doppler blood flow imaging

This paper presents a general embedded processing system implemented in a field-programmable gate array providing high frame rate and high accuracy for a laser Doppler blood flow imaging system. The proposed system can achieve a basic frame rate of flow images at 1 frame/second for 256×256 images with 1024 fast Fourier transform (FFT) points used in the processing algorithm. Mixed fixed-floating point calculations are utilized to achieve high accuracy but with a reasonable resource usage. The implementation has a root mean square deviation of the relative difference in flow values below 0.1% when compared with a double-precision floating point implementation. The system can contain from one or more processing units to obtain the required frame rate and accuracy. The performance of the system is significantly higher than other methods reported to date. Furthermore, a dedicated field-programmable gate array (FPGA) board has been designed to test the proposed processing system. The board is linked with a laser line scanning system, which uses a 64×1 photodetector array. Test results with various operating parameters show that the performance of the new system is better, in terms of noise and imaging speed, than has been previously achieved.     

Development of a PC-based Radiological Imaging Workstation

Low-cost image processing systems which can provide convenient access to image processing and analysis techniques hold great potential as diagnostic and research tools in medical imaging. At the University of Washington, we have developed a PC-based medium performance image processing system for use as an experimental radiological workstation. The workstation uses a standard IBM PC/AT personal computer augmented with a custom designed image processor implemented on two IBM PC/AT prototyping boards. Features of the system include up to 52 512 × 512 × 8 bit frame buffers (4 on the image processor board and up to 48 in the host computer memory) and a 512 × 512 × 4 bit graphics overlay memory, hardware zoom, pan and scroll, pseudo coloring, and a 60 Hz noninterlaced display. Many image processing and analysis functions are provided in this workstation, and all user requests are supported in an interactive fashion. For example, arithmetic and logical point operations between two 512 × 512 frame buffers require approximately 170 ms, while computationally intensive functions such as an 11 × 11 convolution or a full screen geometric transformation (warping) can be completed in less than 10 seconds. A full screen 2-D Fast Fourier Transform (FFT) and Inverse FFT (IFFT) based on the row-column method can be completed in less than 20 seconds. The developed system can easily be configured into a DIN/PACS workstation or a biological imaging system. Hardware and software details of this workstation as well as user interface functions implemented will be discussed in the paper. Copyright © 1988 by the International Society for Optical Engineering. Proc. SPIE 914:1257-1264, 1988. Reprinted with permission.     

基于电磁定位的超声图像与CT图像的融合方法

在超声引导经皮介入治疗中,为集成多模态图像信息来弥补单一超声图像的不足,提出一种实时超声图像与CT图像的融合方法,使临床医生在实施介入治疗时得到患者病灶的多模态图像信息成为可能。首先,利用电磁定位系统,得到12个铅球球心的磁场坐标和CT图像坐标,利用两个点集的ICP配准算法,将磁场坐标系和CT图像坐标系进行配准;其次,利用电磁定位系统,将和超声探头固连在一起的电磁传感器自身坐标系与磁场坐标系进行配准;然后,利用超声探头的机械设计尺寸,将超声坐标系与电磁传感器自身坐标系进行配准;最后,通过多个坐标系的转换关系将超声坐标系配准到CT图像坐标系,最终将实时超声图像统一到CT图像中,并在软件中测量融合误差。在该方法下,实时超声图像与CT图像的融合误差为(0.71±0.03)mm,在软件中可以清晰地看到两种图像的实时融合效果。因此,该方法可以有效地将实时超声图像与CT图像进行融合,为介入治疗的精准性提供相应的技术支持。     

Fast Fourier transform convolution calculations of x-ray isodose distributions in homogeneous media

Convolution concepts were implemented using the discrete fast Fourier transform (FFT) to model the three-dimensional dose distribution due to x-rays produced by a medical linear accelerator. Convolution kernels were employed that had been calculated by Mackie using the EGS4 Monte Carlo code. The EGS4 code was also used to estimate initially the spectrum by simulating the production, filtering, and flattening of the beam in the collimator of the linear accelerator. The continuous bremsstrahlung spectrum was modeled using five discrete energies. The more subtle field-size effects of collimator scattering on the spectrum were obtained by calculating corrections to the spectral components using a least-squares search technique. Dose distributions were obtained using FFT convolutions of the kernels for each energy with the spectrally weighted fluence distributions for that energy. The dose distributions were compared with isodose distributions measured in a water phantom. The agreement was generally found to be better than 1% on the central axis. The calculation time for a single three-dimensional beam was approximately 20 min using a VAX/750 without an array processor. Methods were explored to reduce the calculation time using similar hardware, and estimates were made of how to reduce the calculation time using a more sophisticated computer system.     

Area weighted convolutional interpolation for data reprojection in single photon emission computed tomography

A data reprojection algorithm has been developed for use in single photon emission computed tomography on an array processor equipped computer system. The algorithm makes use of an accurate representation of pixel activity (uniform square pixel model of intensity distribution), and is rapidly performed due to the efficient handling of an array-based algorithm and the fast Fourier transform on parallel processing hardware. The algorithm consists of using a pixel driven nearest-neighbor projection operation to an array of subdivided projection bins. The subdivided project bin array is then convolved with the angle-dependent projection of the area of a uniform square pixel and compressed to original bin size. The new algorithm has thus been named the area weighted convolution (AWC) method of interpolation. When compared to nearest-neighbor and linear interpolation algorithms, the new AWC algorithm was found to be more accurate, having an accuracy approaching that of the line length algorithm. It also yielded an easier and more efficient implementation on parallel hardware than line length or linear interpolation, with faster execution times than either.