Micro CT投影图像噪声的去除

目的:研究Micro CT投影图像噪声的去除,提高Micro CT系统重建图像的质量.方法:分析了Micro CT投影图像的噪声形成因素．提出了Micro CT投影图像校正的方法,分别针对随机噪声、暗场、光场、响应不一致和瑕疵像元进行了校正.结果:通过比较研究提出了一种简单实用的实际响应不一致校正,该方法结合了光场、暗电流、增益不一致校正,只一次循环就解决了3种校正,大大提高了算法效率,并通过实验证明了该校正方案的有效性.结论:该方法可有效去除MicroCT投影图像的噪声.提高Micro CT系统重建图像的质量,为后续三维重建等工作奠定良好的基础.     

投影旋转间隔对CT重建图像的影响

目的探讨CT扇形束扫描的投影旋转间隔对成像时间、成像质量以及图像重建计算齄的影响。方法采用Matlab软件编程,实现对仿真模型的投影数据取得、图像反投影重建,外将此方法用于实际颅脑的CT图像进行投影和反投影重建验证。结果本文通过对模型图像重建研究,得到了投影及重建过程中投影旋转间隔对成像时间、成像质量以及图像重建计算量的影响因素。结论在扇形束投影CT的成像过程中,投影旋转间隔在〈2°的范围内会对成像时间、成像质苗以及计算量产生较小影响。     

组织多普勒超声心脏图像的动态三维重建方法

目的：探讨组织多普勒超声心脏图像动态三维重建方法,以提升诊断的准确性。方法：将解剖结构以及功能参数信息从多普勒超声医学图像中进行分离,结合三维场分布对其进行重建,并将重建结果实施融合显像。结果：该方法科学地展示了功能参数以及解剖结构两者之间的关系,实现了组织多普勒超声心脏图像的动态三维重建。结论：通过将组织多普勒成像技术和超声医学图像三维重建技术相结合,科学地实现并完成组织多普勒超声心脏图像的动态三维重建,在临床医学上具有十分重要的意义和价值。     

基于ITK和OpenGL的医学图像三维重建

目的:提出一种基于ITK和OpenGL开发的医学图像三维重建系统的新模式.方法:在VC++6.0的MFC环境下缟程,设计交互性强、灵活实用的用户界面;集成ITK类库实现医学图像的读写、分割、等值面提取,并利用OpenGL进行三维表面的绘制和渲染.结果:设计并实现了一个医学图像三维重建系统.结论:基于ITK和OpenGL模式开发医学图像三维重建系统,不仅可以解决ITK不具备可视功能、不提供用户界面的缺点,同时可以利用OpenGL强大的三维绘制和渲染功能使三维场景更加逼真.     

医学图像机计算机工作站的初步研究

本文介绍了医学图像工作站的基本构成及模式，并给出了医学图像工作站的内部框图和构成方法，初步探讨了工作站在医学图像的三维重建中的作用，通过应用实例，具有讲述了医学图像工作站的体系结构及特点。     

基于体素的投影算法的研究与实现

在体绘制算法中,本文提出了基于体素的投影算法,将不透明度参数引入绘制过程,得到具有半透明效果的三维图像。本文综合和吸收了体绘制技术的新成果,在PC机上基本实现了医学图像的三维重建,具有广阔的应用前景。     

CT心脏扫描直接三维重建算法研究

随着锥形束CT的出现．投影数据的采集速度明显加快．再加上重建算法的不断改进．心脏的CT成像质量必将得到改善。提出了一种双锥束的扫描结构，它改进了FDK算法．并设计了使用该结构实现心脏图像直接三维重建的方法．从而改善了心脏的CT成像质量。     

Micro-CT系统中对投影图像旋转中心的校正

目的:修正CT投影图像中心和实际旋转中心之间的误差,提高重建图像的质量.方法:分析了投影中心和实际的旋转中心偏差对重建图像产生的影,响提供了一种根据投影图像中物体和背景的灰度值差异特点来计算旋转中心的方法,并根据计算出的旋转中心对投影图像进行修正.结果:根据5～10组相差180°的对称投影图像计算出的投影中心与实际旋转中心偏差在1个像素内,大大提高了重建图像的质量.结论:该校正方法直接从已经获得的投影图像出发,不需要增加辅助条件和投影图像数量,并且计算量较小,作为重建前处理对投影图像进行纠正,基本不影响重建的速度,准确率较高.     

基于数字血管减影的无框架立体定位算法的研究

本文提出了一种基于数字血管减影的无框架立体定位算法。该方法利用一个定位板、四个定位头标和两幅数字血管减影的投影图像，通过定义参考定位坐标系和进行两次坐标变换，可完全确定空间一点相对于参考定位坐标系的三维坐标。经过计算机仿真表明，该算法理论正确，结果可靠，为利用数字血管减影进行颅内血管等组织的立体定位提供了一种方法。这种无框架立体定位算法对于放射治疗和进行神经外科手术具有十分重要的意义。     

DSA三维重建技术在诊断颅内动脉狭窄中的意义

目的：探讨三维重建技术在诊断颅内动脉狭窄中的应用价值。方法：通过对2D DSA和三维重建影像进行对比,来比较血管狭窄处能否正常显示、直径狭窄率和面积狭窄率对血管狭窄程度的精确反映及血管内斑块显示的准确性。结果：2D DSA和三维重建影像在显示颅内狭窄时,无统计学差异,但三维重建影像比二维影像显示更准确,82处狭窄,三维图像均能显示,而二维影像只能显示出其中80处狭窄;三维重建影像通过计算面积狭窄率比2D DSA更加准确地反映出血液动力学的改变;三维重建影像利用VA技术,比2D DSA影像在斑块显示上更具优势。结论：三维重建技术在颅内动脉狭窄的诊断中具有不可替代的作用,比2D DSA影像能提供更加丰富、准确的影像学信息。     

基于匹配点插值算法的半球模型电阻抗三维图像重建

目的:为了得到头颅和乳腺电阻抗成像的三维图像,更好地诊断脑部及乳腺肿瘤病变位置,改变以往的图像二维显示方式,对半球模型电阻抗二维重构图像结果进行三维重建。方法:对浸泡在半球形水槽中电导率为2.1 S/m的半锥形异物模型重构得到二维图像,根据电阻抗图像数据特点,对图像数据作预处理以便插值使用。使用匹配点插值算法对二维电阻抗图像进行插值,形成三维重建模型。结果:插值结果可以体现层数据间的过渡,三维重建结果体现了原模型的位置信息。结论:该算法能够实现电阻抗的三维成像,并能确定异物模型的位置,便于肿瘤疾病的诊断,满足电阻抗成像的实时监护要求。     

Improved numerical modelling of heat transfer in human tissue exposed to RF energy

A novel numerical model to simulate thermal response of human body tissues exposed to RF energy is presented in this article. It is based on a new algorithm for the construction of a realistic blood vessel network, a new model of blood flow velocity distribution and an approach to solve the bio-heat equation in human tissue with variable and initially unknown blood temperature distribution. The algorithm generates a discrete 3D representation of both arterial and venous vascular networks and a continuous blood velocity vector field for arbitrary enclosed geometries required to represent the complex anatomy of human body and blood flow. The results obtained in this article by applying the developed method to realistic exposure conditions demonstrates relative difference in thermal response of the exposed tissue compared to results obtained by conventional bio-heat equation with constant blood perfusion and temperature. The developed technique may provide more accurate and realistic modelling in thermal dosimetry studies of human body RF exposure.     

Chaotic dynamics in arrhythmias

The paper proposes the systematization of cardiac arrhythmias in accordance with a generalized scheme of transition from regular conditions to random changes, which makes it possible to conclude that the occurrence of more menacing arrhythmias in patients with implantable pacemakers may suggest that there is a risk for random disorders, as well as to recommend to change pacing parameters and even to replace the pacemaker. At present the authors are conducting computer-aided studies of the proposed approach in the Matlab medium. The algorithm of search for the facts of complication of the dynamic behavior of the system is based on the odd set theory which is presently most promising for designing cardiological monitoring systems. The new approach suggests that there are changes in the dynamics of arrhythmias and hence it will be of practical value in treating all cardiological patients.     

流固耦合分析技术在胸主动脉血管瘤诊疗中的应用

目的:利用流固耦合分析技术对某特定病例开展胸主动脉血管瘤内血液流场、血管壁、血管瘤壁的变形和应力变化研究,为临床防治血管瘤提供决策支持。方法:在考虑血液与血管壁之间流固耦合作用的基础上,使用三维阈值分割及三维区域增长分割方法提取3D胸主动脉血管瘤表面模型,再利用工程软件CATIA进行光顺表面线型优化,得到血管瘤及其内部血液的3D模型。通过流固耦合计算方法,获得胸主动脉血管瘤血流特性及血管瘤组织变形和受力情况。结果:血流对血管瘤与血管连接区域形成明显冲击,整体血管瘤组织呈现出“呼吸式”往复形位移变化,且血管瘤组织内最大von-Mises应力为75.2 kPa,约为血管瘤承载能力(650 kPa)的11.6%,最大剪切应力约为41.7 kPa。结论:基于流固耦合分析技术对于胸主动脉血管瘤的危险部位预测是有效的,可为临床的诊治提供数据依据。     

双源Flash CT胸部体检对冠状动脉钙化的初步评价

目的：探讨双源Flash CT胸部体检图像对冠脉钙化的显示情况。方法：回顾性分析2012年9月至2013年6月胸部CT平扫发现冠脉钙化的44例体检者的临床资料,其中男33例、女11例,将全部患者CT图像分别用层厚3 mm＋软组织算法B30f（A组）、层厚1 mm＋软组织算法B30f（B组）及层厚1 mm＋骨算法B60f（C组）进行重建,根据冠脉钙化显示情况将图像分为0-3级共4级,评价3组图像对冠脉钙化的显示情况,分析三者之间的统计学差异。结果：44例体检者的3组重建图像对冠脉钙化的显示有明显统计学差异（P〈0.05）;进一步进行两两比较分析,A组与B组、A组与C组及B组与C组之间的差异均有统计学意义（P〈0.05）,其中C组中评分3级的图像明显多于A、B组,对冠脉钙化获得了较好的显示效果,钙化边缘更加锐利,细节清晰,小分支钙化亦可分辨。结论：合理利用后处理技术,将薄层厚及骨算法重建相结合的双源Flash CT胸部平扫可为冠脉钙化观察提供一种非常实用且简便易行的方法,可以较为精确地显示冠脉钙化的部位、形态以及大致范围,为初步评估冠脉钙化提供一定的信息,具有较大的临床应用价值。     

Mapping the FACT-P to the Preference-Based EQ-5D Questionnaire in Metastatic Castration-Resistant Prostate Cancer

ObjectivesTo develop a mapping algorithm for estimating EuroQol five-dimensional (EQ-5D) questionnaire values from the prostate cancer–specific health-related quality-of-life (HRQOL) instrument Functional Assessment of Cancer Therapy–Prostate (FACT-P) instrument.MethodsThe EQ-5D questionnaire and FACT-P instrument data were collected for a subset of patients with metastatic castration-resistant prostate cancer in a multicenter, randomized, double-blind, placebo-controlled phase 3 trial. We compared three statistical techniques to estimate patients’ EQ-5D questionnaire index scores determined by using the UK tariff: 1) generalized estimating equations, 2) two-part model combining logistic regression and generalized estimating equation, and 3) separate mapping algorithms for patients with poor health defined as a FACT-P score of 76 or less (group-specific model). Four different sets of explanatory variables were compared. The models were cross-validated by using a 10-fold in-sample cross-validation.ResultsValues for both instruments were available for 236 patients with metastatic castration-resistant prostate cancer. The group-specific model including the FACT-P subscale scores and baseline variables had the best predictive performance with R² 0.718, root mean square error 0.162, and mean absolute error 0.117. The two-part model and the generalized estimating equation model including the FACT-P subdomain scores and baseline variables also had good predictive performance.ConclusionsThe developed algorithms for mapping the FACT-P instrument to the EQ-5D questionnaire enable the estimation of preference-based health-related quality-of-life scores for use in cost-effectiveness analyses when directly elicited EQ-5D questionnaire data are missing.     

Three‐dimensional visualisation improves understanding of surgical liver anatomy

Medical Education 2010: 44 : 936–940 Objectives Three‐dimensional (3‐D) representation is thought to improve understanding of complex spatial interactions and is being used more frequently in diagnostic and therapeutic procedures. It has been suggested that males benefit more than females from 3‐D presentations. There have been few randomised trials to confirm these issues. We carried out a randomised trial, based on the identification of complex surgical liver anatomy, to evaluate whether 3‐D presentation has a beneficial impact and if gender differences were evident. Methods A computer‐based teaching module (TM) was developed to test whether two‐dimensional (2‐D) computed tomography (CT) images or 3‐D presentations result in better understanding of liver anatomy. Following a PowerPoint lecture, students were randomly selected to participate in computer‐based testing which used either 2‐D images presented as consecutive transversal slices, or one of two 3‐D variations. In one of these the vessel tree of portal and hepatic veins was shown in one colour (3‐D) and in the other the two vessel systems were coloured differently (3‐Dc). Participants were asked to answer 11 medical questions concerning surgical anatomy and four questions on their subjective assessment of the TM. Results Of the 160 Year 4 and 5 medical students (56.8% female) who participated in this prospective randomised trial, students exposed to 3‐D presentation performed significantly better than those exposed to 2‐D images (p < 0.001). Comparison of the number of correct answers revealed no significant differences between the 3‐D and 3‐Dc modalities p > 0.1). Male students gave significantly more correct answers in the 3‐D and 3‐Dc modalities than female students (p < 0.03). The gender difference observed in both 3‐D modalities was not evident in the 2‐D group (p = 0.21). Conclusions This study showed that 3‐D imaging significantly improved the identification of complex surgical liver anatomy. Male students benefited significantly more than female students from 3‐D presentations. Use of colour in 3‐D presentation did not improve student performance.     

计算机辅助外科手术模拟系统的研制与应用

研究三维分割技术在医学整形领域的应用。通过对目标进行CT扫描并进行三维重建，采用基于空间的方法，完成对同类属性组织CT三维图像的三维分割。对手腕骨、眼眶骨、颌面骨、颅面骨的CT图像进行三维重建与分割、控制、移动的结果说明方法的确实可行。用计算机模拟了整形手术过程中对目标的任意区域分割与控制。     

遗传优化的广义回归神经网络在肺结核发病预测中的应用

目的 利用西安市2008年1月至2019年10月结核病月发病率数据分别建立广义回归神经网络和BP神经网络预测模型，提出利用遗传算法的全局搜索能力优化广义回归神经的光滑因子。 方法 以2008年1月至2018年12月发病率作为训练样本，以2019年1月至10月发病率作为测试样本，对两种模型的仿真预测结果进行对比分析。 结果 遗传优化的广义回归神经网络其预测的平均绝对误差（MAE），均方根误差（RMSE），平均相对误差（MAPE）均小于BP神经网络，预测效果更优。 结论 遗传优化的广义回归神经网络较BP神经网络在肺结核发病率预测中有更好的拟合效果和预测精度，其预测效果更理想。其具有良好的实用价值，为肺结核发病率的预测提供了一种有效的方法。     

Bivariate association analyses for the mixture of continuous and binary traits with the use of extended generalized estimating equations

Genome-wide association (GWA) study is becoming a powerful tool in deciphering genetic basis of complex human diseases/traits. Currently, the univariate analysis is the most commonly used method to identify genes associated with a certain disease/phenotype under study. A major limitation with the univariate analysis is that it may not make use of the information of multiple correlated phenotypes, which are usually measured and collected in practical studies. The multivariate analysis has proven to be a powerful approach in linkage studies of complex diseases/traits, but it has received little attention in GWA. In this study, we aim to develop a bivariate analytical method for GWA study, which can be used for a complex situation in which continuous trait and a binary trait are measured under study. Based on the modified extended generalized estimating equation (EGEE) method we proposed herein, we assessed the performance of our bivariate analyses through extensive simulations as well as real data analyses. In the study, to develop an EGEE approach for bivariate genetic analyses, we combined two different generalized linear models corresponding to phenotypic variables using a seemingly unrelated regression model. The simulation results demonstrated that our EGEE-based bivariate analytical method outperforms univariate analyses in increasing statistical power under a variety of simulation scenarios. Notably, EGEE-based bivariate analyses have consistent advantages over univariate analyses whether or not there exists a phenotypic correlation between the two traits. Our study has practical importance, as one can always use multivariate analyses as a screening tool when multiple phenotypes are available, without extra costs of statistical power and false-positive rate. Analyses on empirical GWA data further affirm the advantages of our bivariate analytical method.