Detection of Tuberculosis in Sputum Smear Images by Gaussian Mixture Models

结核病是严重危害人类健康的一类疾病。通过计算机图像处理手段进行自动检测结核菌计数可以大幅提高医生诊断效率。高斯混合模型是单一高斯分布的延伸,是使用多个高斯分布加权来拟合给定的数据样本,通过确定拟合参数确定每个样本的分类概率。该文首先通过向量量化算法对图像预处理,降低所需处理数据量,然后从HSV、CIEl*A*b*、yCbCr颜色空间提取特征分量并送入高斯混合模型进行训练。根据实验结果,高斯混合模型比其他无监督分类算法(如k-MEAnS算法)准确度更高,与有监督的分类算法(如朴素贝叶斯分类算法)相比可以简化训练样本的制作,具有一定优势。Cell recognition plays an important role in medical image-processing.First,we preprocess the images with vector quantization algorithm to reduce the computation.Then we extract different feature channels from HSV,CIEL*a*b* and YCbCr color spaces and put them into a Gaussian mixture model.Gaussian mixture models is a mature method for clustering unknown data.To determine the parameters of GMM,we use expectation maximization algorithm,which uses unlabeled data for model training.The experiment shows GMM finished the initial work of TB detection,while its performance wasn't high enough.基于前节OCT图像的闭角型青光眼诊断及治疗仿真方法研

基于神经网络的脑组织图像分割方法的研究

本文采用模糊自组织特征映射网络的图像分割方法,以颅脑图像为研究对象,以精确分割出白质﹑灰质﹑脑脊液等脑组织为目的.在分割过程中,对算法进行了改进,获得了较好的效果

An Dose Optimization Algorithm in Brachytherapy

高剂量率后装近距离治疗现在已成为放射治疗的常用方法之一,近距放射治疗计划系统的应用也越来越广泛,主要目的就是通过优化源的驻留位置和时间来改善剂量分布,提高治疗质量。提出了一种连续驻留位置和驻留时间的近距离放疗剂量优化算法。在插值路径为直线、照射源为点源的情况下,首先将驻留时间T看成是位置X的一个连续函数,计算每个参考剂量点的剂量,再用计算剂量和目标剂量值之差的加权平方和为目标函数,然后用复合型调优法求解最优的曲线参数。曲线可以根据具体情况进行分段,得到曲线后再用积分的数值逼近方法将其离散化,得到最终的驻留位置和驻留时间。实验结果表明,本算法不仅避免了负的驻留时间问题,还可使相邻驻留位置的驻留时间更加平滑;在最后的离散化过程中,可以得到不同的驻留位置和驻留时间结果,使计划具有更好的灵活性。Brachytherapy is an anti-tumor treatment by means of radioactive sources that are placed at short distances from the target tumor tissues and becoming more and more widely used.In this paper,we proposed an algorithm to optimize the dwell time of radioactive source for computer-based high-dose-rate afterloading implants planning system of brachytherapy.The dwell time was considered as a continuous function of the dwell position,calculated the dose values of referenced dose points.The minimal difference between these dose values and demanded dose values was used as the objective to get the optimized function parameters.The function curve could be separated to several sects.The optimized curve was dispersed using compound trapezoid formula to get the dwell positions and dwell times.This method could avoid the emergence of negative dwell time,and reduce the dwell time gradient as well.When dispersing the curves,different dwell times and dwell positions could be obtained,which made the brachytherapy treatment plan more flexible.国家自然科学基金资助项目(60371012、60701022

Computer Simulation of Nasopharyngeal Carcinoma Brachytherapy

近距离放疗是鼻咽癌治疗的主要手段之一。其计算机仿真可帮助医生制定详细的放疗方案,对鼻咽癌精确放疗具有显著意义。一个完整的鼻咽癌近距离放疗仿真的方案被提出。首先,对CT图像进行分割,重建三维组织模型。然后,设计了基于Ta-chih Lee细化算法的鼻咽腔放疗源虚拟输送路径。最后,对125I柱状放射源放射剂量分布进行了蒙特卡罗仿真。初步实现了鼻咽癌近距离放疗的计算机仿真。Brachytherapy is one of the major means of nasopharyngeal carcinoma treatments. Computer simulation of the process is of great value to radiotherapy planning. A complete solution for computer simulation of nasopharyngeal carcinoma brachytherapy was proposed. Firstly,the CT images of the nasopharyngeal tissues were segmented and the 3D models of nasopharyngeal tissues were reconstructed. Then the 3D delivery path of radioactive source based on Ta-chih Lee’s thinning algorithm was designed. Finally,the simulation of cylindrical 125I dose distribution was realized by Monte Carlo method. A primary computer simulation of nasopharyngeal carcinoma Brachytherapy was realized.国家自然科学基金项目(60601025);; 福建省科技重点项目(2005Y0018

Study for the Anterior Capsule of Human Crystalline Lens with Nonlinear Finite Element Analysis

在临床试验获得的形态数据和物理数据的基础上,建立了连续环形撕囊后前囊膜的物理模型,利用非线性有限元分析法对撕开口大小与囊膜最大拉伸长度之间的关系进行了仿真计算。结果表明,随撕开口的增大,囊膜所能承受的最大拉伸长度显著增加,最大拉伸状态下的撕开口周长Cr与撕开口初始周长Cc的比值(Cr/Cc)也增大。该结论与实验研究的结论一致,表明前囊膜的可拉伸性能随着撕开口的增大而增大。进一步分析指出,拉伸时,撕开口边缘处外力作用的范围会显著影响最大拉伸长度:外力作用范围越大,囊膜所能承受的最大拉伸长度也就越大;增大幅度随作用范围的增加而减小。研究结果表明,仿真分析取得的结果与实验研究结果相符。Based on experimental data,a nonlinear finite element model of the anterior capsule was constructed to study the relationship between the diameter of continuous circular capsulorhexis(ccc) and the maximum extend of the anterior capsule by finite element analysis.Calculating results showed that the capsule could be extended larger by an external force as the diameter of CCC aperture increasing.This result is accord with the results of experimental studies on lens capsules of human body.Furthermore,simulation indicates that the contact area of the external force has a great influence on the max extend length: giving the same diameter of CCC,the capsule's extend length increasing as the contact area of the external force become larger.This result remains undiscovered in experimental studies.The current work demonstrates that simulation analysis is believed to be a promising,powerful tool in the field of biology medical engineering.国家自然科学基金资助项目(60371012);; 福建省科技重点项目(2002Y021

Retinal Vessel Image Segmentation and Three-dimensional Reconstruction of Retinal Vessel

眼底视网膜图像的血管分布情况为高血压、糖尿病等疾病的早期诊断提供了重要依据.计算机处理眼底图像可以减少医生的重复劳动.本文提出了一种新的眼底视网膜血管图像分割算法.利用构建的局部归一化方法消除视网膜血管图像背景的差异性.利用期望最大化算法进行聚类,实现了眼底视网膜血管图像分割.最后,根据眼底图像成像原理,通过投影逆变换构建了眼底视网膜图像的三维模型.构建的模型可以进行多角度观察分析.Retinal vessel appearance is an important indicator for many early diagnoses,including diabetes,hypertension, and arteriosclerosis.Computer processing can help doctors' work and a retinal vessel image segmentation algorithm was proposed.A local normalization algorithm was used to eliminate background differences.Expectation-maximization algorithm was used to classify the pixels into several classes to obtain segmentation results.At last,based on the anatomical and physiological characteristics of the eye,a reconstruction method to reconstruct three-dimensional retinal vessel was realized by inverse projection theory.The model can be viewed from different directions.国家自然科学基金(60371012;60601025)资助---

Computer Simulation in Acute Angle-closure Glaucoma Based on Parameter Model

急性闭角型青光眼是一种严重危害人体健康的疾病,由于其诊断和治疗手段的主观性,对其进行建模与仿真研究具有重要医学意义。以参数化人眼前节模型为基础,在后房高眼压的条件下,对眼前节进行有限元分析,得到相应的眼前节应力与位移分布。尝试以仿真方法对急性闭角型青光眼发病进程进行研究,力图获得定量分析结果。仿真结果表明,该有限元分析方法是可行且合理的。The researches on the field of modeling and simulation of acute angle- closure glaucoma(AACG) has great medicinal significance,as the subjectivity of the diagnosis and therapeutic tool for AACG,which is a serious disease.Finite element analysis was used to investigate anterior segment,which endures posterior chamber high intraocular pressure,as the basement of parameter anterior segment model.And the displacement and stress of anterior segment was obtained.In order to attain quantitative analysis of the results,computer simulation method was used to study the disease process.As the conclusion,it is shown that finite element analysis is feasible.国家自然科学基金(60601025)~

Cornea Segmentation in Human Eye Tissue Slice Images Based on BP Neural Network

角膜是人眼的一个关键部分,了解角膜的精细结构具有十分重要的意义.本文提出了一种基于BP(Back-propa-gation)网络的,针对组织切片图像序列提取角膜局部信息的新方法.首先对切片序列进行预处理,截取包含角膜信息的原1/2图像,其次选取预处理过的图像序列中角膜颜色差异的若干图片做训练样本,以人工分割后的图像作为导师信号,通过分析选取6个图像特征作为输入向量,对三层BP神经网络进行训练.训练完成后,采用该网络对图像序列进行分割,最后对分割图像进行后处理包括区域分割、孔洞填充及恢复图像大小.实验结果表明,该方法能够获得较好的图像序列分割效果,为角膜精细形态模型的建立及其后续研究打下基础,同时也为眼内其他重要结构的分割提供一种参考方法.Cornea is one of the most important parts of human body′s eyes.According to the particular obtainment of the human eyes tissue images,in this paper,a method to extract cornea′s local information based on back-propagation(BP) neural network is proposed.First,we capture half of the images including cornea information.Then several images with different cornea colors are chosen as training samples.Manual segmentation images of training samples are used as teacher signals.The network′s input vectors are 6 image features.We can train the BP neutral network with 3 layers and capture the segmented images.Finally,we get the exactly cornea information by region growing with the segmented images and filling holes of images.This method is turned out to get expected purpose and operate little subjective.It is a reference method to segment the other parts of eyes of these tissue slice images,and also is a basis for the research of modal model of cornea.国家自然科学基金(60371012,60601025,30770561);; 卫生部科学研究基金-福建省卫生教育联合攻关计划项目(WKJ2005-2-001)资

Cornea Segmentation in Human Eye Tissue Slice Images Based on BP Neural Network

中文摘要: 角膜是人眼的一个关键部分 ,了解角膜的精细结构具有十分重要的意义.本文提出了一种基于 BP (Back-propa-gation)网络的 ,针对组织切片图像序列提取角膜局部信息的新方法.首先对切片序列进行预处理 ,截取包含角膜信息的原 1/ 2 图像 ,其次选取预处理过的图像序列中角膜颜色差异的若干图片做训练样本 ,以人工分割后的图像作为导师信号 ,通过分析选取 6 个图像特征作为输入向量 ,对三层BP神经网络进行训练.训练完成后 ,采用该网络对图像序列进行分割 ,最后对分割图像进行后处理包括区域分割、 孔洞填充及恢复图像大小.实验结果表明 ,该方法能够获得较好的图像序列分割效果 ,为角膜精细形态模型的建立及其后续研究打下基础 ,同时也为眼内其他重要结构的分割提供一种参考方法. 英文摘要：Cornea is one of the most importantparts of human body′s eyes. According to the particular obtainment of the human eyes tissue images ,in this paper ,a method to extract cornea′s local information based on back-propagation (BP) neural network is proposed. First ,we capture half of the images including cornea information. Then several images with different cornea colors are chosen as training samples. Manual segmentation images of training samples are used as teacher signals. The network′s input vectors are 6 image features. We can train the BP neutral network with 3 layers and capture the segmented images. Finally ,we get the exactly cornea information by region growing with the segmented images and filling holes of images. This method is turned out to get expected purpose and operate little subjective. It is a reference method to segment the other parts of eyes of these tissue slice images ,and also is a basis for the research of modal model of cornea.国家自然科学基金(60371012 ,60601025 ,30770561) ,卫生部科学研究基金2福建省卫生教育联合攻关计划项目(WKJ2005222001)资

Corneal Modeling Based on Finite Element and RK Analysis

放射状角膜切开术简称RK手术,是通过改变角膜的屈光度矫正视力的一种方法。这种手术简单,疗效显著,受到普遍欢迎,但手术前后应力分布及术中参数变化对手术的影响一直是医患双方共同关心的问题。以有限元软件ANSYS为工具,分别建立眼角膜RK手术前后的有限元模型,并在此基础上对比分析手术前后眼角膜的应力分布、眼内压对角膜的影响及RK手术中切口深度对整个手术效果的影响。仿真结果显示:正常情况下的角膜应力主要分布在水平边缘方向,RK手术后的刀口两端有明显的应力集中现象;RK手术中随着切口深度的增加,角膜曲率半径的变化会变大,对近视的矫正效果也越好,但术后风险会加大。The radiate keratotomy, briefly called as RK, is a method to rectify visual acuity through changing corneal diopter. This operation is easy and popular, and has great effect, however, the influence of stress distribution before and after operation as well as the parameter change on operation are always the problems concerned both by doctors and patients. Taking finite element software ANSYS as the tool, it separately builds up the finite element modeling before and after corneal RK, and based on it, it makes contrast and analysis on the stress distribution of cornea before and after operation, the influence of intraocular pressure on cornea, and the influence of cut depth on the effect of entire RK. The simulation result shows: in the normal situation, the corneal stress is mainly distributed on the level edge, and after RK, two ends of blade appear the obvious stress centralization; during RK, with the increase of cut depth, the corneal curvature radius changes greater and greater, and the rectifying effect for myopia becomes better, but the risk after operation becomes larger.国家自然科学基金(编号:60601025)~