检索结果-内蒙古大学图书馆

中国临床康复 2005年第23期9卷 216-217页

作者：柳建华何景光冉虹罗卓鹏查道刚刘伊丽广州市第一人民医院功能检查科广东省广州市510180 南方医科大学南方医院心内科广东省广州市510515

背景:超声评价肾脏功能主要通过测量较粗大的肾脏各级动脉的血流参数或肾切面内动脉彩色血流面积所占的比例来推断,误差较大。目的:应用超声仪器随机配置的彩色多普勒时间-强度曲线软件评价肾脏血流灌注情况。设计:动物实验观察。单位:... 详细信息

背景:超声评价肾脏功能主要通过测量较粗大的肾脏各级动脉的血流参数或肾切面内动脉彩色血流面积所占的比例来推断,误差较大。目的:应用超声仪器随机配置的彩色多普勒时间-强度曲线软件评价肾脏血流灌注情况。设计:动物实验观察。单位:广州市第一人民医院功能检查科。材料:实验于1999-01/2000-04在广州军区广州总医院动物实验室完成,选择8只健康新西兰兔,雌雄各4只,体质量2.5～3.5kg。观察肾脏16个。声学造影剂为全氟显,主要成分为声振白蛋白的微泡,微泡内有一定浓度的全氟丙烷气体。方法:兔外周静脉团注造影剂全氟显后用彩色多普勒能量图、彩色多普勒血流显像和彩色多普勒能量谐波成像连续采集肾脏彩色血流图像,随机配置软件显示时间-强度曲线。主要观察指标:造影增强肾脏血流灌注时间-强度曲线的形态。结果:进入结果分析8只家兔。肾脏血流造影增强的时间-强度曲线呈单峰状,上升支陡直,下降支平缓。调节时间轴上的感兴趣线可作定量分析,回放显示注射造影剂后对应某一时刻的造影增强的彩色多普勒图像。结论:造影增强彩色多普勒血流显像和彩色多普勒能量图的时间-强度曲线能有效的观察肾脏血流灌注特征,既可显示整个肾脏的血流灌注情况,也用于观察低血流灌注区域,发现病灶进一步绘制肾功能图。

关键词：肾灌注超声检查多普勒彩色计算机辅助/方法

来源：评论

学校读者我要写书评

暂无评论

150-250 MeV electron beams in radiation therapy

引用

PHYSICS IN MEDICINE AND BIOLOGY 2000年第7期45卷 1781-1805页

作者： DesRosiers, C Moskvin, V Bielajew, AF Papiez, L Indiana Univ Sch Med Dept Radiat Oncol Indianapolis IN 46202 USA Univ Michigan Ann Arbor MI 48109 USA

High-energy electron beams in the range 150-250 MeV are studied to evaluate the feasibility for radiotherapy. Monte Carlo simulation results from the PENELOPE code are presented and used to determine lateral spread and penetration of these beams. It is shown that the penumbra is comparable to photon beams at depths less than 10 cm and the practical range (R-p) of these beams is greater than 40 cm. The depth dose distribution of electron beams compares favourably with photon beams. Effects caused by nuclear reactions are evaluated, including increased dose due to neutron production and induced radioactivity resulting in an increased relative biological effectiveness (RBE) factor of <1.03.

关键词：算法电子/治疗应用蒙特卡罗法中子体模显象术光子/治疗应用放射测量术/方法放射疗法/方法放射治疗计划计算机辅助/方法软件

来源：评论

学校读者我要写书评

暂无评论

Left ventricular motion reconstruction from planar tagged MR images:: a comparison

引用

PHYSICS IN MEDICINE AND BIOLOGY 2000年第6期45卷 1611-1632页

作者： Declerck, J Denney, TS Öztürk, C O'Dell, W McVeigh, ER Johns Hopkins Univ Dept Biomed Engn Med Imaging Lab Baltimore MD 21205 USA Auburn Univ Dept Elect Engn Auburn AL 36849 USA

Through recent development of MR techniques, it is now possible to assess regional myocardial wall function in a non-invasive way. Using MR tagging, space is marked with planes which deform with the tissue, providing markers for tracking the local motion of the myocardium. Numerous methods to reconstruct the three-dimensional displacement field have been developed. The aim of this article is to provide a framework to quantitatively compare the performance of four methods the authors have developed. Five sets of experiments are described, and their results are reported. Instructions are also provided to perform similar tests on any method using the same data. The experiments show that some characteristic properties of the methods, such as sensitivity to noise or spatial resolution, can be quantitatively classified. Cross-comparison of performances show what range values for these properties can be considered acceptable.

关键词：心脏起搏人工心肌疾病/诊断显像超声心动描记术/方法弹性心室/诊断显像图像处理计算机辅助/方法模型统计学心肌梗死/诊断显像结果可重复性超声检查/仪器和设备超声检查/方法动物狗人类

来源：评论

学校读者我要写书评

暂无评论

Developments in component-based normalization for 3D PET

引用

PHYSICS IN MEDICINE AND BIOLOGY 1999年第2期44卷 571-594页

作者： Badawi, RD Marsden, PK Kings Coll London Guys & St Thomas Clin PET Ctr Div Radiol Sci & Med Engn London WC2R 2LS England

Normalization in positron emission tomography (PET) is the process of ensuring that all lines of response joining detectors in coincidence have the same effective sensitivity. In three dimensional (3D) PET, normalization is complicated by the presence of a large proportion of scattered coincidences, and by the fact that cameras operating in 3D mode encounter a very wide range of count-rates. In this work a component-based normalization model is presented which separates the normalization of true and scattered coincidences and accounts for variations in normalization effects with count-rate. The effects of the individual components in the model on reconstructed images are investigated, and it is shown that only a subset of these components has a significant effect on reconstructed image quality.

关键词：脑/诊断显像计算机方法学氟脱氧葡萄糖F18 图像处理计算机辅助/方法体模显象术放射性药物结果可重复性散射辐射体层摄影术发射型计算机成年人人类

来源：评论

学校读者我要写书评

暂无评论

Efficient nonlinear registration of 3D images using high order co-ordinate transfer functions

引用

JOURNAL OF MEDICAL ENGINEERING & TECHNOLOGY 1999年第5期23卷 157-168页

作者： Barber, DC Royal Hallamshire Hosp Dept Med Phys & Clin Engn Sheffield S Yorkshire England

There is an increasing interest in image registration for a variety of medical imaging applications. Image registration is achieved through the use of a co-ordinate transfer function (CTF) which maps voxels in one image to voxels in the other image, including in the general case changes in mapped voxel intensity. If images of the same subject are to be registered the coordinate transfer function needs to implement a spatial transformation consisting of a displacement and a rigid rotation. In order to achieve registration a common approach is to choose a suitable quality-of-registration measure and devise a method for the efficient generation of the parameters of the CTF which minimize this measure. For registration of images fr om different subjects more complex transforms are required. In general function minimization is too slow to allow the use of CTFs with more than a small number of parameters. However, provided the images are from the same modality and the CTF can be expanded in terms of an appropriate set of basis functions this paper will show how relatively complex CTFs can be used for registration. The use of increasingly complex CTFs to minimize the within group standard deviation of a set of normal single photon emission tomography brain images is used to demonstrate the improved registration of images from different subjects using CTFs of increasing complexity.

关键词：脑/放射性核素显像图像处理计算机辅助/方法模型理论体层摄影术发射型计算机体层摄影术发射型计算机单光子人类

来源：评论

学校读者我要写书评

暂无评论

Treatment planning for brachytherapy: an integer programming model, two computational approaches and experiments with permanent prostate implant planning

引用

PHYSICS IN MEDICINE AND BIOLOGY 1999年第1期44卷 145-165页

作者： Lee, EK Gallagher, RJ Silvern, D Wuu, CS Zaider, M Georgia Inst Technol Sch Ind & Syst Engn Atlanta GA 30332 USA Columbia Univ Dept Med Informat New York NY 10032 USA Columbia Presbyterian Med Ctr Dept Radiat Oncol New York NY 10032 USA Mem Sloan Kettering Canc Ctr Dept Med Phys New York NY 10021 USA

An integer linear programming model is proposed as a framework for optimizing seed placement and dose distribution in brachytherapy treatment planning. The basic model involves using 0/1 indicator variables to describe the placement or non-placement of seeds in a prespecified three-dimensional grid of potential locations. The dose delivered to each point in a discretized representation of the diseased organ and neighbouring healthy tissue can then be modelled as a linear combination of the indicator variables. A system of linear constraints is imposed to attempt to keep the dose level at each point to within specified target bounds. Since it is physically impossible to satisfy all constraints simultaneously, each constraint uses a variable to either record when the target dose level is achieved, or to record the deviation from the desired lever. These additional variables are embedded into an objective function to be optimized. Variations on this model are discussed and two computational approaches-a branch-and-bound algorithm and a genetic algorithm-far finding 'optimal' seed placements are described. Results of computational experiments on a collection of prostate cancer cases are reported. The results indicate that both optimization algorithms are capable of producing good solutions within 5 to 15 min, and that small variations in model parameters can have a measurable effect on the dose distribution of the resulting plans.

关键词：算法近距离放射疗法/仪器和设备近距离放射疗法/方法数学计算器官特异性体模显象术前列腺/解剖学和组织学前列腺肿瘤/放射疗法辐射剂量放射治疗计划计算机辅助/方法人类男(雄)性

来源：评论

学校读者我要写书评

暂无评论

Denoising of electron beam Monte Carlo dose distributions using digital filtering techniques (vol 45, pg 1765, 2000)

引用

PHYSICS IN MEDICINE AND BIOLOGY 2000年第8期45卷 2441-2441页

作者： Deasy, JO MallinckrodtInstituteofRadiology WashingtonUniversitySchoolofMedicineStLouisMO63110USA.deasy@radonc.wustl.edu

The Monte Carlo (MC) method has long been viewed as the ultimate dose distribution computational technique. The inherent stochastic dose fluctuations (i.e. noise), however, have several important disadvantages: noise will affect estimates of all the relevant dosimetric and radiobiological indices, and noise will degrade the resulting dose contour visualizations. We suggest the use of a post-processing denoising step to reduce statistical fluctuations and also improve dose contour visualization. We report the results of applying four different two-dimensional digital smoothing filters to two-dimensional dose images. The Integrated Tiger Series MC code was used to generate 10 MeV electron beam dose distributions at various depths in two different phantoms. The observed qualitative effects of filtering include: (a) the suppression of voxel-to-voxel (high-frequency) noise and (b) the resulting contour plots are visually more comprehensible. Drawbacks include, in some cases, slight blurring of penumbra near the surface and slight blurring of other very sharp real dosimetric features. Of the four digital filters considered here, one, a filter based on a local least-squares principle, appears to suppress noise with negligible degradation of real dosimetric features. We conclude that denoising of electron beam MC dose distributions is feasible and will yield improved dosimetric reliability and improved visualization of dose distributions.

关键词：算法剂量效应关系辐射电子/治疗应用模型理论蒙特卡罗法体模显象术放射测量术/方法放射治疗计划计算机辅助/方法软件

来源：评论

学校读者我要写书评

暂无评论

Estimation of in vivo bone mineral density (BMD) and shape characterization for diagnosing osteoporosis by ultrasonic inspection

引用

JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME 1999年第3期121卷 298-303页

作者： Nogata, F Matsui, K Kagechika, K Sueyoshi, Y Tomita, K Gifu Univ Fac Engn Dept Mech & Syst Engn Gifu 5011193 Japan Sensa Corp Kanazawa Ishikawa 924 Japan Toyama Ken Koshi Rehabil Hosp Toyama 931 Japan Natl Hosp Kanazawa Dept Orthoped Surg Kanazawa Ishikawa 920 Japan Kanazawa Univ Sch Med Dept Orthoped Surg Kanazawa Ishikawa 930 Japan

A new method for estimating in vivo bone mineral density (BMD) and characterizing the shape of cancellous bone has been proposed using the results of ultrasonic inspection for the diagnosis of osteoporosis. The method is based on two-dimensional bone area fraction S (percent bone area between bone and bone marrow) calculated from the difference in the speed of ultrasonic wave propagation through cancellous bone. It was shown that the two-dimensional area fraction of a heel bone gives a good relationship to the BMD by DXA (dual energy x-ray absorptiometry) testing of human heel bone (calcaneus) and spine (vertebrae lumbar), as expressed by the relation, BMD (g/cm(2)) = 0.0167S for heel bone (r = 0.83), and BMD (g/cm(2)) = 0.0254S + 0.123 for the spine (r = 0.77). Shape characterization is based on the image simulation procedure employing eight random variables from a computer and the statistical results of fractal analysis for numerous cancellous bone patterns. We also demonstrate the validity of the shape characterization technique using autopsy specimens as a diagnostic tool for osteoporosis.

关键词：吸收测定法光子算法骨密度骨和骨组织/诊断显像计算机模拟跟/诊断显像跟/病理学图像处理计算机辅助/方法骨质疏松/诊断时间因素超声检查/方法成年人老年人女(雌)性人类中年人

来源：评论

学校读者我要写书评

暂无评论

Visualization and quantification of breast cancer biomechanical properties with magnetic resonance elastography

引用

PHYSICS IN MEDICINE AND BIOLOGY 2000年第6期45卷 1591-1610页

作者： Plewes, DB Bishop, J Samani, A Sciarretta, J Sunnybrook & Womens Coll Hlth Sci Ctr Dept Med Biophys Imaging Bioengn Res Grp Toronto ON M4N 3M5 Canada

A quasistatic magnetic resonance elastography (MRE) method for the evaluation of breast cancer is proposed. Using a phase contrast, stimulated echo MRI approach, strain imaging in phantoms and volunteers is presented. First-order assessment of tissue biomechanical properties based on inverse strain mapping is outlined and demonstrated. The accuracy of inverse strain imaging is studied through simulations in a two-dimensional model and in an anthropomorphic, three-dimensional finite-element model of the breast. To improve the accuracy of modulus assessment by elastography, inverse methods are discussed as an extension to strain imaging, and simulations quantify MRE in terms of displacement signal/noise required for robust inversion. A direct inversion strategy providing information on tissue modulus and pressure distribution is described along with a novel iterative method utilizing a priori knowledge of tissue geometry. It is shown that through the judicious choice of information from previous contrast-enhanced MRI breast images, MRE data acquisition requirements can be significantly reduced while maintaining robust modulus reconstruction in the presence of strain noise. An experimental apparatus for clinical breast MRE and preliminary images of a normal volunteer are presented.

关键词：乳腺肿瘤/诊断乳腺肿瘤/诊断显像弹性图像处理计算机辅助/方法磁共振成像/方法模型统计学模型理论体模显象术超声检查乳房/仪器和设备超声检查乳房/方法女(雌)性人类

来源：评论

学校读者我要写书评

暂无评论

An objective function for radiation treatment optimization based on local biological measures

引用

PHYSICS IN MEDICINE AND BIOLOGY 1999年第2期44卷 479-493页

作者： Alber, M Nüsslin, F Univ Klinikum Tubingen Abt Med Phys D-72076 Tubingen Germany

The implementation of biological optimization of radiation treatment plans is impeded by both computational and modelling problems. We derive an objective function from basic model assumptions which includes the normal tissue constraints as interior penalty functions. For organs that are composed of parallel subunits, a mean response model is proposed which leads to constraints similar to dose-volume constraints. This objective function is convex in the case when no parallel organs lie in the treatment volume. Otherwise, an argument is given to show that a number of local minima may exist which are near degenerate to the global minimum. Thus, together with the measure quality of the objective function, highly efficient gradient algorithms can be used. The number of essential biological model parameters could be reduced to a minimum. However, if the optimization constraints are given as TCP/NTCP values, Lagrange multiplier updates have to be performed by invoking comprehensive biological models.

关键词：模型生物学肿瘤/放射疗法泊松分布辐射剂量放射治疗剂量放射治疗计划计算机辅助/方法散射辐射人类

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：