A focused sound field measurement system by LabVIEW / 中国医疗器械杂志

In this paper, according to the requirement of the focused sound field measurement, a focused sound field measurement system was established based on the LabVIEW virtual instrument platform. The system can automatically search the focus position of the sound field, and adjust the scanning path according to the size of the focal region. Three-dimensional sound field scanning time reduced from 888 hours in uniform step to 9.25 hours in variable step. The efficiency of the focused sound field measurement was improved. There is a certain deviation between measurement results and theoretical calculation results. Focal plane--6 dB width difference rate was 3.691%, the beam axis--6 dB length differences rate was 12.937%.

Análisis numérico sobre esfuerzos y áreas de contacto en una PTR Scorpio II® Stryker®. Base para el diseño de PTR personalizada al fenotipo Mexicano / Numerical analysis on stresses and contact areas in a TKR Scorpio II® of Stryker®. Basis to design of customized TKR in accordance to Mexican Phenotype

El desgaste de los insertos de Polietileno de Ultra-Alto Peso Molecular (UHMWPE pos sus siglas en inglés) continúa afectando la longevidad de las prótesis totales de rodilla (PTR) junto con el aflojamiento aséptico, y ambos constituyen las dos principales causas de falla de las prótesis. Considerando esto, es necesario encontrar soluciones adecuadas para evitar el desgaste excesivo y hasta la ruptura de los insertos de polietileno. En este trabajo se realizó el estudio mediante simulación numérica de una PTR Scorpio II® Stryker®, la cual se retiró por desgaste del inserto de UHMWPE en el Hospital 1° de Octubre del ISSSTE en México. Se utilizaron las hipótesis de Bartel et al. (1995) y Chillag et al. (1991) para la validación del método numérico utilizado, las cuales establecen que el desgaste del polietileno puede reducirse utilizando insertos tibiales de mayor espesor, lo cual disminuye las presiones de contacto. Los análisis se realizaron mediante MEF variando el espesor del inserto de 6, 8, 10, 12 y 14 mm, suponiendo cargas axiales de tipo cuasi-estático en la articulación a cero grados de flexión, para 1.33 veces el peso de un individuo de 75 kg (736 N) empleando el ciclo normalizado de marcha. Los resultados obtenidos muestran similitud con los reportados por Bei et al. (2004) y Deen et al. (2006). Después de validar el método, se desarrolló el modelo de MEF de la PTR y se determinaron las curvas de esfuerzo y de áreas de contacto del inserto de UHMWPE, con lo que se obtuvo información importante para modificar el diseño y obtener una prótesis de geometría conforme en los planos coronal y sagital del inserto femoral y el inserto de polietileno, de acuerdo con el fenotipo mexicano.

Wear of UHMWPE inserts continues affecting the longevity of total knee replacements (TKR) together with septic loosening, and both constitute two main causes of prosthesis failure. It is necessary to find appropriate solutions to avoid excessive wear and failure of polyethylene inserts. In this work a study was carried out by means of numeric simulation of a Scorpio II® Stryker® TKR, which was retired due to wear of UHMWPE in the Hospital 1° de Octubre of ISSSTE in Mexico city. Hypotheses of Bartel et al. (1995) and Chillag et al. (1991) were used, which settle down that wear of polyethylene can decrease using thicker tibial inserts, which can be reduced contact pressures. Analyses of this work was carried out by means of FEM varying insert thickness of 6, 8, 10, 12 and 14 mm, considered quasi-static axial loads actuating on the articulation with zero degrees of flexion and loads equivalent to 1.33 times of bodyweight of a subject of 75 kg (736 N) was considered. Normalized gait cycle was employed and results obtained are similar to those reported by Bei et al. (2004) and Deen et al. (2006). After validating the method, a model of study case of TKR in FEM was developed and the curves of stress and contact areas of UHMWPE were determined, with which important information was obtained to modify the design, as well as to obtain a prosthesis of optimal conformity in both coronal and sagital planes of the femoral and UHMWPE inserts, in agreement with characteristics of the Mexican phenotype.

Comportamento mecânico de sistemas prótese/implante em região dos elementos finitos e interferometria holográfica / Mechanical behavior of prosthesis / implant systems in the anterior maxilla: analysis by finite element method and holographic interferometry

A proposta deste estudo foi analisar, por meio do método de elementos finitos (MEF), o comportamento mecânico das estruturas envolvidas em uma reabilitação implanto suportada de 4 elementos na região anterior de maxila, utilizando apenas 2 implantes, variando os posicionamentos dos implantes e o tipo de conexão protética (hexágono externo, hexágono interno e cone-Morse) e ainda validar metodologia de análise computacional por meio da interferometria holográfica, uma técnica experimental. Modelos tridimensionais baseados em um banco de tomografias computadorizadas foram criados para todas as situações estudadas (Implantes nos Incisivos Laterais - IL; Implantes nos Incisivos Centrais - IC e Implante no Incisivo Central e Incisivo Lateral - ILIC). Uma carga equivalente à 150N foi aplicada a 45° na região de cíngulo de cada elemento dentário. Para a validação da metodologia de elementos finitos por meio da interferometria holográfica, criou-se um modelo prototipado com as mesmas situações estudadas e comparou-se os deslocamentos direcionais resultantes da aplicação de 3 intensidades de força. Como resultado foi observado: o menor deslocamento da estrutura protética e maior deslocamento na estrutura óssea no grupo IC. No tecido ósseo, a tensão de von Misses localiza-se predominantemente na região cortical. O valor máximo de tensão de von Misses foi observado no implante vizinho ao cantilever no grupo ILIC. Na conexão cone Morse, o parafuso protético mostrou metade da tensão de von Misses em relação a conexão hexágono interno e hexágono externo. Comparando-se os deslocamentos direcionais nas duas metodologias, verificou-se que havia uma correlação positiva entre os resultados, porém os valores obtidos experimentalmente eram superiores aos do modelo computacional. Pode-se concluir...

The purpose of this study was to analyze, by finite element method (FEM), the mechanical behavior of structures involved in an implant supported rehabilitation of 4 elements in the anterior maxilla, using only 2 implants, varying the placements of the implants and prosthetic connection types (external hexagon, internal hexagon and Morse taper) Moreover to validate the methodology of MEF by holographic interferometry, an experimental technique. Three-dimensional models based on a database CT scans were created for all situations studied (Implants in Lateral Incisors - IL; Implants in Central Incisors IC and Implant in Central e Lateral Incisor - ILIC). An equivalent load of150N was applied at 45° in the cingulum of each tooth. To validate the finite element method by Holographic Interferometry, a prototyped model was created with the same situations studied and compared the directional displacements, resulting from the application of the 3 intensities of force. As results it was observed: the lowest prosthetic displacement structure and greater displacement in the bone structure in the IC group. In bone tissue, the von Mises stress is located predominantly in the cortical region. The maximum value of von Mises stress was observed in the implant neighboring to cantilever in the group ILIC. In Morse taper connection, the prosthetic screw showed half the von Misses stress in relation to internal and external hexagon connection. Comparing the directional displacement in both methodologies, an positive correlation between the results was found, although the experimentally values obtained were higher than those of the computational model. It can be concluded that the placement of implants and prosthetic connection type have influence in the intensity and distribution of stress/strain on the implant-supported rehabilitation of anterior...

Numerical simulation of LVAD inflow cannulas with different tips / 生物医学工程学杂志

The tip structure is one of the key factors to determine the performance of left ventricular assist device (LVAD) inflow cannulas. The tip structure influences the thrombosis, hemolysis in cannula and left ventricle and suction leading to obstruction in ventricle. We designed four kinds of inflow cannulas that had different tips and built the numerical models of the four historical used inflow cannulas inserted into the apex of left ventricle. We computed the hemodynamic characteristics of inflow cannulas insertion by Fluent software. We researched the backflow, turbulent flow and pressure distribution of the four inflow cannulas. The results showed that the trumpet tipped inflow cannula had smooth flow velocity distribution without backflow or low velocity flow. The trumpet tipped inflow cannula had the best blood compatibility characteristics. The trumpet structure could prevent obstruction. The caged tipped cannula had serious turbulent flow which could possibly cause thrombosis and the low pressure near left ventricle wall and easily lead to ventricle collapse. The trumpet tipped inflow cannula has the best blood compatibility and is difficult to be obstructed. The trumpet tipped inflow cannula is fit to long-term use LVAD.

Content-based automatic retinal image recognition and retrieval system / 生物医学工程学杂志

This paper is aimed to fulfill a prototype system used to classify and retrieve retinal image automatically. With the content-based image retrieval (CBIR) technology, a method to represent the retinal characteristics mixing the fundus image color (gray) histogram with bright, dark region features and other local comprehensive information was proposed. The method uses kernel principal component analysis (KPCA) to further extract nonlinear features and dimensionality reduced. It also puts forward a measurement method using support vector machine (SVM) on KPCA weighted distance in similarity measure aspect. Testing 300 samples with this prototype system randomly, we obtained the total image number of wrong retrieved 32, and the retrieval rate 89.33%. It showed that the identification rate of the system for retinal image was high.

Research progress of computational models of affecting factors for ventricular diastolic function / 生物医学工程学杂志

There have been insufficient numerical methods for particular description and quantitative evaluation of left ventricular diastolic function in the studies in this area. We therefore have summarized the computational models of the affecting factors for diastolic function from five aspects, i. e. the geometry shape of left ventricular, myocardial stiffness, myocardial viscosity, myocardial relaxation and ventricular interaction respectively. Controlling the sensitive parameters and having a mathematical description on left ventricular diastolic dysfunction can provide numerical methods for clinical diagnosis and quantitative evaluation of the disease.

Developing a model for analysis of uncertainties in prediction of floods

A realistic new sediment-laden water prediction computer model was developed. In this model unsteady non-uniform flow computations were incorporated. Using this model, flooding flow-sediments were simulated and compared to earlier research including hydrologic engineering centre [HEC-series] computer models. Uncertain value of parameters and errors in flow-sediment transport equation in existing coupled flow-sediment models were studied. Sensitive nonlinear flow-sediment terms simplified in linear models and state of non-uniform sediment laden flooding flows in loosed boundaries were considered. The new applied modeling of flooding sediment-water transport simulation was tested with data of three rivers and relative merits of the various techniques involved in full phases of flow-sediment in loosed boundaries for real river situations were discussed. Uncertain values of sensitive parameters were investigated through sensitivity analysis of flow-sediment parameters in three hydrologic catchments. Results of numerical analysis were compared to field observations relying on the accuracy of the developed model. Uncertainties and errors involved in; numerical scheme, hydraulic-sediment parameters, the out-reach output, flooding sediment-laden water characteristics, peak outflow, time increments, depth, speed of floods were found rather sensitive to the solution of problems. Computed grid size intervals and the peak outflows increased with space step and decreased with time step. Errors of in-reach parameters, the peak inflow hydrograph and roughness coefficient highlighted out-reach output

Impact of breast density on computer-aided detection (CAD) of breast cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the impact of breast density on computer-aided detection (CAD) for breast cancer and the CAD false-positive rate of normal controls.</p><p><b>METHODS</b>Two hundred and seventy-one histologically proven breast malignant lesions (from Feb. 2008 to Dec. 2009) and 238 randomly selected normal cases were classified by mammographic density according to the American College of Radiology breast imaging reporting and data system (BI-RADS). Mammograms of BI-RADS 1 or BI-RADS 2 density were categorized as non-dense breasts, and those of BI-RADS 3 or BI-RADS 4 density were categorized as dense breasts. Full-field digital mammography (GEMS Senographe) were performed in all patients and controls with craniocaudal (CC) and mediolateral oblique (MLO) views. Then the image data were transferred to review workstation (SenoAdvantage), and the lesions were marked by Second Look Digital CAD system (version 7.2, iCAD). The differences of sensitivity and false-positive rate between dense and non-dense breasts were compared.</p><p><b>RESULTS</b>Overall, the sensitivity of CAD in detection of cancers was 84.1% (228/271), there was a statistically significant difference in CAD of cancers in dense versus non-dense breasts (P = 0.015). The sensitivity of CAD in detection of mass cancers was 76.5% (186/243), in detection of calcification cancers was 79.1% (125/158), there was no statistically significant difference in CAD performance for the detection of mass cancers versus calcification cancers (P = 0.547). There was a significant difference in the CAD performance for the detection of mass cancer cases in non-dense versus dense breasts (P = 0.001), but no significant difference in the CAD for the detection of calcification cancers in non-dense versus dense breasts (P = 0.216). In the controls, the distribution of mass false-positive marks did not differ significantly between non-dense and dense breast tissue cases (P = 0.207), but the distribution of calcification false-positive marks differed significantly between non-dense and dense breast tissue cases (P = 0.001). There was a statistically significant difference of false-positive marks in non-dense versus dense breasts (P = 0.043).</p><p><b>CONCLUSIONS</b>The sensitivity of CAD in the detection of breast cancers is impacted by breast density. There is a statistically significant difference in the CAD performance for the detection of cancer cases in non-dense versus dense breasts. The false-positive rate of CAD is lower in dense versus non-dense breasts. It appears difficult for CAD in the early detection of breast cancer in the absence of microcalcifications, particularly in dense breasts.</p>

Predication of Parkinson's disease using data mining methods: A comparative analysis of tree, statistical, and support vector machine classifiers.

The prediction of Parkinson's disease in early age has been challenging task among researchers, because the symptoms of disease came into existence in middle and late middle age. There are lots of symptoms that lead to Parkinson's disease. But this article focuses on the speech articulation difficulty symptoms of PD affected people and try to formulate the model on the behalf of three data mining methods. These three data mining methods are taken from three different domains of data mining i.e., from tree classifier, statistical classifier, and support vector machine classifier. Performance of these three classifiers is measured with three performance matrices i.e., accuracy, sensitivity, and specificity. Hence, the main task of this article is tried to find out which model identified the PD affected people more accurately.

Numerical evaluation of new control method for schistosomiasis / 生物医学工程学杂志

Schistosomiasis is a kind of common disease around the riverside or lakeside areas, especially popular in rural areas, and causes huge economic loss. Based on existing schistosomiasis dynamic models and data, a new method of working out coefficients, and an improved model were provided in our study. The improved model can be applied to the study of the characteristics of transmission of schistosomiasis, and the effect of new control methods for schistosomiasis was evaluated.

3-Dimentional numerical simulation on internal flow and mixing process of an anesthesia vaporizer / 生物医学工程学杂志

The function theory of an anesthesia vaporizer was studied and the geometry configuration was measured in this study. The internal gas flow and mixing process in the anesthesia vaporizer were simulated using CFD method. Applying tracking in turbulent flow to stochastic particle, for the droplet of anesthesia drug, the moving track of droplet was traced. Based on the results, the internal gas flow variation, the concentration distribution of anesthesia drug volatilization process and mixing process with gas were ascertained. Numerical simulation results showed that, the diluted gas velocity reduction of internal flow in the anesthesia vaporizer was higher. Because of the anesthesia vaporizer geometry, the mixing process between anesthesia drug vapor and diluting gas was not homogeneous. This also influenced the stability and accuracy of anesthesia drug concentration. The optimization precept of anesthesia vaporizer is ascertained.

Numerical simulation of the distribution of shear stress on the bottom of parallel plate flow chamber under different inlet velocity conditions / 生物医学工程学杂志

The distribution of shear stress on the bottom of the parallel plate flow chamber under different inlet velocities was analyzed by numerical simulation. In the present experimental study, the projection planes of the relative errors at 0.7% level were obtained, and then the efficient region and the actual entrance length were further corrected by introducing the concept of relative error. The results showed that the efficient region of the chamber increased with the direction of length while the inlet velocity was increased, and the actual entrance length was much greater than that of the theoretical entrance length. Therefore, in accordance to the needed range of shear stress in experiment and to the needed efficient region area, the optimum design of the flow chamber is necessary.

The encoding and reconstruction of parallel MRI / 生物医学工程学杂志

The advent of parallel MRI over recent years has prompted a variety of techniques for performing parallel imaging. The main distinguishing feature among these is the specific way of solving the problem of image reconstruction from undersampled multiple-coil data. The clearest distinction in this respect is that between k-space method and image-domain method. The present paper reviews the basic reconstruction approaches, aiming to emphasize the common principles along with actual differences. To this end the treatment starts with an elaboration of the encoding mechanisms and sampling strategies that define the reconstruction task. Based on these considerations, the distinction between k-space and image-domain approaches is given. At the close of this paper are presented discussioins concerning noise propagation and control in parallel imaging and an outlook upon key issues to be addressed in the future.

Quantificação computadorizada dos índices de placa e cálculo dentais da imagem digital da superfície vestibular dos dentes de cães / Quantification computed indices card and calculation dealers of the digital picture of vestibular surface of teeth of dogs

A doença periodontal é causada pelo acúmulo de placa bacteriana sobre os dentes e estruturas adjacentes. Para sua mensuração têm sido formulados índices que consideram a quantidade e intensidade de placa bacteriana (PB) e de cálculo dental (CD) existentes na superfície dentária por meio de avaliação visual subjetiva. O presente estudo tem como objetivo avaliar o método de análise computadorizada para medição de área de PB e CD nos dentes de cães através da comparação com a avaliação visual. Foram utilizados 10 cães Beagles, três machos e sete fêmeas, com similares características e mantidos sob o mesmo manejo e dieta alimentar. As avaliações das superfícies vestibulares dos dentes ocorreram antes da profilaxia dentária, que foi realizada sob anestesia geral inalatória, e após sete dias para PB e após 28 dias para CD. A avaliação computadorizada da área de CD demonstrou ser estatisticamente melhor em relação à avaliação visual antes e após a profilaxia; entretanto, não demonstrou diferença significante na avaliação da PB. Concluiu-se que a avaliação computadorizada é vantajosa em relação à visual por conferir maior precisão na obtenção da proporção entre área total do dente e área acometida, mostrando-se estatistticamente superior na quantificação do CD após 28 dias.

Periodontal disease is caused by dental plaque accumulation on teeth and adjacent structures. Indices have been formulated for its measurement considering the amount and intensity of dental plaque (DP) and dental calculus (C) on the surface of teeth through subjective visual evaluation. This study aims at assessing the computerized analysis method for measurement of DP and C areas on the teeth of dogs by comparing it with the visual evaluation in the oral cavity. Ten beagle dogs with similar characteristics and kept under the same management and diet were used. Evaluations of oral cavity occurred before surgical prophylaxis (performed under general inhalation anesthesia) and after seven days for DP and 28 days for C. The computerized C area evaluation showed to be statistically better than the visual evaluation before and after prophylaxis. It was concluded that the computerized evaluation is beneficial when compared to visual evaluation, providing greater precision in the area measurement.

Simulação numérica tridimensional da mecânica do joelho humano / Three-dimensional numerical simulation of human knee joint mechanics

OBJETIVO: Por ser a articulação mecanicamente mais solicitada de nossa estrutura e pelo grande número de lesões associadas, motivaram a construção de um modelo tridimensional da articulação do joelho humano para simular a cinemática da articulação e obter as solicitações mecânicas nos principais ligamentos durante o movimento de flexão do joelho. Essas informações podem futuramente ser empregada como ferramenta de apoio à decisão médica em ortopedia, fornecendo subsídios na escolha do procedimento cirúrgico. MÉTODOS: Método dos Elementos Finitos foi utilizado para construir um modelo biomecânico, tridimensional, da articulação do joelho. Nesse modelo com seis graus de liberdade é aplicado movimento de flexão/extensão sendo os demais cinco graus de liberdade governados pelas interações entre os componentes da articulares. RESULTADOS: Foram obtidas informações dos movimentos, das rotações interna/externa e adução/abdução, das translações anterior/posterior, lateral/medial e superior/inferior e dos esforços nos quatro principais ligamentos articulares, no decorrer de um amplo movimento de flexão/extensão. Estes valores foram comparados, de forma qualitativa, com valores equivalentes obtidos na literatura. CONCLUSÃO: A análise de resultados permitiu observar que vários aspectos cinemáticos são satisfatoriamente reproduzidos. A pré-carga inicial dos ligamentos e o posicionamento das inserções ligamentares no modelo mostraram-se variáveis relevantes nos resultados.

OBJECTIVE: The knee joint is the part of our structure upon which most mechanical demands are placed and a large number of lesions are associated to it. These factors motivated the construction of a three-dimensional model of the human knee joint in order to simulate joint kinematics and obtain the mechanical demands on the main ligaments during knee flexion movements. METHODS: The finite elements method was used to build a three-dimensional, biomechanical model of the knee joint. In this model with six degrees of freedom, the flexion/extension movement is applied, while the other five degrees of freedom are governed by the interactions between joint components. RESULTS: Data was collected on the movements, on the internal/external and adduction/ abduction rotations, on the anterior/posterior, lateral/medial and upper/lower translations, and on the forces acting upon the four main joint ligaments, during a wide flexion/extension movement. These values were qualitatively compared with comparable values available in the literature. CONCLUSIONS: It was observed through an analysis of the results that several kinematic aspects are satisfactorily reproduced. The initial pre-load of the ligaments and the positioning of the ligament insertions in the model were shown to be relevant variables in the results.

The association between lower incisal inclination and morphology of the supporting alveolar bone--a cone-beam CT study / 国际口腔科学杂志·英文版

<p><b>AIM</b>To investigate the relationship between the positioning of the lower central incisor and physical morphology of the surrounding alveolar bone.</p><p><b>METHODOLOGY</b>Thirty-eight patients (18 males, 20 females), with mean age of 13.4 years, were included in this study. As part of orthodontic treatment planning the patients were required to take dental Cone-beam CT (CBCT) covering the region of lower incisors, the surrounding alveolar bone and the mandibular symphysis. The cephalometric parameters were designed and measured to indicate the inclination of lower central incisor and physical morphology of the adjacent alveolar bone. Computer-aided descriptive statistical analysis was performed using SPSS 15.0 software package for Windows. A correlation analysis and a linear regression analysis between the incisor inclination and the alveolar bone morphology were performed.</p><p><b>RESULTS</b>Significant positive correlations were found between the lower central incisor inclination and the morphological contour of the alveolar bone (P < 0.05). The lower central incisor root apex was closer to the lingual alveolar crest when it was buccally inclined.</p><p><b>CONCLUSION</b>The morphology of the alveolar bone may be affected by incisal inclination.</p>

Effect of agitation on hyaluronic acid produced by Streptococcus zooepidemicus by using computational fluid dynamics / 生物工程学报

Agitation plays an important role in the hyaluronic acid (HA) fermentation process. However, views about the effect of agitation on HA production remain controversial. We investigated the effect of agitation on cell growth and HA synthesis during HA fermentation process by using Computational Fluid Dynamics (CFD) technology. The results showed that the biomass and HA yield changed a little with the increase of impeller speed, but the HA molecular weight firstly increased and then decreased. The results of phase agitation control strategy demonstrated that the influence of agitation on the HA molecular weight mainly exhibited at the stage of HA synthesis. Moreover, the CFD simulation results indicated that when impeller speed increased, the mixing time reduced while the shear rate increased significantly. The removal of anchor could moderate the contradiction between the mixing time and shear rate, and finally the HA molecular weight increased by 23.9%. The results of this work could provide guidelines for optimizing the HA fermentation, as well as the bioreactor design and scaling up.

Algorithm of brain pathology detection based on statistical atlas of attribute vectors / 中国医疗器械杂志

To detect lesions of brain CT automatically, a statistical atlas of attribute vectors (SAAV) was designed and created to describe the multiple features of medical images. By comparing the features of study image with those of SAAV, we successfully detected various kinds of brain lesion. It was demonstrated that the algorithm is effective in detecting various kinds of lesions found on brain CT images. Further studies are needed to make the algorithm more acceptable.