Computerized intermediate-frequency therapy apparatus is a kind of widely-used clinical equipment. This paper is to indicate the principle and design method of the central control system based on USB for computerized intermediate-frequency therapy apparatus. With this system, the labor intensity, work efficiency and therapeutic efficacy can all be improved.

Objective To study a semi-automatic segmentation framework for children's brain MRI image ( weighted), which is capable of identifying the different structures of children's MRI images by using the histogram analysis and morphological operations. Methods The framework consisted of four-step segmentation procedures. First, the non-brain structures removal was addressed to obtain the mask of encephalon, then the brain stem and cerebellum were separated respectively from the encephalon mask, and finally, two hemispheres were separated. Results The method behaved well in the segmentation of MRI images of the brain stem, cerebel and two brain hemispheres. Conclusion The method gave the good segmentation results in the children MRI image aging from 5 to 15 years old.

Obiective To develop a new medical image processing platform based on ITK and OpenGL. Methods This platform was designed by VC ++ 6.0 and MFC class library. ITK class library was wsed to fulfill reading, writing,segmentation of images and iso-surface extraction. OpenGL was wsed to realize 3D surface rendering. Results The new 3D-medical imaging reconstruction system was designed. Conclusion This system not only can provide graphic interface which can not be realized by using ITK class library, but also enhance the ability of three-dimension visualization by using OpenGL.

Objective To understand the effects of environmental pollution on blood lead levels of children.Methods The blood lead levels of605children aged2-7in6urban districts of Harbin and307children aged2-7in Jixi were deter-mined by graphite furnace atom absorption spectrophotometry during the period from April to June in1999.Results The data on blood lead levels of children in two cities showed both positive skewness distribution.The geometric means of blood lead lev-els of children were0.354?mol/L in Harbin and0.441?mol/L in Jixi,the medians were0.369?mol/L in Harbin and0.440?mol/L in Jixi,the values of P 95 were1.575?mol/L in Harbin and1.304?mol/L in Jixi.The children with blood lead levels of≥0.483?mol/L accounted for44.5%of total observed in Harbin and44.9%in Jixi.Conclusion Environmental lead pollution had coused potential adverse effects on preschool children health.

BACKGROUND:The electrical impedance tomography (EIT) is a kind of examination that is used to non-invasively measure the change and distribution of electrical bio-impedance by reconstructing the frequency response obtained by electrical stimuli applied onto the human body. The characteristics of impedance of any tissues are of great importance to the imaging of EIT and locating and monitoring the lesion focus.OBJECTIVE: To measure the human brain impedance in the frequency range from 0.1 Hz to 1 MHz and to compare these with those of other human tissues and the rabbit brain tissues.DESIGN: An observational experiment.SETTING:The Department of Medical Electric Engineering of the Biomedical Engineering College of the Fourth Military Medical University of Chinese PLA.MATERIALS:The experiment was conducted at the Otolaryngology Laboratory, Department of Medical Electric Engineering of Biomedical Engineering College, Fourth Military Medical University of Chinese PLA from April, 2000 to June, 2000. Two brains were harvested from two cadavers of adult men who died in less than 12 hours before the brains were taken.INTERVENTIONS :The brains were divided into 15 samples and the Solartron 1255B frequency resoonse analyzer was used to measure the complex impedance of human brain in vitro with four-electrode measurement method in the frequency range from 0.1 Hz to 1 MHz.There were also impedance interface (1294)and self-made experimental measurement box.MAIN OUTCOME MEASURES:The resistivity frequency response,curves of real part and imaginary part of complex impedance as well as the equivalent circuit model of the complex impedance.RESULTS:The resistivity of human brain tissues was about 1 200 Ω·cm in the frequency range of 0.1-100 Hz.But it decreased to 650 Ω·cm in the frequency range of 100-1×106 Hz. The real part of complex impedance remained steady in the frequency range of 0.1-100 Hz and it decreased along with the increase of frequency in the range of 100-1×106 Hz. The absolute value of frequency response curves of the imaginary part of human brain's complex impedance presented a tendency of monotonic increase.CONCLUSION: The resistivity and the real part of complex impedance curve of human brain were in accordance with those of other tissues such as muscles, the liver, kidney and lungs. The frequency response curve of the imaginary part of human brain's complex impedance was different from that of other animal tissues (such as muscles, the liver and kidney) but was in accordance with that of rabbit brain tissues in vitro. The construction of the equivalent circuit model obtained was more complex than other models known.

Breast cancer is one of the most common malignant tumours in women. It threatens the health and life of women. The imaging technology of breast electrical impedance scanning based on the dielectric properties of breast tissues develops a new aspect of early detection and auxiliary diagnosis of the breast cancer. The dielectric properties of human breast tissues reflect the pathological and physiological state of breast tissues and the measurement of these properties serves as the basis for electrical impedance scanning(EIS) technology. In this paper, the measurements and results of dielectric properties of human breast tissues are discussed, and the problems of measurement and the application perspective of the EIS are also explored.

Objective To explore the clinical value of real-time three-dimensional echocardiography (RT-3DE) in percutaneous transcatheter closure treatment of atrial septal defect (ASD). Methods The sizes,shapes and sites of ASD were visualized by RT-3DE and measured by full volume rendered three-dimensional echocardiography (3DE) before operation and after closure operation in 11 ASD patients,and compared with those from two-dimensional echocardiography(2DE) and the operation. Results Before the operation,RT-3DE visualization showed that the secundum ASD′s sites of the 11 patients were central and shapes were mostly ellipse. In this study a significant difference was found in the measurements of long distances of ASD between 3DE and 2DE [( 28.9 ? 8.2 )mm vs ( 20.0 ? 7.3 )mm,P 0.05 ]. Maximal diameters of defects measured by 2DE[( 21.1 ? 3.5 )mm,P

Objective To understand the influential factors for blood lead level of children in Harbin.Methods The lead level in the air,dust,vegetables and the blood of 605 children aged 2-7 years were determineded and family fitment,fuel combustion,the food consumption were investigated.Results The lead contents of air,dust in pollutant areas [(2.037?0.455)?g/m3,(84.000?0.015)mg/kg] were higher compared with the control areas[(1.017?0.595)?g/m3,(72.000?0.025)mg/kg],the differences were significant(P

BACKGROUND: Electrical impedance tomography (EIT) uses non-invasive signals to probe the human body and then detect the responses on the boundary of the body in order to reconstruct an impedance distribution inside the body. Compared to CT and MRI, EIT takes the advantages of realtime technique, lower cost and easiness for both continuous monitoring and functional imaging.OBJECTIVE: This study was designed to perform the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia. And it was to verify the feasibility of EIT in brain functional imaging by ischemia brain functional imaging using EIT.DESIGN: It was a single-sample experiment.SETTING: It was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA.MATERIALS: This study was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA from August to September 2001 and 10 healthy rabbits were selected.METHODS: Cerebral ischemia animal model was made using carotid artery ligation. Then the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia was performed.Dynamic unilateral brain blood supply was recorded using EIT imaging.curves were plot before and after ischemia in the frequency range from 0.1 Hz EIT imagingRESULTS: Nine rabbits entered the statistical analysis and one was omitimpedance increased significantly. The ratio of increasing impedance can be up to 75% at frequencies lower than 10 Hz. And in the range from 1 kHz namic imaging showed that the changes in unilateral brain blood supply is accordant with the corresponding regions having a changing impedance.CONCLUSION: The changes in brain tissue impedance before and after ischemia can be imaged and it could be used as a variable for EIT imaging.

The communication between the students and the teacher was introduced from three aspects of foregone course, communication channel as well as homework and experiment. The individualized teaching mode was described involving expounding common difficulty, assigning and reading over the homework, individualized tutoring after school, on-line responding to the student's question, prompting the student to complete programming and answering questions in evening classes. It's pointed out that the individualized teaching has to take both common knowledge and student difference into considerations. Individulized mode enhances the teaching efficacy greatly.