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Biomedical Engineering, IEEE Transactions on

Issue 10 • Date Oct. 1989

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Displaying Results 1 - 9 of 9
  • Three-dimensional electromagnetic power deposition in tumors using interstitial antenna arrays

    Publication Year: 1989 , Page(s): 977 - 986
    Cited by:  Papers (11)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (906 KB)  

    A three-dimensional model of a tumor of arbitrary shape subjected to the fields of an interstitial antenna array is developed to predict the EM power deposition in an inhomogeneous tumor-tissue medium. The volume integral equation for the imbedded tumor is developed and solved by the method of moments. The incident fields are calculated based on the available formulation of interstitial antennas in homogeneous media. The accuracy of the developed computer code was checked by comparing the results from the volume integral approach with the Mie solution for the special case of spherical tumors. Good comparison was obtained for tumors with properties approximately 25% different from those of the surrounding tissue. Comparisons of results from models of antenna arrays with and without imbedded tumors show significant differences in their predictions of the EM power deposition in the tumor. The developed inhomogeneous model was used to examine the feasibility of controlling the uniformity of the power deposition pattern in large tumors by adjusting the amplitude or relative phase between the array elements. View full abstract»

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  • Evaluation of a semi-cylindrical solenoid as an applicator for radio-frequency hyperthermia

    Publication Year: 1989 , Page(s): 987 - 994
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (826 KB)  

    A modified solenoid having a semicircular cross section is evaluated as an applicator for radio-frequency heating of biological materials. The operating efficiency of this applicator and the distribution of the electric field established within a simulated biological sample are determined for a number of modes of excitation. It is shown that uniform heating to a substantial depth is possible at efficiencies in excess of 80%. View full abstract»

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  • A quasi-static model for the ring capacitor applicator

    Publication Year: 1989 , Page(s): 995 - 1003
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (777 KB)  

    An investigation of the electromagnetic heat dissipation in a radially layered biological tissue inside a ring capacitor applicator is discussed. A quasi-static model is introduced to compute the relevant electromagnetic field quantities. The method of computation uses the spatial Fourier transform of all field quantities with respect to the axial coordinate. After an iterative solution of a dual boundary value problem for the electric potential and the current density at the electrodes, an inverse Fourier transform is carried out to compute the quantities that are of interest to the deep-body system at hand. Comparison of numerical results with phantom measurements shows excellent agreement. View full abstract»

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  • The theoretical development of a multichannel time-series myoprocessor for simultaneous limb function detection and muscle force estimation

    Publication Year: 1989 , Page(s): 1004 - 1017
    Cited by:  Papers (17)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1301 KB)  

    The theoretical development and simulation of a complete time-series myoprocessor which provides reliable and economical predictions of both the magnitude and direction of limb motion from the spectral content of the surface EMG is discussed. Treating multiple channels of surface EMG as a vector-valued autoregressive process incorporates spatially distributed information which extends the operating range of parallel filtering limb function classifiers and reduces their sensitivity to modeling conditions. Active joint moment is estimated simultaneously from the pooled variance of the prewhitened EMG generated during the classification procedure. Estimation from the prewhitened sequence imposes no additional computational requirements and extends optimal myoprocessor to include multiple channels of serially dependent data. Such a system may be applied to the control of actively powered prostheses or orthoses. View full abstract»

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  • The experimental demonstration of a multichannel time-series myoprocessor: system testing and evaluation

    Publication Year: 1989 , Page(s): 1018 - 1027
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    A multichannel time-series myoprocessor which combines the advantages of the parallel filtering limb function classifiers of P. Doerschuk et al. (ibid., vol.BME-130, p.18-28, 1983) and the optimal myoprocessor muscle force estimators described by N. Hogan et al. (ibid., vol.BME-27, p.382-410, 1980) is discussed. Magnitudes and directions of knee movements were identified accurately and robustly from EMG sites intermediate to the major thigh muscles of intact individuals. Electrode placement criteria were tested, and system performance and sensitivity to contraction level as functions of channel number were computed. By including spatially distributed information into the structure of the processor, gains in accuracy and reliability over systems with fewer channels were demonstrated. Operating range increased with the number of channels included in the processor. Joint movement was estimated from multiple channels of temporally correlated data, extending and generalizing previously reported techniques. Identifying the parameters of autoregressive models of the EMG at low levels of contraction resulted in more robust classification and joint movement estimation. View full abstract»

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  • A parametric modeling of membrane current fluctuations with its application to the estimation of the kinetic properties of single ionic channels

    Publication Year: 1989 , Page(s): 1028 - 1037
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    A parametric autoregressive moving average (ARMA) signal modeling of membrane current fluctuations observed in biomembranes is described. Kinetic properties of single ionic channels contributing to membrane current fluctuations and the parameters of the corresponding ARMA process are explicitly related. The model is shown to be effectively applied to the estimation of the kinetic parameters of single ionic channels. Estimation of the parameters via ARMA signal identification is examined in detail for the basic closed-open scheme and the three-state sequential blocking scheme. The estimation accuracy of this method is theoretically evaluated. Computer simulation confirmed the validity of the proposed modeling and the effectiveness of the parametric method for the estimation of kinetic parameters when the model is applied to the estimation. The proposed modeling may form a theoretical base for the parametric analysis of membrane current fluctuations in a variety of kinetic schemes. View full abstract»

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  • On the numerical accuracy of the boundary element method (EEG application)

    Publication Year: 1989 , Page(s): 1038 - 1049
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1207 KB)  

    The numerical accuracy of the boundary element (BE) method used to solve the volume conduction problem of nested compartments, each having a homogeneous conductivity, is studied. The following techniques for improving this accuracy are discussed: the handling of the auto solid angle element Omega ii, the overall refinement of the level of discreteness, the use of a locally refined discrete grid, the isolated problem approach, and an adaptive refined computation of the discrete surface integrals involved in the BE method. The effects of these techniques on the numerical accuracy of the computed electrical potentials are illustrated by taking a volume conductor consisting of four concentric spheres representing the head since for this model an analytical (exact) solution is available. The techniques are of importance for numerically computed electroencephalograms (EEGs) since the numerically computed surface EEGs are severely affected by the relatively low conductivity of the compartment representing the skull. View full abstract»

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  • QRS feature extraction using linear prediction

    Publication Year: 1989 , Page(s): 1050 - 1055
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The use of linear prediction for analyzing digital ECG signals is discussed. There are several significant properties indicating that ECG signals have an important feature in the residual error signal obtained after processing by Durbin's linear prediction algorithm. The prediction order need not be more than two for fast arrhythmia detection. The ECG signal classification puts an emphasis on the residual error signal. For the QRS complex of each ECG, the feature for recognition is obtained from a nonlinear transformation which transforms every residual error signal to a set of three states pulse-code train relative to the original ECG signal. The pulse-code train has the advantage of easy implementation in digital hardware circuits to achieve automated ECG diagnosis. The algorithm performs very well in feature extraction in arrhythmia detection. Using this method, the studies indicate that the PVC (premature ventricular contraction) detection has at least 92% sensitivity for MIT/BIH arrhythmia database. View full abstract»

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  • Anthropomorphic cardiac ultrasound phantom

    Publication Year: 1989 , Page(s): 1055 - 1058
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB)  

    A phantom which simulates the human cardiac anatomy for applications in ultrasound imaging, ultrasound Doppler, and color-flow Doppler imaging is described. The phantom consists of a polymer left ventricle which includes a prosthetic mitral and aortic valve and is connected to a mock circulatory loop. Aerated tap water serves as a blood simulating fluid and ultrasound contrast medium within the circulatory loop. The left ventricle is housed in a Lexan ultrasound visualization chamber which includes ultrasound viewing ports and acoustic absorbers. A piston pump connected to the visualization chamber by a single port pumps degassed water within the chamber which in turn pumps the left ventricle. Real-time ultrasound images and Doppler studies measure flow patterns through the valves and within the left ventricle. View full abstract»

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Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

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Editor-in-Chief
Bin He
Department of Biomedical Engineering