Biomedical Engineering, Vol. 38, No. 3, 2004, pp. 109-111. Translated from Meditsinskaya Tekhnika, Vol. 38, No. 3, 2004, pp. 3-6. Original article submitted February 5, 2004.
Integration of Basic and Applied Biomedical Engineering Research at the Department of Biomedical Systems of Moscow State Institute of Electronic Engineering1 S. V. Selishchev
branches on the basis of the Scientific-Research Institute for Medical Instrument Engineering, Russian Academy of Medical Sciences (VNIIMP). For example, an education and research center was established by the Moscow State Institute of Electronic Engineering (MIET) on the basis of the Scientific-Research Institute for Medical Instrument Engineering. The year 2003 marked the 10th anniversary of the joint education and research center MIETVNIIMPVITA. Integration of basic and applied biomedical engineering research at the Department of Biomedical Systems of Moscow State Institute of Electronic Engineering is based on high standards of higher education in Russia in the fields of biomedical electronics and biomedical engineering. The results underlying these studies were summarized in special issue of the monthly journal Biomedical Technology and Electronics, 2001, No. 12. In 2002-2003, the process of integration of basic and applied biomedical engineering research at the Department of Biomedical Systems of Moscow State Institute of Electronic Engineering proceeded in two main directions: basic physical principles of biomedical systems for diagnosis, therapy, and surgery; optical methods of imaging; computer tomography; neuronal networks; interaction of high-power optical radiation with biological media; acoustic methods; and mechanisms of cardiac defibrillation; biomedical electronics and biomedical computer technologies: analysis and processing of biomedical signals and images; development of hardwaresoftware complexes for physiological information acquisition and processing, photometric devices, external electric defibrillators, and high-current generators with digital control.
Biomedical engineering was formed as an independent field of science and technology in the XX century [1, 2]. The year 2002 marked the 50th anniversary of the International Engineering in Medicine and Biology Society IEEE. Our prominent compatriot, V. K. Zvorykin (1889-1982), played an important role in foundation and development of this society [4]. The history of biomedical engineering in Russia is closely associated with VNIIMP-VITA Ltd. (Scientific-Research Institute for Medical Instrument Engineering, Russian Academy of Medical Sciences). The history of the Institute dates back to 1936, when the Central Scientific-Research Laboratory for Medical Instrument Industry (TsNIL) was founded in Moscow. This laboratory was established by resolution of the Council of Peoples Commissars of the USSR (1936). Since 1977, VNIIMP has been being headed by Academician V. A. Viktorov. Under the supervision of V. A. Viktorov, the All-Union Scientific-Research Institute for Medical Instrument Engineering (VNIIMP) was reorganized both in terms of economy and in terms of scientific research. New areas of research include development of diagnostic systems, computerization, and systemic approach in biomedical research and public health [3]. The major areas of VNIIMP-VITA activity also include organization of educational centers in biomedical engineering. Many universities and institutes opened
Moscow State Institute of Electronic Engineering, Zelenograd, Moscow, Russia; E-mail:
[email protected] 1
This issue of Biomedical Engineering presents the results of basic and applied research obtained at the Department of Biomedical Systems of Moscow State Institute of Electronic Engineering.
109 0006-3398/04/3803-0109 2004 Springer Science+Business Media, Inc.
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Basic Physical Principles of Biomedical Systems for Diagnosis, Therapy, Surgery, and Special Applications The following results were obtained: mathematical principles and algorithms of combined reconstruction of two independent spatial patterns of distribution of light scattering and extinction coefficients in biological media for optical transmission computer tomography based on nonstationary two-flux model of radiation propagation; effect of light refraction and reflection on quality of reconstruction of images; experimental evidence of separation between scattered and ballistic photons in model medium. These results provide a promising approach to development of new diagnostic systems for mammography and neonate brain hypoxia. The first theoretical, numerical, and experimental data were obtained in the field of ultrasonic elastography intended to visualize tissue deformation pattern and detect postcompression ultrasonic signals. Mathematical methods of neuronal network computer segmentation of biomedical images were developed on the basis of both conventional neuronal networks and reverse propagation neuronal networks. The segmentation accuracy was about 82% of expert estimates. New mechanisms of interaction of high-power optical radiation with biological media were suggested. These studies allow eyes and sensitive optical sensors to be protected. Four classes of organic compounds were found to provide effective nonlinear mechanisms of optical radiation limitation: styrene-substituted pyranes, cyanin compounds (cardiogrins), porphyrins, and phthalocyanins. Laser radiation extinction coefficient dependence on laser radiation wavelength and intensity was studied. Limitation of medical laser radiation was suggested as a safety measure for protecting biological tissues outside the operation field. Principles of computer based acquisition and processing of photometric and colorimetric data, as well as corresponding algorithms were developed on the basis of the sliding mean method for weak photometric signal. It was shown that algorithms of diametrical and multichord acoustic models provided high accuracy (~1.5-2%) of determination of the profile of liquid flow across a tube. An effective hydrodynamic model of liquid or gas flow provides an additional tool for ultrasonic studies of disturbed flows. Mathematical algorithms of biomechanical activity monitoring provide methods of study of human cardiac activity in spaceflight conditions.
Selishchev
A new mechanism of passive propagation of cardiomyocyte transmembrane potential in myocardium was suggested to provide a deeper insight into physical principles of cardiac defibrillation. This mechanism is due to the presence of intrinsic electric capacity of myocardium electrolytes, rapid charge diffusion along bioelectrolytes, and additional contribution to transmembrane potential. Biomedical Electronics and Biomedical Computer Technologies The following results have been obtained: a new method of analysis and processing of biomedical information has been suggested. This method provides enhanced resolution and improved diagnostic capacity of ultrasonic imaging on the basis of additional computer processing of signals and images and digital subtraction of probing signal from echo-signals of acoustic scanning. H erot It was shown that this method not only enhanced resolution and improved diagnostic capacity of ultrasonic imaging but also revealed otherwise invisible structures. This procedure can be recommended for additional processing or postprocessing of acoustic scanning data about visually located structures intended to resolve fine structure. New algorithms have been developed for 3D-reconstruction and synthesis of biomedical objects. Graphical interactive 3D-reconstruction and further postprocessing was performed in IDL medium. Both well-known SheppLogan phantoms and actual clinical data obtained at the Herzen Research Institute of Oncology were used as the initial data. Clinical data were obtained in the DICOM standard (Digital Imaging and Communication in Medicine). A distributed hardwaresoftware complex for real time physiological information acquisition and processing has been developed. This system implements principles of dynamic connection and distribution of computation on the basis of the Complex Object Model (COM+) approach. A family of multichannel systems (ECG, EEG, Holter monitor, and polygraph) of biomedical data acquisition and processing has been developed on the basis of the Sigma-Delta analog-to-digital converters (ADCs). The increasing use of digital techniques in biomedical data acquisition systems also contributed to recent interest in cost effective high precision ADCs. Sigma-delta modulation-based analog-to-digital conversion technology is cost effective alternative to high resolution (greater than 12 bits) converters. This reduces requirements for input
Biomedical Engineering Research at MIET
signal bandwidth. Conventional high-resolution ADC, such as successive approximation and flash type converters, require a complicated analog low-pass filter (often called an anti-aliasing filter) to limit the maximum frequency input to the ADC. On the contrary, sigmadelta ADCs use a low resolution ADC with 1-bit quantizer, noise shaping, and very high oversampling rate. An experimental model of monitor of human cardiac activity in spaceflight conditions was developed on the basis of measurement of pulse-related displacement of the cosmonauts body during sleeping. The monitor provides continuos recording and saving of ballistocardiogram during 8 h. Mathematical algorithms of biomechanical activity monitoring and processing were developed. Terrestrial tests of the experimental monitor model were carried out. A microprocessor information and computation system (MICS) has been developed and metrologically tested. This system was used in an experimental photometric device designed to measure the following optical characteristics of liquids within wavelength range from 300 to 1000 nm: transmission coefficient, optical density, rate of optical density changes, solution concentration, and kinetics of enzymatic activity. Experimental models of external electric defibrillators and monitors of electric pulse shape were developed. These devices are based on measurement of patient body resistance and they are powered from 220-V power line or a battery (2.3 A⋅h). The control unit of the defibrillator controls power source unit, high-voltage unit, display, ECG thermorecorder, and data exchange with an external computer. A visualization module implements indication of patient ECG and defibrillation mode. It also provides data processing about the state of the organs of defibrillator control. ECG thermorecorder implements recording of patient ECG on thermal paper. Two sets of electrodes can be used: defibrillator electrodes and external cardioelectrodes. Defibrillation pulses are generated in the high-voltage unit. After the high-voltage unit is on, the defibrillation system undergoes self-diagnosis procedure. Defibrilla-
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tion pulse energy of 5, 10, 25, 50, 75, 100, 150, and 200 J is available within patient resistance range from 25 to 150 Ω. Current pulse envelope mode provides patient resistance decrease up to short-circuiting and positive phase current pulse amplitude up to 50 A. The first stage of development of a portable electrical cardioverteradefibrillator has been accomplished. This device should be constantly carried by a patient during a long period of time and provide automatic restoration of cardiac rhythm in case of appearance of life-threatening arrhythmia. A microelectronic pulse high-current generator with digital control has been developed. The power unit of this device is connected through a low-pass LC-filter rejecting high-frequency components of broad-pulse modulation. A series resistor and a parallel resistive divider are used as current and voltage sensors, respectively. The output signals of the sensors through scaling units are applied to a feedback control circuit of the high-voltage unit. The resulting output voltage of the high-voltage unit is brought to the level of power of a reference curve generator. Different shapes of generator output voltage pulse can be obtained by varying the signal shape of the generator of reference power curve. I am grateful to the Editorial Board of Biomedical Engineering for the opportunity to present the results of biomedical engineering research obtained at the Department of Biomedical Systems of Moscow State Institute of Electronic Engineering in a special issue of the journal. REFERENCES 1. 2.
3. 4.
V. A. Viktorov, Vestn. RAMN, No. 5, 3-7 (2001). V. A. Viktorov, S. V. Selishchev, and M. B. Shtark, Abst. Int. Conf. Biomedpribor-2000, Vol. 1, Moscow (2000), pp. 10-13. Med. Tekh., No. 1, 3-11 (2003). F. Nebeker, IEEE Eng. Med. Biol. Mag., 21, No. 3, 1747 (2002).
