Russian Academy of Sciences
Institute of Applied Physics

Division of
Radiophysical
methods in medicine

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Русская версия
IAP RAS
E-mail:
603950, Nizhny Novgorod, 46 Uljanov str.
Phone: (7 8312) 36-56-60 FAX: (7 8312) 36-37-92


ULTRASONIC METHODS TO STUDY BIOLOGICAL SYSTEMS.

The design of ultrasonic locational methods to study structures and motion of heart, vessels and blood was started in early 70th. Together with leading medical and industrial organizations we successfully designed first USSR pulsed echocardiograph UZKAR-3 for investigation of heart structures, pulsed Doppler echocardiograph UZKAR-D allowing to measure velocities of selected heart structures and blood flow velocities in large vessels, as well as ultrasonic device VETER based on the nonlinear wide-band scattering and intended to detect the stationary gas bubbles in tissues during decompression sickness of divers and astronauts. UZKAR-3 was put into commercial production and was widely used in clinical practice up to 90th. UZKAR-D allowed performing a row of scientific medical investigations. Its modifications were used in fundamental investigations on turbulence development and control in model uniform and pulsed shear flows. A series of precision ultrasonic phase vibrometers was designed for visualization and non-influence measurement of vibration fields on the surface of biological and physical objects.

The new electronics and personal computers appeared in late 80th and allowed to start investigations in new directions.
The principles and software were designed to attach ultrasonic transceivers with PC. It provided a new technology of design and manufacturing of hardware and software systems for ultrasonic medical diagnostics. We avoided to use signal processors converting the most part of device functions, information processing and imaging in real time t the sotware. This software was style-unified for all systems, containing internal functions of information storing and document management including preparation of protocols and on-line reference.
The designed ultrasonic echocardiograph, echoencephalograph, Doppler CW and PW blood flow meters for peripheral and intracranial blood flow are now stock-produced by MEDUZA company and are successfully applied in clinics.

A long-term fruitful cooperation with Institute of Medical and Biological Problems and ZVEZDA scientific industrial association allowed us to develop the unique technology of monitoring of decompression processes in human blood flow during extra-vehicle activity in outer space. The designed midget pulsed Doppler locator can operate in low atmospheric pressure (including oxygen atmosphere) and allows reliable detection of gas bubbles in right ventricle providing high noise-immunity during physical loads of person in space suit.

The significant increase of sensitivity of ultrasonic receivers (due to new electronic components as well as due to signal preprocessing) allowed to design method of acoustic thermotomography. Its principles are similar to those of well-known methods of infra- red and radio thermometry - the receiving of radiation produced by heated body. Acoustic emission of heated objects is registered in wavelength range 0.15-1.5 mm, providing high antenna directivity. The application of sub-millimeter waves in radiothermometry is limited by strong absorption.
First experiments on registration of acoustic radiation and acoustic brightness temperature were carried out in IRE RAS in 1987. First experiments on localization of heated bodies were performed in our institute. First computer-based scanning acoustic thermotomograph with multi-element acoustic antenna was designed and first 2D thermal images were obtained. After development of clinical method these devises will be useful in mass screening of population (e.g. for early tumor detection) and for testing of treatment efficiency (in tumor hyperthermy or pharmacological testing).

The designed high-sensitivity acoustic receivers were applied also for optoacoustic investigations of biological tissues based on tissue irradiation by short laser pulse and receiving of acoustic signal generated during absorption of optical radiation by tissue. In this case one can visualize the objects inside the tissue being weakly acoustically contrast in respect to surrounding tissues and having different absorption coefficient in optical range. The application of relatively low-frequency receivers (1 to 8 MHz) allowed to increase significantly the reception depth keeping rather good spatial resolution. First 2D low-frequency tomograms of tissue samples were also obtained.