gh DIAGNOSTICIAN LASER

The unique device was designed by the physicists of the International Scientific and Educational Laser Center (Lomonosov State University, Moscow). The device is called laser-acoustic tomograph, it is intended for examination of neoplasms in mammary glands. The device through the radiation of a certain wave-length helps to discover heterogeneity as small as the match head in the patient's breast, the radiation of a different wave-length allows to determine whether the neoplasm is benign or malignant. Although the method provides for striking accuracy, the procedure is absolutely painless and takes only a few minutes. The development has been successfully completed thanks to support by Russian Foundation for Basic Research, which highly appreciated this innovation project. The tomograph prototype model has been designed with the help of the "ANTARES" Research-and-Production Company.

The devise is based on two methods. Figuratively speaking, the laser makes the tumor sing, and the acoustic microscope finds it by sound and determines the tumor nature by the timbre of phonation. To implement this principle in "metal", i.e. to pass from the concept to the prototype model, the inventors had to develop not only the tomograph construction, but also the appropriate software. That allows to get optical image of the tumor hidden at the depth of up to 7 centimeters and to precisely determine its location.

First comes the laser, which is able to generate radiation at two wave-lengths in the short-distance infra-red waveband - they are certainly generated consecutively. Initially, the operator scans the patient's breast by a beam of one wave-length - that is the search for tissue heterogeneities. The tissue gets slightly warmer - by fractions of a degree - in the location of irradiation due to heating the tissue expands. Since the impulse time makes fractions of microsecond, the expansion also happens quickly. When expanding, the tissue produces a faint acoustic signal -it squeaks quietly. Certainly, the squeak can be picked up only with the help of an extremely sensitive receiver and aerophones. The new tomograph is already equipped with all that.

As the tumor has more blood vessels, it gets warm stronger than the normal tissue, and the ultrasonic signal is generated upon heating with different parameters. Therefore, "X-raying" and "auscultating" the breast from all sides, the source of "incorrect" acoustic signal can be found and its borders can be determined.

The next stage is the neoplasm diagnostics. Diagnostics is based on the fact that blood supply of the tumor also differs from the standard one - there is less oxygen in blood of the malignant growth than in the benign one. Since the absorption spectra of blood depend on the content of oxygen in blood, that gives the opportunity to determine the nature of neoplasm. The method is noninvasive - that means it is painless, quick and secure. For this purpose, the researchers suggested that laser infrared radiation should be used with a different wave-length.

As a result, having processed the obtained acoustic signals the operator can get the real-time image on the display of the device, the image being 5х5 centimeters of the tumor of 2-3 millimeters located at the depth of up to 7 centimeters. That allows to determine whether the tumor is benign or malignant. "So far, we have a functioning model of the device, says Alexander Karabutov, Doctor of Science (Physics&Mathematics), project manager. We hope that the prototype of our laser-acoustic tomograph will be ready soon, we are planning to prepare it for testing in the clinic already by the end of the next year. There is high demand for this device in clinic."

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