Surely each of us has had an ultrasound scan at least once in his life and knows what the setup for this examination looks like. Even the smallest devices that are called "portable" are about the size of CRT monitors from the mid-1990s. And while this isn't the most accurate method of examining organs, it remains one of the most popular, largely because of its cost compared to MRI. Scientists are constantly developing in this direction and have even recently been able to test an innovative ultrasound device on humans.
Why do ultrasound?
Ultrasound is mainly used to create "images" of a person's internal organs. Conventional ultrasound devices use devices with quartz crystals through which an electric current vibrates them and emits ultrasound waves that travel through human tissue. The waves are reflected differently by different organs and come back, which is detected by the sensor. Changes are converted into an electrical impulse and projected onto the screen in the form of a familiar image.
At the same time, ultrasound has great problems with accuracy. The latter depends in particular on the force with which the doctor presses the device onto the patient's body. Whoever finds a good ultrasound specialist, therefore only goes to him – the human factor is very strongly expressed here.
Incidentally, the most portable and cheapest ultrasound device was developed in 2018.
What is non-contact ultrasound?
Yes, in order to do an ultrasound, it is not at all necessary to smear (well, almost) with a special liquid and feel how the doctor moves the sensor over a certain area of the body. Non-contact ultrasound works according to the photoacoustic method: In this case, the surface of the skin is illuminated by a laser beam that stimulates vibrations in the tissue. Nevertheless, the receiver of this beam (piezoelectric sensor) is still fixed on the skin. Therefore, scientists have developed a completely non-contact ultrasound method.
Researchers at the Massachusetts Institute of Technology used a model for their development in which the laser is not only the exciter of vibrations in human tissue, but also the receiver of the return signal. A laser was used as the source, which emits light with a wavelength of 1540 nanometers. The receiver was a laser vibrometer with a wavelength of 1550 nanometers.
The essence of the method is that a laser beam that hits the skin periodically warms the skin, causing it to expand. Because of this, ultrasonic vibrations occur, which spread deep into the tissue, so that the resulting image is then displayed on the doctor's screen.
The tests were carried out with the help of four volunteers with laser beams projected onto their forearms. According to the results of the study, the scientists received images of the forearm that show not only the skin and muscles, but also the bones. The results were also compared to the data obtained using the classic ultrasound method to verify the accuracy of the certificate.
The most accurate ultrasound
The researchers believe that the ultrasound method they developed is one of the most accurate, because in this case the light almost does not penetrate deep into the tissue. Because of this, the beam focuses on the surface of the skin, which can increase the amplitude of the ultrasound entering the body.
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The first users of the device will of course be doctors and paramedics who have the necessary qualifications in the field of using ultrasound. If such devices appear in Russia, it is not clear – although human tests have been successful, it is necessary to certify the development to meet international health standards.