Skoltech scientists have created a solution to quickly verify the correct functionality of photoacoustic microscopes and tomography—the devices using ultrasonic and laser radiation in the visible and infrared ranges, without X ray , can detect malignant breast tumors and potentially perform early diagnostic detection of skin cancer and - endoscopic performance - to determine the type of atherosclerotic plaque. The test system described in ACS Photonics provides for the first time the rapid diagnosis of photoacoustic imaging devices in three dimensions, suitable for devices with different operating wavelengths and different resolutions, up to 10 microns.
photoacoustic tomography is set with carbon "nano-gusli"
photoacoustic imaging is a new type of medical diagnostic technology that has been approved in the United States for screening breast cancer , which can be widely used in the future until it is proposed to use "endoscopy-strobe" to find atherosclerotic plaques in the blood vessels in Skoltech. The advantage of photoacoustics is that it can adjust the visualization according to specific biomolecules and is free of harmful radiation.
photoacoustic microscope and tomography combine light and sound in their work. "Suppose you want to visualize a blood vessel network or even a capillary. This can be done by using an acoustic sensor to receive ultrasonic signals from certain blood cells , red blood cells , a microphone that works at ultrasonic frequencies, explained Dmitry Gorin, Professor Skoltech, one of the two leaders in the study.
- To make red blood cells “smooth”, irradiate the red blood cells with pulses (scint) lasers with a pulse duration of several nanoseconds, tuning them to the wavelength at which light is fully absorbed by the hemoglobin molecules in the red blood cells. The energy of each laser pulse is absorbed, and the red blood cells convert it into heat and deform it to become a source of ultrasonic vibrations, propagating in biological tissue with minimal attenuation and can be detected by acoustic sensors. “
Although photoacoustic imaging technology for early detection of breast cancer has been approved by U.S. regulators and used in clinics, staff have no convenient, standard and simple solutions to quickly perform system health checks.
"We came up with a test object for medical and laboratory photoacoustic systems, including multi-spectral systems tuned to multiple wavelengths. Our system enables installers to quickly understand whether the system operates in the required mode and whether it provides the necessary sensitivity and spatial resolution," commented Margarita Chetyrkina, its first author, graduate student at the Photonics and Photonics Technology Center.
test sample is somewhat similar to string instrument like harp , which is a frame in which several strings are stretched at different heights. Each of them is single-walled carbon nanotube fibers - a material that is in turn composed of graphene sheets rolled into cylinders, i.e. a layer of hexagonal honeycomb structure with carbon atoms thick.
Due to additional modifications to the string, especially stranding the two fibers together, it turns out that the lower limit of the device's spatial resolution can be quantified, which will be able to distinguish the structure of the bundle, or "look" such string into a straight line. This makes the calibration system available both for photoacoustic microscopes with 10 micron resolution and for tomography scanners with greater penetration depth and lower resolution (hundreds of microns or tenths of a millimeter).
Since several strings are stretched in frames of different heights, it can be used to check the visual resolution of three dimensions at a time, which distinguishes the new calibration system from the previously described systems in the literature.
"An important advantage of carbon nanotube compared to the previously described materials used in the calibration system is that the tube absorbs a wide range of light, which means that this test is suitable for multi-spectral devices that irradiate tissue at multiple wavelengths simultaneously," added the study's author, a graduate student at the center of photon science and photon technology by Skoltech Yuliyana Tsvetinovich.
Skoltech scientists from the Nanomaterials Laboratory led by Professor Albert Nasibulin and the Biophotonics Laboratory led by Professor Dmitry Gorin participated in the project. In addition to Skoltech, researchers from Saratov National Research University and the Finnish company Kanatu Limited have contributed to the work.
