Interview with Aleksandr Selyunin, a head of the project "Development of deep tissue oxygenation measurement systems using time-domain diffuse optics" that received financial support within the JINR competition
The DLNP Group of Scientific Communications had a talk with Aleksandr Selyunin, a head of the project group, researcher of the DLNP Department of Particle Physics.
— Aleksandr Sergeevich, how long have you been working at the JINR Laboratory of Nuclear Problems? What are your scientific interests?
I have been working at DLNP JINR for 15 years, since September 2010. My scientific interests have been changing and I have been participating in various projects since then. However my work and work of my group are connected with photodetectors. We are developing detector systems using photodetectors both photomultipliers, long used in science, and modern types of photodetectors, such as silicon photomultipliers.
The first project I worked on was the COMPASS experiment within which we participated in development and creation of the electromagnetic calorimenter. Within the next experiment, JUNO, we developed methods and technique of the mass testing of photomultipliers. For this purpose, a dark room was constructed in the Laboratory of Nuclear Problems.
Then we became participants of the DUNE experiment which was conducted on the accelerator in Fermilab (USA). For the near detector of the experiment, we made a system for detecting scintillation light in a liquid-argon time-projection chamber. The project lasted for a long time: we started in 2017 and were actively participating in it for seven years.
— Tell us, please, about the project that received the grant.
The project that participated in the grant competition began with an article that came to us for review as experts in the field of silicon photomultipliers: it was about the application of silicon photomultipliers in time-domain diffuse optics. This area interested us because we are familiar with all the main components for building such systems.
In medicine, red and infrared light can be used to "transilluminate" human tissues. Such light is capable of penetrating deep into tissues, which is used in modern “smart” watches and pulse oximeters. This property of light has been known for a long time and is used in medicine to study human tissues. In recent years, systems using silicon photomultipliers have been widely developed. And we decided to pick up and develop this idea.
Our project is called "Development of deep tissue oxygenation measurement systems using time-domain diffuse optics." In fact, we became interested in and started working on the topic several months before the competition was announced: in our free time, we discussed ideas and worked out the concept. So when the grant competition was announced, we decided to apply. To do this, we formulated our ideas and developments in more detail in the form of a project: goal, objectives, planned result.
The outcome of the three years allocated by the grant for the project should be a prototype of a device for determining the level of tissue oxygenation in the brain, consisting of a photon source, a detector, and a data acquisition and analysis system. Externally, it is a probe several centimeters in diameter, at the end of which a photon source and a detector will be located 2-3 cm apart. For examination, the device is placed near a person's head, the light source emits photons that penetrate the brain tissue to a depth of up to 3-5 cm. We detect the "returned" photons using a silicon photomultiplier, simultaneously measuring the arrival time of the photons at the photodetector, record and analyze the data. If the level of blood oxygenation in the tissues changes, we will be able to understand this from the analysis results.
This technology differs from that used in pulse oximeters in that they operate in so-called continuous mode and analyze not individual photons, but a light flux of a certain wavelength. Thus, the oxygenation level can be measured on average. And our method will allow measuring the difference in oxygenation levels with depth in tissues. This makes it possible to assume, for example, the presence of a stroke location.
Similar devices exist in the world, but most of them are not available in the Russian Federation or are very expensive. Similar developments are also being carried out in our country, for example in Skolkovo and other institutes.
Our task is to make the diagnostic device compact so that it can be transported, for example, on ambulance calls. The result of the development should be a multi-channel system with several sources and detectors in the form of a helmet. So that it can be put on a patient, "illuminated" and immediately build a complete picture: in which areas of the brain there is a lack of oxygen in the tissues. This may indicate a developing stroke and provide information for doctors to take measures.
In addition to the compactness of the device, we strive for its low cost. Photodetectors are already mass-produced and are inexpensive. As a photon source, we will use a laser diode, from which we managed to obtain light pulses shorter than a hundred picoseconds. We also plan to use an inexpensive one, made from available components. We have already found some of the most effective and inexpensive samples and are currently optimizing them.
The project is being carried out by a team of 10 people, mainly staff members of the DLNP Department of Particle Physics. The group includes a staff member of the Faculty of Chemistry of Moscow State University, as well as two students from Moscow State University: a physicist and a medical student. After all, our project is tied to medicine.
Therefore, we are also in contact with Oleg Stepanovich Medvedev, head of the Department of Pharmacology of the Faculty of Fundamental Medicine of Moscow State University, and Denis Aleksandrovich Shashurin, senior researcher at the Medical Research and Education Center of Moscow State University. Thanks to them, we are in contact with various medical centers, for example, the Bakulev Scientific Center for Cardiovascular Surgery and the Russian scientific center of surgery named after academician B. V. Petrovsky. There, doctors are interested in using the device during operations. In general, doctors are interested in modern medical technologies.
— Why do you think your application won the grant?
I think it was a combination of the project's interesting goal and its thorough preparation. That's why we decided to participate in the competition, relying on this experience and on our developments and achievements in physical experiments.
— How will the received grant help the project develop?
The grant will be used to purchase materials and components, as well as to organize off-site meetings, pay salaries to staff members, and conduct related research.
