D.D. Mantserov – Post-graduate Student, Department «Information-measuring and biomedical techniques»,  V.F. Utkin Ryazan State Radio Engineering University

E-mail: danax2014@yandex.ru

E.M. Proshin – Dr.Sc. (Eng.), Professor, Department «Information-measuring and biomedical techniques»,  V.F. Utkin Ryazan State Radio Engineering University; Honorary Worker of Higher Professional Education of the Russian Federation, Laureate of the Ryazan Region on Science and Technology n.a. Academician V.F. Utkin

E-mail: proshin39@mail.ru

At the present moment, in view of the development of radiation therapy (hereinafter LT) and the expanding range of LT use in situations requiring monitoring of the human pulse and respiration (in-tissue therapy, remote LT with correction of the radiation beam by breathing, etc.), there is an important problem of using the most non-sensitive to radiation devices. In this situation, it is necessary to conduct a study of the expected operating conditions of the potential device, as well as to determine the possible impact on it from the radiation. In view of this, to develop a means of monitoring the state of the patient, it is necessary, if possible, to assess the operating conditions of the sensors measured on the patient by the radiation background. To this end, the radiation background, the expected locations of the sensors and the calculation of the effective atomic number of the device were measured.

As a working environment, the plane of the table of the gamma-ray machine for remote radiation therapy was chosen. The choice of the gamma-ray machine is dictated by the need for a "pure" beam (as a radiation source in the gamma-ray machine, Cobalt-60 is used, which in its decay chain allocates two high-energy photons and one electron, the energy of which is not enough to provide therapeutic EF-fect) and in order to assess the impact on the equipment (photople-tismiographic sensor) only hard radiation, without EMC, which is present on the LUE(linear electron accelerator). Taking into account the task, a measurement plan was drawn up, in accordance with which measurements were carried out. The distance on a straight parallel axis of rotation, as well as the width of the intended therapeutic field were used as variable parameters of the measurement. The scheme of the conducted research with a detailed description of the equipment and conditions of the experiment is given. 

As a result of the work carried out, the dose distribution in the proposed location of the pulse sensor was analyzed, and the effective atomic number of the element for our device was calculated, which will further allow a deeper assessment of the conditions of the device. The measurement result clearly revealed the relationship between the background level and the size of the treatment field, as well as the dependence of the radiation level on the location of the sensor on the direct parallel axis of the device. The data obtained clearly shows that the "secondary radiation" (high-energy electrons knocked photons from their orbitals) can have a significant impact on the device, since due to the design of the table in some places the metal is replaced by a plastic grid, in this location the background radiation level falls, which indicates the absence of "secondary" knocked out or reflected, crystal lattice metal plane of the table, particles. The data obtained from the measurements are processed and presented in tables. They-stupno indicate the dependence of the level of photon radiation. from developed settings.

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