Equivalent Analysis of Thermo-Dynamic Blow-Off Impulse under X-ray Irradiation

X-ray thermodynamic effect is an important damage mode for spacecraft. Blow-off impulse as the main thermodynamic damage parameter has been widely studied by combining laboratory and numerical simulations. In this paper, most calculations and analyses have been carried out by using the self-developed software RAMA, including the equivalent calculation of blow-off impulse of monoenergetic and blackbody X-ray, and soft/hard blackbody X-ray irradiated at different incidence angles of LY-12 aluminium target. The results show that the characteristic mono-energetic X-ray can be exploited to simulate the blow-off impulse of the blackbody X-ray under certain conditions as a feasible equivalent method for the equal-flux and equal-impulse relations between mono-energetic and intense pulse blackbody of blow-off impulse. Moreover, the equivalent thermodynamic effect can be achieved between the point source radiation and parallel X-ray of X-ray. Furthermore, the cosine distribution of blow-off impulse is conducive to designing and calculating X-ray radiation load of hard aluminium corresponding to 1–5 keV blackbody spectrum. The mentioned results can be referenced for pulse X-ray simulation source and enhance the fidelity of the thermal-mechanical effect by electron beam. It is noteworthy that the study on the thermodynamic effects of intense pulsed X-ray is of high significance.

Opportunities to reduce the radiation exposure during computed tomography to assess the changes in the lungs in patients with COVID-19: use of adaptive statistical iterative reconstruction

BACKGROUND: Several COVID-19 patients are subjected to multiple imaging examinations during hospitalization, the cumulative effect of which can significantly increase the total dose of radiation received. The effective radiation dose can be reduced by lowering the current and voltage of the X-ray tube, but this reduces image quality. One possible solution is to use adaptive statistical iterative reconstruction technology on the raw CT data. Recently, data on the efficacy of low-dose CT (LDCT) in the diagnosis of COVID-19 have appeared in the literature. AIM: To analyze the quality and diagnostic value of LDCT images of the lungs after applying an iterative processing algorithm and to assess the possibility of reducing the radiation load on the patient when diagnosing COVID-19. MATERIALS AND METHODS: Patients from the Infectious Diseases Department of the Moscow State University Hospital participated in the prospective study. CT examinations were performed at the time of patient admission and discharge and were repeated as needed during hospitalization. In the first study, a standard CT protocol with a tube voltage of 120 kV and automatic current modulation in the range of 200400 mA was used; in repeated CT scans, the LDKT protocol was used with reduced tube voltage parameters (100 or 110 kV) and automatic current modulation in the range of 40120 mA. To assess the diagnostic value of LDCT in comparison with standard CT, a survey was conducted among doctors from the Department of Radiation Diagnostics at Moscow State University Hospital. The questionnaire included a comparison of the two methods for identifying the following pathological processes: ground-glass opacities, compaction of the lung tissue with reticular changes, areas of lung tissue consolidation, and lymphadenopathy. RESULTS: The study included 151 patients. The average age was 5814.2 years, with men accounting for 53.6% of the population. During LDCT the radiation load was reduced by 2.96 times on average, CTDI by 2.6 times, DLP by 3.1 times, the current on the tube by 1.83 times, and the voltage on the tube by 1.2 times. The results indicate that the effectiveness of detecting the main signs of viral pneumonia and assessing the dynamics of the patients condition does not differ significantly from CT performed according to the standard protocol. CONCLUSIONS: The results of a comparison of standard and low-dose CT show that there is no significant loss of diagnostic information and image quality as the radiation load is reduced. Thus, chest LDCT can be used to successfully diagnose COVID-19 in routine practice.

Comparative analysis of dose distribution to critical organs in radiation therapy of left breast cancer with respiratory synchronization

Relevance: Breast cancer is one of the most common oncological diseases. Today, it leads among female cancers. Patients with left breast cancer undergoing radiation therapy have a considerable risk of developing cardiovascular diseases caused by ionizing radiation. Various methods are introduced to reduce the radiation load to critical organs to ensure compliance with the main radiation therapy principle. One of these methods is radiation therapy with synchronized breathing, including deep inspiration breath-hold (DIBH). DIBH can significantly reduce the dose load to the heart and the left lung. The study aimed to compare the radiation load to the heart and the left lung during radiation therapy for left breast cancer with free breathing and respiratory synchronization. Results: During radiation therapy with synchronized breathing, the average radiation load to the heart is 1.7 times lower and to the left lung – 1.26 times lower compared to radiation therapy with free breathing. Conclusion: The study results confirm that respiratory synchronization in radiation therapy for left breast cancer reduces the dose to the heart and the left lung.

Comparative analysis of dose distribution to critical organs in radiation therapy of left breast cancer with respiratory synchronization

Relevance: Breast cancer is one of the most common oncological diseases. Today, it leads among female cancers. Patients with left breast cancer undergoing radiation therapy have a considerable risk of developing cardiovascular diseases caused by ionizing radiation. Various methods are introduced to reduce the radiation load to critical organs to ensure compliance with the main radiation therapy principle. One of these methods is radiation therapy with synchronized breathing, including deep inspiration breath hold (DIBH). DIBH can significantly reduce the dose load to the heart and the left lung. The study aimed to compare the radiation load to the heart and the left lung during radiation therapy for left breast cancer with free breathing and respiratory synchronization. Results: During radiation therapy with synchronized breathing, the average radiation load to the heart is 1.7 times lower and to the left lung – 1.26 times lower compared to radiation therapy with free breathing. Conclusion: The study results confirm that respiratory synchronization in radiation therapy for left breast cancer reduces the dose to the heart and the left lung.

Algorithm for constructing an organizational and technological model for dismantling NPP buildings

In coming decade the practical implementation of work on the decommissioning of nuclear power plants will begin. Failure to take into account the decommissioning stage for NPPs of the first generations, the presence of a radiation component in the building structures of NPP buildings and structures, the need to destroy protective barriers are the main problems in the issue of dismantling works. The destruction of barriers and the specifics of dismantling technological processes can lead to the release of radioactivity into the environment, which will lead to an increase in the radiation load on personnel and the population. Radioactive contamination of structures leads to the formation of a large volume of radioactive waste, the amount of which can be significantly reduced due to the competent separation of waste into classes, taking into account the holding time. In this study the design of the reactor building for unit 1 of the Novovoronezh NPP was considered. Based on the analysis of the data of the comprehensive engineering and radiation surveys (CERS), which was completed in 2004, a classification of buildings into three groups was proposed. Based on the results of CERS, the dependences of the total activity of the main radionuclides and the cost of maintaining the block under observation from time are presented. As a result of the performed studies, an algorithm for constructing an organizational and technological model for dismantling buildings and structures of NPP that are being decommissioned is proposed.

The indisputable value of ultrasound diagnostics in acute small bowel obstruction

The use of ultrasound in the diagnosis of acute small bowel obstruction is justified from a tactical point of view, since it is not delayed in time, does not weigh down the patient's condition, has sufficient information and does not carry radiation load. Due to its safety and ease of use, this technique can be used repeatedly in the process of conservative treatment to determine further treatment tactics.

XANES Measurements for Studies of Adsorbed Protein Layers at Liquid Interfaces

X-ray absorption near edge structure (XANES) spectra for protein layers adsorbed at liquid interfaces in a Langmuir trough have been recorded for the first time. We studied the parkin protein (so-called E3 ubiquitin ligase), which plays an important role in pathogenesis of Parkinson disease. Parkin contains eight Zn binding sites, consisting of cysteine and histidine residues in a tetracoordinated geometry. Zn K-edge XANES spectra were collected in the following two series: under mild radiation condition of measurements (short exposition time) and with high X-ray radiation load. XANES fingerprint analysis was applied to obtain information on ligand environments around zinc ions. Two types of zinc coordination geometry were identified depending on X-ray radiation load. We found that, under mild conditions, local zinc environment in our parkin preparations was very similar to that identified in hemoglobin, treated with a solution of ZnCl2 salt. Under high X-ray radiation load, considerable changes in the zinc site structure were observed; local zinc environment appeared to be almost identical to that defined in Zn-containing enzyme alkaline phosphatase. The formation of a similar metal site in unrelated protein molecules, observed in our experiments, highlights the significance of metal binding templates as essential structural modules in protein macromolecules.

Radionuclides Content in Tissues and Organs of Pumpkinseed Lepomis gibbosus (Linnaeus, 1758) from the Zaporizhzhia (Dnipro) Reservoir

The article presents the results of studies on the content of artificial (137Cs, 90Sr) and natural radionuclides (226Ra, 232Th, 40K) in tissues and organs of various individuals of pumpkinseed Lepomisgibbosus (Linnaeus, 1758) from the Zaporizhzhia (Dnipro) reservoir. It has been revealed that in the bones of sexually mature pumpkinseed females, the content of radionuclides 137Cs and90Sr is 24.7% and 28.6% less, respectively, than in the bones of males. Summing up the materials of radioecological studies of 2017–2018, the following sequence of tissues and organs of the pumpkinseed by the ability to accumulate radionuclides was obtained: bone> muscle> scales> gills. Research results can be useful for further study on the fish radiation load in the basins of the Dnipro River and during monitoring radioecological research. It was determined that the content of radionuclides in the pumpkinseed muscles did not exceed the permissible levels of radionuclide content for fish as a food product (permissible levels of radionuclide content for 137Cs – 150 Bq/kg, 90Sr – 35 Bq/kg).

Radiation load of the personnel of the Samara region during medical procedures for the period 2016-2018

A comparative analysis of the radiation dose rates of medical workers of the Samara region during medical procedures for the period from 2016 to 2018 was carried out. The results of the average annual individual dose of personnel working with sources of ionizing radiation showed stable values of radiation exposure comparable to the dose limit for the population.