The impact of the COVID-19 pandemic on the structure of radiation diagnostics and collective doses of the population of the Russian Federation under medical irradiation in 2020.

Computed tomography has become the main method of early diagnostics of COVID-19 during the pandemic of the novel coronavirus infection. Based on results of computed tomography of the chest it is possible to diagnose viral pneumonia associated with COVIS-19, to quickly assess the lung damage volume and severity of changes, to perform quick routing of patients and to start antiviral treatment. Hence, 2020 was associated with a rapid increase in the number of computed tomography examinations with corresponding changes in the structure of X-ray diagnostics. The aim of the current study was to evaluate the impact of the pandemic of the novel coronavirus infection on the structure of X-ray diagnostics and collective doses from medical exposure in the Russian Federation in 2019-2020. The study was based on the results of analysis of the federal state statistical surveillance forms 3-DOZ and 30 as well as on the data on Covid-19 morbidity in the regions of the Russian Federation. The results of the study indicate that there were no significant changes in the structure of X-ray diagnostics in 2020 compared to 2019 except for the increase in the number of computed tomography examinations. Their contribution to the total number of X-ray examinations has increased to 8,2% in 2020 compared to 4,6% in 2019. Contribution of other imaging modalities to the total number of X-ray examinations has not changed significantly. In 2020 the number of X-ray examinations decreased by 20% in average, varying from 6% for diagnostic nuclear medicine to 42% for interventional examinations. At the same time, the number of computed tomography examinations has rapidly increased by 60%. The structure of collective dose from medical exposure has significantly changed in 2020. Contribution of computed tomography to the collective dose in 2020 accounted for to 74% compared to 57% in 2019. Contribution of other imaging modalities has decreased by the factor of 1,5-2. Contribution of radiography examinations has decreased to 10,5% compared to 19% in 2019. Collective doses have correspondingly decreased by 20-30% for all imaging modalities except for computed tomography. Collective dose from computed tomography has increased by 71% compared to 2019. The number of all X-ray examinations in the Russian Federation has decreased by 12%: from 294 million in 2019 to 258 million in 2020. Collective dose from medical exposure has rapidly increased in 2020 by 30% to 115 thousand man.-Sv compared to 88 thousand man.-Sv in 2019. In average, in regions of the Russian Federation in 2020 each second computed tomography examination has been performed as a part of COVID-19 diagnostics with 2,3 computed tomography examinations per person infected with COVID.Copyright © 2022, Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev. All rights reserved.

Revisiting the Paradox of Smoking: Radioactivity in Tobacco Smoke or Suppressing the SARS-CoV-2 Receptor, Angiotensin-Converting Enzyme 2, via Aryl-Hydrocarbon Receptor Signal?

Despite current controversies, some reports show a paradoxical mitigating effect associated with smoking in individuals with symptomatic COVID-19 compared to the general population. To explain the potential mechanisms behind the lower number of hospitalized COVID-19 patients, it has been hypothesized that cigarette smoking may reduce the odds of cytokine storm and related severe inflammatory responses through cholinergic-mediated anti-inflammatory mechanisms. Japanese scientists have recently identified a potential mechanism behind the lower numbers of COVID-19 cases amongst smokers compared to non-smokers. However, we believe that this mitigative effect may be due to the relatively high concentration of deposited energy of alpha particles emitted from naturally occurring radionuclides such as Po-210 in cigarette tobacco. Regarding COVID-19, other researchers and our team have previously addressed the anti-inflammatory and immune-modulating effects of low doses of ionizing radiation. MC-simulation using the Geant4 Monte Carlo toolkit shows that the radiation dose absorbed in a spherical cell with a radius of .9 µm for a single 5.5 MeV alpha particle is about 5.1 Gy. This energy deposition may trigger both anti-inflammatory and anti-thrombotic effects which paradoxically lower the risk of hospitalization due to COVID-19 in smokers.

Translational PET imaging evaluation of [18F]Favipiravir by positron emission tomography

Objectives: With over 90 million cases reported in the globe, the COVID-19 pandemic caused by SARS-CoV-2 has been a serious public health crisis. Development of novel and specific antiviral drugs against the SARS-CoV-2 has been an urgent demand. One such drug is Favipiravir, initially developed as an antiviral drug against influenza. Now Favipiravir has received approvals for emergency use against SARS-CoV-2 in many countries. A better understanding of Favipiravir’s biodistribution and pharmacokinetics in vivo will facilitate the clinical development of antiviral drugs against the SARS-CoV-2. Herein, we reported the evaluation of [18 F]Favipiravir with PET in cross-species studies to demonstrate the drug’s biodistribu-tion and pharmacokinetics and investigate the potentially increased risk of neurodegenerative diseases and/or neuroinflammation to COVID-19. Methods: The radiosynthesis of [18 F]Favipiravir was via labeling a commercially available precursor, methyl-5-chloroisoxazolo[4,5-b] pyrazine-3-carboxylate with K[18F]F/K222 and K2CO3 in DMSO at 130°C for 10 min, followed by hydrolysis with NaOH (aq.) at 110°C for 15 min.1 The whole body distribution on CD-1 mice was performed at four time points (5, 15, 30, 60 min). PET studies were carried out in CD-1 mice and AD mice (5XFAD) and naïve rhesus monkeys. We also performed the radiometabolite analysis of [18 F]Favipiravir in plasma and brain of CD-1 mice at 30 min post-injection. Results: [18 F]Favipiravir was obtained in 29% isolated radiochemi-cal yield (decay corrected). The radiochemical purity of the tracer was greater than 99%. No sign of radiolysis was observed for [18F] Favipiravir up to 120 min after formulation with 10% EtOH/saline. High radioactivity accumulation was observed in blood, lung, liver, kidney, and bone (around or more than 5% ID/g, injected dose per gram of wet tissue). The radioactivity level reached a plateau in small intestine, kidney and liver at 30,15 and 5 min, respectively, followed by slow washout, indicating that [18F]Favipiravir was possibly eliminated via the hepatobiliary and urinary pathway. For the radio-metabolic analysis of [18F]Favipiravir, average 41% and 89% of the radioactivity was parent fraction in the mice brain and plasma at 30 min post-injection (n=2), respectively. In PET imaging of CD-1 mice, the standard uptake value (SUV) of [18F]Favipiravir in brain reached its max value of 0.5 at 10 min and slowly reduced to 0.4 at 60 min. The results of PET imaging of AD mice with [18 F]Favipiravir were similar with that of CD-1 mice. In PET imaging of Rhesus monkeys, the brain uptake of [18 F]Favipiravir reached the max value of 0.5 SUV at 5 min and subsequently decreased to 50-60% of the maximum at 60 min. Conclusion: The evaluation of [18F]Favipiravir has demonstrated with bio-distribution and PET in mice and NHPs. Further evaluation of pharmacokinetics of [18F]Favipiravir in whole body monkey scans and LPS-induced neuroinflammation models is underway.

Determination of natural radioactivity material concentrations consumed widely during Corona pandemic in Thi Qar province.

The present study was carried out to assess the potential radiation hazards to the public, especially the persons who consumed onion and garlic plants widely during coronavirus disease in Thi Qar province South of Iraq. Nine samples collected from the market (5 samples onion and 4 sample Garlic), which classified according to their origin. Using 3″x3″ NaI (Tl) gamma ray spectroscopy system, the radioactivity concentrations of the natural radionuclides radium-226, thorium-232 and potassium-40 were determined. The results obtained showed that the average concentration of radioactivity of radium-226, thorium-232 and potassium-40 is 3.398 Bqkg-1, 4.667 Bqkg-1 and 216.738 Bqkg-1, respectively, for onion and 2.808 Bqkg-1, 3.524 Bqkg-1, and 172.064 Bqkg-1 for garlic. The results also showed that the average annual total effective dose of the three nuclides is 122.955 µ S v . y - 1 for onion and 97.231 µ S v . y - 1 for garlic. Other relevant risk parameters were also calculated, such as equivalent activity concentrations, absorbed dose, excess lifetime cancer risks, and other health risk parameters. One of the most important conclusions reached by this study is that the natural radioactive elements in onions and garlic do not pose a great danger to their consumers, especially those infected with the COVID-19. Because the concentrations of these radioactive elements do not exceed the permissible limits recommended by recognized scientific organizations and agencies such as International Commission on Radiological Protection (ICRP), United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and World Health Organization (WHO).

Same pollution sources for climate change might be hyperactivating the NLRP3 inflammasome and exacerbating neuroinflammation and SARS mortality.

We have reviewed a considerable amount of recent scientific papers relating inflammation caused by air pollution with chronic and severe medical conditions. Furthermore, there are evidences relating organ inflammation caused by not only outdoor long-term but also short-term inhaled radioisotopes contained in high polluted air or in household natural radioactive background aerosols, in addition to SARS-COV-2 attached to bioaerosols, which are related with a worst evolution of severe acute respiratory syndrome patients. Reactive oxygen species (ROS) production induced by the interaction with environmental ionizing radiation contained in pollution is pointed out as a critical mechanism that predispose mainly to elder population, but not excluding young subjects, presenting previous chronic conditions of lung inflammation or neuroinflammation, which can lead to the most serious consequences.