Comparative Analysis of Approaches to Regulation and Monitoring of Workers for Internal Radiation Exposure

Purpose: Harmonization and improvement of the system for regulating the internal radiation exposure of workers and the basic requirements for ensuring radiation safety with international requirements and recommendations. Material and methods: Issues related to the development of approaches to regulation and monitoring of workers for internal radiation exposure in the process of evolution of the ICRP recommendations and the national radiation safety standards, are considered. The subject of analysis is the standardized values: dose limits for workers and permissible levels as well as directly related methods of monitoring of workers for internal radiation exposure, whose purpose is to determine the degree of compliance with the principles of radiation safety and regulatory requirements, including non-exceeding the basic dose limits and permissible levels. The permissible levels of inhalation intake of insoluble compounds (dioxide) of plutonium-239 are considered as a numerical example. Results: Based on the analysis of approaches to the regulation and monitoring of workers for internal radiation exposure for the period from 1959 to 2019, it is shown that a qualitative change in the approach occurred in the 1990s. It was due to a decrease in the number of standardized values by introducing a single dose limit for all types of exposure: the effective dose E, which takes into account the different sensitivity of organs and tissues for stochastic radiation effects (WT), using the previously accepted concepts of the equivalent dose H and groups of critical organs. From the analysis it follows that the committed effective dose is a linear transformation of the intake, linking these two quantities by the dose coefficient, which does not depend on the time during which the intake occurred, and reflects certain exposure conditions of the radionuclide intake (intake routes, parameters of aerosols and type of radionuclide compounds). It was also shown that the reference value of the function z(t) linking the measured value of activity in an organ (tissue) or in excretion products with the committed effective dose for a reference person, which is introduced for the first time in the publications of the ICRP OIR 2015-2019, makes it possible to standardize the method of measuring the normalized value of the effective dose. Based on the comparison of the predicted values of the lung and daily urine excretion activities following constant chronic inhalation intake of insoluble plutonium compounds at a rate equal annual limit of intake (ALI) during the period of occupational activity 50 years it was shown that the modern biokinetic models give a slightly lower level (on average 2 times) of the lungs exposure compared to the models of the previous generation and a proportionally lower level (on average 1.4 times) of plutonium urine excretion for the standard type of insoluble plutonium compounds S. However, for the specially defined insoluble plutonium compound, PuO2, the level of plutonium urine excretion differs significantly downward (on average 11.5 times) compared to the models of the previous generation. Conclusion: With the practical implementation of new ICRP OIR models, in particular for PuO2 compounds, additional studies should be carried out on the behavior of insoluble industrial plutonium compounds in the human body. Besides, additional possibilities should be used to determine the intake of plutonium by measuring in the human body the radionuclide Am-241, which is the Pu-241 daughter. To determine the plutonium urine excretion, the most sensitive measurement techniques should be used, having a decision threshold about fractions of mBq in a daily urine for S-type compounds and an order of magnitude lower for PuO2 compounds. This may require the development and implementation in monitoring practice the plutonium-DTPA Biokinetic Model.

Regolith and Radiation: The Cosmic Battle

This chapter discusses regolith utilization in habitat construction mainly from the point of view of radiation protection of humans on missions of long duration. It also considers other key properties such as structural robustness, thermal insulation, and micrometeoroid protection that all have to be considered in parallel when proposing regolith-based solutions. The biological hazards of radiation exposure on the Moon are presented and put in the context of lunar exploration-type missions and current astronaut career dose limits. These factors guide the research in radiation protection done with lunar regolith simulants, which are used in research and development activities on Earth due to the reduced accessibility of returned lunar samples. The ways in which regolith can be used in construction influence its protective properties. Areal density, which plays a key role in the radiation shielding capacity of a given material, can be optimized through different regolith processing techniques. At the same time, density will also affect other important properties of the construction, e.g. thermal insulation. A comprehensive picture of regolith utilization in habitat walls is drawn for the reader to understand the main aspects that are considered in habitat design and construction while maintaining the main focus on radiation protection.

University Marching Band Members Noise Dosages and Hearing Health-Related Knowledge

Objectives: (1) To measure sound exposures of marching band and non-marching band students during a football game, (2) to compare these to sound level dose limits set by NIOSH, and (3) to assess the perceptions of marching band students about their hearing health risk from loud sound exposure and their use of hearing protection devices (HPDs). Methods: Personal noise dosimetry was completed on six marching band members and the band director during rehearsals and performances. Dosimetry measurements for two audience members were collected during the performances. Noise dose values were calculated using NIOSH criteria. One hundred twenty-three marching band members responded to a questionnaire analyzing perceptions of loud music exposure, the associated hearing health risks, and preventive behavior. Results: Noise dose values exceeded the NIOSH recommended limits among all six marching band members during rehearsals and performances. Higher sound levels were recorded during performances compared to rehearsals. The audience members were not exposed to hazardous levels. Most marching band members reported low concern for health effects from high sound exposure and minimal use of HPDs. Conclusion: High sound exposure and low concern regarding hearing health among marching band members reflect the need for comprehensive hearing conservation programs for this population.

The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonization Group Recommendations for Сontouring of OARs

QUANTEC report summarized the data of the dose constrains for critical structures in radiotherapy. The authors of this report determined that one of the obstacles to obtaining meaningful data on tolerant doses was inconsistency in the nomenclature of names. And inconsistencies in the guidelines for contouring the organs at risk increase the variability in contouring. Eliminating these inconsistencies increases the speed and safety of the workflow within each individual healthcare facility and improves the accuracy and reliability of the data underlying the dose limits that are developed. The standardization of terminology facilitates the integration of dosimetry data, the creation of various templates and scripts to automate the creation of a prescription for the RT course for similar cases, and the automation of reports. It helps to train the systems supporting artificial intelligence. AAPM report TG-263 resolved the nomenclature problem, however, different anatomical boundaries of different organs were still hidden under the same names in various large research centers. In 2020 The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonization Group published an article. It summarized the many years of work by the scientific radiotherapy community to standardize the approach to delineating the OARs. This article provides an overview of the article key points and provides links to outline guides. A special attention it was paid to clarifying the anatomical boundaries of such OARs: heart, femoral heads, skin, individual structures of the gastrointestinal tract and substructures of the eye.

Investigation of Predictors to Achieve Acceptable Lung Dose in T-Shaped Upper and Middle Esophageal Cancer With IMRT and VMAT

PurposeThe purpose of this study is to investigate whether there are predictors and cutoff points that can predict the acceptable lung dose using intensity-modulated radiation therapy (IMRT) and volume-modulated arc therapy (VMAT) in radiotherapy for upper ang middle esophageal cancer.Material and MethodsEighty-two patients with T-shaped upper-middle esophageal cancer (UMEC) were enrolled in this retrospective study. Jaw-tracking IMRT plan (JT-IMRT), full-arc VMAT plan (F-VMAT), and pactial-arc VMAT plan (P-VMAT) were generated for each patient. Dosimetric parameters such as MLD and V20 of total lung were compared among the three plannings. Ten factors such as PCTVinferior length and PCTVinferior length/total lung length were calculated to find the predictors and cutoff points of the predictors. All patients were divided into two groups according to the cutoff points, and the dosimetric differences between the two groups of the three plans were compared. ANOVA, receiver operating characteristic (ROC) analysis, and Mann–Whitney U-test were performed for comparisons between datasets. A p <0.05 was considered statistically significant.ResultThe quality of the targets of the three plannings was comparable. The total lung dose in P-VMAT was significantly lower than that in JT IMRT and F-VMAT. Monitor unit (MU) of F-VMAT and P-VMAT was significantly lower than that of JT IMRT. ROC analysis showed that among JT IMRT, F-VMAT, and P-VMAT, PCTVi-L, and PCTVi-L/TLL had diagnostic power to predict the suitability of RT plans according to lung dose constraints of our department. For JT IMRT, the cutoff points of PCTVi-L and PCTVi-L/TLL were 16.6 and 0.59. For F-VMAT, the cutoff points of PCTVi-L and PCTVi-L/TLL were 16.75 and 0.62. For P-VMAT, the cutoff points of PCTVi-L and PCTVi-L/TLL were 15.15 and 0.59. After Mann–Whitney U-test analysis, it was found that among the three plannings, the group with lower PCTVi-L and PCTVi-L/TLL could significantly reduce the dose of total lung and heart (p <0.05).ConclusionPCTVi-L <16.6 and PCTVi-L/TLL <0.59 for JT IMRT, PCTVi-L <16.75 and PCTVi-L/TLL <0.62 for F-VMAT and PCTVi-L <15.15, and PCTVi-L/TLL <0.59 for P-VMAT can predict whether patients with T-shaped UMEC can meet the lung dose limits of our department.

To the Question About Pharmacological Protection During Irradiation in Non-infecting Doses: Maybe, Necessary? Part 1. General Overview of Medical-tactical and Phenomenological Aspects

Purpose: Review of modern concepts of the biological effect of ionizing radiation in medium doses on a living organism and the consequences of radiation in order to assess the need for the use of drugs suitable for the purpose of modifying the effects; stimulation of discussion on the issue under consideration. Results: The conditions of origin and the list of possible radiation effects from irradiation at medium doses of the 0.1–1 Gy range were assessed, the scale and phenomenology of the consequences were assessed as a subject of modification by antiradiation agents. Conclusions: Pharmacological support (use of PLC) under conditions of short-term and prolonged irradiation with a low dose rate and in the dose range of 0.2–1 Gy seems to be necessary due to the reality of deterministic effects when the dose limits are exceeded (partly at the premorbid or preclinical level, with pronounced psychogenic reactions – components of the final state), as well as with the possibility of stochastic effects in excess of spontaneous ones, although, according to approximate estimates, with an insignificant frequency.

Versatile microporous polymer-based supports for serial macromolecular crystallography

Serial data collection has emerged as a major tool for data collection at state-of-the-art light sources, such as microfocus beamlines at synchrotrons and X-ray free-electron lasers. Challenging targets, characterized by small crystal sizes, weak diffraction and stringent dose limits, benefit most from these methods. Here, the use of a thin support made of a polymer-based membrane for performing serial data collection or screening experiments is demonstrated. It is shown that these supports are suitable for a wide range of protein crystals suspended in liquids. The supports have also proved to be applicable to challenging cases such as membrane proteins growing in the sponge phase. The sample-deposition method is simple and robust, as well as flexible and adaptable to a variety of cases. It results in an optimally thin specimen providing low background while maintaining minute amounts of mother liquor around the crystals. The 2 × 2 mm area enables the deposition of up to several microlitres of liquid. Imaging and visualization of the crystals are straightforward on the highly transparent membrane. Thanks to their affordable fabrication, these supports have the potential to become an attractive option for serial experiments at synchrotrons and free-electron lasers.

Radiation Protection of Personnel in Contact Radiation Therapy in Ophthalmology

Purpose: To ensure radiation safety of medical staff personal protective equipment (PPE). Material and methods: In order to not make assumptions of possible protective materials optical distortion, estimated the dependence of light transmission in the wavelength range 330–660 nm leaded glass brands of TF-1 and TF-5, as well as the intensity of glow glasses when exposed to light and X-rays. Results: We trace the degree of browning and the nature of the recovery of transparency of glass after irradiation. To determine the optimum thickness of lead glass for eyewear experimentally evaluated attenuation of X-rays with energy efficiency 30 and 80 keV. Lead equivalent values for lead glass, was determined so for Eeff ~ 20 keV at a multiplicity of weakening k = 10 lead glass brand TF-5 thickness 2.0 mm equivalent 0.8 mm Pb, etc. For the possible use of other additives in the window shows the curves of the attenuation of photon radiation radionuclide 241Am (20–60 keV) filters from 9Be, 26Al, 56Fe, 64Cu, 99Mo, 112Cd, 184W, 207Pb Conclusion: Possible introduction of new dose limits for the lens of the eye can be successful only in case of both existing and newly developed PPE. To reduce the impact of domestic lead glass radiation can be used for staff in the form of screens and glasses.

Impact of accounting of 238U chemical toxicity on its permissible release level to atmosphere

At present, the permissible atmospheric release levels of 238U are evaluated only on a basis of its radiation impact on population. At the same time, uranium belongs to the 1st hazard class (extremely dangerous chemicals) by its toxic effect. Limitation of the 238U release to the atmosphere is calculated separately using two criteria – radiation protection (annual dose limits) and chemical toxicity of uranium. It is shown that the permissible release level of 238U by radiation criteria is 100 – 250 times higher than the maximum release level limited by chemical toxicity of uranium. Annual intake limit of 238U for population 8400 Bq/year, established by Radiation Safety Norms NRB-99/2009, under condition of its uniform intake is equal to 184 mkg/kg of body mass per day for the indicated age group. It is 306 times higher than the tolerable daily intake of uranium estimated by World Health Organization. Compliance with the public health regulations in radiation safety does not guarantee that the annual intake of uranium by population would not exceed the tolerable toxicity levels indicated by World Health Organization. Therefore, the established value of the annual intake limit of 238U for the population needs to be revised taking into account the recent World Health Organization publications and the research results in the field of chemical toxicity of uranium. The revised value could be incorporated to the system of establishing the permissible atmospheric releases levels of radioactive substances.