Basis for the ICRP’s updated biokinetic model for systemic astatnie

The ICRP recently updated its biokinetic models for workers in a series of reports called the OIR (Occupational Intakes of Radionuclides) series. A new biokinetic model for astatine, the heaviest member of the halogen family, was adopted in OIR Part 5 (ICRP Publication 151, in press). This paper provides an overview of available biokinetic data for astatine; describes the basis for the ICRP’s updated model for astatine; and tabulates dose coefficients for intravenous injection of each of the two longest lived and most important astatine isotopes, 211At and 210At. Astatine-211 (T1/2 = 7.214 h) is a promising radionuclide for use in targeted α-particle therapy due to several favorable properties including its half-life and the absence of progeny that could deliver significant radiation doses outside the region of α-particle therapy. Astatine-210 (T1/2 = 8.1 h) is an impurity generated in the production of 211At in a cyclotron and represents a potential radiation hazard via its long-lived progeny 210Po (T1/2 = 138 d). Tissue dose coefficients for injected 210At and 211At based on the updated model are shown to differ considerably from values based on the ICRP’s previous model for astatine, particularly for the thyroid, stomach wall, salivary glands, lungs, spleen, and kidneys.

On the occurrence, origin, and intake of the nuclides, 210Po and 210Pb, in sclerotia of Wolfiporia cocos collected in China

The dried sclerotium of the fungus Wolfiporia cocos is edible and has medicinal value. This study aimed to understand the accumulation of radioactivity arising from the alpha 210Po, and beta-emitting 210Pb, in the sclerotium’s shell and core and assess a potential effective dose for consumers. Sclerotia were collected in the wild and from cultivars in China’s Anhui and Yunnan provinces. The mean values of 210Po activity concentration levels were 0.36 Bq kg−1 dry weight in the core and 12.0 Bq kg−1 dw in the shell; 210Pb activities were 0.43 and 9.84 Bq kg−1 dw, respectively. The potential effective radiation doses from core layers (as a major raw material of the sclerotium) ranged from 0.13 to 3.43 µSv kg−1 dw from 210Po decay and from 0.11 to 1.52 µSv kg−1 dw from 210Pb decay. Corresponding values for shell ranged from 0.80 to 42.4 for 210Po and from 0.53 to 13.6 µSv kg−1 dw for 210Pb. In general, the intake of W. cocos sclerotia varies between consumers, but this would not significantly change the effective radiation doses from 210Po and 210Pb isotopes. The consumption thus appears to be safe from a radiological protection point of view. Graphical abstract

Establishing local diagnostic reference levels for adult computed tomography in Morocco

In Morocco, the radiation doses received by adult patients are increasing due to the number of CT examinations performed and the larger number of computed tomography (CT) scanners installed. The aim of this study was to evaluate the radiation doses received by patients for the most common adult CT examinations in order to establish local diagnostic reference levels (DRLs). Data from 1016 adult patients were collected during 3 months from four Moroccan hospitals. Dose length product (DLP) and volumetric computed tomography dose index (CTDIvol) were evaluated by determining the 75th percentile as diagnostic reference levels for the most common examinations including head, chest and abdomen. The DRL for each examination was compared with other studies. The established DRLs in Morocco in terms of CTDIvol were 57.4, 12.3 and 10.9 for CT examinations of the head, chest, abdomen, respectively. For DLP, they were 1020, 632 and 714, respectively. These established DRLs for CTDIvol were almost similar to the UK DRLs at all examinations, higher than the Egyptian DRLs and lower than the Japanese DRLs at the head CT examination, lower than the DRLs from Egypt and Japan at the CT abdomen examination. In terms of DLP, the DRLs were higher than those of the British studies, lower than those of the Egyptian and Japanese studies at the head CT examination were higher at chest CT and lower at abdominal CT than those of all selected studies. The higher level of established DRLs in our study demonstrates the requirement of an optimization process while keeping a good image quality for a reliable diagnosis.

Features of absorbed radiation doses calculation for cattle’s in Krasnoyarsk krai

The article provides an adapted methodology of absorbed dose calculation for the cattle from the territories with long-term man-made contamination. The methodology was developed according to existing regulatory documents in the RF: veterinarian rules VR 13.73.13/12-00, VR 13.5.13/03-00, methodical instructions MI 13.5.13-00, regulation for the state veterinarian control system in radioactive contamination of veterinary surveillance objects in the Russian Federation. The aim of the work is the development of calculation methodology of absorbed radiation doses for the cattle on the territory with long-term man-made isotopes contamination, taking to the account the radionuclide composition of the soil. Methods. The regulatory documents governing absorbed doses calculation has been analyzed; the contribution of external and internal radiation into total annual absorbed dose has been determined. Results. It has been established, that the calculation of external radiation dose needs to be done considering doses in stable and pasture periods. Pasture period dose is a sum of day and night doses considering day length. According to the data of radio ecological situation in Krasnoyarsk krai the internal radiation dose should be calculated as a sum of 137Cs, 90Sr, 60Co, taking to the account different concentration of these radionuclides in green and coarse fodder. Scientific novelty. The methodology of dose calculation for the cattle according to the radio ecological situation in Krasnoyarsk krai has been introduced for the first time. Practical significance. This methodology is recommended for the specialists of radiological departments of veterinarian laboratories and science officers in the field of agricultural radiobiology.

Consideration of the contribution of the natural background component during individual control of radiation doses to personnel

When ensuring radiation safety in the Russian Federation, there is a principle of separate independent assessment of doses from natural, medical, emergency and technogenic exposure. In practice, it is not always possible to comply with this principled approach. The established dose limits are related only to man-made radiation during normal operation of sources of ionizing radiation. However, during the formation of regional and federal databases on individual doses of personnel exposure, information is entered not on technogenic exposure, but on industrial exposure, that is, without subtracting the natural radiation background. The natural component of the individual dose at low radiation doses is quite significant. Failure to its subtraction leads to an overestimation of the individual dose of external exposure of personnel. Difficulties arise in the implementation of the subtraction of the natural radiation background: 1) in what cases it is necessary to subtract the background, 2) what value to choose for the subtracted background, 3) what method to measure the background, 4) at what stage of processing the measurement information to subtract the background. This article proposes a method for solving the problem of subtracting the natural background radiation from the values of individual doses of external exposure to personnel based on results of individual dosimetric control. Using the example of the city of St. Petersburg, the natural background radiation was measured by the thermoluminescent method of individual dosimetry at 50 control points for three consecutive years (2018-2020). To measure the natural background, we used individual thermoluminescent dosimeters of the same type as those used to measure individual equivalents of external radiation doses to personnel. The choice of using the thermoluminescent method as a predominant one for adjusting the average doses of external radiation from technogenic sources of ionizing radiation when subtracting the natural component of the dose has been substantiated. Comparison of official data on personnel exposure doses with the data obtained as a result of our own measurements is made. Recommendations are given on the use of the obtained values of the average natural radiation background in the formation of regional and federal databases on individual doses of personnel exposure.

Radiation therapy with neutrons and hydrons of the liver region using the MCNP code: المعالجة الاشعاعية بالنترونات والهدرونات لمنطقة الكبد باستخدام الكود MCNP

CT images were read and a 3D model of the tumor was created in the liver area, Then the values ​​of the radiation dose in terms of the depth resulting from (photons, neutrons and protons) were estimated and studied using the code (MCNP) after entering the data into it. The value of the radiation dose in terms of depth and curvature in photons, neutrons and protons radiation therapy was studied, from our findings in the research we note that protons are the best option for radiation therapy for high-depth liver cancer of photons and neutrons due to the lower dose at entry compared to the dose absorbed in the tumor area and its ability to deliver a greater amount of dose of neutrons and photons to the tumor area. We note that the values reached are acceptable for the treatment of tumors at a depth close to the surface. As for a large-depth tumor, it is necessary to increase high-energy radiation doses deep in the tumor area by accelerating proton therapy to protect natural organs from high-energy radiation doses.

Effects of Fe-Ions Irradiation on the Microstructure and Mechanical Properties of FeCrAl-1.5wt.% ZrC Alloys

Fe-13Cr-3.5Al-2.0Mo-1.5wt.% ZrC alloy was irradiated by 400 keV Fe+ at 400 °C at different doses ranging from 6.35 × 1014 to 1.27 × 1016 ions/cm2 with a corresponding damage of 1.0–20.0 dpa, respectively, to investigate the effects of different radiation doses on the hardness and microstructure of the reinforced FeCrAl alloys in detail by nanoindentation, transmission electron microscopy (TEM), and atom probe tomography (APT). The results show that the hardness at 1.0 dpa increases from 5.68 to 6.81 GPa, which is 19.9% higher than a non-irradiated specimen. With an increase in dose from 1.0 to 20.0 dpa, the hardness increases from 6.81 to 8.01 GPa, which is an increase of only 17.6%, indicating that the hardness has reached saturation. TEM and APT results show that high-density nano-precipitates and low-density dislocation loops forme in the 1.0 dpa region, compared to the non-irradiated region. Compared with 1.0 dpa region, the density and size of nano-precipitates in the 20.0 dpa region have no significant change, while the density of dislocation loops increases. Irradiation results in a decrease of molybdenum and carbon in the strengthening precipitates (Zr, Mo) (C, N), and the proportionate decrease of molybdenum and carbon is more obvious with the increase in damage.