mSv For Adults Research Articles

Comparative analysis of the results of simulation of the consequences of a serious accident at a Belarusian NPP with the use of J-RODOS and RECASSEXPRESS software complexes

Using the J-RODOS and RECASS-EXPRESS software packages, modeling of the radiological and radiation-ecological consequences of a severe beyond design basis accident at the power unit of the Belarusian NPP with a VVER-1200 reactor was carried out. The simulation results showed that if radionuclides were released from the reactor containment at the level of 2.15·1015 Bq, the maximum values of the fallout from the atmosphere to the surface 1 day after the accident will be 2.98∙105 Bq/m2 for I-131 (J-RODOS) and 7∙105 Bq/m2 (RECASS-EXPRESS), and for Cs-137 − 1.11∙104 Bq/m2 and 1.3∙105 Bq/m2, respectively. The difference in the values of the radionuclide fallout, modeled by these software packages, increases with the distance from the release source and at a distance of more than 10 km reaches 1 order of magnitude. The predicted values of the equivalent thyroid dose for adults and children for the first 7 days after the accident, obtained using J-RODOS calculations, are 3–4 times higher than using RECASS-EXPRESS software product. At a distance of 3–5 km from the NPP site, doses ranged from 3.7 to 14.8 mSv for adults and 16.2 to 32.5 mSv for children. The values of the total effective dose with the J-RODOS simulation are 2 times higher than those with RECASS-EXPRESS at a distance of 3 km from the site (0.60 and 0.32 mSv, respectively) and 1.5 times higher at a distance of 5 km from the site (0.30 and 0.21 mSv respectively). As the distance from the NPP increases, the convergence in the obtained evaluation results of total effective dose increases. None of the obtained prediction results exceeds the established emergency response criteria and do not indicate the need for protective measures for the public.

Estimation of natural radioactive and heavy metals concentration in underground water

Concentrations of natural nuclides (226Ra, 232Th and 4 K) and some heavy metals (Cu, Fe. Ni, Pb and As) were measured in groundwater collected from different locations in Makkah region in Saudi Arabia. In the radioactivity measurement, a high purity germanium detector system was used. In addition, chemical analysis was performed by an Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The average measured activity concentrations of the nuclides 238U, 232Th and 4 K were 0.558, 0.204 and 4.581 BqL−1, respectively. The total annual effective doses for ingestion of radionuclides in the water samples were 0.472 mSv for children and 0.169 mSv for adults. These results were lower than the recommended value (1.0 mSvy−1), as reported by WHO. The chemical analysis results showed that these water samples contain (Ca, Mg, Cu, Fe. Ni, Pb and As) elements. The concentration values were evaluated and compared with the internationally verified values. This study provides essential information for consumers and authorities; those at exposure risk from mineral water intake.

Radioactive Doses — Predicted and Actual — and Likely Health Effects

Five years have passed since the nuclear accident at Fukushima Daiichi Nuclear Power Stations on 11 March 2011. Here we refer to reports from international organisations as sources of predicted values obtained from environmental monitoring and dose estimation models, and reports from various institutes in Japan are used as sources of individual actual values. The World Health Organization, based on information available up to 11 September 2011 (and published in 2012), reported that characteristic effective doses in the first year after the accident, to all age groups, were estimated to be in the 10–50 mSv dose band in example locations in evacuation areas. Estimated characteristic thyroid doses to infants in Namie Town were within the 100–200 mSv dose band. A report from the United Nations Scientific Committee on the Effects of Atomic Radiation published in 2014 shows that the effective dose received by adults in evacuation areas during the first year after the accident was 1.1–13 mSv. The absorbed dose to the thyroid in evacuated settlements was 7.2–35 mSv in adults and 15–83 mSv in 1-year-old infants. Individual external radiation exposure in the initial 4 months after the accident, estimated by superimposing individual behaviour data on to a daily dose rate map, was less than 3 mSv in 93.9% of residents (maximum 15 mSv) in evacuation areas. Actual individual thyroid equivalent doses were less than 15 mSv in 98.8% of children (maximum 25 mSv) in evacuation areas. When uncertainty exists in dose estimation models, it may be sensible to err on the side of caution, and final estimated doses are often much greater than actual radiation doses. However, overestimation of the dose at the time of an accident has a great influence on the psychology of residents. More than 100 000 residents have not returned to the evacuation areas 5 years after the Fukushima accident because of the social and mental effects during the initial period of the disaster. Estimates of radiation doses placed in the public domain must be based on scientific evidence, and the way such information is communicated to residents should be carefully considered to avoid psychosocial effects that may have a greater bearing on health than the radiation itself.

Radioactivity and Chemical Compositions of Some Selected Commercial Bottled Waters in Belarus

The measured chemical composition, concentrations of the uranium and radium isotopes (U-238, U-234, Ra-228, Ra-226) of 17 bottles water purchased from markets in Minsk Belarus and two water samples collected directly from catchments in the area of Minsk are presented. The bottled waters originated from not only Belarus but also Czech Republic, Russia and Georgia. Their mineralization varied from 300 to above 8000 mg/L. The studied waters were rich in magnesium in general and belonged to different hydrochemical types. The measured radium concentrations ranged from below the low limit of determination (5 mBq/L) to 622 mBq/L and below 10 mBq/L to 2080 mBq/L for Ra-226 and Ra-228 respectively. The uranium contents in the waters varied from 15.4 mBq/L to 111 mBq/L for U-238 and from 14.9 to 289 mBq/L for U-234; while the ratio of the uranium isotopes’ activity ratio (U-234/U-238) ranged from 0.77 to 12.7. The estimated annual committed effective dose rate from the radium and uranium isotopes resulting from the consumption of the investigated waters exceeds the maximum recommended value of 0.1 mSv for adults in one case, 6 cases for teenagers and 10 cases for babies, assuming that every adult, teenager and baby consume 70, 185 and 55 liters per year respectively.

Radiation doses among residents living 37 km northwest of the Fukushima Dai-ichi Nuclear Power Plant

External and internal radiation doses were estimated for 15 residents who lived approximately 37 km northwest of the Fukushima Dai-ichi Nuclear Power Plant, which released radioactive plumes on March 11, 2011 as the result of the Tohoku earthquake and subsequent tsunami damage. Residents were interviewed on where they stayed and what they ate after the incident. To estimate external dose, the air dose rate around each person's home was measured, and cumulative effective doses up to 54 d after the deposition were calculated. To estimate committed effective dose, urinary bioassays were performed using a low-background Ge spectrometer on 54 d and 78–85 d after the deposition. The average cumulative effective dose was 8.4 mSv for adults and 5.1 mSv for children. The average committed effective dose from 134Cs and 137Cs was 0.055 mSv for adults and 0.029 mSv for children. Iodine-131 was observed from urinary samples of five residents, the equivalent doses for thyroid gland were 27–66 mSv at maximum. We discuss the necessity of reducing the risk of further exposure.

Estimation of thyroid doses and health risks resulting from the intake of radioactive iodine in foods and drinking water by the citizens of Tokyo after the Fukushima nuclear accident

The release of radioactive materials from the Fukushima nuclear power plant after the Great East Japan Earthquake on 11 March 2011 poses health risks. In this study, the intake of iodine 131 (I-131) in drinking water and foods (milk, dairy products, and vegetables) by citizens of Tokyo was estimated. The effects of countermeasures (restrictions on the distribution of foods and the distribution of bottled water for infants) on reducing intake were also evaluated. The average thyroid equivalent doses without countermeasures from 21 March 2011 were 0.42mSv in adults, 1.49mSv in children, and 2.08mSv in infants. Those with countermeasures were 0.28, 0.97, and 1.14mSv respectively, reductions of 33%, 35%, and 45%. Drinking water contributed more to intake by adults and children than foods. The intake of I-131 within the first 2weeks was more than 80% of the estimated intake, owing to its short half-life, indicating that rapid countermeasures are important in reducing intake. The average risks of cancer incidence and mortality due to I-131 for infants were estimated to be 3×10−5 and 0.2×10−5, respectively, lower than the annual risks of traffic accidents, naturally occurring radioactive material (potassium 40), and environmental pollutants such as diesel exhaust particles.

Tomosynthesis in pulmonary cystic fibrosis with comparison to radiography and computed tomography: a pictorial review

The purpose of this pictorial review is to illustrate chest imaging findings of cystic fibrosis (CF) using tomosynthesis (digital tomography), in comparison to radiography and computed tomography (CT). CF is a chronic systemic disease where imaging has long been used for monitoring chest status. CT exposes the patient to a substantially higher radiation dose than radiography, rendering it unsuitable for the often needed repeated examinations of these patients. Tomosynthesis has recently appeared as an interesting low dose alternative to CT, with an effective dose of approximately 0.08 mSv for children and 0.12 mSv for adults. Tomosynthesis is performed on the same X-ray system as radiography, adding only about 1 min to the normal examination time. Typical pulmonary changes in CF such as mucus plugging, bronchial wall thickening, and bronchiectases are shown in significantly better detail with tomosynthesis than with traditional radiography. In addition, the cost for a tomosynthesis examination is low compared to CT. To reduce the radiation burden of patients with CF it is important to consider low dose alternatives to CT, especially in the paediatric population. Tomosynthesis has a lower radiation dose than CT and gives a superior visualisation of pulmonary CF changes compared to radiography. It is important to further determine the role of tomosynthesis for monitoring disease progression in CF.

Cancer induction caused by radiation due to computed tomography: a critical note

The considerable rise of computed tomography (CT) procedures over the past few decades has urged responsible authorities and researchers to evaluate the risk of carcinogenesis in the population in relation to the radiation dose delivered to the patient. A single patient undergoing CT may receive a radiation equivalent dose that varies between about 2 mSv (head ) to about 20 mSv (CT-based coronary angiography). Whereas the latter represents a substantial dose delivered to one patient it is, however, population-wise far below the area of the so-called low doses, i.e. 50 mSv in children and 100 mSv in adults. While at effective doses above 50 mSv the risk of cancer induction increases linearly with dose, this dose-response relation has not been demonstrated at doses below 50 mSv. Below 50 mSv no convincing epidemiological evidence for cancer risk exists. Calculations on this risk are based on scientifically questionable, if not invalid, extrapolations of data from higher doses. However, the failure to demonstrate that a risk of cancer exists does not mean that there is no risk. This paper summarizes the data mentioned in various articles from recent literature discussing cancer risks due to CT and puts the results of these studies in perspective of current scientific knowledge in the field of radiation protection. For this we follow the lead of the ICRP and UNSCEAR. Furthermore, we review the strategies and efforts of various national and international bodies and manufacturers of CT apparatus to lower the radiation dose to the patient.

Quality control and patient dosimetry in dental cone beam CT

This paper presents the initial experience in performing quality control and patient dose measurements in a cone beam computed tomography (CT) scanner (ILUMA Ultra, IMTEC Imaging, USA) for oral and maxillofacial radiology. The X-ray tube and the generator were tested first, including the kVp accuracy and precision, and the half-value layer (HVL). The following tests specific for panoramic dental systems were also performed: tube output, beam size and beam alignment to the detector. The tests specific for CT included measurements of noise and CT numbers in water and in air, as well as the homogeneity of CT numbers. The most appropriate dose quantity was found to be the air kerma-area product (KAP) measured with a KAP-metre installed at the tube exit. KAP values were found to vary from 110 to 185 microGy m(2) for available adult protocols and to be 54 microGy m(2) for the paediatric protocol. The effective dose calculated with the software PCXMC (STUK, Finland) was 0.05 mSv for children and 0.09-0.16 mSv for adults.

Radiation Doses and Risks in Chest Computed Tomography Examinations

Effective doses, and the corresponding risks of radiation-induced cancers, are presented for patients undergoing chest computed tomography (CT) examinations. Patient dose calculations were based on the characteristics of 16-slice CT scanner from 4 imaging equipment vendors. The dose-length product (DLP) was used to quantify the amount of radiation used to perform chest CT examinations. Values of DLP were converted into a corresponding effective dose (E) using age-dependent E/DLP conversion coefficients applicable to chest CT examinations. Calculations of effective doses were performed for a typical chest CT examination, as well as for a low-dose protocol for patients with cystic fibrosis. Effective doses were used to estimate nominal cancer risks based on data in Report VII of the Committee of the Biological Effects of Ionizing Radiation. Patient effective doses in standard chest CT examinations range from approximately 1.7 millisieverts (mSv) in newborns to approximately 5.4 mSv in adults. The effective dose to a 5-year-old patient with cystic fibrosis using a low-dose protocol is approximately 0.55 mSv, which is about a factor of four lower than a standard chest CT examination. An effective dose of 0.55 mSv for a 5-year-old patient corresponds to a nominal excess risk of carcinogenesis of approximately 1.5 cancers per 10,000 individuals, with half of these being fatal. It is concluded that patients undergoing chest CT examinations should have a benefit that exceeds the (small) radiation risk.

Iodine Prophylaxis following nuclear accidents – a concept how to distribute potassium-iodide tablets out of the central stocks in the event of an accident

Abstract With its recommendation “Iodine prophylaxis following nuclear accidents” (1996) and its reports of 1997 and 2001 the German Commission on Radiological Protection (SSK) followed the recommendations of the WHO “Guidelines for iodine prophylaxis following nuclear accidents” of 1989. The intervention levels were lowered (50 mSv for children/adolescents (up to the age of 18 years) and pregnant women, 250 mSv for adults), the iodine prophylaxis was restricted to persons up to the age of 45 years and the recommended dosage of stable iodine was changed. Due to the lowered reference levels the radius of 25 km around a nuclear power plant that had been the planning radius for the distribution of iodine tablets so far was extended to 100 km. Based on these recommendations the German authorities began to set up new strategies for the provision and distribution of potassium-iodide tablets (iodine tablets). Since 2004, within the radius of 25 km the iodine tablets are pre-distributed to households and/or stored at several points in the municipality for persons up to the age of 45 years. For the new planning radius of 25 – 100 km iodine tablets are stored in 8 central stocks in Germany for children/adolescents (up to the age of 18 years) and pregnant women. A working group with representatives from federal and Länder authorities has developed a distribution strategy for the distribution out of these central stocks in the event of an accident. It describes a possibility of organising and implementing the distribution of the iodine tablets within the radius of 25 – 100 km in a nationwide standardised way.

Transfer of chlorine from the environment to agricultural foodstuffs

The factors governing chlorine transfer from Phaeozem and Greyzem soils to various important crop species (foodstuff and forage) were determined in natural conditions in the Kiev region of Ukraine. The stable chlorine concentration ratio (CR) values were the lowest in apple (0.5 ± 0.3) and strawberry (2 ± 1), higher in vegetables (5 ± 3), seeds (15 ± 7) and reached a maximum in straw (187 ± 90). The average CR values of 36Cl were estimated for the most important crops using all experimental data on 36Cl and stable chlorine transfer into plants from various soils. It was experimentally shown that boiling potatoes in water leads to an equilibrium between 36Cl specific content in the water and moisture in the cooked potato. The 36Cl processing factor (PF) for boiling various foodstuffs is equal to the ratio of water mass in the cooked foodstuff to the total water mass (in the food and the decoction). 36Cl PF for cereal flour can be estimated as 1. The 36Cl processing factor for dairy products is equal to the ratio of residual water mass in the product to initial water mass in milk. At a 36Cl specific activity in soil of 1 Bq kg −1, the estimated annual dietary 36Cl intake into human organism (adult man) is about 10 kBq. Sixty to seventy percent of the above amount will be taken in via milk and dairy products, 7–16% via meat, 14–16% via bread and bakery items and 8–12% via vegetables. The highest annual 36Cl intake, 10.7 kBq, is predicted for 1-year-old children. The expected effective doses from annual 36Cl intake are higher for younger age groups, increasing from 0.008 mSv in adults to 0.12 mSv in 1-year-old children.

Determination and evaluation of natural radioactive nuclides in drinking water from selected water supplies of the Erzgebirge and the Vogtland regions / Bestimmung und Bewertung natürlicher Radionuklide in Trinkwässern ausgewählter Wasserversorgungsanlagen im Erzgebirge und im Vogtland

Investigations have been carried out to determine the natural radionuclide content of drinking and raw waters, in water supplies of the Erzgebirge and the Vogtland region. The maximum concentration values for the typical nuclides have proved to be lower than the concentration levels published in 1995 by the German Commission on Radiological Protection (SSK) for waters which are possibly susceptible to influences from uranium mining. Taking into consideration the nuclides Pb-210, Po-210, Ra-226, U-234, U-238, and Th-232, the average annual ingestion dose totals 20 mSv for infants, and 15 mSv for adults, which is relatively low compared to the other pathways of natural radiation exposure. Under application of conservative assumptions, the annual ingestion dose can reach 480 mSv and 360 mSv, respectively. The dose-predominate nuclides are usually Ra-226 and Pb-210. The reduction of concentrations of natural radionuclides in drinking water, which is achieved through the treatment of raw waters in water works is usually low. It decreases in the following order : Pb-210, Ra-226, Po-210, thorium isotopes, uranium isotopes.