Time filter

Source Type

Prouza Z.,National Radiation Protection Institute, Czech Republic
Radiation protection dosimetry | Year: 2010

During recent years, the assessment of possible radiological consequences of a terrorist attack associated with a release of radioactive substances (RaS) has been in the focus of interest of emergency preparedness and radiation protection specialists, as well as experts dealing with the dispersion of harmful substances in the atmosphere. Suitable tools for these analyses are applications of mathematical and physical models and simulation of this attack under 'realistic' conditions. The work presented here summarises the results of four tests, in which a RaS (a Tc-99 m solution) was dispersed over a free area with the use of an industrial explosive. Detection methods and techniques employed in these tests are described and values characterising the RaS dispersion--dose rates, surface activities in horizontal and vertical directions, volume activities, their space and time distributions and mass concentrations of aerosols produced after the explosion are presented and compared. These data will be applied to a comparison of outcomes of models used for the assessment of radiation accidents as well as in future field tests carried out under conditions of more complex geometry (indoor environment, terrain obstacles, etc.).


Tomasek L.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2014

Eleven underground miners studies evaluated the risk of lung cancer from exposure in underground mines. Nearly 68 000 miners were included in the joint study, contributing to nearly 2700 lung cancers. The resulting model of the Biological Effects of Ionizing Radiation (BEIR) VI Committee considered linear exposure response relationship, which was modified by time since exposure (TE), attained age and exposure rate. The effect of age at exposure (AE) was not explicitly evaluated. The presentation aims to show that the modifying effect of AE is substantial if time-since-exposure modification is simultaneously used in the model. When the excess relative risk per unit exposure (ERR/WLM) is adjusted for TE, the ERR/WLM corresponding to AE <15 is 0.013 and in subsequent categories decreased gradually up to the AE of 40 and more years, which was only 0.004. In comparison with the BEIRVI model, the present model predicts higher risks at younger ages and the risk decreases more rapidly. © The Author 2014. Published by Oxford University Press. All rights reserved.


Ekendahl D.,National Radiation Protection Institute, Czech Republic | Judas L.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2012

Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses. © The Author 2011. Published by Oxford University Press. All rights reserved.


Fojtikova I.,National Radiation Protection Institute, Czech Republic | Navratilova Rovenska K.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2014

Due to the large number of subsidies for energy-saving reconstructions granted, and expecting a strong influence of reconstruction on the radon level in building, the long-term measurements of radon concentration are offered free of charge to kindergartens in the Czech Republic. Classrooms and playrooms where the radon levels exceeded the reference value for kindergartens, which is 400 Bq m-3, are monitored continuously for at least a week to obtain the average activity concentration of radon when children are present. Some of the kindergartens were previously measured in the 1990s. These earlier measurements have provided an opportunity to compare the results. This paper presents some lessons learned from radon diagnosis carried out in particular cases and an analysis of the influence of reconstruction work on the radon level in the buildings. © The Author 2014. Published by Oxford University Press. All rights reserved.


Holgye Z.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2013

Excretion rates of 210Po and 210Pb in the urine were investigated in 40 healthy inhabitants of Prague (22 males, 18 females, age: 23-70 y, non-smokers). In 20 inhabitants the excretion rates of 210Po and 210Pb in faeces were also studied. The mean urinary excretion rates of 210Po and 210Pb were 4.1 and 6.0 mBq d-1, respectively. It was demonstrated, statistically, that the urinary excretion rates of 210Po and 210Pb are higher in men than those in women. The highest excretion rates of 210Po and 210Pb found in the participants were 10.8 and 16.6 mBq d-1, respectively. The mean activity ratio of 210Po/210Pb in the urine was 0.73. The mean excretion rates of 210Po and 210Pb in faeces were 56.5 and 54.6 mBq d-1. The mean activity ratio of 210Po210Pb in faeces was 1.0. © The Author 2013. Published by Oxford University Press. All rights reserved.


Tomasek L.,National Radiation Protection Institute, Czech Republic
Journal of Radiological Protection | Year: 2012

The present study is based on 9978 Czech uranium miners with 1141 lung cancer deaths observed in an updated follow-up 1952-2010 and corresponding to 31years of mean follow-up. The objectives of the study are to obtain more reliable estimates for the exposure-response relationship, including factors that modify this relationship. Lung cancer in relation to cumulative exposure to radon decay products is linear with substantial modifications by time since exposure, age at exposure and exposure rate using exposure windows. The crude excess relative risk (ERR) per unit exposure in working level months (WLM) in the cohort is 0.0097 (90% confidence interval (CI) 0.0074-0.0127). The ERR/WLM corresponding to exposure rates below 7 working levels (WL) is substantially higher 0.0145 (90% CI 0.0109-0.0193). In the final model, the inverse effect of exposure rate is observed for high exposure rates >7WL with the ERR/WLM reduced to 31%. The ERR/WLM decreases to 32% and 9% in periods 20-29 and 30+years since exposure in comparison to the period of 5-19years since exposure. Simultaneously, the ERR/WLM decreases with age at exposure 63% and 49% at ages 30-39 and 40+years in comparison to age at exposure <30years. © 2012 IOP Publishing Ltd.


Tomasek L.,National Radiation Protection Institute, Czech Republic
Neoplasma | Year: 2012

The presented study reports lung cancer mortality in a cohort of 11 842 subjects exposed to high levels of radon covering the period 1961-2010. Exposure estimates were based on one year measurements of radon progeny in most houses of the study area (72%), missing values in the studied area were replaced by measurements in proxy houses (9%) and exposures outside the area (19%) were based on country radon mapping. Mean concentration of 448 Bq m-3 in the study is higher than the country mean by a factor of 5. By 2010, a total of 293 lung cancers were observed. The risk is significantly related to cumulated exposure with ERR/100Bq m-3 0.11 (90%CI: 0.04 - 0.25). This value is consistent with the risk coefficients in other indoor studies and also with the risks observed among uranium miners. The present follow-up demonstrated that increased incidence of lung cancer depends mainly on exposure from previous 5-19 years. The relative risk of lung cancer in the present study derived from this model is 1.53 (90%CI: 1.39 - 1.69).


Fronka A.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2011

Detailed knowledge of radon transport mechanisms from the subsoil into the indoor environment is essential for the correct interpretation of results of short-term indoor radon measurements and for proper and effective design of radon mitigation systems. Radon transfer factor time variations have been studied based on simultaneous continuous indoor and soil gas radon measurements within the framework of complex radon diagnosis of individual buildings. In this context, the key influencing factors have been identified and analysed in order to provide satisfactory explanation on radon entry variations under different measurement conditions. Moreover, a new significant manner of radon entry into the indoor environment has been identified and will be discussed in detail. © The Author 2011. Published by Oxford University Press. All rights reserved.


Tomasek L.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2011

The study is based on a case-control study nested within a cohort study (11 000 miners and 1074 lung cancers). The controls were individually matched by year of birth and attained age. Smoking data were collected in person or from relatives of deceased subjects or from medical files. The study resulted in 850 cases of lung cancer with smoking data. The linear dependence of lung cancer relative risk (RR) on radon exposure adjusted for smoking was not substantially different from analyses when smoking was ignored and reflected mainly the risk among smokers. However, the excess RR per unit exposure among never smokers (70 cases) was substantially higher in comparison with that in smokers, reflecting differences in lung morphometry and clearance. The RRs from combined effects are substantially lower than the risk derived from the multiplicative model, but somewhat higher than those from the additive model. The work was supported by the Czech Ministry of Health (IGA NS 10596). © The Author 2011. Published by Oxford University Press. All rights reserved.


Ekendahl D.,National Radiation Protection Institute, Czech Republic | Judas L.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2011

NaCl is a cheap and widely available material. This study investigated the potential of NaCl in the form of a household salt as a retrospective and accident dosemeter using optically stimulated luminescence (OSL). Samples of the investigated household salt were stimulated using blue light of linearly modulated power. Attention was concentrated on sensitivity, dose dependence of the OSL signal, fading, optimisation of the read-out procedure and application of analytical protocols that do not require a specific calibration. A potential of NaCl as a complementary dosemeter within emergency preparedness was considered. The behaviour of the OSL signal observed was found to be favourable for dosimetry. © The Author 2010. Published by Oxford University Press. All rights reserved.

Loading National Radiation Protection Institute, Czech Republic collaborators
Loading National Radiation Protection Institute, Czech Republic collaborators