Recommended Action Level Research Articles

Risk assessment of radon exposure inside residential dwellings in Safi city, Morocco

ABSTRACT A radon study was conducted in 50 residences in Safi city, Morocco, using LR-115 detectors. The annual effective dose and Excess Lifetime Cancer Risk were also estimated. The measured radon concentrations ranged between the Lower Limit of Detection (LLD) and 132 Bq.m−3 with an arithmetic mean of 53 Bq.m−3 and a geometric mean of 41 Bq.m−3 (2.32). The results indicated that 58% of the obtained values exceeded the worldwide average value (39 Bq.m−3). In addition, the results revealed significant impacts of floor level and region on indoor radon levels. Inhabitants of the surveyed houses were found to receive a mean annual effective dose of 1.5 ± 0.1 mSv.y−1, corresponding to an Excess Lifetime Cancer Risk of 0.6%. Importantly, all annual effective dose values were below the recommended action level by the ICRP (3–10 mSv.y−1). Using the Ordinary Kriging method implemented in the QGIS software, an indoor radon map was created based on the collected data. The findings in this study serve as baseline values for future studies concerning radon concentrations and their fluctuations.

Indoor radon, external dose rate and assessment of lung cancer risk in dwellings: the case of Ebolowa town, Southern Cameroon

ABSTRACT The present work reports indoor Radon-222 activity concentration measurements, external gamma dose rate measurements, and assessment of cancer risk in the different dwellings in Ebolowa town, southern Cameroon. The geological formations of this studied area are mainly granites. This studied area extends over the equatorial climatic zone. The mean temperature of the zone varies from 25°C to 26°C with two rainy and two dry seasons with a relative humidity of (70–80) % recorded throughout the year. The indoor radon activity concentrations were carried out using RADTRACK2 devices, which are the alpha track detectors made of CR-39 plastic films contained in an antistatic black holder. Each device was hung in an inhabited room of each selected dwelling for an average period of three months. Radon concentrations in dwellings ranged between (23 ± 10) Bq m–3 and (2620 ± 480) Bq m–3 with an arithmetic mean of 135.6 Bq m–3 and a geometric mean of 63 Bq m–3. The estimated annual effective doses due to external gamma exposure ranged from (0.15 ± 0.01) mSv y−1 to (0.38 ± 0.06) mSv y−1 with an average value of 0.26 mSv y−1. The estimated annual effective dose due to indoor radon ranged between 0.43 mSv y−1 and 49.6 mSv y−1 with an arithmetic mean of 2.6 mSv y−1. This value was below the International Commission on Radiological Protection (ICRP) recommended action level. The Excess Lifetime Cancer Risk (ELCR) ranged from 1.39% to 158% with a mean value of 8.2%. According to these results, cancer risk due to inhalation of radon-222 must be further investigated in the population living in Ebolowa town.

Inhalation dose in the indoor environment of Eloor industrial area, Kerala, India

Radon (222Rn) and Thoron (220Rn), the members of Uranium and Thorium decay series respectively, are ubiquitous in nature. Being airborne alpha active radioisotopes, they are the major contributors of inhalation dose especially in the indoor environments. This study measures the Potential Alpha Energy Concentration (PAEC) of radon/thoron progenies in the dwellings of Eloor industrial region in Kerala and thereby evaluate the internal/inhalation dose to the population. Aerosol samples were collected from 100 locations in the study area using high volume air sampler and gross particulate activity measurement was done using ZnS(Ag) alpha counter. The PAEC of radon progeny in the study area varied from 0.13 to 2.94 and that of thoron progeny varied from 0.3 to 7.7. It has been observed that the dwelling with marble floor possesses relatively higher concentration of radon and thoron progenies while lower concentrations were observed in dwellings with tile floors. Taking the mean concentrations of 222Rn and 220Rn progeny levels of 100 samples collected, the inhalation dose was 0.14 mSvy-1 for radon and 0.09 mSv y-1 for thoron, which delivers a total inhalation dose of 0.23 mSv y-1 to the population residing in that area. Measured data show below compared to the ICRP recommended action level of 3–10 mSvy-1 for general populace. Although measured data requires no immediate action to reduce the hazardous radon and thoron level in the studied area, however the radiation risk from such hazardous gas is not completely discarded. Since human spent more than 80% of time in indoor and the radiation hazards follows linear no threshold model, therefore the indoor environment should be well ventilated to reduce any unexpected health hazards.

Annual effective dose from radon-222 concentration levels in underground water in bungoma south sub - county, Kenya

This research measured the concentration levels of radon in groundwater and determined the ingestion and inhalation dose. The study used RAD7 detector with RAD7-H2O accessory from Durridge Company to determine the radon levels. Thirty water samples in granitic dominated regions were collected from various areas of Bungoma County: ten from boreholes (BH), ten from hand dug wells (WL) and ten from springs (SP). The water samples were collected in 250 ml bottles which were tightly covered with lid to avoid radon leakage. The highest value was 303±4.00 KBq/m3 recorded in Kanduyi well and the lowest was 126±11.4kBq/m3 from where most of the samples recorded a high radon concentration with a mean of 269±5.25 KBq/m3 in wells, 213±7.96 KBq/m3 in boreholes and 290±7.70 KBq/m3 in springs. The average ingestion dose was found to be 1.5±0.07mSv/yr, 1.9±0.09 mSv/yr and 2.1±0.1 mSv/yr. The average annual effective dose rate for the samples collected were 2±0.1 mSv/yr for boreholes, 2.6±0.13 mSv/yr for wells and 2.7±0.14 mSv/yr for springs. The samples reported an average value of AED higher than the world average of 1.15 mSv/yr but below the exception limit of recommended action level of 10 mSv/yr hence the radon concentration levels in underground water in the study area has minimal health implications to the population.

Assessment of Indoor Radon Concentration in Residential Buildings at Ouagadougou and Estimation of the Annual Effective Dose

The second most important cause of lung cancer after smoking is a radon gas. Thus, the determination of indoor radon concentrations in residential buildings is an important public health concern. The purpose of this research was to measure the concentration of radon gas in residential homes in the city of Ouagadougou and evaluate the annual effective dose, effective dose equivalent and the relative risk of lung cancer. The present study used the digital radon detector air things of cranium to determine the concentration of radon in twenty one homes at Ouagadougou. The digital radon detector air Things of corentium was placed in each residential building for a minimum period of one week and the concentration values are read every 24 hours. The values recorded are the short term average and the long term average. This study showed that the average radon concentration was 26.90±2.58 Bq/m³ in residential homes at Ouagadougou. The average radon effective dose rate was calculated as 0.68 mSv per year and the average effective dose equivalent of 1.63 mSv per year. The average relative risk of lung cancer (RRLC) due to indoor exposure was 1.02. The concentration of radon in one house was found to be greater than 100 Bq/m³, which is above the level allowed by the World Health Organization (WHO). The radon Effective Dose Equivalent in 14.3% of homes were slightly larger than the limit of the recommended action level (3-10 mSv per year) as reported by the ICRP-1993. It seems necessary to increase the public’s awareness of this issue and to take action to reduce radon in homes when the concentrations are above.

Determination of 226Ra in Urine Using Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry.

Measuring 226Ra in urine at low levels is critical for both biomonitoring and radiological emergency response. Here we report a new analytical method to quantify 226Ra, as developed and validated by a simple dilute-and-shoot procedure, followed by Inductively Coupled Plasma-triple quadrupole-mass spectrometry detection using 'No Gas MS-MS' mode. The method provides rapid and accurate results for 226Ra with a limit of detection (LOD) down to 0.007ng/l (0.26Bq/l). This LOD is well below the recommended action levels for 226Ra detection in children and pregnant women (C/P) set by the Clinical Decision Guide (NCRP Report #161). Results for 226Ra obtained by this method are within ±7.0% of the target values of standard reference materials spiked in the urine.

Associations Between School Characteristics and Classroom Radon Concentrations in Utah's Public Schools: A Project Completed by University Environmental Health Students.

Radon (²²²Rn), a radioactive gas, is the second leading cause of lung cancer deaths in the U.S. Classroom radon concentrations in public schools in our target area had never been measured or had not been measured in many years. We had university students, primarily enrolled in environmental health courses, measure radon concentrations in 2289 classrooms in 66 of Utah’s public schools and identify school characteristics associated with classroom radon concentrations. The geometric mean (GM) classroom radon concentration was 31.39 (95% confidence interval (CI): 27.16, 36.28) Bq/m3 (GM: 0.85; 95% CI: 0.72, 0.98 pCi/L). Thirty-seven (2%) classrooms in 13 (20%) schools had radon concentrations at or above the U.S. Environmental Protection Agency’s (EPA) recommended action level of 148 Bq/m3 (4.0 pCi/L). Number of classrooms had a u-shaped association with classroom radon concentrations. The year the heating, ventilation, and air conditioning (HVAC) system was installed was inversely associated with having classroom radon concentrations at or above the EPA’s recommended action level. Number of classrooms and number of students had u-shaped associations with having classroom radon concentrations at or above the EPA’s recommended action level. Classroom radon concentrations decreased when schools’ HVAC systems were on. Replacing HVAC systems and turning/keeping them on may be effective radon mitigation strategies to prevent radon-associated lung cancer, especially for small and large schools.

An examination of radon awareness, risk communication, and radon risk reduction in a Hispanic community

Purpose: Radiation risk communication is a critical component of radiation protection and the public’s understanding of radiation risks and benefits. Risk communication becomes even more complicated when considering cultural and language differences. In the US, many diverse communities face risk communication challenges. We obtained radon testing data to evaluate patterns of radon testing in Allentown, the third largest city in Pennsylvania. Radon exposure is the second leading cause of lung cancer after smoking and is associated with over 21,000 lung cancer deaths in the US annually. It is estimated that 1 in every 15 homes in the US has elevated radon levels above the recommended action level set by the US Environmental Protection Agency. Allentown has some of the highest reported levels of indoor radon in the country, yet only a small portion of the population has tested their homes. This is true particularly among self-identified Hispanics, who make up nearly half of the city’s population. This study seeks to (1) characterize the difference in testing rates between self-identified Hispanics and non-Hispanics in Allentown, (2) quantify the level of radon awareness and knowledge, (3) identify potential obstacles to radon testing among the Allentown population that self-identifies as Hispanic, and (4) determine whether more effective risk communication is needed.Method: Radon test results in Allentown were analyzed to better understand the nature of radon testing. To evaluate radon awareness and knowledge, a cross-sectional study was conducted using a face-to-face survey. This data was informative in assessing testing and mitigation practices, ethnicity, income level, age, education level, homeowner status, zip code and primary language.Results: Ethnicity was an independent predictor of radon awareness and knowledge. Statistically significant differences were found between the number of self-identified Hispanics (39%) and non-Hispanics (84%) who indicated that they had ever heard of radon; 13% of Hispanics and 49% of non-Hispanics knew that they lived in an area with typically high radon levels. There was a statistically significant association between self-reported ethnicity and radon testing with non-Hispanics (43%) more likely to test their homes for radon than Hispanics (32%).Conclusion: Individual and community understanding of the risks of exposure to radiation sources such as radon is dependent upon communication that informs and spurs appropriate action. This study demonstrates the need for culturally appropriate radon risk communication strategies targeted to a Hispanic population. Successful communication will raise awareness and knowledge that can lead to better public health protection.

PCB in air, dust and surface wipes in 73 Danish homes.

As part of an investigation of the total indoor exposure of residents in PCB contaminated apartments in a building estate in Denmark, 73 homes were visited. Samples of air, vacuum cleaner dust and surface wipes were taken and analysed for 15 PCB congeners. The 53 apartments located in high-rise buildings with indoor PCB containing sealants showed significant elevated total concentrations of PCB in air, dust and surface wipes compared to 20 reference homes. The average concentration in exposed homes was 2330ng PCBtotal/m3 in air, 12.000ng PCBsum15/g in dust and for surface wipes 529ng PCBsum15/wipe. These values were respectively 40, 25 and 50 times higher than the averages found in reference homes. The air concentration in all exposed homes was higher than the lower recommended action level of 300ng PCBtotal/m3 from the Danish Health Authority, whereas all reference homes were below. The air concentrations in exposed homes were variating, partly due to indoor temperature. The concentrations in air and dust samples were significantly correlated for PCBsum7 in exposed homes. No significant correlation was observed between samples of air and surface wipes, despite surface wipes from exposed homes were significantly different from wipes taken in reference homes. Both dust samples and surface wipes have a potential as screening tool for identifying elevated levels of the less chlorinated PCBs in air. Additional short-term measurements of air concentrations in a subgroup of exposed homes indicated limited diurnal variations within the individual homes. The congener patterns were rather uniform within the respective media from the exposed homes and dominated by tri- and tetraPCBs. The pattern of air differed from that of dust and surface wipes, which were more alike. The study demonstrates a wide spread PCB contamination of the indoor environment in buildings with PCB in indoor sealants and confirms the need for identifying and alleviate PCB in buildings causing a health concern to the occupants.

Radon activity concentration measurements in water sources from Perak state Malaysia

Radon activity concentration in water samples from Perak state Malaysia and their possible health risk was assessed. The Samples were from lakes, hot springs, and rivers. The RAD7 Detector was used for in-situ measurement of radon concentration. The radon activity concentration ranged from 0.04 ± 0.08 — 3.98 ± 0.39 Bq l – 1, with mean of 0.69 Bq l – 1 and standard deviation of 0.92 Bq l – 1. The activity concentration ranged from 0.08 ± 0.12 — 0.45 ± 0.27, 0.04 ± 0.08 — 0.62 ± 0.32, 0.33 ± 0.23 — 3.98 ± 0.39 Bq l – 1, with a mean of 0.24 ± 0.19, 0.30 ± 0.21, 1.26 ± 0.34 Bq l – 1 for lakes, hot springs, and rivers respectively. The result was below the UNSCEAR, USEPA and WHO action levels of 11.1 Bq l– 1and100 Bq l – 1respectively. The 222Rn contribution from water to indoor air was found to be below the recommended action level . The annual effective dose for inhalation and ingestion ranged from 0.000102 — 0.009954 mSv y – 1 and 0.000102 — 0.010112 mSv y – 1, with mean annual effective dose of 0.001733 and 0.001759 mSv y – 1 respectively. The effective doses for both inhalation and ingestion were below the world average of 0.002 mSv y – 1. The 222Rn activity concentration in the study could be termed normal and without threat to human health.

Radon Concentration and Its Ventilation Dependence Measured in Some Dwellings of Debresina, Ethiopia

Ionizing radiation has been proved a major stress that can induce carcinogenesis. Among these ionizing radiations the most significant one is radon which is a source of 43% of the annual dose averaged over the population of the world. If it is present in enhanced level beyond maximum permissible limit, it may cause lung cancer. In the present work a set of indoor radon measurements has been carried out in some houses of Debresina district, Ethiopia using cellulose nitrate LR-115 type-II plastic track detectors in the bare mode. The detectors were fixed in the houses for one month to be exposed with indoor radon from February to March 2018. Etching of detectors was done with 2.5 N NaOH solution for 75 minutes at 60°C in the Soil physics laboratory and counting of tracks recorded was done using optical microscope in the Department of Earth Science, Bahirdar University. It is found that the value of radon concentration in those dwellings ranges from 12.24 to 251.94 Bq/m³ with an average of 102.87 Bq/m³ and standard deviation of 81.97 Bq/m³. The annual effective dose rates are found to vary from 0.31 to 6.29 mSv y^-1 with an average of 2.57 mSv y^-1 and a standard deviation of 2.05 mSv y^-1. The indoor radon concentration has been found to have strong correlation with the ventilation condition. Ventilated houses have shown less radon concentration than unventilated houses. Though most of the indoor radon concentration values measured are well within the recommended action level of ICRP, more than half of these values are above the new recommended level of WHO.

Avaliação e caracterização de insalubridade pro exposição á ruído em uma empresa de reciclagem de plástico

As condições de trabalho em muitas empresas e indústrias possibilitam situações de risco à qualidade de vida dos seus colaboradores, dentre essas situações está à exposição aos altos níveis de ruído. Portanto, o presente trabalho tem como objetivo avaliar a higiene ocupacional de um colaborador no processo de extrusão de plástico em uma empresa de reciclagem, através da análise da emissão de ruído, com a perspectiva do cálculo de insalubridade. O trabalho foi realizado em uma empresa de recuperação de plástico do município de Caçador/SC, para os cálculos de insalubridade seguiu a partir da dose e exposição ao ruído conforme a NR-15 e NHO-01. Através do estudo pode-se observar que o colaborador da empresa está sob uma situação de exposição inaceitável, obtendo a consideração técnica como critica e nível de atuação recomendada para ações de controle urgente, conformes as diretrizes de cálculos da NR-15 e NHO-01, visto que o nível do ruído Leq é de 87,18 dB(A), buscando atenuar esse questão o colaborador recebe Equipamento de Proteção Individual (EPI) que atenua o ruído. Assim, é preciso de um monitoramento continuo da segurança do trabalhador em questão, visto que se o mesmo não realizar a utilização do EPI o mesmo pode sofrer consequências no seu processo de audição.
 Palavras-chave: Monitoramento do Ruído. Ruído Ocupacional. Ruído.

Performance evaluation and secondary monitor unit checkout for a dedicated accelerator in intraoperative electron radiotherapy

Quality assurance in intraoperative electron radiotherapy (IOERT) is a mandatory issue, because of single shot nature. Employed equipment for IOERT implementation, especially the treatment machine, should have a very stable performance for reliable treatment delivery. Calculated MUs is also an important factor which can affect the treatment quality. The aim of this study is to evaluate the performance characteristics of a dedicated accelerator in IOERT as well as a secondary MU check to ensure the validity of employed software for such purpose.The LIAC12 accelerator was considered in this study. The performance characteristics of accelerator including linearity, short term repeatability (STR) and Long term repeatability (LTR) were measured by ionometric dosimetry over a long time period of 48 weeks. LIAC Monitor Unit calculation (LMUCalculation) software is currently used for MU calculations of LIAC in IOERT. The validity of this software was evaluated through development of a secondary MU calculation worksheet and comparing the obtained results by two methods.The results showed that the LIAC accelerator fulfils the desired performance for IOERT. A perfect linear response was observed at different electron energies. The STR and LTR of LIAC response were less than 1% and 4%, respectively, at all of studied electron energies. The mean difference between calculated MUs by LMUCalculation and the developed manual approach was 1.23%.The obtained results guarantee the validity of LIAC performance for intraoperative radiotherapy purposes. Furthermore, accuracy of calculated MUs by LMUCalculation software was confirmed according to the recommended action level (2%) by AAPM TG-40 protocol.

Indoor risk assessment of radon gas in the science college buildings-University of Mustansiriyah using RAD-7 detector

In the present work, a set of indoor Radon concentration measurements was carried out in a number of rooms and buildings of Science College in the University of Mustansiriyah for the first time in Iraq using RAD-7 detector which is an active method for short time measuring compared with the passive method in solid state nuclear track detectors (SSNTD's). The results show that, the Radon concentrations values vary from 9.85±1.7 Bq.m-3 to 94.21±34.7 Bq.m-3 with an average value 53.64±26 Bq.m-3 which is lower than the recommended action level 200-300 Bq/m3 [ICRP, 2009].The values of the annual effective dose (A.E.D) vary from 0.25 mSv/y to 2.38 mSv/y, with an average value 1.46±0.67 mSv/y which is lower than the recommended the range 3-10 mSv/y [ICRP, 1993]. While the values of lung cancer cases per year per million person vary from 4.50 per million person to 42.84 per million person with an average value 24.35±12 per million person which is lower than the recommended range 170-230 per million person [ICRP, 1993].The values of the potential alpha energy concentration were found to vary from 10.18 mWL to 1.06 mWL, with an average value 5.79±2.8 mWL which is lower than the recommended value of 53.33 mWL given by [UNSCEAR, 1993].

ESTIMATION OF RESIDENTIAL RADON DOSES FROM THE EXHALATION RATE MEASUREMENTS-A CORRELATION OF EXPERIMENTAL AND THEORETICAL CALCULATIONS.

The annual effective radon doses for residents of 92 dwellings in Jazan city located in Northern Saudi Arabia are calculated from the radon concentration and equilibrium factor F, measured using passive technique. The overall average (±1 SD) of radon concentration, equilibrium factor and annual effective dose are 118 ± 12 Bq m-3, 0.3 ± 0.02 and 2.32 ± 0.17 mSv, respectively. Although 93% of the dwellings have radon concentrations below the reference level, about 24% of the dwellings have annual effective radon doses within the range of recommended action level of 3-10 mSv. The exhalation rate of radon from different environmental samples was measured and used in theoretical calculations to estimate the annual effective dose of radon at different conditions of ventilation and dwelling size. The correlation between the experimental measurements and theoretical estimation of radon doses is good at high ventilation rate (low F) and shows some deviation at low ventilation rate (high F). The theory gives lower radon doses than those measured especially at low ventilation and is likely attributed to the influence of building design and the variety of living style at the homes.

Study on Radon and Thoron Levels in and Around Different Industries of Tumkur and Bangalore Districts

Radon, Thoron and their progenies were estimated in and around the industrial area of Tumkur and Bangalore rural district by using Solid State Nuclear Track Detector (SSNTD) method. In this study the rice mills, paint industries, bio fuels, tyre recycling industries, granite industries, stone crushing industries, brick industries, oil seed industries, and garments are selected for indoor radon thoron measurements. The study shows that the concentration of radon and thoron are widely varies and also depends on the industrial activity and type of construction of industry. The study shows that the concentration of radon varies from 35.51 ± 1.31 to 245.36 ± 1.21 Bqm-3 with an average value of 115.31 Bqm-3 and thoron varies from 25.95 ± 2.36to 312.72 ± 1.58 Bqm-3 with an average value of 110.44 Bqm-3. The average radon concentrations are less than the lower limit of the action levels (200-300 Bqm-3) as recommended by ICRP. The corresponding progeny level of radon varies from 0.24 to 13 mWL and thoron progeny varies from 0.11 to 11 mWL. The annual effective doses received by the industrial workers are slightly lower than the recommended action level (3-10 mSvy-1).

Indoor radon concentrations in Al-Hasahisa and Rufaa towns in the central part of Sudan

Indoor radon was systematically surveyed in the towns of Al Hasahisa and Rufaa in the central part of Sudan. The radon concentrations were measured in 276 measurements, using CR-39 etched track detectors. The radon concentration in the corresponding towns was found to vary from (86 ± 10) Bqm-3 in Al-Hasahisa to (66 ± 8) Bqm-3 in Rufaa. Assuming an indoor occupancy factor of 0.8 and 0.4 for the equilibrium factor of radon indoors, we found that the effective dose rate from 222Rn in the studied towns ranges from (2.18 ± 0.26) to (1.67 ± 0.20) mSv y-1 and the relative lung cancer risk (RRLC) for radon exposure was 1.078 to 1.059% in Al Hasahisa and Rufaa towns respectively. The recorded values of indoor radon concentration in this study are much lower than the radon action level as recommended by ICRP-1993, lower than the new reference level set by WHO and below the action level recommended by the Environmental Protection Agency (EPA). The values of the radon effective dose rate in this survey are slightly larger than the 'normal' background level as quoted by UNSCEAR-2000, but way below even the lower limit of the recommended action level as reported by the ICRP- 1993. The reported values of RRLC are almost negligible.

Assessment of Radon Concentration within Construction Materials Used in Wolaita Sodo, Ethiopia

The inhalation of radon decay products is the second most leading reasons for lung cancer after smoking. Building materials are an important source of indoor radon. This article describes the determination of the exhalation rate of radon from construction materials by the use of commercially available digital radon measuring device. Six types of construction materials were collected from the study area; these are cement, metal, sand, rock, clay brisk and gypsum. The measurements of effective radium content and radon concentration in those materials were investigated. The concentration was measured by alpha spectroscopy detection technique with Corentium digital radon detector. It was found that the overall average radon concentration in the construction materials varied from 58.46 Bq/m<SUP>3</SUP> to 307.84 Bq/m<SUP>3</SUP>, which is above the recommended action level. The average effective radium content varies from 69.85 Bq/kg to 367.79 Bq/kg which is below the maximum permissible value of 370 Bq/kg as recommended by Organization for Economic Corporation and Development (OECD) but it is near to maximum, so it can pose significant threat to the population. The average annual effective inhalation dose varied from 0.53 mSv/yto 2.77 mSv/y. The mean excess lung cancer risk estimated by this work was found to range from 1.17% to 6.16% within average value of 2.92%. The average of Excess Lifetime Cancer Risk (ELCR) is greater than with the estimated risk of 1.3% due to a radon exposure of 148 Bqm<SUP>–3</SUP> which is the action level of Environmental protection agency (EPA). The mass exhalation rates of radon vary from 14.98 × 10<SUP>−6</SUP> to 97.91 × 10<SUP>−6</SUP> Bq.kg<SUP>−1</SUP>.d<SUP>−1</SUP> with a mean value of 57.91×10<SUP>−6</SUP> Bq.kg<SUP>−1</SUP>.d<SUP>−1</SUP>. The surface exhalation rates of radon have been found to vary from 23.85 × 10<SUP>−5</SUP> to 155.91 ×10<SUP>−5</SUP> Bq.kg<SUP>−1</SUP>.d−<SUP>1</SUP> with a mean value of 91.46 ×10<SUP>−5</SUP> Bq.kg<SUP>−1</SUP>.d−<SUP>1</SUP>. This indicates the contributions of construction materials in the indoor radon are very high.

Quality controls for CBCT devices: The efomp guideline for quality assurance of images and dose

Introduction Current guidelines for quality control of CBCT devices consider the available applications (dental, radiotherapy, interventional radiology and guided surgery) as different entities. However, the data acquisition and reconstruction methods are similar. Henceforth, the evaluation parameters for image quality and dose can be unified. Purpose The purpose of this guideline (under discussion since January 2014 within an EFOMP working group) is to present an objective, practical and unifying procedure for quality control of all imaging CBCT applications Materials and methods The parameters used for image quality assessment are uniformity, accuracy of density values (or Hounsfield units where appropriate), geometrical evaluation, noise, low contrast resolution (including contrast to noise ratio) and high contrast resolution. Results Detailed procedures using free software and commercially available test phantoms are described. The dosimetric quantities under consideration are CTDI, kerma area product and detector incident air kerma. Recommended action levels and test frequency are indicated together with references wherever possible. Conclusion This guideline includes the minimum tests that should be performed to ensure reliable, safe and consistent performance of CBCT devices. This minimum has been sought to guarantee compatibility with all manufacturers and existing European documents (DIN 6868161, HPACRCE010 and RP 172 for dental applications). Disclosure Nothing to disclose.

MEASUREMENTS AND SEASONAL ANALYSIS OF RADIOACTIVE GASES IN THE ENVIRONMENT OF RAMPUR AND NEARBY TOWN (U.P.) BY USING SOLID STATE NUCLEAR TRACK DETECTOR (SSNTD) TECHNIQUE

Measurements of radioactive gases i.e. radon and thoron &amp; their progeny concentration were carried out in some selected dwellings in Rampur and nearby towns of Uttar Pradesh by using Solid State Nuclear Track Detector (SSNTD).The radon-thoron twin dosimeter cups were used for the measurements. The measurement was repeated on a time integrated four quarterly cycles to cover all the four seasons (summer, rainy, autumn &amp;winter) of the calendar year.&#x0D; During summer, rainy, autumn and winter seasons the radon concentration was found to vary from 9 Bq/m3 to 55 Bq/m3 with an average of 18.72 Bq/m3, 11Bq/m3 to 40 Bq/m3 with an average of 24.41 Bq/m3, 15 Bq/m3 to 46 Bq/m3 with an average of 29.95 Bq/m3and 25 Bq/m3 to 85 Bq/m3 with an average of 44.92 Bq/m3 respectively where as its progeny concentration varied from 0.57mWL to 5.94mwL with an average value of 2.02mWL, 1.18mWL to 4.32mWL with an average value of 2.63mWL, 1.62mWl to 4.97mWL with an average value of 3.23mWL and 2.70mWL to 9.18mWL with an average value of 4.85mWL respectively.&#x0D; The thoron concentration was found to vary from 7.33 Bq/m3 to 22.5Bq/m3 with an average value of 11.86Bq/m3, 10.50 Bq/m3 to 23Bq/m3 with an average value of 16.06 Bq/m3, 11.66 Bq/m3 to 24.5 Bq/m3 with an average value of 17.44 Bq/m3, and 17.66 Bq/m3 to 30 Bq/m3 with an average value of 21.35 Bq/m3 respectively where as its progeny concentration varied from 0.19mWL to 0.60mWL with an average value of 0.32mWL, 0.28mWL to 0.62mWL with an average value of 0.43mWL, 0.31mWl to 0.66mWL with an average value of 0.47mWL and 0.47mWL to 0.81mWL with an average value of 0.57mWL respectively in different seasons.&#x0D; All values were observed below the recommended action level (200Bq/m3) set by the various organizations (ICRP, 1993)