Radiation Survey Meter Research Articles

Survey of Radiological Parameters at a Dumpsite Near an Oil and Gas Facility in Bayelsa State, Nigeria

The issue of proper waste management is becoming more critical with the increase of civilization and urbanization. Waste generation and disposal could increase levels of human radiation exposure. The dose rates from possible radioactive materials at Gbaraun-toru dumpsite have been investigated. Radiation survey meter was used to assess the dose rates at the site. Model equations were also used to estimate the health-related radiological parameters for the flux of scavengers and individuals using the dump site. The values of the measured dose rates at the dumpsites lie between (0.01 – 0.016) mRh-1 with a mean of 0.013 mRh-1. Absorbed dose rates and equivalent dose rates estimated ranged from (87.4 – 139.4) with a mean of 116.2 and (0876 – 1.402) with a mean of 1.113 . Annual effective dose rates, organ doses, and the excessive lifetime risk of cancer ranged from (0.357– 0.572) with mean 0.454 mSvy-1, (0.139 – 0.248) and (0.94 – 1.54) × 10-6 with mean of 1.28 × 10-6 respectively. Conclusively, the estimated absorbed measured rates for the study are above the safe limit (54 nGyh-1), while, others are within the safe limit (1 mSvh-1). This suggests that there may be an increment in the level of exposure of the workers at the dump sites, hence, regular radiological studies should be carried out in the study area

Investigation of radiation doses and dose constraint values of nonmedical planned exposure radiation practices in Taiwan

In Taiwan, the Nuclear Safety Commission (NUSC) is the competent authority responsible for ensuring the safety of ionizing radiation operations. In recent years, the NUSC has introduced the concepts of ALARA and dose constraints (as recommended by the International Commission on Radiological Protection), to control the radiation safety of various radiation sources, and to review the protective control measures. Consideration of these concepts can help ensure that industry operators optimize radiation protection in planned exposure situations. This study investigated the occupational exposure of facility operators using nonmedical planned exposure radiation sources in Taiwan. The NUSC provided a sampling roster, and survey respondents were randomly selected. An on-site radiation safety survey was conducted using a calibrated handheld radiation survey meter to measure the doses that radiation workers were exposed to during normal operations. In addition, the dose constraints of multiple radiation practices were evaluated through the statistical analysis of dose data. From 2020 to 2023, on-site radiation dose surveys were conducted on 1614 radiation sources. Additionally, the average occupational exposure doses of workers in relation to multiple nonmedical radiation operations were evaluated, and recommended dose constraints for these operations were proposed.

Forensic GIS γ-Radiation Mapping and Associated Radiological Health Risk Assessment of the Premier Cities of Sapele, Oghara and Koko; South-South Nigeria

The GIS mapping of the terrestrial γ -radiation levels and evaluation of the radiological health hazard to residents of Sapele, Oghara and Koko cities in Nigeria have been carried out, using a Digilert nuclear radiation survey meter, geographical positioning system (GPS) and arc ArcGIS software. In Sapele (4 zones), the measured average gamma radiation levels ranged from 0.011 ± 0.003 mR h − 1 to 0.014 ± 0.005 mR h − 1 , while in Oghara (5 zones), the average gamma radiation levels ranged from 0.013 ± 0.002 mR h − 1 to 0.026 ± 0.009 mR h − 1 and for Koko(4 zones), the values obtained ranged from 0.018 ± 0.003 mR h − 1 (1.54 ± 0.11 mSvy − 1 ) to 0.023 ± 0.008 mR h − 1 respectively, with overall mean value of 0.017 ± 0.006 mR h − 1 (1.43 ± 0.51 mSvy − 1 ) . The mean absorbed gamma dose rate for three cities of Sapele, Oghara and Koko are 106.50 ± 22.33 nGy h − 1 , 167.28 ± 22.59 nGy h − 1 and 176.80 ± 24.74 η Gyh − 1 respectively. The mean annual effective dose rate (AEDR) for the three cities is 0.13 ± 0.03 mSvy − 1 , 0.20 ± 0.07 mSvy − 1 and 0.22 ± 0.06 mSvy − 1 mSvy − 1 respectively , while the mean excess lifetime cancer risk (ELCR) values are (0.47, 0.72 and 0.77) x10−3 respectively. The results obtained in the cities indicate that the BIR levels, and corresponding estimated health risk parameters in Koko > Oghara > Sapele. The estimated effective dosage to organs shows that liver receiving the least dose of 0.07mSvy−1 (11%) while testes got the highest dose of 0.12 mSvy−1 (19%). The overall results obtained show that all the thirteen zones’ BIR levels and their estimated risk parameters exceeded their recommended limits for the public and were also higher than reported values in previous studies reviewed. The reported significant elevation of the obtained background ionizing radiation (BIR) values may not necessarily establish any immediate likelihood of radiological health risk, but call for caution on possible accumulative radiation effects in future on the residents of the study area.

Quantitative assessment of occupational radiation exposure in CT: a comparative study using two radiation survey meters for year-long dose monitoring of staff

Introduction: Computed Tomography (CT) is crucial in medical imaging but exposes healthcare workers to ionizing radiation. It is essential to quantify and mitigate occupational radiation exposure. This study provides a comprehensive quantitative analysis of CT settings, using two radiation survey meters, over a year-long monitoring period. Methodology: Healthcare workers operating CT scanners were included. Two radiation survey meters, Meter A (GMC-300E, uSv/h) and Meter B (RAR R311516, uSv/h), were used concurrently for continuous measurement and recording of radiation doses. Statistical analysis compared data from both meters and assessed compliance with regulatory limits and quality assurance standards. Results: The study demonstrated excellent consistency in dose measurements between Meter A and Meter B throughout the year, with no statistically significant discrepancies (p≤; 0.05). Cumulative radiation doses of staff remained within legal limits, indicating the efficacy of current safety measures. Conclusion: The study highlights the reliability of Meter A and Meter B for measuring occupational radiation exposure in CT settings. The convergence of results emphasizes their suitability for healthcare settings requiring precise radiation dose monitoring, enhancing radiation safety in CT scanning and protecting healthcare personnel from ionizing radiation exposure.

Basic Performance Evaluation of a Radiation Survey Meter That Uses a Plastic-Scintillation Sensor.

After the Fukushima nuclear power plant accident in 2011, many types of survey meters were used, including Geiger-Müller (GM) survey meters, which have long been used to measure β-rays. Recently, however, a novel radiation survey meter that uses a plastic-scintillation sensor has been developed. Although manufacturers' catalog data are available for these survey meters, there have been no user reports on performance. In addition, the performance of commercial plastic-scintillation survey meters has not been evaluated. In this study, we experimentally compared the performance of a plastic-scintillation survey meter with that of a GM survey meter. The results show that the two instruments performed very similarly in most respects. The GM survey meter exhibited count losses when the radiation count rate was high, whereas the plastic-scintillation survey meter remained accurate under such circumstances, with almost no count loss at high radiation rates. For measurements at background rates (i.e., low counting rates), the counting rates of the plastic-scintillation and GM survey meters were similar. Therefore, an advantage of plastic-scintillation survey meters is that they are less affected by count loss than GM survey meters. We conclude that the plastic-scintillation survey meter is a useful β-ray measuring/monitoring instrument.

Intake dose rate due to various granite samples of Bangalore city, India

The majority of total radiation dose received by the world population comes from background natural radiation. The distinguishing features of this radiation include relatively persistent exposure of a population at a specific place. The amount of background radiation that is generally present in the environment is greatly influenced by the inhalation of radon (Rn), thoron (Tn), and their offspring. In light of this, measurement of dose rate exposure due to granite flooring has been attempted in Bangalore. Fifteen different granite samples, used as flooring for construction in buildings, were examined for a period of three years. Solid state nuclear track detector-based dosimeters, can technique, and radiation survey meters have been used. All the experimental observations were made according to the standard protocols provided by the Bhabha Atomic Research Centre, Mumbai, India. The arithmetic mean dose rate varied between 1.39 ± 0.06 and 2.09 ± 0.10 mSv y1. The values of dose rates were found to be higher in granite and lower in coarse-grained dolerite. All 15 types of granite samples have undergone a minimum of 30 measurements. The greater activity concentration of radionuclides found in granite samples leads to higher dose rates.

Measurements of the ambient dose equivalent rates around the Manyoni uranium deposit in Tanzania

In this study, pre-mining ambient gamma dose equivalent rates at 1 m above the ground were measured using a Gamma-Scout portable radiation survey meter at two sites, A and B, around the Manyoni uranium deposit in Tanzania. Site A is expected to receive mine-dust particles with an aerodynamic diameter ≤ 10 µm (PM10) that have mean annual ground level concentrations (AGLC) ≥ 10% of the WHO air quality guideline limit of 20 µg/m3, and Site B is expected to receive PM10 with a mean AGLC ≥ 20 µg/m3. At Site A, the average of the ambient dose equivalent rates was 0.25 ± 0.03 µSv/h and ranged from 0.08 to 0.69 µSv/h. Similarly, at Site B, the average of the ambient dose equivalent rates was 0.23 ± 0.02 µSv/h and ranged from 0.12 to 0.34 µSv/h. The effect of the local geology on the measured dose rates was also presented. Since the ambient dose equivalent is an operational quantity for area monitoring, the results of this study will be very useful for comparing with the operational monitoring results of Sites A and B once uranium mining starts in Manyoni. This can help mine operators and regulatory agencies keep an eye on any rise in background radiation so they can take the necessary measures to safeguard locals and the environment from the harmful effects of ionising radiation.

Generation of map on natural environmental background absorbed dose rate in India

A systematic mapping of natural absorbed dose rate was carried out to assess the existing exposure situation in India. The mammoth nationwide survey covered the entire terrestrial region of the country comprising of 45127 sampling grids (grid size 36 km2) with more than 100,000 data points. The data was processed using Geographic Information System. This study is based on established national and international approaches to provide linkage with conventional geochemical mapping of soil. Majority (93%) of the absorbed dose rate data was collected using handheld radiation survey meters and remaining were measured using environmental Thermo Luminescent Dosimeters. The mean absorbed dose rate of the entire country including several mineralized regions, was found to be 96 ± 21 nGy/h. The median, Geometric Mean and Geometric Standard Deviation values of absorbed dose rate were 94, 94 and 1.2 nGy/h, respectively. Among the High Background Radiation Areas of the country, absorbed dose rate varied from 700 to 9562 nGy/h in Karunagappally area of Kollam district, Kerala. The absorbed dose rate in the present nationwide study is comparable with the global database.

Exposure of Dose Rate due to Granites of Bangalore Metropolis Area, India

Introduction: The majority of total radiation dose received by the world's population comes from natural radiation. The distinguishing features of this radiation include relatively persistent exposure to a population at a specific place. Inhalation of 222Rn (radon), 220Rn (thoron), and their offspring contributes the majority of the dose from natural radiation in background regions that are typically present. In light of this, a measurement of dose rate exposure due to some granite floorings has been attempted in Bangalore Metropolis, Karnataka, India. For a period of three years, fifteen distinct granite samples that were used as flooring for construction in buildings were examined.
 Objectives: Measurement of exposure of dose rate due to building construction materials by the inhabitants of Bangalore city
 Methods: Solid state nuclear track detector based dosimeters, CAN techniques and radiation survey meters were used and all the experimental observations were made as per the standard protocols provided by the Bhabha atomic research centre, Mumbai, India were followed.
 Results: The arithmetic mean values of dose rate varied between 2.09 ± 0.10 and 1.39 ± 0.06 mSvy-1. The observed dose rates were found to be higher in granite and lower in coarse-grained dolerite.
 Conclusions: All 14 types of granite samples have undergone a minimum of 30 measurements. The greater activity concentration of radionuclides found in granite samples leads to higher dose rates.

Spatial Scattering Radiation to the Radiological Technologist during Medical Mobile Radiography.

Mobile radiography allows for the diagnostic imaging of patients who cannot move to the X-ray examination room. Therefore, mobile X-ray equipment is useful for patients who have difficulty with movement. However, staff are exposed to scattered radiation from the patient, and they can receive potentially harmful radiation doses during radiography. We estimated occupational exposure during mobile radiography using phantom measurements. Scattered radiation distribution during mobile radiography was investigated using a radiation survey meter. The efficacy of radiation-reducing methods for mobile radiography was also evaluated. The dose decreased as the distance from the X-ray center increased. When the distance was more than 150 cm, the dose decreased to less than 1 μSv. It is extremely important for radiological technologists (RTs) to maintain a sufficient distance from the patient to reduce radiation exposure. The spatial dose at eye-lens height increases when the bed height is high, and when the RT is short in stature and abdominal imaging is performed. Maintaining sufficient distance from the patient is also particularly effective in limiting radiation exposure of the eye lens. Our results suggest that the doses of radiation received by staff during mobile radiography are not significant when appropriate radiation protection is used. To reduce exposure, it is important to maintain a sufficient distance from the patient. Therefore, RTs should bear this is mind during mobile radiography.

Determination of linear attenuation coefficient of aggregate serpentine concrete exposed to gamma and neutron radioactive sources

This research was designed to perform linear attenuation calculations for ordinary concrete both through simulation and experiment. The linear attenuation coefficient is an essential parameter for radiation shielding design for both source transport casks and storage bunkers. The shielding properties of concrete designed with Serpentine aggregates of different granule sizes were investigated. The simulation was performed using Radpro computer Software while the experiment involved sourcing for local Serpentine rock, crushing into four different granule sizes of 5 mm, 10 mm, 15 mm and 20 mm respectively and casting the concrete samples, exposure of the samples to gamma and neutron radioactive sources and monitoring with a radiation survey meter, sample weight measurements and concrete sample crushing using a load testing machine for determination of the concrete compressive strength. The results of the linear attenuation calculations showed that there was high consistency in the values obtained by simulation with those obtained via experiment. Very high linear attenuation property was observed when the serpentine concrete samples were exposed to a neutron source, which corroborates the fact that Serpentine rock is a Boron-rich mineral and Boron is known to have high neutron absorption property. The experimentally determined linear attenuation coefficients showed that the values at 15 mm aggregate sizes were higher than those at 5 mm, 10 mm and 15 mm sizes respectively, which demonstrates that better shielding optimization, will be obtained when the concrete cask is fabricated with 15 mm aggregate size.

Analysis of precautions taken for protection from X-rays in a hospital in Gaziantep in the context of workplace health and safety

ObjectiveHealthcare personnel who work in units of hospitals where ionizing radiation is used are in an at risk group, and their health statuses should be periodically monitored. Although some health problems do not emerge right after exposure to low-dose radiation, various diseases can arise in the long term. The purpose of this study is to promote responsibility among radiology professionals and prevent diseases that may emerge in the future by drawing attention to context of workplace health and safety. In this study, measurements were made at locations where radiology personnel worked. MethodRadiation measurements were obtained based on five repeated measurements at different points of the drafting chambers. It has been observed that the measurement values are close to each other. However, comparisons were made by taking the average values. In this study, X-ray measurements were made with three patients in four different hospital units. The Fluke 451 Ion Chamber Radiation Survey Meter device was used in the measurements, and the measurements were made based on the positions of the personnel in the radiation field in all units of the hospital where X-rays were used. The minimum measurement value was found behind the lead screen as 0.01 μSv, while the highest value was found in the room where the images were taken by wearing lead aprons and thyroid shields as 410 μSv. ResultsThe findings of this paper include the minimum and maximum values of X rays during imaging at different hospital units which are mammography, computed tomography, fixed X-ray machine and bone densitometry machine. ConclusionTo prevent these personnel from exceeding the standard exposure limits in terms of workplace health and safety, ensuring that they constantly use protective equipment and limiting the number of imaging procedures they carry out will be beneficial in terms of health in the long term.

A RADIATION SAFETY ASSESSMENT OF X-RAY DIAGNOSTIC UNITS IN S.M.S HOSPITAL JAIPUR: AN INSTITUTIONAL STUDY

The aim of a quality assurance (QA) program is to assist a radio-diagnostic facility in consistently obtaining adequate radiological information with a minimum of dose and a minimum of cost. An integrated part of a quality assurance program is quality control (QC) in which a series of examinations and checks on equipment performance are undertaken, so that any changes can be objectively monitored and remedies made. The main objective of the present work was to carry out an independent audit of the important features of QA tests and radiation safety parameters in medical X-ray installations, which would reflect the safety status and to assess the regulatory requirements of the safety code. We conducted a radiological safety and quality assurance audit of 32 medical X-ray diagnostic machines installed in SMS hospital, Jaipur. A QA kit consisting of a kVp test meter, ionization chamber-based radiation survey meter and other standard accessories were used for the required measurements. The study mainly covered eight quality control checks that is accuracy check of accelerating potential (kVp), linearity of tube current (mA station)and timer, congruence of radiation and optical field, and total filtration, beam alignment, focal spot size, leakage radiation survey, and beam out. The status test is carried out in order to establish the functional status of the equipments. They operated and functioned correctly and prevented movement when activated. All measured values were well within the tolerance limit.

New Radioprotective Device that can be Used for Fluoroscopic Exam: Possibility to Contribute to Staff Exposure Protection During VFSS.

The videofluoroscopic swallowing study (VFSS) is a recognized standard diagnostic imaging technique that is used to investigate swallowing disorders and dysphagia. Patients were assessed in a seated posture on a chair or wheelchair. Using X-ray fluoroscopy, the state of patients' swallowing was checked by eating and drinking according to the physician's instructions. VFSS procedures are prolonged, and VFSS staff members are exposed to radiation. Therefore, we evaluated original lead shielding device (OLSD) that can be attached to the handrail of a table and placed vertically. The OLSD has a lead-equivalent thickness of 0.3 mmPb, weighs about 6kg, and has the dimensions 50cm × 50cm × 8.0mm. We used a human phantom and a radiation survey meter with and without protection from scattered radiation at the positions of the physician and medical staff at the height of 150cm above the floor (i.e., the height of the eye's crystalline lens). After measuring the scattered radiation, we created radiation maps with and without the OLSD. The dose rate at the physician's position without and with the OLSD was 190 µSv/h and 92 µSv/h, respectively, and a dose reduction of 51.6% with the plate. Moreover, the radiation maps added clarity to the distribution of the scattered radiation. Such information should lead to greater awareness about exposures to physicians and other medical staff. Thus, the OLSD effectively provided protection from scattered radiation at the physician's position during fluoroscopy. It may contribute to the reduction of staff exposure for VFSS.

Assessment on Radiation Hazard Indices from Selected Dumpsites in Lafia Metropolis, Nasarawa State, Nigeria

This research reports an assessment of ionizing radiation in some chosen Dumpsites in Lafia Local government area of Nasarawa State. Ionizing radiation measurement was conducted at four Dump sites. The survey was done using a radiation survey meter (Radex one Outdoor 55130719 NA). Radiation exposure rate in micro sievert per hour (μSvhr-1) was measured. Readings were taken by placing the detector at gonad level about 1 meter above the ground. Result showed that the average annual effective dose rate in the selected dumpsites were 0.22 mSv/yr for Lafia modern market, 0.17 mSv/yr for dumpsite opposite governor Isa house, 0.15 mSv/yr for Timber shade Lafia and 0.20 mSv/yrfor Science School Lafia respectively with a mean value of 0.19 mSv/yr for all location, while the mean calculated excess life cancer risk (ELCR) is 0.65 x 10-3.Dumpsites yearly absorbed dose rate and their corresponding ELCR values did not exceed the 1.0 mSv/y Basic Safety Standard set for the masses by International Council on Radiation Protection (ICRP, 1999) and mean world average ECLR value of 1.16 x 10-3. Based on these results there are no radiation consequence to the scavengers, dumpsite workers and residents living around the dumpsites.

Assessment of Background Radiation, Annual Effective Dose and Excess Lifetime Cancer Risk in Gonabad City

Purpose: Humans are always exposed to ionizing radiation from their environment, which can have destructive effects. This study aimed to measure background gamma radiation and estimate annual effective dose and excess cancer risk in Gonabad city. Materials and Methods: The dose rate due to indoor and outdoor background radiation was measured by RDS-30 radiation survey meter at five zones on the map, including North, South, East, West, and center. Then, the annual effective dose and excess lifetime cancer risk were calculated by associated equations. Results: Mean dose rates for outdoor and indoor spaces were 0.111 µSv/h and 0.139 µSv/h, respectively. The mean background dose rate of indoor space was significantly higher than that of outdoor space. Annual effective dose and excess lifetime cancer risk were obtained as 0.817 and 2.85×10-3, respectively. Conclusion: Background radiation dose, annual effective dose, and cancer risk for Gonabad city were higher than global ones. Further investigations are needed to encompass internal background radiation doses in annual effective dose.

Assessment of Ionizing Radiation Dose and Risk Levels associated with Radioactivity in Oraifite, Nigeria.

Radioactivity has been natural occurrence in human environment and its adverse effects are highly undesirable. This study assessed radiation risk levels associated with radioactivity in Oraifite using gamma ray (Ɣ-ray) spectrometry and radiation survey meter. The mean value of background ionizing radiation (BIR) exposure rate ranged from 0.011 to 0.014mRh-1. The mean activities of 226Ra, 232Th, 40K ranged from 23.54±4.89 to 41.03±4.28 BqKg-1, 9.69±1.88 to 11.34±1.86 BqKg-1, 419.22±3.41 to 737.91±4.78 BqKg-1 respectively. Mean values of radium equivalent (Raeq), absorbed dose (D), Igamma (IƔ),  internal hazard index (Hin), external hazard index (Hex) and annual effective dose equivalent (AEDE), were 60.05Bqkg-1, 55.75nGh-1, 0.86, 0.41, 0.30 and 0.07mSvy-1 respectively. Excess lifetime cancer risk (ELCR) which is estimation of the probability of cancer incidence in a population of individuals for a specific lifetime had a mean value of 0.25x10-3 and this is lower than the world permissible limit of 0.29x10-3. The average dose to human organs/tissues; lungs, ovaries, bone marrow, testes, kidney, liver and whole body were 0.033, 0.028, 0.033, 0.040, 0.028, 0.023, and 0.033 mSvy-1 respectively, meaning that all the computed organ dose were far much lower than the maximum allowable standard value of 1.0 mSvy-1. Virtually all hazard indices were below the ICRP recommended values and in general the residents of Oraifite are not under ionizing radiation threat.

In-situ assessment of background gamma radiation dose levels in outdoor environment of Enugu urban areas, Enugu state, Nigeria

In this study, in-situ measurements of absorbed dose rates of background gamma radiation in 146 outdoor locations within Enugu urban areas were carried out by means of a hand held radiation survey meter equipped with Geiger-Muller tube. In order to assess the radiological health status of the studied environment, annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated from the measured dose rates. The measured radiation dose rates across the locations ranged from 77.21 to 180.53 nGy h−1 with a mean value of 124.92 ± 2.00 nGy h−1. The AED and ELCR values ranged from 0.09 to 0.22 mSv y−1 with overall mean of 0.15 mSv y−1 and 0.33 × 10−3 to 0.77 × 10−3 with overall mean of 0.54 × 10−3, respectively. The measured dose rates were significantly higher than world average gamma radiation dose of 59 nGy h−1 for outdoor environment. The dose rates revealed an elevated background radiation levels signifying a radiation contaminated environment. The ELCR values indicate that the accumulation of low-level radiation doses over a lifetime exposure can initiate cancer development in residents of Enugu urban areas.

Assessment of background ionizing radiation dose levels in quarry sites located in Ebonyi State, Nigeria

The study presents a radiometric survey of Background Ionizing Radiation (BIR) dose levels in ten quarry sites located in Ebonyi State, Nigeria. In-situ BIR dose rate measurements, by means of nuclear radiation survey meter, at 1 m above ground level were carried out at the excavation section (ES) and quarrying section (QS) of the investigated quarry sites. The obtained results indicated dose rates ranging from from 0.14 to 0.18 μSv/h with mean of 0.15±0.01 μSv/h at the ES and 0.16 to 0.19 μSv/h with mean value of 0.18±0.01 μSv/h at the QS. While the values obtained at the QS are respectively higher than those measured at the ES, they are all higher than the worldwide average value of 84 nSv/h signifying BIR elevated environments. The estimated mean annual effective dose (AED) and excess lifetime cancer risk (ELCR) are 0.27±0.03 mSv/y and 0.94×10–3 respectively at the ES and 0.31±0.02 mSv/y and 1.07×10–3 at the QS. The obtained AED values for all the sites are well above the outdoor worldwide average value of 0.07 mSv/y but lower than the International Commission on Radiological Protection recommended permissible limits of 1.0 mSv/y for the general public. Generally, the BIR levels of the quarry sites are within acceptable limits and no immediate radiological health threat may be derived from the current levels. However, long-term health effects due to continuous exposure to low-level radiation doses may manifested in future over a lifetime exposure of 70 years as indicated by the ELCR values.
 Keywords: Background ionizing radiation, Dose rate, Annual effective dose, Quarry site, Ebonyi State

EVALUATION OF INDOOR/OUTDOOR GAMMA EXPOSURE RATES AND EXCESS LIFE TIME CANCER RISK IN DIFFERENT CITIES OF PAKISTAN.

This study presents a detailed measurement of indoor and outdoor terrestrial gamma radiation levels in different cities of Pakistan. The measurements covered dwellings in 27 cities, covering all provinces and region of Azad Kashmir. Most of the houses were of attached type, made of brick walls and concrete roofs. The measurements were made by a handheld radiation survey meter containing Geiger-Muller tube. The average absorbed dose rate in air was 100±32 nGy h-1 for indoor and 74±30 nGy h-1 for outdoor. The population-weighted mean terrestrial dose rates were 90 nGy h-1 for indoor and 78 nGyh-1 for outdoor. The ratio of indoor to outdoor absorbed dose rate was 1.5 as compared to 1.3 for the world average. The estimated average annual effective dose rate was 0.58±0.18mSv a-1 and the mean excess life time cancer risk was 2.0×10-3.