Assessment of indoor and outdoor radiation levels and human health risk in Sheda Science and Technology Complex and its environ, Abuja, Nigeria
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Abstract:
A study to assess the Indoor and Outdoor Background Ionizing Radiation (BIR) of Sheda Science and Technology Complex, Abuja has been conducted. An in-situ measurement using a portable factory calibrated radiation dose rate meter, Radiagem 2000, was used to ascertain the radiation level. The measured radiation dose rates were used to evaluate the radiological health hazards and radiation effective doses to different body organs using well established radiological relations. The results shows that the total Dose Rate (indoor and outdoor), the Total Annual Equivalent Dose (indoor and outdoor), total Annual Effective Dose Equivalent (indoor and outdoor) and the total Excess Lifetime Cancer Risk (indoor and outdoor) are 0.113±0.022 (μSv/h), 0.071±0.016 (μSv/h), 0.794±0.155 mSv/y, 0.0.124±0.074 mSv/y, 0.556±0.109 mSv/y, 0.087±0.020 mSv/y, 1.945±0.379, 0.304±0.104 respectively for the three zones. The dosage to organs received shows that the testes have the highest dose while the liver has the lowest dose (indoor and outdoor) for the three zones. Generally the study shows that the Annual Effective Dose Equivalents were within the permissible limits of 1 mSv/y for general public exposure recommended by the (ICRP). Also, the effective doses to different body organs are all below the recommended limits of 1 mSv/y. The calculated Excess Lifetime Cancer Risk values indicates that the chance of contacting cancer by workers and residents of the study area is not probable hence the study area could be said to be radiologically safe.Keywords: Ionizing Radiation, Equivalent Dose, Effective Dose, Excess Lifetime Cancer RiskKeywords:
Equivalent dose
Dose rate
Background radiation
Reference dose
This study was achieved to calculate the annual effective dose equivalent (AEDE) in units of (mSv.y-1), and the average radiation dose rate (ADR) in units of (μSv.h-1) which were measured by portable devices. The study was carried out on the workers of the destroyed radiochemistry laboratory located at Al-Twuitha nuclear site (south of Baghdad). Radiation background was determined for comparison with the radioactive dose of soil samples measured with HPGe detector and portable devices type LUDLUM. The radioactivity levels of the area around the radiochemistry laboratory building were within the limits of radiation background. The result showed a significant increase of the annual effective dose of C1 laboratory workers, as the annual effective dose of the lysate cell 1 (AHC1)in the lab was about 18.995 mSv/y, with an occupancy factor of 0.042, for an average working hours of one hour per day. An annual effective dose of 24.073 mSv/y was also recorded in hot cell 2 (HCL2), an increase of more than 4 mSv/y, for an occupancy factor of 0.083, equivalent to 2 hours of work per day. The glove boxes 11 (GB11) of Laboratory C2 recorded an annual effective dose of 19,720 mSv/y for an occupancy factor of 0.125, equivalent to 3 working hours per day. The C3 Laboratory and the rest of the laboratories and the health physics rooms recorded an annual effective dose within the workers’ allowable limits of 20 mSv/y.
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The biological effects of radiation are of two types: stochastic (such as radiation‐induced cancer) and deterministic (such as erythema).The effective dose is used to assess the risk of stochastic effects, and the dose equivalent is used to assess the risk of deterministic effects. However, the effective dose and dose equivalent, body‐related protection quantities, are not measurable. Therefore, operational quantities (1‐cm dose equivalent and 70‐μm dose equivalent) are used to assess the effective dose and dose equivalent. Generally, the 1‐cm dose equivalent, determined using a monitoring badge, is used to assess effective dose, whereas the 70‐cm dose equivalent, determined using a monitoring badge, is used to assess dose equivalent. Furthermore, when using two monitoring badges, the 1‐cm dose equivalent of each badge is converted into the effective dose using calculation algorithms.
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Conceptual changes and new quantities made it necessary to reassess dose rate quantities. Calculations of the dose rate constant were carried out for air kerma, ambient dose equivalent and directional dose equivalent. The number of radionuclides is more than 200. The threshold energy is selected as 20 keV for the dose equivalent constants. The dose rate constant for the photon equivalent dose as used mainly in German speaking countries as a temporary quantity is also included.
Equivalent dose
Kerma
Dose rate
Constant (computer programming)
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Objective
To investigate the current situation of radiation protection in nuclear medicine diagnosis workplace.
Methods
The study was performed in 3 hospitals in northeast, north and central of China from February to December in 2013. The γ dose rate instrument was used to detect the workplace ambient dose equivalent rate of medicine preparation, leaching, packing, injection and imaging. Individual effective dose and equivalent dose were evaluated by photoluminescent dosimeter.
Results
The ambient dose equivalent rate was up to 1.92 mSv/h at repacking place and 1.2 mSv/h at injection place. The ambient dose equivalent rate of patients after injection was 5.36-240 μSv/h. The hand equivalent dose was 0.01-0.02 mGy. Moreover, there were problems of staff route intersection, as well as the patients after injection staying in the public area.
Conclusions
Radiation workers should pay more attention to individual protection, and improve the operation proficiency to shorten the operation time. Furthermore, in order to protect public from unnecessary irradiation, there should be some changes in staff route and patients administration.
Key words:
Nuclear medicine diagnosis; Radiation protection; Ambient dose equivalent rate; Equivalent dose
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Dose rate
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The average outdoor absorbed dose rate in air and the average annual effective dose equivalent due to terrestrial gamma radiation from 40K, 238U and 232Th in rocks in Ondo and Ekiti States, Southwestern Nigeria have been evaluated from measurements of the concentrations of these radionuclides in this environmental material. The concentration measurements were obtained using a very sensitive gamma spectroscopic system consisting of a 7.6 cm x 7.6 cm NaI(Tl) scintillation detector coupled to a computerised ACCUSPEC installation. The average absorbed dose rate and average annual effective dose equivalent was found to be 8.33 +/- 2.76 nGy x h(-1) and 8.7 +/- 2.9 microSv x y(-1) respectively.
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Dose rate
Equivalent dose
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Internal dose
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The ICRP has recommended a system of dose limitation based on the dose equivalents in various organs and on the effective dose equivalent HE. Because HE is unmeasurable, it was agreed to estimate HE on the basis of dose equivalents in the ICRU sphere. In the past it has already been shown that for external photon radiation the ambient dose equivalent, H*(10), is conservative for HE of the mathematical anthropomorphic phantoms ADAM and EVA. As the dose equivalents of children became more and more important, new anthropomorphic phantoms, based on whole body CT data for a baby and a 7-year-old child were recently developed at GSF. A CT voxel phantom of an Alderson Rando phantom was constructed also. The effective dose equivalents and some organ dose equivalents of these three voxel phantoms are related to the ambient dose equivalent, H*(10), for different photon energies and various geometries.
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Aims: To evaluate the radiological impact parameters on mine workers.
Study Design: The research work was carried out by using a gamma–ray spectrometer with a NaI (TI) detector.
Place and Duration of Study: Centre for Energy and Research Development (CERD), Obafemi Awolowo University, Ile- Ife, Osun State, Nigeria between September 2016 and June 2017.
Methodology: The activity concentrations of 226Ra, 232Th, and 40K were determined in ten samples which were used to evaluate the absorbed dose rate, radium equivalent activity, external and internal hazard indices, representative level index, and annual effective dose equivalent.
Results: The average activity concentrations of 226Ra (24068.11, 232Th (387.72 , 40K (9509.24) and absorbed dose rate (11720.77) were higher than their respective recommended world mean values of 35 , 45 , 420 and 59 by UNSCEAR. The mean values of radium equivalent activity, external hazard index (Hex), internal hazard index (Hin), representative level index, and annual effective dose equivalent of the area under study were determined as 25346.82, 68.52, 135.43, 357.95, and 14374.36 respectively. This study revealed that all the radiological parameters were higher than their respective recommended world average values.
Conclusion: With the high concentrations obtained in this study, it is therefore concluded that this may pose a serious health risk to the miners and the general public. It is therefore advised that necessary guidelines should be provided for the exploration of minerals in this mining site.
Radium
Equivalent dose
Absorbed dose rate
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