Average Effective Dose Equivalent Research Articles

Evaluation of Natural Radioactivity Level in Surface Soil from Bambasi District in Benishangul Gumuz Region, Ethiopia

The study assessed the concentration of natural radionuclides in soil samples from the Bambasi district in Ethiopia’s Benishangul Gumuz region using a gamma‐ray spectrometer equipped with a high‐purity germanium (HPGe) detector. The measured activity concentrations of 238U, 232Th, and 40K in soil samples varied from 46.2 ± 2.25 to 88.49 ± 5.73 Bq/kg, 73.4 ± 4.12 to 119.65 ± 8.45 Bq/kg, and 176.78 ± 8.63 to 396.71 ± 25.39 Bq/kg, respectively. The average concentration of 238U and 232Th exceeded the recommended worldwide population weighted average values of 32.0 and 45.0 Bq/kg, respectively, while the average concentration of 40K was below the recommended value of 420.0 Bq/kg. The mean absorbed dose rate was calculated to be 91.6 ± 5.1 nGy/h, which is above the recommended safe value of 59 nGy/h. The average annual effective dose equivalents for indoor and outdoor exposure were determined to be 2.65 ± 0.14 mSv/y and 0.66 ± 0.1 mSv/y, respectively. The calculated mean values of the internal hazard index, external hazard index, and gamma index across all soil samples were 0.72 ± 0.05, 0.55 ± 0.02, and 0.72 ± 0.02, respectively, all below the recommended safe threshold of one. These findings suggest that the activity concentrations observed in the soil samples exceed safe levels, indicating the necessity for further investigation into radioactivity levels and epidemiological studies regarding potential hazards from high background radiation.

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.

Assessment of Effective Dose Equivalent from Internal Exposure to 222Rn in Ramsar City

Introduction In this study, effective dose equivalent for the public due to internal exposure to 222radon (222Rn) was evaluated in three regions of Ramsar, a northern coastal city in Iran. Materials and Methods Measurements were carried out using a radon monitoring device. Outdoor and indoor radon concentrations were measured within 24 hours with an integration interval of 3 hours. Regions were selected with respect to our previous study on areas of Ramsar with high levels of environmental background radiation. Results This study showed that indoor 222Rn concentration reached to 465 Bq/m3 in one of the selected regions (Talesh Mahalleh) in early morning (5-8 a.m.). Our study also showed that the average effective dose equivalents (due to both indoor and outdoor exposures) in the selected regions (Talesh Mahalleh, Sadat Mahalleh, and Chaparsar) were 9.5±2.8, 5.1±2.1, and 3.2±1.2 mSv/y, respectively. Conclusion It is clear that the annual effective dose from internal exposure to 222Rn in areas of Ramsar with high levels of natural radiation was significantly higher than the maximum annual effective dose permissible for public.

Application of Customized Navigated Template for Percutaneous Radiofrequency Thermocoagulation Treatment of Primary Trigeminal Neuralgia

Objective: To investigate the successful rate and accuracy of percutaneous radiofrequency thermocoagulation (PRT) for treatment of primary trigeminal neuralgia (PTN) with customized navigated template via three dimensional (3D) printing technique. Methods: 65 patients with PTN were recruited from January 2014 to March 2015 and randomly divided into two groups: template group (n = 28) and traditional group (n = 37). The patients in traditional group received PRT under guidance of C-arm fluoroscopy, while the ones in template group were treated with customized navigated templates. The data of time, depth and accuracy rate of puncture, the average effective dose equivalent of radiation, complications after operation were collected and analyzed. Results: No intra-operative failures occurred in the template group: the pain was alleviated immediately after operation. Accuracy rate of the template group was 100% while 96% was achieved in traditional group. However, the average time of puncture by the template was significantly reduced compared with traditional group (2.37 ± 0.64 minutes and 24.2 ± 6.55 minutes, respectively; P 0.05). No complications were observed in template group while several complications such as blooding, leakage of cerebrospinal fluid and dizziness were observed in traditional group. Conclusion: The application of customized template is advocated for improving the accuracy of PRT.

137Cs and 40K in some traditional herbal teas collected in the mountain regions of Serbia

Herbal teas are an important part of traditional medicine in Serbia. The objective of the present study was to determine the activity concentrations of 40K and 137Cs in herbal tea, using the gamma spectroscopy method. The samples were collected during the period 2011–2012 in three mountain regions in Western and Central Serbia. The activity concentrations of 40K and 137Cs were found to be in the range of 130–1160 and 0.7–124 Bq kg−1, respectively. The average annual effective dose equivalents from ingestion of 40K and 137Cs for an adult person consuming one cup of herbal tea daily were found to be 588.4–5250.2 nSv for 40K and 4.0–706.1 nSv for 137Cs. Our investigation showed that the herbal teas originating from Maljen, Zlatibor and Tara mountains are radiologically safe for human consumption.

Countrywide radiation dose in different locations, dwellings and free spaces of Bangladesh

The research work was aimed to determine the fatal cancer risk due to the radiation exposure on population of Bangladesh. The total risk is somewhat higher. However, the average total fatal probability coefficient was found to be 101 cases per million people, the range of which was from 78 to 144 per million people. The lowest risk was found for the people of Srimangal (Maulavibazar) and Sandweep, while the risk was highest for the people of Nachole (Chapai Nawabgonj) and Badalgachhi (Naogaon), the two locations are in the Borendra region. The risk factors were found to be around average level for the people of Dhaka, Chittagong and Rajshahi. Since a very significant portion of people of Bangladesh live in these areas, the calculated average risk factor become more meaningful. Moreover, as both the average effective dose equivalents and the population density in Bangladesh are higher than those of the countries compared, the people of Bangladesh are in more risk than those countries.

Environmental dose rate assessment from an active fault zone in Western Anatolia, Turkey: towards retrospective epidemiology

In this study we present data regarding natural radioactivity from a populated active tectonic area based on site measurements using a field gamma spectrometer. The results will provide data to the scientists for dating studies as well as epidemiological studies towards ancient human life, also termed as retrospective epidemiology. The study area covers an active tectonic region in western Anatolia surveyed using on-site gamma spectrometer. More than 500 sites were measured across the region on a 150- km grid. Radiation background shows relatively non-homogenous level of radiation in the area. The gamma dose rate measured in Gediz graben was found in the range between 0.8120- 1.7540 mGya–1 (94-203 nGyh–1) with an average value of 1.2292 mGy/a (142 nGyh–1), whereas it was in the range between 0.5530-1.1491 mGy/a (64-133 nGyh–1) with an average value of 0.8397 mGy/a (97 nGyh–1) across Buyuk Menderes graben. The relative contribution of 238U decay chain to gamma dose rate is between 0.2002- 0.4630 mGya–1, of 232Th decay series is 0.3089- 0.8136 mGya–1, and of 40K is 0.1270- 0.3468 mGya–1 in the whole studied area. The average annual effective dose equivalents from the calculated outdoor terrestrial gamma radiation was between 90-215 μSva–1, above world average of 70 μSv per year, and the measured outdoor dose rate (terrestrial plus cosmic) on the ground was between 133-257 μSva–1. The significance of all these numbers is discussed in the framework of epidemiological studies, in order to correlate these enhanced dose rate values directly to specific diseases such as cancer.

Human Biodistribution and Dosimetry of the PET Radioligand [11C]Flumazenil (FMZ)

We measure the whole-body distribution of IV injected [¹¹C]Flumazenil (FMZ) as a function of time in adult subjects and determine the absorbed radiation doses. After injection with 770 MBq of [¹¹C]FMZ (nominal), each of six subjects underwent nine consecutive whole body PET scans. Twelve source organs were identified using PET attenuation and emission images. Activity within each organ as a function of time was determined from the sequence of the nine PET scans. Source organ time activity curves were integrated and normalized by the injected dose to yield source organ residence times for the no voiding situation. Separate bladder residence-time calculations were performed for the cases of a 1- and a 2-h voiding interval. Using the source organ residence times as input, the program OLINDA/EXM (Stabin et al. in J Nucl Med. 46:1023-1027, 2005) was used to perform dosimetry calculations for the various body organs and for the whole body. For the no voiding situation, the average whole-body radiation equivalent dose was 3.02 × 10⁻³ mSv/MBq of injected [¹¹C]FMZ. The average effective dose and effective dose equivalent was 7.57 × 10⁻³ and 1.12 × 10⁻² mSv MBq⁻¹, respectively. The organ receiving the highest equivalent dose was the urinary bladder wall with an average of 6.32 × 10⁻² mSv MBq⁻¹. On average, the administration of less than 790 MBq (21 mCi) of [¹¹C]FMZ yields (no voiding model) an organ equivalent dose of under 50 mSv [the single dose limit for research studies under US regulations (21CFR361.1) to body organs other than blood forming organs, gonads or the lens of the eye] to all organs. Equivalent dose to the blood forming organs and gonads from a 790 MBq administered FMZ dose is well under the 30 mSv limit provided under 21CFR361.1. Additionally, administration of less than 1320 MBq (35.7 mCi) yields an effective dose [International Commission on Radiation Protection (ICRP) 60 tissue weighting scheme] of under 10 mSv, which is the ICRP IIb (minor to intermediate) risk category limit.

PET-Derived Biodistribution and Dosimetry of the Benzodiazepine Receptor-Binding Radioligand 11C-(R)-PK11195 in Children and Adults

The PET tracer (11)C-(R)-PK11195 (PK) is an antagonist of the peripheral-type benzodiazepine binding site and allows the noninvasive imaging of microglial activation seen in several neurologic disorders affecting the mature and developing brain. The objective of this study was to derive the biodistribution and in vivo radiation dose estimates of PK in children studied for brain inflammatory conditions and in healthy adults. Twenty-two children (mean age +/- SD, 9.5 +/- 4 y; range, 4-17 y; 10 girls) who underwent dynamic PK PET for conditions involving brain inflammation were studied. Seven healthy adults (age, 27.4 +/- 7.5 y; range, 22-41 y; 3 women) were evaluated using the same protocol. Normal-organ time-activity curves and residence times were derived and absorbed doses then calculated using the OLINDA software. Two other healthy young adults (1 man, 1 woman) also underwent sequential whole-body PET using a PET/CT scanner to obtain corresponding CT images and PK pharmacokinetics. PK uptake was highest in the gallbladder and urinary bladder, followed by the liver, kidney, bone marrow, salivary gland, and heart wall, with minimal localization in all other organs including normal brain and lungs. PK was excreted through the hepatobiliary and renal systems. The average effective dose equivalent was 11.6 +/- 0.6 microSv/MBq (mean +/- SD) for young children (age, 4-7 y), 7.7 +/- 1.0 microSv/MBq for older children (age, 8-12 y), 5.3 +/- 0.5 muSv/MBq for adolescents (age, 13-17 y), and 4.6 +/- 2.7 microSv/MBq for adults. The gallbladder wall received the highest radiation dose in children younger than 12 y, whereas the urinary bladder wall received the highest dose in older children and adults. For an administered activity of 17 MBq/kg (0.45 mCi/kg), the effective dose equivalent was about 5 mSv or below for all age groups. At clinically practical administered activities, the radiation dose from (11)C-PK11195 in both children and adults is comparable to that from other clinical PET tracers and diagnostic radiopharmaceuticals in routine clinical use.

Assessment of dose rates around Manisa (Turkey)

Natural radionuclide activity concentration of surface soils at 64 locations in central Manisa were measured using gamma spectrometry (ORTEC). The natural gamma radioactivity of the terrestrial radionuclides in soil samples and the gamma-absorbed dose rates of these radionuclides in air were calculated. In this study, track etch film (CR-39) was used to determine the distribution of radon levels in dwellings. The average annual effective dose equivalents from the calculated outdoor terrestrial gamma radiation for a person in Manisa is 66 μ Sv , whilst the annual effective dose equivalent from 222Rn is calculated to be 4.83 mSv/yr.

Natural background radiation Dosimetry in the highest altitude region of Iran

The natural background radiation has been measured in one of the highest altitude regions (Zagros Mountains), Chaharmahal and Bakhtiari province, in the south west of Iran. The outdoors-environmental monitoring exposure rate of radiation was measured in 200 randomly chosen regions using portable Geiger-Muller and scintillation detectors. Eight measurements were made in each region and an average value was used to calculate the exposure rate from natural background radiation. The average exposure rate was found to be 0.246 microGy/h and the annual average effective dose equivalent was found to be 0.49 mSv. An overall population-weighted mean outdoor dose rate was calculated to be 49 nGy/h, which is higher than the world-wide mean value of 44 nGy/h, as reported by UNSCEAR in 1998, and is comparable to the annual effective dose equivalent of 0.38 mSv. A good correlation between the altitude and the exposure rate was observed, as the higher altitude regions have higher natural background radiation levels.

Indoor radon levels and influencing factors in houses of Patras, Greece

Measurements of indoor radon concentrations were performed in 28 low-rise houses and 30 apartments in Patras area from December 1996 to November 1997, using nuclear track detectors. The investigation was focused on the effects of season and floor number, as well as on the existence of a basement in low-rise houses on indoor radon levels. It was found that the differences in mean radon concentrations between adjacent seasons, in a number of 61 selected sampling sites distributed in 28 houses, were statistically significant. As expected, a maximum was found in winter and a minimum in summer. The differences in mean radon concentration on different floors of the same houses were also statistically significant and followed a linear decrease from underground to 2nd floor. In addition, indoor radon concentrations in the ground floor were found to be influenced by the existence or not of a basement. The average annual radon concentration was found to be 41 Bq m −3 for the houses, 28 Bq m −3 for the apartments and 38 Bq m −3 for all the dwellings. These values lead to an average effective dose equivalent of 1.1, 0.7 and 0.9 mSv y −1, respectively. Residents living on the underground in low-rise houses, during winter, where the average effective dose equivalent is 2.1 mSv y −1, attain the higher risk.

Baseline Studies of Terrestrial Outdoor Gamma Dose Rate Levels in Nigeria

The outdoor ? radiation exposure dose rates due to the radioactivity concentration of 40K, 238U and 232Th in the soil across different environments in Nigeria have been carried out using the low-cost method of in situ ? ray spectrometry. Measurements were made in 18 cities, spread across the three major zones of the country. The radioactivity concentrations of these radionuclides in the soil were used to determine their ? radiation absorbed dose rates in the air. The range of average total dose rate due to the three radionuclides in the Eastern zone is between 0.025 and 0.081 µGy.h-1 with an average of 0.040 ± 0.006 µGy.h-1, 0.041 and 0.214 µGy.h-1 with a mean of 0.089 ± 0.014 µGy.h-1 for the Western zone and between 0.066 and 0.222 µGy.h-1 with a mean of 0.102 ± 0.032 µGy.h-1 for the Northern zone. The average annual outdoor effective dose equivalents of 51 ± 8 µSv.y-1, 114 ± 18 µSv.y-1 and 130 ± 41 µSv.y-1 have been estimated for the Eastern, Western and Northern zones, respectively. The average annual effective dose equivalent for the country has been estimated to be 98 ± 15 µSv.y-1 and the collective effective dose equivalent as 9.7 x 103 man.Sv.y-1. Measurements have been taken as representing the baseline values of natural radioactivity as no artificial radionuclide was detected at any of the sites surveyed.

A study of indoor radon levels in Indian dwellings, influencing factors and lung cancer risks

Passive integrating solid state nuclear track detectors (SSNTDs) were used to study the Radon-222 (Rn) concentrations in Indian dwellings. The study was made in 300 dwellings in the cities of Lucknow and Kanpur in northern India. The influence of some factors e.g. age of the house, number of floors and ventilation conditions, etc. on indoor Rn concentrations were studied. The equilibrium factor in 65 dwellings were also investigated. Average Rn concentrations in living rooms were found to be 34±8 Bq.m −3 and 40±10 Bq.m −3 respectively, with equilibrium factors of 0.35 and 0.38. Assuming an occupancy factor of 0.8, the annual average effective dose equivalents in living rooms of the two places are estimated as 0.8 and 1.0 mSv respectively. The average life-time risks of lung cancer for radon exposure of the Lucknow and Kanpur populations at home would be about 0.26% and 0.34% respectively and the mean relative loss of life expectancies were 0.06% and 0.074% respectively.

Assessment of Dose Rate and Collective Effective Dose Equivalent Due to Terrestrial Gamma Radiation in the City of Lagos, Nigeria

The average annual effective dose equivalent and the collective effective dose equivalent have been determined from measurements of the concentrations of 40 K, 238 U and 232 Th in top soil in and around the city of Lagos using in situ γ spectrometry. The average outdoor absorbed dose rate was (0.041 ± 0.012) μGyh -1 resulting in an annual average effective dose equivalent of 50 μSv.y -1 . The collective effective dose equivalent to the population in the city is 2.84 x 10 2 man.Sv.y -1 .

Human biodistribution and dosimetry of [ 123 I]FP-CIT: a potent radioligand for imaging of dopamine transporters

This study reports on the biodistribution and radiation dosimetry of iodine-123-labelled N-omega-(flu- oropropyl)-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I]FP-CIT), a promising radioligand for the imaging of dopamine transporters. In 12 healthy volunteers, conjugate whole-body scans were performed up to 48 h following intravenous injection of approximately 100 MBq [123I]FP-CIT. Attenuation correction was performed using a transmission whole-body scan obtained prior to injection of the radioligand, employing a 123I flood source. Blood samples were taken and urine was freely collected up to 48 h after injection of the radiotracer. For each subject, the percentage of injected activity measured in regions of interest over brain, striatum, lungs and liver were fitted to a multicompartmental model to give time-activity curves. The cumulative urine activity curve was used to model the urinary excretion rate and, indirectly, to predict faecal excretion. Using the MIRD method, nine source organs were considered in estimating absorbed radiation doses for organs of the body. The images showed rapid lung uptake and hepatobiliary excretion. Diffuse uptake and retention of activity was seen in the brain, especially in the striatum. At 48 h following the injection of [123I]FP-CIT, mean measured urine excretion was 60%+/-9% (SD), and mean predicted excretion in faeces was 14%+/-1%. In general, the striatum received the highest absorbed dose (average 0.23 mGy/MBq), followed by the urinary bladder wall (average 0.054 mGy/MBq) and lungs (average 0.043 mGy/MBq). The average effective dose equivalent of [123I]FP-CIT was estimated to be 0.024 mSv/MBq. The amount of [123I]FP-CIT required for adequate dopamine transporter imaging results in an acceptable effective dose equivalent to the patient.

Distribution of 226Ra, 232Th, and 40K in soils of Rio Grande do Norte (Brazil)

A survey programme aimed at studying the environmental radioactivity in the Brazilian state of Rio Grande do Norte was undertaken. Fifty-two soil samples, together with two rock and two uraniferrous ore samples were collected from the eastern and central regions of this state. Concentrations of radioelements in samples were determined by γ-ray spectrometry. The average concentrations of 226Ra, 232Th, and 40K in the surveyed soils were 29.2 ± 19.5 (SD), 47.8 ± 37.3, and 704 ± 437Bq kg −1, respectively. Higher values were found in the rock samples. The distributions of 226Ra and 232Th were fitted by log-normal curves. Radiological measurements carried out with a portable scintillometer at the sampled sites revealed an average absorbed dose rate of 55 ± 27 (SD) nGy h −1. Computed dose rates obtained through the Beck formula ranged from 15–179nGy h −1, with a mean value of 72.6 ± 38.7 (SD) n Gyh −1, and their distribution fitted a log-normal curve. An annual average effective dose equivalent of 552 μSv (range: 117–1361 μSv) was estimated for 51 sites in Rio Grande do Norte.

قياس تركيز الرادون داخل مباني جامعة الخليل

TASTRAK, a solid state nuclear track detector has been used to measure indoor radon concentrations at Hebron University. Fifty- four radon pot detectors were mounted in the four university buildings. It was found that the radon concentrations vary considerably from about 1 Bq/m 3 to 250 Bq/m3 The average radon concentrations vary from 20.5 Bq/m3 in the Main Building to 41.3 Bq/m3 in the Agriculture Building. The average radon concentration in the four buildings is found to be 29.8 Bq/m 3. This leads to an average effective dose equivalent of 1.49 mSvly. This dose is slightly higher than the global value of 1.3 mSv/y. Elevated radon concentrations have been found in few rooms. However, these concentrations are well below the action level of 150 Bq/m3.

Estimation of dose rate for indoor radon from building materials.

The internal dose rate due to indoor radon (Rn) emissions from building materials is estimated. It is observed that the contribution from building materials to the dose rate is very small. The average indoor radon concentration in 75 different rooms is found to be 55 +/- 12 Bq. m-3. Assuming an occupancy factor of 0.8, the annual average effective dose equivalent is 1.7 mSv. It seems that soil gas is mainly responsible for the internal exposure from indoor Rn.

Equilibrium Factor and Dosimetry of Radon by CR-39 Nuclear Track Detector

Various national and international surveys have demonstrated an increase in radon (Rn) levels, relative to outdoors, in dwellings and consequently there is a continuous growing concern about its health effects on the population. In order to evaluate the effective dose equivalent from the inhalation of Rn and its progeny, we have started a programme to measure the indoor radon and daughter concentrations in houses in Bangladesh. In the present study time integrated solid state nuclear track detectors were employed for the measurement of radon concentration and potential alpha energy exposure level in more than 160 houses of different types. From these values the equilibrium factor (F) between radon and its progeny was estimated for each house. An average value of 0.4 was obtained. The effective dose equivalent (Hg) for each location was also estimated. The average effective dose equivalent was found to be Hg=1.195 mSv.y-1.