This work presents data on the amount of radiation leakage from 117 microwave ovens in domestic a... more This work presents data on the amount of radiation leakage from 117 microwave ovens in domestic and restaurant use in the West Bank, Palestine. The study of leakage is based on the measurements of radiation emissions from the oven in real-life conditions by using a frequency selective field strength measuring system. The power density from individual ovens was measured at a distance of 1 m and at the height of centre of door screen. The tested ovens were of different types, models with operating powers between 1000 and 1600 W and ages ranging from 1 month to >20 y, including 16 ovens with unknown ages. The amount of radiation leakage at a distance of 1 m was found to vary from 0.43 to 16.4 μW cm(-2) with an average value equalling 3.64 μW cm(-2). Leakages from all tested microwave ovens except for seven ovens (∼6 % of the total) were below 10 μW cm(-2). The highest radiation leakage from any tested oven was ∼16.4 μW cm(-2), and found in two cases only. In no case did the leakage exceed the limit of 1 mW cm(-2) recommended by the ICNIRP for 2.45-GHz radiofrequency. This study confirms a linear correlation between the amount of leakage and both oven age and operating power, with a stronger dependence of leakage on age.
This work presents qualitative and quantitative evaluation of environmental radioactivity in the ... more This work presents qualitative and quantitative evaluation of environmental radioactivity in the central and southern areas of the West Bank, Palestine. For this purpose, the technology of in situ gamma-ray spectroscopy is used with a scintillation of 7.6 x 7.6 cm NaI(Tl) crystal connected to multichannel analyzer InSpector 2000 from Canberra instruments and laptop computer. Gamma-ray spectra were collected using the detector placed 1 m above the ground surface. Calibration of the detection system for in situ measurements of gamma-emitting radionuclides in open terrain is performed theoretically using Monte Carlo techniques. Measurements are conducted in 18 locations in 3 regions across the West Bank. The vast majority of identified radionuclides are naturally occurring gamma-emitting sources (the decay products of (238)U, (232)Th and (40)K). The only identified anthropogenic radionuclide is (137)Cs. Activity concentrations of (40)K, (238)U, (232)Th as well as the total outdoor gamma dose rate from these radionuclides were determined from the gamma-ray spectra. The highest activity concentrations of the three primordial radionuclides were 203 Bq kg(-1) for (40)K, 32 Bq kg(-1) for (238)U and 30 Bq kg(-1) for (232)Th. The total outdoor gamma dose rate calculated for the whole study area at 1 m above ground ranged from 6 to 30 nGy h(-1) with a mean of 18 +/- 7 nGy h(-1), which represents about 30% of the world average value.
Theoretical assessments of power density in far-field conditions were used to evaluate the levels... more Theoretical assessments of power density in far-field conditions were used to evaluate the levels of environmental electromagnetic frequencies from selected GSM900 macrocell base stations in the West Bank and Gaza Strip. Assessments were based on calculating the power densities using commercially available software (RF-Map from Telstra Research Laboratories-Australia). Calculations were carried out for single base stations with multiantenna systems and also for multiple base stations with multiantenna systems at 1.7 m above the ground level. More than 100 power density levels were calculated at different locations around the investigated base stations. These locations include areas accessible to the general public (schools, parks, residential areas, streets and areas around kindergartens). The maximum calculated electromagnetic emission level resulted from a single site was 0.413 μWcm −2 and found at Hizma town near Jerusalem. Average maximum power density from all single sites was 0.16 μWcm −2. The results of all calculated power density levels in 100 locations distributed over the West Bank and Gaza were nearly normally distributed with a peak value of~0.01% of the International Commission on Non-Ionizing Radiation Protection's limit recommended for general public. Comparison between calculated and experimentally measured value of maximum power density from a base station showed that calculations overestimate the actual measured power density by~27%.
Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from ch... more Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from chest CT scans are presented for 200 female patients surveyed from 10 hospitals in the West Bank and Gaza Strip, Palestine. Patient data were collected and organized in a database from May to November 2016. Data include age (15-80 years), weight, height, and calculated body mass index. Exposure data were also recorded for every examination. Exposure data includes milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index, dose length product, manufacturer, name and type of operated CT scanner. Organ and effective doses were evaluated using a web-based commercially available Monte Carlo software: VirtualDose™CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent phantoms of all ages and sizes including pregnant patients. The corresponding phantom was selected for every patient according to patient's tomographic parameters. Calculated organ doses were used to estimate the LAR of breast cancer according to BEIR VII Phase 2 report. It was found that radiation doses resulting from the same exam vary widely between different hospitals, depending on the parameters used and the type of scanner. For all patients, the breast organ dose ranged from 6.5 to 28 mGy per examination, with an average breast organ dose of 15 mGy. The effective dose from chest CT scan per examination ranged from 3 to 14.7 mSv with an average of 7 mSv. For younger females (15-29 years), the LAR of breast cancer risk was estimated to be around 0.05%. For older female patients (60-79 years), the risk was~0.001%. It was found that LAR decreases remarkably with patient's age. Values obtained in this study vary between hospitals, they are generally low and consistent with other studies reported worldwide.
This study deals with a method nuclear technique method utilizing Gamma Ray Spectroscopy for the ... more This study deals with a method nuclear technique method utilizing Gamma Ray Spectroscopy for the assessment of material bulk densities, specially soil density. The spectroscopy system consists of; 3" × 3" inch scintillation NaI(Tl) detector connected to multichannel analyzer Inspector 2000 from Canberra instruments and a laptop computer, 137 Cs radiation source and four different bulk materials with known densities. To calibrate the spectrometric system, detector and radiation source were placed in direct contact with the surface of the bulk materials located in wood boxes manufacture for this purpose. The distance between the radiation source and the detector varies from 10 cm to 30 cm. The Radiation source was shielded so that the emitted photons from the source travel in direction perpendicular to the top surface of the bulk material, and therefore the detector will register photons interacting with the material and scattered towards it. A relation was established between the density of the materials used for calibration and the count rate in different parts of the gamma ray spectrum, the full energy peak, the region of expected backscattering peak (from 50 Kev to 250 Kev), and the region containing Compton's continuum and the full energy peak as well. Actual field measurements on Terra Rosa soils showed that, the best results of bulk density evaluation were obtained when the detector and the radiation source are separated by 20 cm distance. Based on which parts of the spectrum are used for data analysis, the differences in bulk densities measured in the field and real values varies between 0.5% and 6%.
Abstract This work deals with the evaluation of radiation doses from chest x rays for 240 male an... more Abstract This work deals with the evaluation of radiation doses from chest x rays for 240 male and female pediatric patients selected randomly from four Palestinian hospitals. The patient population was divided into five age groups: Newborn, 1, 5, 10, and 15 y old. Doses were theoretically calculated by using Monte Carlo based codes: CALDOSE-X5 and PCXMC-2.0. Patients’ data and type of radiographic systems used as well as exposure factors were provided by the administrations of the selected hospitals. Absorbed organ doses from AP and PA projections were evaluated for 76 pediatric patients selected from one hospital in East Jerusalem. The highest mean organ dose for these patients was 0.085 mGy to the breast in AP projection. Effective doses were estimated for the five age groups for all patients. The highest average effective dose was found for patients in the age group of 10 y and was about 0.13 mSv, while the lowest average effective dose was found for the 5-y age group, about 0.06 mSv. The mean effective dose for all investigated patients in the five age categories was about 0.08 mSv. Variations in effective doses for the same age group and x-ray examination among involved hospitals are remarkable.
In this study, levels of extremely low-frequency electric and magnetic fields originated from ove... more In this study, levels of extremely low-frequency electric and magnetic fields originated from overhead power lines were investigated in the outdoor environment in Ramallah city, Palestine. Spot measurements were applied to record fields intensities over 6-min period. The Spectrum Analyzer NF-5035 was used to perform measurements at 1 m above ground level and directly underneath 40 randomly selected power lines distributed fairly within the city. Levels of electric fields varied depending on the line's category (power line, transformer or distributor), a minimum mean electric field of 3.9 V/m was found under a distributor line, and a maximum of 769.4 V/m under a high-voltage power line (66 kV). However, results of electric fields showed a log-normal distribution with the geometric mean and the geometric standard deviation of 35.9 and 2.8 V/m, respectively. Magnetic fields measured at power lines, on contrast, were not log-normally distributed; the minimum and maximum mean magneti...
The counting efficiency and detection limit of a thyroidal 131 I monitoring system using a whole ... more The counting efficiency and detection limit of a thyroidal 131 I monitoring system using a whole body counter facility is described. Calibration factors are presented for a collimated high purity Ge detector (HPGe) of 12.5% efficiency and thyroid phantoms for two groups of people of different ages: children of 10 and 15 years old and ICRP reference man and woman. The construction of a neck human phantom with a human-like thyroid gland of various volumes used in calibration permits the correction of measured thyroidal 131 I activity to the thyroid depth in neck tissue. Counting efficiencies of the proposed thyroid realistic phantom are compared with calibration data from the often used cylindrical thyroid phantom of two separated lobes
A simple method is presented for calibrating HPGe detectors used for whole-body counting by trans... more A simple method is presented for calibrating HPGe detectors used for whole-body counting by transfer of calibration data from one detector to another. The method can be used for calibration of high purity Ge detectors (HPGe) in various counting method has been verified for HPLGe detectors with relative efficiencies of 12.5% and 61.8% (relative to 7.6x7.6 cm NaI). In comparison with precise calibrations (by phantoms and/or Monte Carlo calculations) the calibration method by data transfer yields results with differences up to 25% for photons in the energy range from 0.15 MeV to 1.5 MeV
Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medica... more Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medical centers in the West Bank and East Jerusalem-Palestine. Absorbed organ and effective doses were calculated for a total of 428 adult male and female patients by using commercially available Monte Carlo based softwares; CALDOSE-X5 and PCXMC-2.0, and hermaphrodite mathematical adult phantoms. Patients were selected randomly from medical records in the time period from November 2014 to February 2015. A database of surveyed patients and exposure factors has been established and includes: patient's height, weight, age, gender, X-ray tube voltage, electric current (mAs), examination projection (anterior posterior (AP), posterior anterior (PA), lateral), X-ray tube filtration thickness in each X-ray equipment, anode angle, focus to skin distance and X-ray beam size. The average absorbed doses in the whole body from different projections were: 0.06, 0.07 and 0.11 mGy from AP, PA and lateral projections, respectively. The average effective dose for all surveyed patients was 0.14 mSv for all chest X-ray examinations and projections in the four investigated medical centers. The effect of projection geometry was also investigated. The average effective doses for AP, PA and lateral projections were 0.14, 0.07 and 0.22 mSv, respectively. The collective effective dose estimated for the exposed population was~60 man-mSv.
A total of 271 measurements were conducted at 69 different sites including homes, hospitals, educ... more A total of 271 measurements were conducted at 69 different sites including homes, hospitals, educational institutions and other public places to assess the exposure to radiofrequency emission from wireless local area networks (WLANs). Measurements were conducted at different distances from 40 to 10 m from the access points (APs) in real life conditions using Narda SRM-3000 selective radiation meter. Three measurements modes were considered at 1 m distance from the AP which are transmit mode, idle mode, and from the client card (laptop computer). All measurements were conducted indoor in the West Bank environment. Power density levels from WLAN systems were found to vary from 0.001 to ~1.9 μW cm-2 with an average of 0.12 μW cm-2. Maximum value found was in university environment, while the minimum was found in schools. For one measurement case where the AP was 20 cm far while transmitting large files, the measured power density reached a value of ~4.5 μW cm-2. This value is however 221 times below the general public exposure limit recommended by the International Commission on Non-Ionizing Radiation Protection, which was not exceeded in any case. Measurements of power density at 1 m around the laptop resulted in less exposure than the AP in both transmit and idle modes as well. Specific absorption rate for the head of the laptop user was estimated and found to vary from 0.1 to 2 mW/kg. The frequency distribution of measured power densities follows a log-normal distribution which is generally typical in the assessment of exposure resulting from sources of radiofrequency emissions.
Theoretical assessments of power density in far-field conditions were used to evaluate the levels... more Theoretical assessments of power density in far-field conditions were used to evaluate the levels of environmental electromagnetic frequencies from selected GSM900 macrocell base stations in the West Bank and Gaza Strip. Assessments were based on calculating the power densities using commercially available software (RF-Map from Telstra Research Laboratories-Australia). Calculations were carried out for single base stations with multiantenna systems and also for multiple base stations with multiantenna systems at 1.7 m above the ground level. More than 100 power density levels were calculated at different locations around the investigated base stations. These locations include areas accessible to the general public (schools, parks, residential areas, streets and areas around kindergartens). The maximum calculated electromagnetic emission level resulted from a single site was 0.413 μWcm −2 and found at Hizma town near Jerusalem. Average maximum power density from all single sites was 0.16 μWcm −2. The results of all calculated power density levels in 100 locations distributed over the West Bank and Gaza were nearly normally distributed with a peak value of~0.01% of the International Commission on Non-Ionizing Radiation Protection's limit recommended for general public. Comparison between calculated and experimentally measured value of maximum power density from a base station showed that calculations overestimate the actual measured power density by~27%.
The present work describes the construction and optimisation of parameters of a mobile whole-body... more The present work describes the construction and optimisation of parameters of a mobile whole-body counter (MWBC). The counter employs a 12.5 cm X 12.5 cm scintillation Nal (T1) crystal from Nuclear Enterprises. The optimising of the detector shielding as well as the shielding of the human subject is achieved with respect to background reduction, sensitivity and the portability of the counter. The counter is mounted in a Czechoslovak made vehicle type Praga V3S and should be considered as a convenient and reliable instrument for accident monitoring and monitoring of workers with open radioactive sources. The minimum detectable amount (MDA) of 137 Cs for 10 min measuring time and the 95% confidence level is about 450 Bq.
A group of 219 subjects of Slovak adults from both sexes were studied for potassium body content ... more A group of 219 subjects of Slovak adults from both sexes were studied for potassium body content by measuring the whole body activity of naturally occurring 40K using a whole body counter. The average body potassium value is 1.68 f 0.33 g kg-' body weight for males and 1.60 f 0.30 g kg-' for females. For both sexes the average body content of K was 1.62 f 0.30 g kg-'. The concentration of potassium varies inversely with age. The specific activity of 40 K varies inversely with slenderness. The total body potassium varies directly with body-build index for males, while its value is essentially constant for young females and tends to decrease with bodybuild index for old females. The average annual dose from 40K is 150 * 30 pGy for males and 140 f 30 pGy for females. For both sexes the average annual dose is 142 f 30 pGy. Both total potassium body content and annual dose from 40K for older subjects are below the values reported by the UNSCEAR.
A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Ban... more A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Bank and Gaza Strip were investigated for organ and effective doses from abdominal computed tomography scan. The organs considered in this study are liver, stomach and colon. Assessment of radiation doses was performed by using a commercially available Monte Carlo based software VirtualDose™ CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent mathematical phantoms of all ages and sizes from new born up to morbidly obese patients. The corresponding phantom was selected for every patient according to patient's demographic parameters. Patient demographic data, scanning parameters and dose indicators (including patient body mass index (BMI), milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index (CTDIvol), dose length product (DLP), manufacturer, name and type of operated CT scanner) were recorded for every examinat...
This work presents data on the amount of radiation leakage from 117 microwave ovens in domestic a... more This work presents data on the amount of radiation leakage from 117 microwave ovens in domestic and restaurant use in the West Bank, Palestine. The study of leakage is based on the measurements of radiation emissions from the oven in real-life conditions by using a frequency selective field strength measuring system. The power density from individual ovens was measured at a distance of 1 m and at the height of centre of door screen. The tested ovens were of different types, models with operating powers between 1000 and 1600 W and ages ranging from 1 month to >20 y, including 16 ovens with unknown ages. The amount of radiation leakage at a distance of 1 m was found to vary from 0.43 to 16.4 μW cm(-2) with an average value equalling 3.64 μW cm(-2). Leakages from all tested microwave ovens except for seven ovens (∼6 % of the total) were below 10 μW cm(-2). The highest radiation leakage from any tested oven was ∼16.4 μW cm(-2), and found in two cases only. In no case did the leakage exceed the limit of 1 mW cm(-2) recommended by the ICNIRP for 2.45-GHz radiofrequency. This study confirms a linear correlation between the amount of leakage and both oven age and operating power, with a stronger dependence of leakage on age.
This work presents qualitative and quantitative evaluation of environmental radioactivity in the ... more This work presents qualitative and quantitative evaluation of environmental radioactivity in the central and southern areas of the West Bank, Palestine. For this purpose, the technology of in situ gamma-ray spectroscopy is used with a scintillation of 7.6 x 7.6 cm NaI(Tl) crystal connected to multichannel analyzer InSpector 2000 from Canberra instruments and laptop computer. Gamma-ray spectra were collected using the detector placed 1 m above the ground surface. Calibration of the detection system for in situ measurements of gamma-emitting radionuclides in open terrain is performed theoretically using Monte Carlo techniques. Measurements are conducted in 18 locations in 3 regions across the West Bank. The vast majority of identified radionuclides are naturally occurring gamma-emitting sources (the decay products of (238)U, (232)Th and (40)K). The only identified anthropogenic radionuclide is (137)Cs. Activity concentrations of (40)K, (238)U, (232)Th as well as the total outdoor gamma dose rate from these radionuclides were determined from the gamma-ray spectra. The highest activity concentrations of the three primordial radionuclides were 203 Bq kg(-1) for (40)K, 32 Bq kg(-1) for (238)U and 30 Bq kg(-1) for (232)Th. The total outdoor gamma dose rate calculated for the whole study area at 1 m above ground ranged from 6 to 30 nGy h(-1) with a mean of 18 +/- 7 nGy h(-1), which represents about 30% of the world average value.
Theoretical assessments of power density in far-field conditions were used to evaluate the levels... more Theoretical assessments of power density in far-field conditions were used to evaluate the levels of environmental electromagnetic frequencies from selected GSM900 macrocell base stations in the West Bank and Gaza Strip. Assessments were based on calculating the power densities using commercially available software (RF-Map from Telstra Research Laboratories-Australia). Calculations were carried out for single base stations with multiantenna systems and also for multiple base stations with multiantenna systems at 1.7 m above the ground level. More than 100 power density levels were calculated at different locations around the investigated base stations. These locations include areas accessible to the general public (schools, parks, residential areas, streets and areas around kindergartens). The maximum calculated electromagnetic emission level resulted from a single site was 0.413 μWcm −2 and found at Hizma town near Jerusalem. Average maximum power density from all single sites was 0.16 μWcm −2. The results of all calculated power density levels in 100 locations distributed over the West Bank and Gaza were nearly normally distributed with a peak value of~0.01% of the International Commission on Non-Ionizing Radiation Protection's limit recommended for general public. Comparison between calculated and experimentally measured value of maximum power density from a base station showed that calculations overestimate the actual measured power density by~27%.
Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from ch... more Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from chest CT scans are presented for 200 female patients surveyed from 10 hospitals in the West Bank and Gaza Strip, Palestine. Patient data were collected and organized in a database from May to November 2016. Data include age (15-80 years), weight, height, and calculated body mass index. Exposure data were also recorded for every examination. Exposure data includes milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index, dose length product, manufacturer, name and type of operated CT scanner. Organ and effective doses were evaluated using a web-based commercially available Monte Carlo software: VirtualDose™CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent phantoms of all ages and sizes including pregnant patients. The corresponding phantom was selected for every patient according to patient's tomographic parameters. Calculated organ doses were used to estimate the LAR of breast cancer according to BEIR VII Phase 2 report. It was found that radiation doses resulting from the same exam vary widely between different hospitals, depending on the parameters used and the type of scanner. For all patients, the breast organ dose ranged from 6.5 to 28 mGy per examination, with an average breast organ dose of 15 mGy. The effective dose from chest CT scan per examination ranged from 3 to 14.7 mSv with an average of 7 mSv. For younger females (15-29 years), the LAR of breast cancer risk was estimated to be around 0.05%. For older female patients (60-79 years), the risk was~0.001%. It was found that LAR decreases remarkably with patient's age. Values obtained in this study vary between hospitals, they are generally low and consistent with other studies reported worldwide.
This study deals with a method nuclear technique method utilizing Gamma Ray Spectroscopy for the ... more This study deals with a method nuclear technique method utilizing Gamma Ray Spectroscopy for the assessment of material bulk densities, specially soil density. The spectroscopy system consists of; 3" × 3" inch scintillation NaI(Tl) detector connected to multichannel analyzer Inspector 2000 from Canberra instruments and a laptop computer, 137 Cs radiation source and four different bulk materials with known densities. To calibrate the spectrometric system, detector and radiation source were placed in direct contact with the surface of the bulk materials located in wood boxes manufacture for this purpose. The distance between the radiation source and the detector varies from 10 cm to 30 cm. The Radiation source was shielded so that the emitted photons from the source travel in direction perpendicular to the top surface of the bulk material, and therefore the detector will register photons interacting with the material and scattered towards it. A relation was established between the density of the materials used for calibration and the count rate in different parts of the gamma ray spectrum, the full energy peak, the region of expected backscattering peak (from 50 Kev to 250 Kev), and the region containing Compton's continuum and the full energy peak as well. Actual field measurements on Terra Rosa soils showed that, the best results of bulk density evaluation were obtained when the detector and the radiation source are separated by 20 cm distance. Based on which parts of the spectrum are used for data analysis, the differences in bulk densities measured in the field and real values varies between 0.5% and 6%.
Abstract This work deals with the evaluation of radiation doses from chest x rays for 240 male an... more Abstract This work deals with the evaluation of radiation doses from chest x rays for 240 male and female pediatric patients selected randomly from four Palestinian hospitals. The patient population was divided into five age groups: Newborn, 1, 5, 10, and 15 y old. Doses were theoretically calculated by using Monte Carlo based codes: CALDOSE-X5 and PCXMC-2.0. Patients’ data and type of radiographic systems used as well as exposure factors were provided by the administrations of the selected hospitals. Absorbed organ doses from AP and PA projections were evaluated for 76 pediatric patients selected from one hospital in East Jerusalem. The highest mean organ dose for these patients was 0.085 mGy to the breast in AP projection. Effective doses were estimated for the five age groups for all patients. The highest average effective dose was found for patients in the age group of 10 y and was about 0.13 mSv, while the lowest average effective dose was found for the 5-y age group, about 0.06 mSv. The mean effective dose for all investigated patients in the five age categories was about 0.08 mSv. Variations in effective doses for the same age group and x-ray examination among involved hospitals are remarkable.
In this study, levels of extremely low-frequency electric and magnetic fields originated from ove... more In this study, levels of extremely low-frequency electric and magnetic fields originated from overhead power lines were investigated in the outdoor environment in Ramallah city, Palestine. Spot measurements were applied to record fields intensities over 6-min period. The Spectrum Analyzer NF-5035 was used to perform measurements at 1 m above ground level and directly underneath 40 randomly selected power lines distributed fairly within the city. Levels of electric fields varied depending on the line's category (power line, transformer or distributor), a minimum mean electric field of 3.9 V/m was found under a distributor line, and a maximum of 769.4 V/m under a high-voltage power line (66 kV). However, results of electric fields showed a log-normal distribution with the geometric mean and the geometric standard deviation of 35.9 and 2.8 V/m, respectively. Magnetic fields measured at power lines, on contrast, were not log-normally distributed; the minimum and maximum mean magneti...
The counting efficiency and detection limit of a thyroidal 131 I monitoring system using a whole ... more The counting efficiency and detection limit of a thyroidal 131 I monitoring system using a whole body counter facility is described. Calibration factors are presented for a collimated high purity Ge detector (HPGe) of 12.5% efficiency and thyroid phantoms for two groups of people of different ages: children of 10 and 15 years old and ICRP reference man and woman. The construction of a neck human phantom with a human-like thyroid gland of various volumes used in calibration permits the correction of measured thyroidal 131 I activity to the thyroid depth in neck tissue. Counting efficiencies of the proposed thyroid realistic phantom are compared with calibration data from the often used cylindrical thyroid phantom of two separated lobes
A simple method is presented for calibrating HPGe detectors used for whole-body counting by trans... more A simple method is presented for calibrating HPGe detectors used for whole-body counting by transfer of calibration data from one detector to another. The method can be used for calibration of high purity Ge detectors (HPGe) in various counting method has been verified for HPLGe detectors with relative efficiencies of 12.5% and 61.8% (relative to 7.6x7.6 cm NaI). In comparison with precise calibrations (by phantoms and/or Monte Carlo calculations) the calibration method by data transfer yields results with differences up to 25% for photons in the energy range from 0.15 MeV to 1.5 MeV
Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medica... more Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medical centers in the West Bank and East Jerusalem-Palestine. Absorbed organ and effective doses were calculated for a total of 428 adult male and female patients by using commercially available Monte Carlo based softwares; CALDOSE-X5 and PCXMC-2.0, and hermaphrodite mathematical adult phantoms. Patients were selected randomly from medical records in the time period from November 2014 to February 2015. A database of surveyed patients and exposure factors has been established and includes: patient's height, weight, age, gender, X-ray tube voltage, electric current (mAs), examination projection (anterior posterior (AP), posterior anterior (PA), lateral), X-ray tube filtration thickness in each X-ray equipment, anode angle, focus to skin distance and X-ray beam size. The average absorbed doses in the whole body from different projections were: 0.06, 0.07 and 0.11 mGy from AP, PA and lateral projections, respectively. The average effective dose for all surveyed patients was 0.14 mSv for all chest X-ray examinations and projections in the four investigated medical centers. The effect of projection geometry was also investigated. The average effective doses for AP, PA and lateral projections were 0.14, 0.07 and 0.22 mSv, respectively. The collective effective dose estimated for the exposed population was~60 man-mSv.
A total of 271 measurements were conducted at 69 different sites including homes, hospitals, educ... more A total of 271 measurements were conducted at 69 different sites including homes, hospitals, educational institutions and other public places to assess the exposure to radiofrequency emission from wireless local area networks (WLANs). Measurements were conducted at different distances from 40 to 10 m from the access points (APs) in real life conditions using Narda SRM-3000 selective radiation meter. Three measurements modes were considered at 1 m distance from the AP which are transmit mode, idle mode, and from the client card (laptop computer). All measurements were conducted indoor in the West Bank environment. Power density levels from WLAN systems were found to vary from 0.001 to ~1.9 μW cm-2 with an average of 0.12 μW cm-2. Maximum value found was in university environment, while the minimum was found in schools. For one measurement case where the AP was 20 cm far while transmitting large files, the measured power density reached a value of ~4.5 μW cm-2. This value is however 221 times below the general public exposure limit recommended by the International Commission on Non-Ionizing Radiation Protection, which was not exceeded in any case. Measurements of power density at 1 m around the laptop resulted in less exposure than the AP in both transmit and idle modes as well. Specific absorption rate for the head of the laptop user was estimated and found to vary from 0.1 to 2 mW/kg. The frequency distribution of measured power densities follows a log-normal distribution which is generally typical in the assessment of exposure resulting from sources of radiofrequency emissions.
Theoretical assessments of power density in far-field conditions were used to evaluate the levels... more Theoretical assessments of power density in far-field conditions were used to evaluate the levels of environmental electromagnetic frequencies from selected GSM900 macrocell base stations in the West Bank and Gaza Strip. Assessments were based on calculating the power densities using commercially available software (RF-Map from Telstra Research Laboratories-Australia). Calculations were carried out for single base stations with multiantenna systems and also for multiple base stations with multiantenna systems at 1.7 m above the ground level. More than 100 power density levels were calculated at different locations around the investigated base stations. These locations include areas accessible to the general public (schools, parks, residential areas, streets and areas around kindergartens). The maximum calculated electromagnetic emission level resulted from a single site was 0.413 μWcm −2 and found at Hizma town near Jerusalem. Average maximum power density from all single sites was 0.16 μWcm −2. The results of all calculated power density levels in 100 locations distributed over the West Bank and Gaza were nearly normally distributed with a peak value of~0.01% of the International Commission on Non-Ionizing Radiation Protection's limit recommended for general public. Comparison between calculated and experimentally measured value of maximum power density from a base station showed that calculations overestimate the actual measured power density by~27%.
The present work describes the construction and optimisation of parameters of a mobile whole-body... more The present work describes the construction and optimisation of parameters of a mobile whole-body counter (MWBC). The counter employs a 12.5 cm X 12.5 cm scintillation Nal (T1) crystal from Nuclear Enterprises. The optimising of the detector shielding as well as the shielding of the human subject is achieved with respect to background reduction, sensitivity and the portability of the counter. The counter is mounted in a Czechoslovak made vehicle type Praga V3S and should be considered as a convenient and reliable instrument for accident monitoring and monitoring of workers with open radioactive sources. The minimum detectable amount (MDA) of 137 Cs for 10 min measuring time and the 95% confidence level is about 450 Bq.
A group of 219 subjects of Slovak adults from both sexes were studied for potassium body content ... more A group of 219 subjects of Slovak adults from both sexes were studied for potassium body content by measuring the whole body activity of naturally occurring 40K using a whole body counter. The average body potassium value is 1.68 f 0.33 g kg-' body weight for males and 1.60 f 0.30 g kg-' for females. For both sexes the average body content of K was 1.62 f 0.30 g kg-'. The concentration of potassium varies inversely with age. The specific activity of 40 K varies inversely with slenderness. The total body potassium varies directly with body-build index for males, while its value is essentially constant for young females and tends to decrease with bodybuild index for old females. The average annual dose from 40K is 150 * 30 pGy for males and 140 f 30 pGy for females. For both sexes the average annual dose is 142 f 30 pGy. Both total potassium body content and annual dose from 40K for older subjects are below the values reported by the UNSCEAR.
A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Ban... more A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Bank and Gaza Strip were investigated for organ and effective doses from abdominal computed tomography scan. The organs considered in this study are liver, stomach and colon. Assessment of radiation doses was performed by using a commercially available Monte Carlo based software VirtualDose™ CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent mathematical phantoms of all ages and sizes from new born up to morbidly obese patients. The corresponding phantom was selected for every patient according to patient's demographic parameters. Patient demographic data, scanning parameters and dose indicators (including patient body mass index (BMI), milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index (CTDIvol), dose length product (DLP), manufacturer, name and type of operated CT scanner) were recorded for every examinat...
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