Nabil El-Faramawy - Academia.edu (original) (raw)
Papers by Nabil El-Faramawy
In this work the impact of reading out of the un-irradiated LiF TLDs based on the post irradiatio... more In this work the impact of reading out of the un-irradiated LiF TLDs based on the post irradiation readout was investigated. Four types of LiF detectors were used. The first three TLDs were MTS-N, MTS-6 and MTS-7 which differ only in the percentage abundance of Li 6 and Li 7 isotopes. The present results were discussed and compared with similar LiF (TLD-100, TLD-600 and TLD-700) fabricated by another company. MCP-N LiF dosimeters were also studied and compared with similar detectors of different only in the doping materials. The current results indicated that all of the LiF doped with Mg and Ti detectors were affected dramatically by the pre-irradiation readout process regardless of the fabrication companies. Otherwise, the impact of different doping materials was contradictious. These dramatic changes could be attributed to the occurrence of the nonradiative recombination through the irradiation process which yield high temperature peaks in the glow curve of the investigated LiF: M...
Radiation and Environmental Biophysics, 2017
Radiation Research, 2005
Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual b... more Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual biological dosimeter for external dose assessment. However, the presence of 90Sr in the tooth tissues makes the task of interpreting EPR tooth dosimetry more complicated. The determination of the dose contribution of incorporated 90Sr in calcified tissue to the total dose measured by EPR is one of the main aspects of correct interpretation of EPR tooth dosimetry. In this work, experimental and numerical calculations were performed to convert the measured beta-particle dose rate to 90Sr concentration in calcified tissue. The cumulative beta-particle dose was measured by exposing artificially contaminated dentin and enamel to thin-layer alpha-Al2O3:C detectors in two different exposure geometries. Numerical calculations were performed for experimental exposure conditions using calculations of electron transport and secondary photons [Monte Carlo n-Particle Transport code version 4C2 (MCNP)]. Numerical calculations were performed to optimize the sample size and exposure geometry. The applicability of two different exposure conditions to be used in routine analysis was tested. Comparison of the computational and experimental results demonstrated very good agreement.
Radiation Protection Dosimetry, 2002
... (London: Van Nostrand Reinhold Company), 451, (1963). 8. Wahl, W., Maushart, R., König, K., H... more ... (London: Van Nostrand Reinhold Company), 451, (1963). 8. Wahl, W., Maushart, R., König, K., Hornung-Lauxmann, L. and Burkart, W. Combined Beta/Gamma Radiation and Bremsstrahlung Monitor for Measurements of Incorporated Radionuclides: The Sr-90 in Vivo Counter. ...
Radiation Physics and Chemistry, 2000
The dosimetric characteristics of Li2B4O7 prepared in-house and doped with Cu are studied using t... more The dosimetric characteristics of Li2B4O7 prepared in-house and doped with Cu are studied using the thermoluminescence (TL) technique. The temperature at which the TL is observed to be most intense is at 178°C. The pre-irradiation annealing condition is 300°C for 10 min while the corresponding value of the post-irradiation annealing is 300°C for 30 min. Furthermore, this study indicated that this material has low fading and wide linear dose response (10−3–103 Gy).
Radiation Measurements, 2000
Portland cement mixed with dierent percentages of granulated lead is studied as shields for gamma... more Portland cement mixed with dierent percentages of granulated lead is studied as shields for gamma radiation. The samples are cured at 100% relative humidity for various time intervals. It is found that cement containing 5% lead has the higher attenuation coecient value. The results are interpreted by study of the bulk density and the compressive strength of the pastes. The formation of more packed structure of tobermorite by lead addition is studied using the XRD analysis and the SEM micrographs.
Radiation Measurements, 1998
ÐAn autoclaving treatment for disks made of neat Portland cement and cement with 5% silica fume h... more ÐAn autoclaving treatment for disks made of neat Portland cement and cement with 5% silica fume hardened pastes was carried out to obtain suitable shield blocks for gamma radiation sources. The attenuation parameters such as the total linear attenuation coecients, the mean-free-paths and the half-value thickness for dierent thicknesses at various periods of autoclaving were obtained. It was found that the attenuation by the neat cement disks autoclaved for 12 h and of 13.8 cm thickness and the disks of cement with 5% silica fume autoclaved for 6 h and of 12.9 cm thickness were the same and identical to that obtained by 3 cm thick sheets of lead. These results are interpreted by measuring the bulk density of the samples and are supported by measuring the compressive strength for the hardened samples.
Radiation and Environmental Biophysics, 2013
This article focuses on the study of 90 Sr in the tooth tissues of Techa riverside residents 60 y... more This article focuses on the study of 90 Sr in the tooth tissues of Techa riverside residents 60 years after intake. The Techa River was contaminated by radioactive wastes in the 1950s. Contamination of the river system, including water, bottom sediment, floodplain soil, and grass, depended on the distance from the source of releases. Therefore, the average 90 Sr intake was different in different settlements located downstream the river. An additional factor influencing 90 Sr accumulation in the teeth is the rate of tissue mineralization at the time of intake which depended on the donor's age at the time of releases. Measurements of 90 Sr concentration in various dental tissues (enamel, crown, and root dentin) of 166 teeth were performed about 60 years after the main intake using the method of thermoluminescence passive beta detection. The paper presents the current levels of tooth tissue contamination, and the tooth-to-tooth variability of 90 Sr concentration in tooth tissues was assessed for the tissues which were matured at the time of massive liquid radioactive waste releases into the Techa River. A model describing the expected levels of 90 Sr in matured dental tissues depending on age and intake has been elaborated for the population under study. The results obtained will be used for calculation of internal dose in enamel and for interpretation of tooth doses measured by means of the electron paramagnetic resonance method, among the population of the Techa River region.
Journal of American …, 2011
... Radiation Protection Dosimetry (2010), pp. 15. 10. Gual MR, Milian FM, Deppman A., Coelho PR... more ... Radiation Protection Dosimetry (2010), pp. 15. 10. Gual MR, Milian FM, Deppman A., Coelho PRP. Study of DNA damage with a new system for irradiation of samples in a nuclear Page 8. Journal of American Science, 2011;7(3) http://www.americanscience.org 803 reactor. ...
Applied Radiation and Isotopes, 2005
From previous work, it is known that CO 2 À radicals in tooth enamel are induced by gamma as well... more From previous work, it is known that CO 2 À radicals in tooth enamel are induced by gamma as well as by UV-light exposure. The parameters of the EPR signal of the CO À 2 radical were found to be independent of the source of exposure. However, it would be desirable for retrospective dosimetry to identify other characteristic features of the EPR spectrum of tooth enamel, which would allow differentiation between the two sources of exposure. In the present work, enamel of deciduous molars was exposed to g-radiation from a 60 Co-source and 254 nm UV-light from a low-pressure mercury lamp. The resulting EPR spectra were deconvoluted, and the native spectrum simulated from spectra of the CO À 2 radical, and two further EPR lines. Both EPR signals of the native spectrum were located at g=2.0046, but were different in line shape and width. One was a 1 mT wide isotropic signal of Gaussian line shape while the other was a 0.7 mT wide axial signal of Lorentzian line shape. A comparable study of the amplitudes of the native and CO 2 À signals was done before and after gand UV-light exposure. While the native signals were found to be only slightly sensitive to g-radiation, their amplitude increased significantly on UV-light exposure. Feasibilities are discussed to distinguish different radiation sources by exposure-induced alterations of the native EPR spectrum.
Applied Radiation and Isotopes, 2005
Enamel from 34 molars from 22 individuals in the general population are used to evaluate the back... more Enamel from 34 molars from 22 individuals in the general population are used to evaluate the background radiation in six cities in India. The estimation of the background dose for each tooth is evaluated using two EPR methods: the calibration-curve method and the additive-dose method. The variation of the estimated EPR dose with tooth position is investigated by using eight teeth taken from the same person. Contribution of the dental X-ray treatments to the enamel-absorbed dose was evaluated using another 17 teeth exposed from 1 to 10 times.
Radiation Protection Dosimetry, 2006
Measurements of the response of thermoluminescent (TL) detectors after gamma ray doses high enoug... more Measurements of the response of thermoluminescent (TL) detectors after gamma ray doses high enough to observe signal saturation provide input to microdosimetric models which relate this gamma-ray response with the energy response after low doses of photons (gamma rays and low-energy X rays) and after high-LET irradiation. To measure their gamma ray response up to saturation, LiF:Mg,Ti (MTS-7 and MTT), LiF:Mg,Cu,P (MCP-7), CaSO 4 :Dy (KCD) and Al 2 O 3 :C detectors were irradiated with 60 Co gamma rays over the range 1-5000 Gy. The X-ray photon energy response and TL efficiency (relative to gamma rays) after doses of beta rays and alpha particles, were also measured, for CaSO 4 :Dy and for Al 2 O 3 :C. Microdosimetric and track structure modelling was then applied to the experimental data. In a manner similar to LiF:Mg,Cu,P, the experimentally observed under response of a-Al 2 O 3 :C to X rays <100 keV, compared with cross-section calculations, is explained as a microdosimetric effect caused by the saturation of response of this detector without prior supralinearity (saturation of traps along the tracks). The enhanced X-ray photon energy response of CaSO 4 :Dy is related to the supralinearity observed in this material after high gamma ray doses, similarly to that in LiF:Mg,Ti. The discussed model approaches support the general rule relating dose-, energy-and ionisation density-responses in TL detectors: if their gamma ray response is sublinear prior to saturation, the measured photon energy response is lower, and if it is supralinear, it may be higher than that expected from the calculation of the interaction cross sections alone. Since similar rules have been found to apply to other solid-state detector systems, microdosimetry may offer a valuable contribution to solid-state dosimetry even prior to mechanistic explanations of physical phenomena in different TL detectors.
Egyptian Journal of Solids, 2000
Different concentrations from copper were added to lithium borate, as a doping material to get a ... more Different concentrations from copper were added to lithium borate, as a doping material to get a good dosimeter compatible with the commercial one. It was found that the gradual addition of Cu to Li 2 B 4 O 7 causes gradual enhancement in the TL intensity up to a concentration value of 0.023 wt%, above that a draw back on the TL intensity occurs. It was also found that for preparation of this dosimeter the optimum sintering temperature was 850°C for 1 hour followed by quenching in liquid nitrogen. The use of liquid nitrogen as a cooling agent after the sintering treatment increases the phosphor sensitivity with about 4 times. Moreover, the kinetic parameters of the main peak of Li 2 B 4 O 7 :Cu phosphor was calculated and it stood in good agreement with the previous work. So, Li 2 B 4 O 7 :Cu phosphor can be prepared in the laboratory with high quality and can be used for radiation protection dosimetry applications.
Radiation Effacts and Defects in Solids, 2020
To deliver the desired absorbed dose to the tumor and save the neighboring healthy tissue the sou... more To deliver the desired absorbed dose to the tumor and save the neighboring healthy tissue the sources of errors in the assessment of the therapeutic dose should be minimized. In the current work, 64 of LiF dosimeters (TLD-700 and TLD-600) were used. The sensitivity factor of each dosimeter with its percentage deviations σ % was calculated and the samples which have σ (> 2) more than the desired uncertainty were excluded. Three protocols for the treatments of the TLD data were applied. Firstly, by subtraction the zero dose reading; secondly, by eliminating the high-temperature range of the glow curve, and thirdly, by taking the maximum height of the fifth dosimetric peak (P5). Improvement in the linearity dose response range used in therapeutic doses was achieved using the second method. The suggested proposal succeeded in reducing the linear measurements region in radiotherapy to 1.1 mGy. ARTICLE HISTORY
Journal of Materials Science: Materials in Electronics
The present article deals with potassium magnesium borate glass activated with copper that was pr... more The present article deals with potassium magnesium borate glass activated with copper that was prepared by a melting quenching technique to study the feasibility of this glass as a radiation dosimeter. The prepared glasses were characterized through X-ray diffraction and FTIR spectroscopy and some of the glasses optical and physical parameters have been interpreted. The thermoluminescence properties of the prepared samples were studied, and the results revealed that the potassium magnesium borate doped with 0.07 wt% with copper has the highest thermoluminescent response. The glow curve of potassium magnesium borate doped with 0.07 wt% of copper has seven overlapping peaks with maximum temperatures of 383.09, 400.71, 413.26, 426.59, 445.98, 476.57 and 534.04 K, and the TL-response is linear from 0.11 to 165 Gy. From the present study, the potassium magnesium borate doped with 0.07 mol% from copper may be applicable for measuring the radiation dose.
Luminescence, 2020
Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with... more Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with different concentrations of dysprosium (Dy) was done in the current work. The samples were prepared by a melting method at 1100 °C and irradiated with β-particles. The results indicated that the glass samples doped with 0.1% of Dy display the best TL dosimetric properties among the other compositions. The deconvoluted analyses of the glow curves displayed five overlapping TL glow peaks located between 392.0 and 510.3 K. A good linear TL dose response for β-particles was obtained in dose range 66.6 mGy - 33.3 Gy. The minimum detectible dose was evaluated to be 205.4 μGy and the samples revealed thermal fading in 312 h to 29 % from its original value.
Environmental Science: an Indian journal, 2013
The dosimetric characteristics of prepared MgB4O7 doped with Dy have been studied using the therm... more The dosimetric characteristics of prepared MgB4O7 doped with Dy have been studied using the thermoluminescence (TL) technique. The TL was observed at the most intense temperature of 187±2 oC that is applied on varied Dy concentration. The response recorded was linear with gamma doses in the range from1 Gy up to 2 kGy and a good linear index coefficient at all applied doses but notin dose range from 100 to 500 mGy. The MgB4O7:Dy dosimeters have shown a TL-sensitivity of 2.2 times higher than that of TLD-100. Furthermore, the study indicated that the dosimeters subject of study, are highly affected by fading.
Radiation Physics and Chemistry, 2021
Abstract The current study was going to investigate the thermoluminescence properties of brownish... more Abstract The current study was going to investigate the thermoluminescence properties of brownish calcite of sedimentary origin in Gebel El Galala, Egypt. The analytical characteristics of the calcite samples were performed using XRD and atomic spectroscopy techniques. The samples were irradiated to different doses of beta particles from 0.11 Gy up to 330 Gy. The TL glow curves of the samples were deconvoluted using new TL software. The deconvolution indicated the presence of 6 overlapping glow peaks. The kinetic parameters were obtained using different methods and their results were in a good agreement with each other. The samples exhibited sensitivity in average of 322.356 Gy−1 mg−1 and a minimum detectable dose of 976.221 μGy. The samples exhibited a long range of linearity from 1.1 up to 330 Gy responding to beta particles irradiation. The fading results recommended to start the measurements of the calcite samples after 2 days to give established measurements.
Radiation Physics and Chemistry, 2021
Abstract The current work was going to study the TL properties of natural milky quartz mineral as... more Abstract The current work was going to study the TL properties of natural milky quartz mineral associated with tin-tungsten-fluorite mineralization in the Eastern Desert of Egypt. The chemical compositions of the investigated samples were examined by Atomic Absorption Spectrometer. The samples were irradiated to different gamma doses from 250 mGy up to 2 kGy. The kinetic analysis of the glow curve was carried out and it revealed that there were composed of six trapping sites at energies 0.92, 0.99, 1.08, 1.22, 1.32 and 1.48 eV responsible for deconvoluted glow peaks at 417.1, 433.9, 474.1, 532.1, 571.8 and 641.7 K respectively. The TL response exhibited a linear behavior in the range from 5 Gy up to 500 Gy and supralinear attitude in the range 500 Gy up to 2 kGy. The minimum detectable dose of the investigated samples was evaluated as 627 μGy and the sensitivity was measured to be 293.27 Gy−1 mg−1. For the fading results, the TL-intensity of the samples was decreased to be 55% from its original value in five days and after then no change in the intensity was observed up to two months.
The Saudi Dental Journal, 2021
Background Radiotherapy is one of the most significant treatment modality of head and neck cancer... more Background Radiotherapy is one of the most significant treatment modality of head and neck cancers. However, it has various hazards on the normal tissues in the radiation field. One of these affected tissues is the lingual mucosa with their papillae such as circumvallate papilla. The effects of radiation on the lingual specialized mucosa may be represented by radiation-induced mucositis and taste alteration including partial or complete loss of taste. Objectives The aim of the study was to evaluate the dose-dependent response of circumvallate papillae to gamma radiation by immunohistochemical expression of caspase-3. Material and methods Twenty-four adult male albino rats were divided into 3 equal groups irradiated at 2.0, 4.0 and 6.0 Gy whole-body gamma radiation doses. Six non-irradiated rats were used as the control group. The radiation effects on circumvallate papillae were evaluated three days after irradiation via histomorphometric investigation of the papillary size and taste buds’ distortion in addition to an immunohistochemical assessment of the apoptotic activity using Caspase-3 marker. Results Dose-related changes were observed in the circumvallate papillae size and morphology and taste buds affection. The changes were obviously detected in rats irradiated at 4 Gy and 6 Gy doses. The detection of caspase-3 marker was evident in a dose-dependent manner in all the irradiated groups, more noticeably in the taste bud cells. Conclusions It could be concluded that circumvallate papillae are adversely affected in a dose-dependent manner by gamma radiation particularly in 4 Gy and 6 Gy doses.
In this work the impact of reading out of the un-irradiated LiF TLDs based on the post irradiatio... more In this work the impact of reading out of the un-irradiated LiF TLDs based on the post irradiation readout was investigated. Four types of LiF detectors were used. The first three TLDs were MTS-N, MTS-6 and MTS-7 which differ only in the percentage abundance of Li 6 and Li 7 isotopes. The present results were discussed and compared with similar LiF (TLD-100, TLD-600 and TLD-700) fabricated by another company. MCP-N LiF dosimeters were also studied and compared with similar detectors of different only in the doping materials. The current results indicated that all of the LiF doped with Mg and Ti detectors were affected dramatically by the pre-irradiation readout process regardless of the fabrication companies. Otherwise, the impact of different doping materials was contradictious. These dramatic changes could be attributed to the occurrence of the nonradiative recombination through the irradiation process which yield high temperature peaks in the glow curve of the investigated LiF: M...
Radiation and Environmental Biophysics, 2017
Radiation Research, 2005
Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual b... more Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual biological dosimeter for external dose assessment. However, the presence of 90Sr in the tooth tissues makes the task of interpreting EPR tooth dosimetry more complicated. The determination of the dose contribution of incorporated 90Sr in calcified tissue to the total dose measured by EPR is one of the main aspects of correct interpretation of EPR tooth dosimetry. In this work, experimental and numerical calculations were performed to convert the measured beta-particle dose rate to 90Sr concentration in calcified tissue. The cumulative beta-particle dose was measured by exposing artificially contaminated dentin and enamel to thin-layer alpha-Al2O3:C detectors in two different exposure geometries. Numerical calculations were performed for experimental exposure conditions using calculations of electron transport and secondary photons [Monte Carlo n-Particle Transport code version 4C2 (MCNP)]. Numerical calculations were performed to optimize the sample size and exposure geometry. The applicability of two different exposure conditions to be used in routine analysis was tested. Comparison of the computational and experimental results demonstrated very good agreement.
Radiation Protection Dosimetry, 2002
... (London: Van Nostrand Reinhold Company), 451, (1963). 8. Wahl, W., Maushart, R., König, K., H... more ... (London: Van Nostrand Reinhold Company), 451, (1963). 8. Wahl, W., Maushart, R., König, K., Hornung-Lauxmann, L. and Burkart, W. Combined Beta/Gamma Radiation and Bremsstrahlung Monitor for Measurements of Incorporated Radionuclides: The Sr-90 in Vivo Counter. ...
Radiation Physics and Chemistry, 2000
The dosimetric characteristics of Li2B4O7 prepared in-house and doped with Cu are studied using t... more The dosimetric characteristics of Li2B4O7 prepared in-house and doped with Cu are studied using the thermoluminescence (TL) technique. The temperature at which the TL is observed to be most intense is at 178°C. The pre-irradiation annealing condition is 300°C for 10 min while the corresponding value of the post-irradiation annealing is 300°C for 30 min. Furthermore, this study indicated that this material has low fading and wide linear dose response (10−3–103 Gy).
Radiation Measurements, 2000
Portland cement mixed with dierent percentages of granulated lead is studied as shields for gamma... more Portland cement mixed with dierent percentages of granulated lead is studied as shields for gamma radiation. The samples are cured at 100% relative humidity for various time intervals. It is found that cement containing 5% lead has the higher attenuation coecient value. The results are interpreted by study of the bulk density and the compressive strength of the pastes. The formation of more packed structure of tobermorite by lead addition is studied using the XRD analysis and the SEM micrographs.
Radiation Measurements, 1998
ÐAn autoclaving treatment for disks made of neat Portland cement and cement with 5% silica fume h... more ÐAn autoclaving treatment for disks made of neat Portland cement and cement with 5% silica fume hardened pastes was carried out to obtain suitable shield blocks for gamma radiation sources. The attenuation parameters such as the total linear attenuation coecients, the mean-free-paths and the half-value thickness for dierent thicknesses at various periods of autoclaving were obtained. It was found that the attenuation by the neat cement disks autoclaved for 12 h and of 13.8 cm thickness and the disks of cement with 5% silica fume autoclaved for 6 h and of 12.9 cm thickness were the same and identical to that obtained by 3 cm thick sheets of lead. These results are interpreted by measuring the bulk density of the samples and are supported by measuring the compressive strength for the hardened samples.
Radiation and Environmental Biophysics, 2013
This article focuses on the study of 90 Sr in the tooth tissues of Techa riverside residents 60 y... more This article focuses on the study of 90 Sr in the tooth tissues of Techa riverside residents 60 years after intake. The Techa River was contaminated by radioactive wastes in the 1950s. Contamination of the river system, including water, bottom sediment, floodplain soil, and grass, depended on the distance from the source of releases. Therefore, the average 90 Sr intake was different in different settlements located downstream the river. An additional factor influencing 90 Sr accumulation in the teeth is the rate of tissue mineralization at the time of intake which depended on the donor's age at the time of releases. Measurements of 90 Sr concentration in various dental tissues (enamel, crown, and root dentin) of 166 teeth were performed about 60 years after the main intake using the method of thermoluminescence passive beta detection. The paper presents the current levels of tooth tissue contamination, and the tooth-to-tooth variability of 90 Sr concentration in tooth tissues was assessed for the tissues which were matured at the time of massive liquid radioactive waste releases into the Techa River. A model describing the expected levels of 90 Sr in matured dental tissues depending on age and intake has been elaborated for the population under study. The results obtained will be used for calculation of internal dose in enamel and for interpretation of tooth doses measured by means of the electron paramagnetic resonance method, among the population of the Techa River region.
Journal of American …, 2011
... Radiation Protection Dosimetry (2010), pp. 15. 10. Gual MR, Milian FM, Deppman A., Coelho PR... more ... Radiation Protection Dosimetry (2010), pp. 15. 10. Gual MR, Milian FM, Deppman A., Coelho PRP. Study of DNA damage with a new system for irradiation of samples in a nuclear Page 8. Journal of American Science, 2011;7(3) http://www.americanscience.org 803 reactor. ...
Applied Radiation and Isotopes, 2005
From previous work, it is known that CO 2 À radicals in tooth enamel are induced by gamma as well... more From previous work, it is known that CO 2 À radicals in tooth enamel are induced by gamma as well as by UV-light exposure. The parameters of the EPR signal of the CO À 2 radical were found to be independent of the source of exposure. However, it would be desirable for retrospective dosimetry to identify other characteristic features of the EPR spectrum of tooth enamel, which would allow differentiation between the two sources of exposure. In the present work, enamel of deciduous molars was exposed to g-radiation from a 60 Co-source and 254 nm UV-light from a low-pressure mercury lamp. The resulting EPR spectra were deconvoluted, and the native spectrum simulated from spectra of the CO À 2 radical, and two further EPR lines. Both EPR signals of the native spectrum were located at g=2.0046, but were different in line shape and width. One was a 1 mT wide isotropic signal of Gaussian line shape while the other was a 0.7 mT wide axial signal of Lorentzian line shape. A comparable study of the amplitudes of the native and CO 2 À signals was done before and after gand UV-light exposure. While the native signals were found to be only slightly sensitive to g-radiation, their amplitude increased significantly on UV-light exposure. Feasibilities are discussed to distinguish different radiation sources by exposure-induced alterations of the native EPR spectrum.
Applied Radiation and Isotopes, 2005
Enamel from 34 molars from 22 individuals in the general population are used to evaluate the back... more Enamel from 34 molars from 22 individuals in the general population are used to evaluate the background radiation in six cities in India. The estimation of the background dose for each tooth is evaluated using two EPR methods: the calibration-curve method and the additive-dose method. The variation of the estimated EPR dose with tooth position is investigated by using eight teeth taken from the same person. Contribution of the dental X-ray treatments to the enamel-absorbed dose was evaluated using another 17 teeth exposed from 1 to 10 times.
Radiation Protection Dosimetry, 2006
Measurements of the response of thermoluminescent (TL) detectors after gamma ray doses high enoug... more Measurements of the response of thermoluminescent (TL) detectors after gamma ray doses high enough to observe signal saturation provide input to microdosimetric models which relate this gamma-ray response with the energy response after low doses of photons (gamma rays and low-energy X rays) and after high-LET irradiation. To measure their gamma ray response up to saturation, LiF:Mg,Ti (MTS-7 and MTT), LiF:Mg,Cu,P (MCP-7), CaSO 4 :Dy (KCD) and Al 2 O 3 :C detectors were irradiated with 60 Co gamma rays over the range 1-5000 Gy. The X-ray photon energy response and TL efficiency (relative to gamma rays) after doses of beta rays and alpha particles, were also measured, for CaSO 4 :Dy and for Al 2 O 3 :C. Microdosimetric and track structure modelling was then applied to the experimental data. In a manner similar to LiF:Mg,Cu,P, the experimentally observed under response of a-Al 2 O 3 :C to X rays <100 keV, compared with cross-section calculations, is explained as a microdosimetric effect caused by the saturation of response of this detector without prior supralinearity (saturation of traps along the tracks). The enhanced X-ray photon energy response of CaSO 4 :Dy is related to the supralinearity observed in this material after high gamma ray doses, similarly to that in LiF:Mg,Ti. The discussed model approaches support the general rule relating dose-, energy-and ionisation density-responses in TL detectors: if their gamma ray response is sublinear prior to saturation, the measured photon energy response is lower, and if it is supralinear, it may be higher than that expected from the calculation of the interaction cross sections alone. Since similar rules have been found to apply to other solid-state detector systems, microdosimetry may offer a valuable contribution to solid-state dosimetry even prior to mechanistic explanations of physical phenomena in different TL detectors.
Egyptian Journal of Solids, 2000
Different concentrations from copper were added to lithium borate, as a doping material to get a ... more Different concentrations from copper were added to lithium borate, as a doping material to get a good dosimeter compatible with the commercial one. It was found that the gradual addition of Cu to Li 2 B 4 O 7 causes gradual enhancement in the TL intensity up to a concentration value of 0.023 wt%, above that a draw back on the TL intensity occurs. It was also found that for preparation of this dosimeter the optimum sintering temperature was 850°C for 1 hour followed by quenching in liquid nitrogen. The use of liquid nitrogen as a cooling agent after the sintering treatment increases the phosphor sensitivity with about 4 times. Moreover, the kinetic parameters of the main peak of Li 2 B 4 O 7 :Cu phosphor was calculated and it stood in good agreement with the previous work. So, Li 2 B 4 O 7 :Cu phosphor can be prepared in the laboratory with high quality and can be used for radiation protection dosimetry applications.
Radiation Effacts and Defects in Solids, 2020
To deliver the desired absorbed dose to the tumor and save the neighboring healthy tissue the sou... more To deliver the desired absorbed dose to the tumor and save the neighboring healthy tissue the sources of errors in the assessment of the therapeutic dose should be minimized. In the current work, 64 of LiF dosimeters (TLD-700 and TLD-600) were used. The sensitivity factor of each dosimeter with its percentage deviations σ % was calculated and the samples which have σ (> 2) more than the desired uncertainty were excluded. Three protocols for the treatments of the TLD data were applied. Firstly, by subtraction the zero dose reading; secondly, by eliminating the high-temperature range of the glow curve, and thirdly, by taking the maximum height of the fifth dosimetric peak (P5). Improvement in the linearity dose response range used in therapeutic doses was achieved using the second method. The suggested proposal succeeded in reducing the linear measurements region in radiotherapy to 1.1 mGy. ARTICLE HISTORY
Journal of Materials Science: Materials in Electronics
The present article deals with potassium magnesium borate glass activated with copper that was pr... more The present article deals with potassium magnesium borate glass activated with copper that was prepared by a melting quenching technique to study the feasibility of this glass as a radiation dosimeter. The prepared glasses were characterized through X-ray diffraction and FTIR spectroscopy and some of the glasses optical and physical parameters have been interpreted. The thermoluminescence properties of the prepared samples were studied, and the results revealed that the potassium magnesium borate doped with 0.07 wt% with copper has the highest thermoluminescent response. The glow curve of potassium magnesium borate doped with 0.07 wt% of copper has seven overlapping peaks with maximum temperatures of 383.09, 400.71, 413.26, 426.59, 445.98, 476.57 and 534.04 K, and the TL-response is linear from 0.11 to 165 Gy. From the present study, the potassium magnesium borate doped with 0.07 mol% from copper may be applicable for measuring the radiation dose.
Luminescence, 2020
Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with... more Characterization of thermoluminescence (TL) properties of lithium borate glass samples doped with different concentrations of dysprosium (Dy) was done in the current work. The samples were prepared by a melting method at 1100 °C and irradiated with β-particles. The results indicated that the glass samples doped with 0.1% of Dy display the best TL dosimetric properties among the other compositions. The deconvoluted analyses of the glow curves displayed five overlapping TL glow peaks located between 392.0 and 510.3 K. A good linear TL dose response for β-particles was obtained in dose range 66.6 mGy - 33.3 Gy. The minimum detectible dose was evaluated to be 205.4 μGy and the samples revealed thermal fading in 312 h to 29 % from its original value.
Environmental Science: an Indian journal, 2013
The dosimetric characteristics of prepared MgB4O7 doped with Dy have been studied using the therm... more The dosimetric characteristics of prepared MgB4O7 doped with Dy have been studied using the thermoluminescence (TL) technique. The TL was observed at the most intense temperature of 187±2 oC that is applied on varied Dy concentration. The response recorded was linear with gamma doses in the range from1 Gy up to 2 kGy and a good linear index coefficient at all applied doses but notin dose range from 100 to 500 mGy. The MgB4O7:Dy dosimeters have shown a TL-sensitivity of 2.2 times higher than that of TLD-100. Furthermore, the study indicated that the dosimeters subject of study, are highly affected by fading.
Radiation Physics and Chemistry, 2021
Abstract The current study was going to investigate the thermoluminescence properties of brownish... more Abstract The current study was going to investigate the thermoluminescence properties of brownish calcite of sedimentary origin in Gebel El Galala, Egypt. The analytical characteristics of the calcite samples were performed using XRD and atomic spectroscopy techniques. The samples were irradiated to different doses of beta particles from 0.11 Gy up to 330 Gy. The TL glow curves of the samples were deconvoluted using new TL software. The deconvolution indicated the presence of 6 overlapping glow peaks. The kinetic parameters were obtained using different methods and their results were in a good agreement with each other. The samples exhibited sensitivity in average of 322.356 Gy−1 mg−1 and a minimum detectable dose of 976.221 μGy. The samples exhibited a long range of linearity from 1.1 up to 330 Gy responding to beta particles irradiation. The fading results recommended to start the measurements of the calcite samples after 2 days to give established measurements.
Radiation Physics and Chemistry, 2021
Abstract The current work was going to study the TL properties of natural milky quartz mineral as... more Abstract The current work was going to study the TL properties of natural milky quartz mineral associated with tin-tungsten-fluorite mineralization in the Eastern Desert of Egypt. The chemical compositions of the investigated samples were examined by Atomic Absorption Spectrometer. The samples were irradiated to different gamma doses from 250 mGy up to 2 kGy. The kinetic analysis of the glow curve was carried out and it revealed that there were composed of six trapping sites at energies 0.92, 0.99, 1.08, 1.22, 1.32 and 1.48 eV responsible for deconvoluted glow peaks at 417.1, 433.9, 474.1, 532.1, 571.8 and 641.7 K respectively. The TL response exhibited a linear behavior in the range from 5 Gy up to 500 Gy and supralinear attitude in the range 500 Gy up to 2 kGy. The minimum detectable dose of the investigated samples was evaluated as 627 μGy and the sensitivity was measured to be 293.27 Gy−1 mg−1. For the fading results, the TL-intensity of the samples was decreased to be 55% from its original value in five days and after then no change in the intensity was observed up to two months.
The Saudi Dental Journal, 2021
Background Radiotherapy is one of the most significant treatment modality of head and neck cancer... more Background Radiotherapy is one of the most significant treatment modality of head and neck cancers. However, it has various hazards on the normal tissues in the radiation field. One of these affected tissues is the lingual mucosa with their papillae such as circumvallate papilla. The effects of radiation on the lingual specialized mucosa may be represented by radiation-induced mucositis and taste alteration including partial or complete loss of taste. Objectives The aim of the study was to evaluate the dose-dependent response of circumvallate papillae to gamma radiation by immunohistochemical expression of caspase-3. Material and methods Twenty-four adult male albino rats were divided into 3 equal groups irradiated at 2.0, 4.0 and 6.0 Gy whole-body gamma radiation doses. Six non-irradiated rats were used as the control group. The radiation effects on circumvallate papillae were evaluated three days after irradiation via histomorphometric investigation of the papillary size and taste buds’ distortion in addition to an immunohistochemical assessment of the apoptotic activity using Caspase-3 marker. Results Dose-related changes were observed in the circumvallate papillae size and morphology and taste buds affection. The changes were obviously detected in rats irradiated at 4 Gy and 6 Gy doses. The detection of caspase-3 marker was evident in a dose-dependent manner in all the irradiated groups, more noticeably in the taste bud cells. Conclusions It could be concluded that circumvallate papillae are adversely affected in a dose-dependent manner by gamma radiation particularly in 4 Gy and 6 Gy doses.