In this study, thermoluminescence detectors (TLD)‐600 and TLD‐700 were used under different condi... more In this study, thermoluminescence detectors (TLD)‐600 and TLD‐700 were used under different conditions to study neutron dosimetry for its application in medical dosimetry as albedo dosimeters. 6LiF has a high cross‐section for neutrons and is more sensitive to neutrons than to gamma radiation. Conversely, TLD‐700 showed a better response to gamma radiation. Therefore, to obtain the response for neutrons, the responses for TLD‐600 and TLD‐700 were subtracted. A cadmium sheet was used to absorb incident thermal neutrons so that detector measured only backscattered neutrons from the albedo dosimeter. A Perspex sheet was used as a moderator to thermalize the fast neutron source Am‐Be used in the experiment. CR‐39 was used to detect fast neutrons and act as an albedo dosimeter when covered with a 10B disc. Both TLD and CR‐39 dosimeters were successful in detecting scattered neutrons in radiotherapy rooms.
International Journal of Physics and Research (IJPR), 2013
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: Mg,Ti in contrary to LiF: Mg,Cu,P detectors.
There is a need to synthesis a new TL material has a simple glow curve, glow peak and tissue equi... more There is a need to synthesis a new TL material has a simple glow curve, glow peak and tissue equivalent suitable to study the biological effects of ionizing radiation. New 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole derivatives of 4-thiomethyl-quinazoline have been synthesized by cyclization of hydrazide, amidrazone and thiosemicarbazide derivatives via their treatments with carbon disulfide, sulfuric acid, sodium hydroxide, and mercuric oxide. 1,3-Thiazole derivatives were prepared from thiosemicarbazide and arylidene derivative after its treatment with ethylchloroactate, phenacyl bromide and mercaptoacetic acid. The radiation dosimetric properties of new 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,4-triazole and 1,3-thiazole derivatives of 4-thiomethyl-quinazoline have been investigated. The TL-radiation response was found to be sensitive to the compound composition quantitatively and qualitatively due to different created trap centers according to the type of doping oxide...
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...
The linearity of thermoluminescence (TL) dose response curve, in low dose levels, is affected by ... more The linearity of thermoluminescence (TL) dose response curve, in low dose levels, is affected by background signals appearing at the tail of the glow curves. The effects of these signals also restrict the use of the high temperature glow peaks in many applications. In this study, a new reading out procedure was presented to reduce the background signals and increase the resolution of the high temperature glow peaks in LiF:Mg,Ti (TLD-600 and TLD-700) dosimeters in both gamma and neutron irradiation processes. The new reading out procedure was performed in two steps with different temperature zone range. In the first step, the temperature zone range was set to 100:210 o C with heating rate R= 1 o C/sec. This step is followed by a second reading (second step) with a temperature zone range of 100:400 o C with the same R. A comparison between this new procedure and the usual one (in which the reading out is only one step with a temperature zone of 100:400 o C) was performed. The new beha...
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 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. ...
Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescen... more Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescence dosimeters are widely used in many applications. It was noticed that post-irradiation glow curves of LiF dosimeters that had undergone pre-irradiation background dose measurements dramatically differed from the curves of dosimeters irradiated without such preliminary measurements. Three types of dosimeters were studied in this respect, namely, TLD-700, TLD-600, and TLD-100. Impact of pre-irradiation background measurements on the glow curve areas, peak positions, and individual peak intensities were investigated using computerized glow curve analysis. Similarities in the behavior of the dosimeters of all three types were found. Areas of the glow peaks P₂a, P₃, P₄, P₅, and P₆ increased. Peak P₃ grew most significantly, followed by P₂, and P₅. Also, one of the common features was a shift of T(max) of P₅ to higher temperatures. Pre-irradiation background readings increase the total area of the glow curve in general and affect relative intensities and positions of specific peaks, which changes the shape of the glow curve. It is strongly recommended to perform pre-irradiation background measurements for all LiF-based dosimeters regardless of the values of the background doses relative to the radiation doses to be given.
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.
PURPOSE Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly me... more PURPOSE Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA). Understanding the limitations and use of dosimeters to measure these dose distributions is critical to safe IMRT implementation. In this work, we used Monte Carlo simulations to investigate the possible sources of discrepancy between our measurement with 2D array system and our dose calculation using our treatment planning system (TPS). MATERIAL AND METHODS MCBEAM and MCSIM Monte Carlo codes were used for treatment head simulation and phantom dose calculation. Accurate modeling of a 6MV beam from Varian trilogy machine was verified by comparing simulated and measured percentage depth doses and profiles. Dose distribution inside the 2D array was calculated using Monte Carlo simulations and our TPS. Then Cross profiles for different field sizes were compared with actual measurements for zero and 90° gantry angle setup. Through the anal...
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: Mg,Ti in contrary to LiF: Mg,Cu,P detectors.
In this study, thermoluminescence detectors (TLD)‐600 and TLD‐700 were used under different condi... more In this study, thermoluminescence detectors (TLD)‐600 and TLD‐700 were used under different conditions to study neutron dosimetry for its application in medical dosimetry as albedo dosimeters. 6LiF has a high cross‐section for neutrons and is more sensitive to neutrons than to gamma radiation. Conversely, TLD‐700 showed a better response to gamma radiation. Therefore, to obtain the response for neutrons, the responses for TLD‐600 and TLD‐700 were subtracted. A cadmium sheet was used to absorb incident thermal neutrons so that detector measured only backscattered neutrons from the albedo dosimeter. A Perspex sheet was used as a moderator to thermalize the fast neutron source Am‐Be used in the experiment. CR‐39 was used to detect fast neutrons and act as an albedo dosimeter when covered with a 10B disc. Both TLD and CR‐39 dosimeters were successful in detecting scattered neutrons in radiotherapy rooms.
International Journal of Physics and Research (IJPR), 2013
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: Mg,Ti in contrary to LiF: Mg,Cu,P detectors.
There is a need to synthesis a new TL material has a simple glow curve, glow peak and tissue equi... more There is a need to synthesis a new TL material has a simple glow curve, glow peak and tissue equivalent suitable to study the biological effects of ionizing radiation. New 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole derivatives of 4-thiomethyl-quinazoline have been synthesized by cyclization of hydrazide, amidrazone and thiosemicarbazide derivatives via their treatments with carbon disulfide, sulfuric acid, sodium hydroxide, and mercuric oxide. 1,3-Thiazole derivatives were prepared from thiosemicarbazide and arylidene derivative after its treatment with ethylchloroactate, phenacyl bromide and mercaptoacetic acid. The radiation dosimetric properties of new 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,4-triazole and 1,3-thiazole derivatives of 4-thiomethyl-quinazoline have been investigated. The TL-radiation response was found to be sensitive to the compound composition quantitatively and qualitatively due to different created trap centers according to the type of doping oxide...
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...
The linearity of thermoluminescence (TL) dose response curve, in low dose levels, is affected by ... more The linearity of thermoluminescence (TL) dose response curve, in low dose levels, is affected by background signals appearing at the tail of the glow curves. The effects of these signals also restrict the use of the high temperature glow peaks in many applications. In this study, a new reading out procedure was presented to reduce the background signals and increase the resolution of the high temperature glow peaks in LiF:Mg,Ti (TLD-600 and TLD-700) dosimeters in both gamma and neutron irradiation processes. The new reading out procedure was performed in two steps with different temperature zone range. In the first step, the temperature zone range was set to 100:210 o C with heating rate R= 1 o C/sec. This step is followed by a second reading (second step) with a temperature zone range of 100:400 o C with the same R. A comparison between this new procedure and the usual one (in which the reading out is only one step with a temperature zone of 100:400 o C) was performed. The new beha...
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 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. ...
Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescen... more Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescence dosimeters are widely used in many applications. It was noticed that post-irradiation glow curves of LiF dosimeters that had undergone pre-irradiation background dose measurements dramatically differed from the curves of dosimeters irradiated without such preliminary measurements. Three types of dosimeters were studied in this respect, namely, TLD-700, TLD-600, and TLD-100. Impact of pre-irradiation background measurements on the glow curve areas, peak positions, and individual peak intensities were investigated using computerized glow curve analysis. Similarities in the behavior of the dosimeters of all three types were found. Areas of the glow peaks P₂a, P₃, P₄, P₅, and P₆ increased. Peak P₃ grew most significantly, followed by P₂, and P₅. Also, one of the common features was a shift of T(max) of P₅ to higher temperatures. Pre-irradiation background readings increase the total area of the glow curve in general and affect relative intensities and positions of specific peaks, which changes the shape of the glow curve. It is strongly recommended to perform pre-irradiation background measurements for all LiF-based dosimeters regardless of the values of the background doses relative to the radiation doses to be given.
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.
PURPOSE Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly me... more PURPOSE Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA). Understanding the limitations and use of dosimeters to measure these dose distributions is critical to safe IMRT implementation. In this work, we used Monte Carlo simulations to investigate the possible sources of discrepancy between our measurement with 2D array system and our dose calculation using our treatment planning system (TPS). MATERIAL AND METHODS MCBEAM and MCSIM Monte Carlo codes were used for treatment head simulation and phantom dose calculation. Accurate modeling of a 6MV beam from Varian trilogy machine was verified by comparing simulated and measured percentage depth doses and profiles. Dose distribution inside the 2D array was calculated using Monte Carlo simulations and our TPS. Then Cross profiles for different field sizes were compared with actual measurements for zero and 90° gantry angle setup. Through the anal...
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: Mg,Ti in contrary to LiF: Mg,Cu,P detectors.
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Papers by Arafa I Abd El-Hafez