Kenyatta National Hospital (KNH) is the largest public referral hospital with a comprehensive cancer treatment facility in East and Central Africa. Occupational radiation monitoring is a significant technique for demo...Kenyatta National Hospital (KNH) is the largest public referral hospital with a comprehensive cancer treatment facility in East and Central Africa. Occupational radiation monitoring is a significant technique for demonstrating compliance of radiation regulatory limits. The objective of the study was to carry out assessment of occupational radiation exposure among radiotherapy personnel at KNH using thermoluminescence dosimeter, TLD. KNH staff were monitored using dosimeter type TLD-100 made of LiF:Mg,Ti, on monthly basis. The reader system used for analysis was Harshaw 8800. The measurement established the average monthly accumulated occupational personnel dose for KNH to be 0.21 mSv and 0.29 mSv for Hp (10) and Hp (0.07) respectively. The accumulated dose results were within the maximum acceptable dose of 1.67 mSv/month and 41.6 mSv/month for Hp (10) and Hp (0.07) respectively. The investigation results were higher than the acceptable public limit of 0.08 mSv/month. Moreover, incidences were noted where the fetus dose limit 0.42 was also exceeded. Evaluation of statistical dose exposure among doctors, nurses and radiographers’ measurement results were within ±0.02 mSv. The study established the average KNH occupational radiation exposure levels for both Hp (10) and Hp (0.07) were within the ICRU recommendation, validating radiation protection safe practice. Data analysis of healthcare workers did not indicate exposure trend biased to any healthcare profession. Hence radiation risk cut across all professional categories. It is recommended that Radiation Monitoring program be reviewed to include non-clinical staff who access the facility. Radiation reporting should not be limited to one facility, but reflect cases where workers are involved in multiple multiple jobs.展开更多
Polycrystalline powder samples of dysprosium doped Zn（BO2）2 phosphors were prepared by solid state reaction in air at high temperature and characterized by X-ray powder diffraction. The IR, Photoluminescence （PL）,...Polycrystalline powder samples of dysprosium doped Zn（BO2）2 phosphors were prepared by solid state reaction in air at high temperature and characterized by X-ray powder diffraction. The IR, Photoluminescence （PL）, diffuse reflectance and three-dimensional （3D） thermoluminescence （TL） emission spectrum after 60^Co gamma ray irradiation were investigated. The characteristic 3D TL emission bands at about 425, 481 and 573 um with a main emission band of around 573 um were attributed to the host emission, 4^F9/2→6H15/2 and F9/2→6^H13/2 f-f transitions of Dy^3＋ ions. No emission from Dy^2＋ ions was observed in the measurement wavelength range. The TL-dose response of the Zn（BO2）2：Dy polycrystalline powder sample to gamma ray radiation in the range from 1 to 100 Gy at clinical dose levels was almost linear. The experimental results showed that Zn（BO2）2：Dy had potential use as the materials of gamma-ray thermoluminescence dosimeter （TLD） for clinical dosimetry.展开更多
Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%）...Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%） single crystals （hereafter called crystal-I）. The TL glow exhibited four glow peaks in the temperature region 300-500 K. The TL response with dose was studied up to -7.5 kGy. The total glow showed linear, supra linear and exponential growth with dose. The TLE showed bands characteristic of Dy^3＋ ions （around 1.65, 1.87, 2.18 and 2.63 eV） and sodium associated （SA） colour centres （CCs） such as MNa （around 1.67 eV） and XNa （a new SA CC, with an emission band around 2.63 eV）. The OA bands of MNa CC around 3.23 and 2.07 eV were found to decrease with temperature almost in accordance with the TL glow. The R＋A centre absorption around 2.48 eV was found to grow with temperature initially and then decayed. The formation/growth of the CCs R＋A and XNa might be from the conversion of the irradiation produced CC MNa. An attempt was made to explain the TL mechanism in the present system.展开更多
Foraminiferal shells from two piston cores separately located at the Ninetyeast Ridge and the Bengal Fan of the Indian Ocean were selected and purified for measurements of natural thermoluminescence （NTL） intensity ...Foraminiferal shells from two piston cores separately located at the Ninetyeast Ridge and the Bengal Fan of the Indian Ocean were selected and purified for measurements of natural thermoluminescence （NTL） intensity by a high precision thermoluminescence meter （RGD-3）. Variations of the NTL intensity along the two core sequences both spanning the last two glacial--interglacial cycles displayed a strong, identical signal of the global ice volume cycles, which matched well with their corresponding oxygen isotope data. As higher NTL intensity occurred within interglacial periods and changes in an NTL signal were most likely influenced by the temperature of ambient seawater in which the planktonic foraminiferal shells long existed, the NTL signal could be considered as a potential proxy for orbital scale temperature changes of bottom seawater in the tropical Indian Ocean.展开更多
This article describes the measurement of internal alpha dose-rate in pottery using ultrathin CaSO4: Tin thermoluminescence dosimeter. Among the advantages ofthe techllique are not only convenience, accuracy, lowcost,...This article describes the measurement of internal alpha dose-rate in pottery using ultrathin CaSO4: Tin thermoluminescence dosimeter. Among the advantages ofthe techllique are not only convenience, accuracy, lowcost, but also the beta dose--ratefrom pottery can be obtained at the same time.展开更多
Thirty-eight surficial deposit samples were collected from the equatorial North Pacific, and the natural thermoluminescence （TL） characteristics of both bulk and clay fraction samples （ 〈 2μm fractions） were stu...Thirty-eight surficial deposit samples were collected from the equatorial North Pacific, and the natural thermoluminescence （TL） characteristics of both bulk and clay fraction samples （ 〈 2μm fractions） were studied by the FJ427 - AI automatic TL Dosimeter for the first time. With the measurements of clay mineral composition, element composition by XRD and ICP, the correlations between TL intensity and sedimentary environment proxies were analyzed, such as water depth, ratio of FeO to Fe2 O3 contents, LOI, and major clay mineral concentration, and it was found the bulk sample＇ s TL signal was stronger than the clay ones. Usually, increase in the clay components may result in the decrease of TL intensity. From the shape of TL curves, the pelagic sediments can be divided into two groups： the majority group has two glow peaks, in general, the first peak is broad and flat, but the second narrow and sharp; the minority group only has a single peak because the first is absent. The peak centers of TL curves are almost fixed, falling in the temperature sections 230 ~ 260 and 390 ~ 405℃ respectively. Lorentz model packed in the Origin 7.5 was chosen to deal with the TL curves. From the processing results, three parameters （H, C and A ） , corresponding to the height, center, and kurtosis of TL curve, were obtained to describe the curve characteristics. The correlations between TL curve parameters and sedimentary environment proxies were also calculated. On the basis of the above work, the relationship between TL characteristics and sediment type, mineral composition, sedimentary environment of surface sediments was discussed in the study area, and a conclusion is： sediments from the environment of shallower water, higher organic contents and weaker reductivity have stronger TL signals.展开更多
The thermoluminescence （TL） properties of Ce3＋ doped NaSr4（BO3）3 phosphor under the β-ray irradiation were reported. The polycrystalline sample was synthesized by high temperature solid-state reaction. The TL gl...The thermoluminescence （TL） properties of Ce3＋ doped NaSr4（BO3）3 phosphor under the β-ray irradiation were reported. The polycrystalline sample was synthesized by high temperature solid-state reaction. The TL glow curve of NaSr4（BO3）3：Ce3＋ phosphor was composed of only one peak. TL kinetic parameters of NaSr4（BO3）3：Ce3＋ were deduced by the peak shape method, the activation energy （E） was 0.590 eV and the frequency factor was 1.008×10^6S^-1. TL dose response was linear in the range of measurement. The 3-dimensional （3D） TL emission spectrum was also recorded, the emission spectrum consisted of two bands located at 441 and 479 nm respectively, corresponding to the characteristic 4f^05d^1→2F（5/2,7/2） transitions of the Ce3＋ ion. The fading behavior of the NaSr4（BO3）3：Ce3＋ phosphor over a period of 15 d was also studied.展开更多
SrB6010：Tb phosphor was synthesized by high-temperature solid state reaction. The influences of Ce or Li as a co-dopant, Tb concentration and irradiation dose exposure on TL of SrB6010 ： Tb were investigated. Result...SrB6010：Tb phosphor was synthesized by high-temperature solid state reaction. The influences of Ce or Li as a co-dopant, Tb concentration and irradiation dose exposure on TL of SrB6010 ： Tb were investigated. Results show that Ce or Li as a co-dopant can not improve the sensitivity of SrB6010：Tb phosphor. TL response depends on Tb concentration and 0.02 is the optimum in the concentration range from 0.01 to 0.10. Using the optimum Tb concentration, we calculated the kinetic parameters of SrB6010：Tb employing the peak shape method, and suggested the phosphor obeying the second order kinetics. TL emission intensity is linearly dependent on the irradiation dose within the dose range of 50 - 200 Gy. The characteristic Tb^3＋ ion emission was observed in TL emission spectrum.展开更多
Through the study of the thermoluminescence(TL) of BaFClxBr1-x: Sm(0<x<1) system, it is found that former assignment of the glow peaks of BaFX(X = Cl, Br) is plausible. Through detailed study by several methods ...Through the study of the thermoluminescence(TL) of BaFClxBr1-x: Sm(0<x<1) system, it is found that former assignment of the glow peaks of BaFX(X = Cl, Br) is plausible. Through detailed study by several methods and techniques, a correct assignment is given in this paper, i.e. the first, second, and third glow peaks of BaFClxBr1-xSm are assigned to F(F-), F(Cl-), F(Br-) centers respectively, and the first andsecond glow peaks of BaFX are assigned to F(F-) and F(X-) centers respectively. This results are confirmed by theoretical consideration. Possible reasons for former plausible assignment are also pointed out here.展开更多
文摘Kenyatta National Hospital (KNH) is the largest public referral hospital with a comprehensive cancer treatment facility in East and Central Africa. Occupational radiation monitoring is a significant technique for demonstrating compliance of radiation regulatory limits. The objective of the study was to carry out assessment of occupational radiation exposure among radiotherapy personnel at KNH using thermoluminescence dosimeter, TLD. KNH staff were monitored using dosimeter type TLD-100 made of LiF:Mg,Ti, on monthly basis. The reader system used for analysis was Harshaw 8800. The measurement established the average monthly accumulated occupational personnel dose for KNH to be 0.21 mSv and 0.29 mSv for Hp (10) and Hp (0.07) respectively. The accumulated dose results were within the maximum acceptable dose of 1.67 mSv/month and 41.6 mSv/month for Hp (10) and Hp (0.07) respectively. The investigation results were higher than the acceptable public limit of 0.08 mSv/month. Moreover, incidences were noted where the fetus dose limit 0.42 was also exceeded. Evaluation of statistical dose exposure among doctors, nurses and radiographers’ measurement results were within ±0.02 mSv. The study established the average KNH occupational radiation exposure levels for both Hp (10) and Hp (0.07) were within the ICRU recommendation, validating radiation protection safe practice. Data analysis of healthcare workers did not indicate exposure trend biased to any healthcare profession. Hence radiation risk cut across all professional categories. It is recommended that Radiation Monitoring program be reviewed to include non-clinical staff who access the facility. Radiation reporting should not be limited to one facility, but reflect cases where workers are involved in multiple multiple jobs.
基金the National Key Project of Basic Research of China (G1998061312)Science and Technology Project of Jilin Province (200505264)the Foundation of Doctoral Subject of Beihua University
文摘Polycrystalline powder samples of dysprosium doped Zn（BO2）2 phosphors were prepared by solid state reaction in air at high temperature and characterized by X-ray powder diffraction. The IR, Photoluminescence （PL）, diffuse reflectance and three-dimensional （3D） thermoluminescence （TL） emission spectrum after 60^Co gamma ray irradiation were investigated. The characteristic 3D TL emission bands at about 425, 481 and 573 um with a main emission band of around 573 um were attributed to the host emission, 4^F9/2→6H15/2 and F9/2→6^H13/2 f-f transitions of Dy^3＋ ions. No emission from Dy^2＋ ions was observed in the measurement wavelength range. The TL-dose response of the Zn（BO2）2：Dy polycrystalline powder sample to gamma ray radiation in the range from 1 to 100 Gy at clinical dose levels was almost linear. The experimental results showed that Zn（BO2）2：Dy had potential use as the materials of gamma-ray thermoluminescence dosimeter （TLD） for clinical dosimetry.
基金supported by the encouragementsupport rendered by the Management of SSN
文摘Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%） single crystals （hereafter called crystal-I）. The TL glow exhibited four glow peaks in the temperature region 300-500 K. The TL response with dose was studied up to -7.5 kGy. The total glow showed linear, supra linear and exponential growth with dose. The TLE showed bands characteristic of Dy^3＋ ions （around 1.65, 1.87, 2.18 and 2.63 eV） and sodium associated （SA） colour centres （CCs） such as MNa （around 1.67 eV） and XNa （a new SA CC, with an emission band around 2.63 eV）. The OA bands of MNa CC around 3.23 and 2.07 eV were found to decrease with temperature almost in accordance with the TL glow. The R＋A centre absorption around 2.48 eV was found to grow with temperature initially and then decayed. The formation/growth of the CCs R＋A and XNa might be from the conversion of the irradiation produced CC MNa. An attempt was made to explain the TL mechanism in the present system.
基金The National Natural Science Foundation of China under contract Nos 40306017 and 40272074
文摘Foraminiferal shells from two piston cores separately located at the Ninetyeast Ridge and the Bengal Fan of the Indian Ocean were selected and purified for measurements of natural thermoluminescence （NTL） intensity by a high precision thermoluminescence meter （RGD-3）. Variations of the NTL intensity along the two core sequences both spanning the last two glacial--interglacial cycles displayed a strong, identical signal of the global ice volume cycles, which matched well with their corresponding oxygen isotope data. As higher NTL intensity occurred within interglacial periods and changes in an NTL signal were most likely influenced by the temperature of ambient seawater in which the planktonic foraminiferal shells long existed, the NTL signal could be considered as a potential proxy for orbital scale temperature changes of bottom seawater in the tropical Indian Ocean.
文摘This article describes the measurement of internal alpha dose-rate in pottery using ultrathin CaSO4: Tin thermoluminescence dosimeter. Among the advantages ofthe techllique are not only convenience, accuracy, lowcost, but also the beta dose--ratefrom pottery can be obtained at the same time.
基金This work was financially supported by the China 0cean Mineral Resources Research and Development Association under contract No.DY105-01-03-02the National Natural Science Foundation of China under contract No.49776295.
文摘Thirty-eight surficial deposit samples were collected from the equatorial North Pacific, and the natural thermoluminescence （TL） characteristics of both bulk and clay fraction samples （ 〈 2μm fractions） were studied by the FJ427 - AI automatic TL Dosimeter for the first time. With the measurements of clay mineral composition, element composition by XRD and ICP, the correlations between TL intensity and sedimentary environment proxies were analyzed, such as water depth, ratio of FeO to Fe2 O3 contents, LOI, and major clay mineral concentration, and it was found the bulk sample＇ s TL signal was stronger than the clay ones. Usually, increase in the clay components may result in the decrease of TL intensity. From the shape of TL curves, the pelagic sediments can be divided into two groups： the majority group has two glow peaks, in general, the first peak is broad and flat, but the second narrow and sharp; the minority group only has a single peak because the first is absent. The peak centers of TL curves are almost fixed, falling in the temperature sections 230 ~ 260 and 390 ~ 405℃ respectively. Lorentz model packed in the Origin 7.5 was chosen to deal with the TL curves. From the processing results, three parameters （H, C and A ） , corresponding to the height, center, and kurtosis of TL curve, were obtained to describe the curve characteristics. The correlations between TL curve parameters and sedimentary environment proxies were also calculated. On the basis of the above work, the relationship between TL characteristics and sediment type, mineral composition, sedimentary environment of surface sediments was discussed in the study area, and a conclusion is： sediments from the environment of shallower water, higher organic contents and weaker reductivity have stronger TL signals.
基金supported by the National Key Project of Basic Research of China (G1998061312)
文摘The thermoluminescence （TL） properties of Ce3＋ doped NaSr4（BO3）3 phosphor under the β-ray irradiation were reported. The polycrystalline sample was synthesized by high temperature solid-state reaction. The TL glow curve of NaSr4（BO3）3：Ce3＋ phosphor was composed of only one peak. TL kinetic parameters of NaSr4（BO3）3：Ce3＋ were deduced by the peak shape method, the activation energy （E） was 0.590 eV and the frequency factor was 1.008×10^6S^-1. TL dose response was linear in the range of measurement. The 3-dimensional （3D） TL emission spectrum was also recorded, the emission spectrum consisted of two bands located at 441 and 479 nm respectively, corresponding to the characteristic 4f^05d^1→2F（5/2,7/2） transitions of the Ce3＋ ion. The fading behavior of the NaSr4（BO3）3：Ce3＋ phosphor over a period of 15 d was also studied.
文摘SrB6010：Tb phosphor was synthesized by high-temperature solid state reaction. The influences of Ce or Li as a co-dopant, Tb concentration and irradiation dose exposure on TL of SrB6010 ： Tb were investigated. Results show that Ce or Li as a co-dopant can not improve the sensitivity of SrB6010：Tb phosphor. TL response depends on Tb concentration and 0.02 is the optimum in the concentration range from 0.01 to 0.10. Using the optimum Tb concentration, we calculated the kinetic parameters of SrB6010：Tb employing the peak shape method, and suggested the phosphor obeying the second order kinetics. TL emission intensity is linearly dependent on the irradiation dose within the dose range of 50 - 200 Gy. The characteristic Tb^3＋ ion emission was observed in TL emission spectrum.
文摘Through the study of the thermoluminescence(TL) of BaFClxBr1-x: Sm(0<x<1) system, it is found that former assignment of the glow peaks of BaFX(X = Cl, Br) is plausible. Through detailed study by several methods and techniques, a correct assignment is given in this paper, i.e. the first, second, and third glow peaks of BaFClxBr1-xSm are assigned to F(F-), F(Cl-), F(Br-) centers respectively, and the first andsecond glow peaks of BaFX are assigned to F(F-) and F(X-) centers respectively. This results are confirmed by theoretical consideration. Possible reasons for former plausible assignment are also pointed out here.
