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The equivalent dose of body surface can be calculated using a thermoluminescence dosimeter (TLD). The TLD must be calibrated during the initial testing process using the TLD Reader and this process will zero the dose which means the equivalent dose in it will be erased. This study is to read doses for TLD that have not been registered/calibrated in TLD Reader. The sample is 40 calibration cards of TLD Harshaw's shared in 5 sets testing with different dose, so every sets consists of 8 calibration cards. The calibration card was irradiated with 137Cs source at a dose of 2 mSv, 3 mSv, 5 mSv, 7.5 mSv, and 10 mSv. The calibration curve was created by comparing the irradiation dose with the response calibration readings of the TLD Reader. The best calibration curve is the calibration curve on the polynomial/ quadratic model with R2 = 0.9968 its mean pass the reference that good calibration curve have value of R2 ≥. 0.990. The standard deviation of the dose measurement results at −3.87% to 21.98%, which means that the value is still in the range of −30% to 50% or not to exceed −30% to 50%. Equivalent dose in uncalibrated TLD can read using a polynomial calibration curve formula as evidenced by the value of R2 ≥ 0.990 and a standard deviation that does not exceed −30% to 50%. [ABSTRACT FROM AUTHOR]

One of the challenges of individual dosimetry in Iran is the absence of standard radiation fields with different energies for calibration. For dosimetry in the photon fields, only the standard fields of Co-60 and Cs-137 sources, located in the (SSDL) can be utilized. This study aims to determine energy response of a personal thermoluminescence dosimeter (TLD) designed for determining the personal dose-equivalent, Hp(10), in order to investigate whether the calibration curve in the Co-60 gamma field can be utilized for assessing the dose-equivalent in the photon fields with different energies. To do this, first, the TLD dosimeters (an appropriate plastic badge including a TLD-100 chip) are irradiated with a few Hp(10) values using the Co-60 source in the Karaj SSDL. The badges are placed on a water phantom (slab), one meter distant from the source. Then, MCNP4C code is used to calculate the energy response at 662 keV and 1.25 MeV energies. Next, these responses are validated with the experimental data. Finally, the calculation is carried out for several other energies in the range of 20 keV to 1.25 MeV. Obtained results show that for the energies more than 400 keV, The response of the dosimeter is independent of the photon energy, within 10% uncertainty. On the other hand, for the energies smaller than 400 keV, a significant dependence on the energy is observed; such that in 40 keV the response is about 2 times larger than that at 1.25 MeV. Consequently, a method to reduce this uncertainty is needed. [ABSTRACT FROM AUTHOR]

Thermoluminescent dosimeters (TLD) and optically stimulated luminescent dosimeters (OSLD) are practical, accurate, and precise tools for point dosimetry in medical physics applications. The objective of this study is to investigate the luminescence properties—both OSL and TL—of lithium fluoride (LiF) doped with magnesium (Mg), copper (Cu), and phosphorous (P) (LiF: Mg, Cu, P), commercially known as TLD-100H. The goal is to devise a methodological approach for dose measurement that allows for obtaining two independently measured dose values at each irradiation point, thereby improving accuracy and precision. The luminescence properties of TLD-100H were studied using a beta irradiation source (90Sr/90Y) integrated into the TL/OSL DA-15 automated Risø reader. This study identified the ideal experimental conditions for optimal dose evaluation and used them for dosimeter calibration across doses ranging from 0.5 to 4.0 Gy. The results demonstrated that, under optimal measurement parameters, the OSL and residual thermoluminescence (ResTL) signals—correlated to two trap systems within the dosimeter—exhibited high reproducibility, stability over multiple cycles, and high precision and accuracy (≤2%). Specifically, the OSL response showed good linear behavior across the investigated dose range, while the ResTL signal exhibited linear behavior between 0.5 and 2 Gy and sublinear behavior for doses >2 Gy. [ABSTRACT FROM AUTHOR]

In this study, the thermoluminescece (TL) behavior of potassium chloride dosimeter doped with dysprosium impurity (KCl:Dy) was studied. Evaluation of the morphology, shape and size of prepared crystal were done by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Potassium chloride was prepared by co-precipitation with different percentages of dysprosium impurities and the best TL response was determined for gamma rays in 0.5 mol% of impurity. The optimum annealing regime was obtained at 700 for 30 minutes. Using a general order kinetic based on computer simulator, the glow curve and corresponding kinetics parameters were calculated. The TL glow curve of synthesized dosimeter shows two peaks at 393 and 415 K. Also, other dosimetric properties such as fading and TL dose response were studied

Objectives: The purpose of this research is to synthesize the Yttrium doped PEG-coated ZnO nanostructures and characterize them especially as thermoluminescence material for gamma dosimetry. The dosimetry characteristics were evaluated by irradiating the sample with gamma radiation with different doses (10 and 100 Gray) at a temperature range of 0–400 °C. Methods: Uncoated undoped ZnO NPs and PEG-coated ZnO Nanoparticles (NPs) with 0, 5, 7, and 10 at% Yttrium (Y) doping concentration were synthesized via hydrothermal technique. Synthesized nanoparticles were examined through various characterization techniques (XRD, SEM, EDS, UV, Tyndall test and TLD) for their morphology, PEG-coating confirmation and to evaluate their Thermoluminescence properties. Results: XRD analysis confirmed the wurtzite hexagonal structure and doping of Yttrium into ZnO. SEM analysis showed PEG-coated ZnO has well-rounded nanoplates

The goal of this study is to examine the thermoluminescence (TL) properties of materials obtained by depositing rare earth ion-doped yttrium stannate (Y2Sn2O7) phosphor powders on metallic surfaces using friction stir technique. Y2Sn2O7 phosphors doped with Tb, Eu and Dy rare earth ions were produced by the solid-state reaction synthesis method by sintering at 1450 °C. TL properties of Y2Sn2O7:Eu, Dy and Tb were examined under X-ray irradiation, UV radiation (254 nm) and beta radiation. Thermoluminescence dosimeter (TLD) reader was used for recording the TL glow curves, and linear heating rate was selected as 2 Ks−1. The thermoluminescence glow curves of deposited phosphors showed prominent glow peaks at 225 °C for Y2Sn2O7:Tb, 185 °C and 295 °C for Y2Sn2O7:Eu and 150 and 260 °C for Y2Sn2O7:Dy after irradiated with X-ray radiation. TL properties of phosphor composites deposited by friction stir processing are a pioneering study. [ABSTRACT FROM AUTHOR]

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 back-scattered 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. [ABSTRACT FROM AUTHOR]

This study describes the preparation method of alumina (Al2O3) as a type of thermoluminescence dosimeter (TLD) to monitor gamma photons (γ‐rays) in abroad band of radioactive doses (0.5 : 2000 Gy). Alumina is selected in this study because it has a relatively low cost TL material and can be easily prepared. Aluminum oxide (Al2O3) was chemically prepared using two different methods which are the Sol‐Gel and Co‐precipitation methods. For each method, the produced alumina (Al2O3) was divided into 4 groups which was thermally treated at (400, 600, 800, 1100 °C) respectively for 6 hours for each group. The crystalline features, morphology and sample composition of the prepared samples were chemically characterized by X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X‐ray (EDX). Al2O3 prepared by the Co‐precipitation method which was treated at 1100 °C (P4) was found to exhibit the highest gamma ray response compared to other samples. The deconvolution analysis showed that the main TL glow curve consisted of (5) overlapped peaks corresponding to number of traps. The linearity of the gamma response for this sample appeared in doses ranging from 1 Gy up to 200 Gy. The minimum detectable dose that can be detected by precipitated‐alumina sample (P1) was calculated mathematically to be 3.653 mGy. The fading was found to be 45.6 % after being stored for 45 days at room temperature and approximately 65 % after 90 days. This sample was reproducible according to the repeated TL results for the same sample for 5 times as their values were very close from one other with standard deviation (±σ) 0.96 %. Henceforth, Co‐precipitated α‐alumina can be used as a TL‐Micro dosimeter. [ABSTRACT FROM AUTHOR]

In this study, the feasibility of using a thermoluminescent slab dosimeter (TLSD) in postal dosimetry audit for radiotherapy systems is examined. First, changes in material structure are evaluated by measuring changes in TLSD weight and temperature after heating and cooling. Then, a fading correction factor is derived by measuring the relationship between the elapsed time after irradiation and thermoluminescence (TL) intensity. Finally, the uncertainty in the absorbed dosimetry using the TLSD with the TL absorbed dose correction factor is evaluated. It is shown that the TLSD weight and heat flow change after heating. These changes are reversible upon cooling. Therefore, the material structure of the TLSD does not change after heating. The fading effect for the TLSD can be minimized by setting the elapsed time to more than 100 h. Furthermore, measurement accuracy can be improved by correcting the fading. The overall measurement uncertainty or expanded relative standard uncertainty for this measurement method is 1.80%. The TLSD has high material stability and measurement accuracy under a certain condition equivalent to that of conventional postal dosimetry audit conducted using a glass dosimeter. The TLSD can be used as a 2D measurement device for postal dosimetry audit. [ABSTRACT FROM AUTHOR]

Purpose: The thermoluminescence dosimeter (TLD) has desirable features including low cost, reusability, small size, and relatively low energy dependence. However, the commonly available poly‐crystal TLDs (e.g., TLD‐100) exhibit high interdetector variability that requires individual calibration for high detection accuracy. To improve individual TLD tracking robustness, we developed an optical fingerprinting method to identify the TLD‐100 chips. Methods: Seven hundred and fifty‐two images were initially captured using a digital microscope camera to build a feature library for both facets of 376 TLD‐100 chips. A median intensity thresholding method was used to segment images into foreground and background. The affine transformation was used to register the segmented images to the same position. The fingerprint of each image was calculated from its registered image. All fingerprints were then recorded in an Elasticsearch® search database. The TLD fingerprint match was tested three times when the library was established and repeated once 20 months later. All chips were irradiated at 0, 1, 4, and 8 Gy on a calibrated clinical MV linac to establish the individual calibration curve. Results: The true positive rate of identifying TLDs based on their optical fingerprints was 100% at initialization of the inventory. After 20 months and multiple deployments for characterization, calibration, and dose measurement, the true positive match rate dropped to 99% with zero false‐positive matches. The TLDs exhibited high self‐consistency in the dose–response test with R2 between 0.988 and 1 with linear regression. Conclusions: The TLD‐100 chips surface textures are unique and sufficient to support accurate identification based on the optical fingerprinting. This method provides inexpensive and robust management of the TLDs for individual calibration and dosimetry. [ABSTRACT FROM AUTHOR]

Traditional treatment planning in nasopharyngeal cancer is now replaced by reverse planning using optimization techniques Intensity Modulated Radiotherapy-Intensity Modulated Arc Therapy (IMRT-IMAT) and Hybrid therapy planning using both. Hybrid plans are needed especially for critical organ doses that cannot be reduced in IMAT or IMRT treatment plans, or for PTV volumes that are not well covered. The dose calculations of the Treatment Planning Systems (TPS) that make these complex calculations need to be verified by dosimetric methods. In this study, TPS accuracy was tested by Thermoluminescence dosimeter (TLD). Computed tomography images of the Alderson® Rando Phantom for treatment planning in nasopharyngeal cancer were scanned. Planned Target Volume 70 Gy (PTV70) and critical organs (right parotid, left parotid, medulla and brain stem) were detected while computed tomography sections of a standard nasopharyngeal tumor patient were utilized by fusion. IMRT, IMAT and Hybrid treatment plans were created with the same dose prescription on the phantom using Eclipse (version 8.9.17) TPS. In Alderson® Rando Phantom, TLDs placed in the right and left parotid, medulla spinalis and brain stem were converted to cumulative doses and compared with the dose values on the treatment planning computer. The highest difference between Eclipse TPS and TLD mean reading values was found to be 3.5% in the left parotid IMRT plan, 2.78% in the brain stem in the IMAT plan and 3.16% in the brain stem in the hybrid plan. In this study, we determined dosimetric accuracy of the Hybrid treatment plan for nasopharynx is less than 4% in TPS. [ABSTRACT FROM AUTHOR]

Abstract Lithium fluoride thermoluminescent radiation detectors with different dopant concentrations (7LiF:Mg,Ti and 7LiF:Mg,Cu,P) were exposed to 1H and 4He ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in order to investigate their response to energetic light charged particles. Computer simulations with the Monte Carlo code PHITS were performed for a better interpretation of the experimental data. The results were compared with literature efficiency data and with the results of a recently developed microdosimetric efficiency model. In case of the main peak signal of 7LiF:Mg,Ti detectors, the determined efficiency values are in good agreement with previous investigations. Discrepancies in the efficiency of high temperature signal due to well-known non-linearity effects are reported. For 7LiF:Mg,Cu,P detectors, an anomalous thermoluminescence behavior in the low temperature part of the signal was found and discussed. Depending on the light quantification process, differences up to 30% in the dose assessment can be obtained, affecting also the relative efficiency determination process. An explanation of this phenomenon as a consequence of local migration of the charged carriers between the low temperature peaks and the main peak is presented. The implications of these findings on the use of LiF:Mg,Cu,P detectors in radiation environments characterized by the presence of 1H and 4He ions (i.e. space and proton therapy) are discussed. In order to avoid the occurrence of this anomalous behavior, it is advised to pre-heat the detectors after energetic light particle exposures. Highlights • LiF:Mg,Ti and LiF:Mg,Cu,P thermoluminescent detectors were exposed to 1H and 4He ions. • An anomalous low temperature behavior was found for LiF:Mg,Cu,P detectors. • This can affect the dose assessment process with LiF:Mg,Cu,P detectors up to 30%. [ABSTRACT FROM AUTHOR]

A Cr-doped alumina (Al2O3:Cr) ceramic thermoluminescent detector (TLD) has the potential to be applied as a two-dimensional (2D) imaging device in radiation therapy. In this work, we investigated the linearity in the dose level of radiotherapy and the linear energy transfer (LET) dependence of Al2O3:Cr ceramic TLD using several species of heavy charged particles (HCPs). The Al2O3:Cr ceramic TLD had good linearity as a function of irradiation dose. However, the large LET-dependent response made it difficult to apply the detector directly to dose measurement in HCP therapy. The combination of two Al2O3 ceramic TLDs, one with Cr doping and one without Cr doping, may be expected to be applied to the measurement of LET distributions because of the different LET dependences. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the photon energy dependence of absorbed dose measurements, in a comparison of optically stimulated luminescence (OSL) in NaCl with thermoluminescence (TL) in LiF:Mg,Cu,P. The comparisons were made at exposure to ionizing radiation in the photon energy range 20 keV to 1.3 MeV. Specially designed dosemeter kits containing both NaCl and LiF were used under i ) laboratory conditions using defined radiation fields, ii ) laboratory conditions using sealed point sources mimicking unintentional exposures, and iii ) field conditions in areas in Japan that were affected by the Fukushima Daiichi nuclear disaster in 2011. The dosemeter kits used in Japan showed that absorbed doses as low as 100 μGy can be assessed from the OSL signal in NaCl. The ratio of the dosemeter readings using OSL in NaCl and TL in LiF increases after irradiation at lower photon energies (less than a few hundred keV) as determined under laboratory conditions. Compensating for this energy dependence of the absorbed dose determinations obtained from OSL in NaCl would thus require an energy-dependent conversion factor for photon energies below 600 keV. On the other hand, the difference in the photon energy dependence between NaCl and LiF may be used to assess the mean effective energy of the photon field. The signal ratios between NaCl and LiF after exposure to radiation in the Fukushima Dashii contaminated areas in Japan, 1.67 ± 0.26 (2013) and 1.63 ± 0.32 (2015), indicate that the mean photon energy in this area was 300–400 keV during the years of the survey. [ABSTRACT FROM AUTHOR]

The International Commission on Radiological Protection (ICRP) recommended that the equivalent dose limit for the lens of the eye be decreased from 150 mSv/y ( ICRP, 2007 ) to 20 mSv/y averaged over five years ( ICRP, 2011 ). How to accurately measure the eye-lens dose has, therefore, been an issue of interest recently. Interventional radiologists are at a higher risk of radiation-induced eye injury, such as cataracts, than all other occupational radiation workers. The main objective of this study is to investigate the relationship between the doses to the eye lenses of interventional radiologists measured by different commercial eye-lens dosimeters. This study measured a reference eye-lens dose, which involved placing thermoluminescent dosimeter (TLD) chips at the surface of the eye of the Rando Phantom, and the TLD chips were covered by a 3-mm-thick tissue-equivalent bolus. Commercial eye-lens dosimeters, such as a headband dosimeter and standard personnel dose badges, were placed at the positions recommended by the manufacturers. The results show that the personnel dose badge is not an appropriate dosimeter for evaluating eye-lens dose. Dose deviations for different dosimeters are discussed and presented in this study. [ABSTRACT FROM AUTHOR]

We focus on the development of Ge-doped silica thermoluminescent dosimeters with sensitivity superior to that of the LiF (Mg,Ti) phosphors popularly used in x-ray diagnostic imaging dosimetry, the latter typically being referred to through use of the product identifier TLD-100. Of interest are Ge-doped silica telecommunication fibres (SMF) and tailor-made doped photonic crystal fibres (PCFc), the latter Ge-doped or also co-doped with boron. The PCFs are formed of capillaries that at high temperatures and under vacuum are made to collapse inwards (PCFc), the internal walls fusing and generating strain-related defects. To-date, the fabricated SMF, PCFc-Ge and PCFc-Ge-B have been observed to provide TL yields which weight-for-weight are some 2, 10 and 15x that of TLD-100. In present study we test the linearity of TL yield for x-ray doses from 0.1- to 10 mGy, use being made of an x-ray tube operated at 80 kVp, an operating potential typically selected in chest radiography. For a dose of 10 mGy, a study of energy dependence has been conducted using x-ray tube potentials of 80 kVp 100 kVp, and 120 kVp, with inherent filtration 0.9 mm Al measured at 75 kVp, and total filtration of 2.8 mm Al at 80 kVp. [ABSTRACT FROM AUTHOR]

Thermoluminescent detectors (TLDs) are solid state detectors commonly used for dose monitoring and dose mapping in many earth and space applications. Among all the crystals available, the ones based on lithium fluoride (LiF) are the most widely spread and studied around the world. In the last years the use of these TLDs in complex heavy charged particles (HCPs) fields, as in spacecraft or in radiotherapy beams, has grown rapidly leading to the necessity of an accurate characterization of the detectors’ response in these radiation environments. In this work, 6 LiF:Mg,Ti, 7 LiF:Mg,Ti, 6 LiF:Mg,Cu,P and 7 LiF:Mg,Cu,P detectors were exposed to different radiation qualities in order to investigate the dependence of their relative luminescence efficiency on the linear energy transfer (LET) of the incident particles. The measured efficiencies were in good agreement with literature. In relation to this issue, different dose assessment methods, i.e. peak height, signal integration over different regions of interest (ROIs) and glow curve deconvolution, were compared and their influence on the measured relative luminescence efficiency values was assessed. For both LiF:Mg,Ti and LiF:Mg,Cu,P detectors, no relevant differences were found in the relative luminescence efficiency evaluated by means of main peak height, main peak ROI and main peak deconvolution. On the other hand, if the integration of the signal is extended to the high temperature zone (248–310 °C) of LiF:Mg,Ti or the low temperature zone (125–185 °C) of LiF:Mg,Cu,P, significant deviations were found. [ABSTRACT FROM AUTHOR]

Occupational radiation exposure can occur due to various human activities, including the use of radiation in medicine. Occupationally exposed personnel surpassing 7.4 millions, and respresent the biggest single group of employees who are exposed to artificial radiation sources at work. This study compares the occupational radiation dose levels for 145 workers in four different hospitals located in the Aseer region in Saudi Arabia. The occupational exposure was quantified using thermoluminescence dosimeters (TLD-100). The levels of annual occupational exposures in targeted hospitals were calculated and compared with the levels of the international atomic energy agency (IAEA) Safety Standards. An average yearly cumulative dose for the two consecutive years. The average, highest and lowest resulted occupational doses under examination in this work is 1.42, 3.9 mSv and 0.72 for workers in various diagnostic radiology procedures. The resulted annual effective dose were within the IAEA approved yearly dose limit for occupational exposure of workers over 18, which is 20 mSv. Staff should be monitored on a regular basis, according to current practice, because their annual exposure may surpass 15% of the annual effective doses. • Annual occupational dose (Hp(10) were evaluated at four diagnostic radiology department. • Staff doses represent approximately 15% of the annual effective dose. • Students and trainees should be monitored on a regular basis, according to current practice. • Occupational exposure is comparable with the most previously published studies. [ABSTRACT FROM AUTHOR]

This study demonstrated a novel sensor based on a semiconductor–metal–semiconductor multilayer film for photonic dosimetry that was synthesized at 300 °C using radiofrequency RF sputtering. The dosimetric properties of samples exposed to X-ray doses of up to 4 Gy were investigated. The system ZnO (300 nm) /Ag (50 nm) /ZnO (x nm) was chosen based hiest thermoluminescence TL intensity. The glow curve exhibited a single peak with a maximum temperature peak Tm of 246 °C. In addition, the proposed dosimeter has a linear dose-response up to 4 Gy. The heating rate with the highest TL intensity was 3 °C/s. The best annealing protocol for optimal TL intensity and minimum standard deviation was found at 200 °C and 30 min. Most dosimeter parameters were investigated, including homogeneity, precision, and fading properties.. The kinetic parameters of the dosimeter were calculated and employed two methods: peak shape and initial rise. The results showed that the trap has activation energies at 0.51 and 0.53 eV and frequency factor between 0.25 × 108 and 0.5 × 109. Other features, like recycling, the receding of TL at room temperature, and optical fading, have been investigated. The suggested dosimeter demonstrated good radiation-measuring characteristics. The glow curve was immediately acquired, the annealing process was uncomplicated, and the dosimeter had a high sensitivity of 1.49 of TLD-100, making it suitable for radiation monitoring. • ZnO (300 nm) /Ag (50 nm) /ZnO (x) thin films were synthesized using RF sputtering. • The structural and optical properties were investigated. • Dosimetric properties of thin film was studied via TLD reader 3500. • The newly dosimeter exhibited single TL peak and good stability. • Kinetic parameters were calculated using two methods. [ABSTRACT FROM AUTHOR]

Ceramic thermoluminescence detectors (TLDs) are low-cost devices with high spatial resolution and very easy to use. The basic characteristics of alumina-based ceramic TLDs (Chiba Ceramic Mfg. Co., Ltd. A8) in response to X-ray and charged particle beams (H, He, C, Ne, Ar) have been reported in an effort to apply TLDs as a QA/QC tool for charged particle therapy. The glow curve has two peaks, and the main peak is located at 148 °C and 694 nm. For each irradiation, four dose levels were given: 0.5, 1.0, 2.0, and 5.0 Gy in water. The main peak showed good linearity and repeatability for X-rays. However, thermoluminescence efficiency decreased slightly with increasing irradiation dose with charged particle irradiation. The thermoluminescence efficiency of the main peak showed a very small dependence on linear energy transfer (LET) compared with common TLDs. This ceramic TLD may be applicable as a verification tool in a limited LET range such as proton therapy. [ABSTRACT FROM AUTHOR]

The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing 10 B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3 mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed. [ABSTRACT FROM AUTHOR]

This study derived a simple equation of effective dose ( E ) versus normal organ of patients with varying body weights undergoing lung cancer treatment of helical tomotherapy (TOMO). Five tissue-equivalent and Rando phantoms were used to simulate lung cancer patients. This study then measured E and equivalent dose of organ or tissues ( D T ) using thermoluminescent dosimetry (TLD-100H). The TLD-100H was calibrated using TOMO 6 MV photons, then inserted into phantom positions that closely corresponded with the position of the represented organs and tissues. Both E and D T were evaluated by ICRP 103. Peripheral doses varied markedly at positions close to the tumor center. The maximum statistical and total errors were 16.7–22.3%. This analytical result indicates that E of Rando and tissue-equivalent phantoms was in the ranged of 9.44±1.70 (10 kg) to 4.58±0.83 (90 kg) mSv/Gy. Notably, E decreased exponentially as phantom weight increased. Peripheral doses were also evaluated by TLD as a function of distance from the tumor center. Finally, experimental results are compared with those in literature. These findings will prove useful to patients, physicians, radiologists, and the public. [ABSTRACT FROM AUTHOR]

This study intends to measure the radiation dose to patients and staff during (i) Dynamic Hip Screw (DHS) and (ii) Dynamic Cannula Screw (DCS) and to evaluate entrance surface Air kerma (ESAK) dose and organ doses and effective doses. Calibrated Thermoluminescence dosimeters (TLD-GR200A) were used. The mean patients’ doses were 0.46 mGy and 0.07 mGy for DHS and DCS procedures, respectively. The mean staff doses at the thyroid and chest were 4.69 mGy and 1.21 mGy per procedure. The mean organ and effective dose for patients and staff were higher in DHS compared to DCS. Orthopedic surgeons were exposed to unnecessary radiation doses due to the lack of protection measures. The radiation dose per hip procedure is within the safety limit and less than the previous studies. [ABSTRACT FROM AUTHOR]

This review of dosimetry for second cancer risk estimation introduces work carried out by Working Group 9 (WG9: Radiation Protection Dosimetry in Medicine) of the European Radiation Dosimetry Group (EURADOS). The work concentrates on the measurement of out-of-field doses in water phantoms using a variety of dosimeters to measure photon and neutron doses. These include optically stimulated luminescence (OSL), radiophotoluminescence (RPL) and thermoluminescence (TLD) dosimeters for photon dosimetry (together with ion chambers for reference measurements) and track etch and superheated emulsion detectors for neutron measurements. The motivation of WG 9 was to assess undue, non-target patient doses in radiotherapy and the related risks of second malignancy. Improvements in cancer treatment have increased survival times and thus increased incidence of second cancer may be expected in the future. In addition, increased whole body exposure may result from some developments in radiotherapy. This means that radiotherapy clinics will need to simulate their treatments in order to estimate and minimise doses to healthy tissues and organs. The proposed work is designed to generate a robust dataset of out-of-field dose measurements which can be used for the development and validation of dose algorithms. [ABSTRACT FROM AUTHOR]

Thermoluminescent dosimeters (TLDs) are routinely used to measure the dose around brachytherapy sources due to their small size and high precision. This work presents a concise overview of the use of LiF:Mg,Ti TLDs for brachytherapy dosimetry including the experimental procedures required to achieve high-precision measurements as well as new results regarding the intrinsic energy dependence with some of the commonly used brachytherapy sources. Equations to correct TLD light output to air kerma are outlined and a description of the method to determine the intrinsic energy dependence is presented. For the intrinsic energy dependence investigation, a review of previously published results is presented as well as new experimental results using 125 I, 103 Pd, 192 Ir, and miniature x-ray brachytherapy sources at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The results of these experiments are consistent with previous work and give valuable insight to investigators using TLDs for brachytherapy measurements. [ABSTRACT FROM AUTHOR]

Abstract: Recent developments in advanced radiotherapy techniques using small field photon beams, require small detectors to determine the delivered dose in steep dose gradient fields. Commercially available glass jewellery beads exhibit thermoluminescent properties and have the potential to be used as dosimeters in radiotherapy due to their small size (<5mm), low cost, reusability and inert nature. This study investigated the dosimetric characteristics of glass beads. The beads were irradiated by 6MV photons using a medical linear-accelerator and 60Co gamma rays over doses ranging from 1 to 2500cGy. A thermoluminescence (TL) system and an electron paramagnetic resonance (EPR) system were employed for read out. Both the TL and EPR studies demonstrated a radiation-induced signal, the sensitivity of which varied with bead colour. White coloured beads proved to be the most sensitive for both systems. The smallest and therefore least sensitive bead sizes allowed measurement of doses of 1cGy using the TL system while that for the EPR system was approximately 1000cGy. The fading rate was found to be 10% 30 days after irradiation with both readout systems. The dose response is linear with measured dose over the dose range 1 to 2500cGy, with an R 2 correlation coefficient of greater than 0.999. The batch-to-batch reproducibility of a set of dosimeters after a single irradiation was found to be 3% (1 SD). The reproducibility of individual dosimeters was found to be 1.7%. No measurable angular dependence was found (results agreed within 1%). Dose rate response was found to agree within 1% for dose rates of 100 to 600cGy/min. These results demonstrate the potential use of glass beads as TL dosimeters over the dose range commonly applied in radiotherapy. [Copyright &y& Elsevier]

The purpose of this research is to synthesize the Yttrium doped PEG-coated ZnO nanostructures and characterize them especially as thermoluminescence material for gamma dosimetry. The dosimetry characteristics were evaluated by irradiating the sample with gamma radiation with different doses (10 and 100 Gray) at a temperature range of 0–400 °C. Uncoated undoped ZnO NPs and PEG-coated ZnO Nanoparticles (NPs) with 0, 5, 7, and 10 at% Yttrium (Y) doping concentration were synthesized via hydrothermal technique. Synthesized nanoparticles were examined through various characterization techniques (XRD, SEM, EDS, UV, Tyndall test and TLD) for their morphology, PEG-coating confirmation and to evaluate their Thermoluminescence properties. XRD analysis confirmed the wurtzite hexagonal structure and doping of Yttrium into ZnO. SEM analysis showed PEG-coated ZnO has well-rounded nanoplates <100 nm confirming the successful growth inhibition of PEG working as surfactant. The particle size was found to grows with increasing Y concentration. UV visible results reveal an increase in the optical band gap of ZnO with Yttrium doping. With doping, TL response has enhanced significantly, and glow peak shifted towards higher temperature. TL analysis showed two broad peaks following the second-order of kinetics and five traps with activation energies 1.25, 0.87, 0.75, 0.82, 1.99 eV, present in the Y doped ZnO. Y doped ZnO is a suitable candidate for high-dose thermoluminescence dosimetry. [ABSTRACT FROM AUTHOR]

Abstract: Results of the investigation concerning thermoluminescence (TL) responses to X, gamma and neutron radiation fields for crystals of complex fluoride K2GdF5 undoped and doped with varying concentrations of Dy3+ ions are presented. Crystals doped with 5.0 at% Dy3+ have shown the most efficient TL response, with a linear response to doses for all the radiation fields. In the X rays range, the maximum TL response has been found to be 15 times more than the response for gamma. The fast and thermal neutron TL outputs were evaluated for K2Gd0.95Y0.05F5 and the contribution of the gamma component in the TL curve was estimated. [Copyright &y& Elsevier]

Résumé: Objectifs de l’étude: Développer une procédure de contrôle qualité externe dédiée aux faisceaux du CyberKnife®. Cette étude, qui s’est déroulée à Nancy, a inclus un protocole de test initialement élaboré par les physiciens de Nancy et de Lille, en collaboration avec le laboratoire Equal-Estro. Matériels et méthodes: Un fantôme anthropomorphique tête et cou et un objet-test de forme cubique, ű MiniCube Ƈ, en plastique équivalent-eau et homogène, ont été utilisés. Des dosimètres thermoluminescents poudre et solide, ainsi que des films radiochromiques, ont permis de réaliser les études respectivement de doses absolues et de dose relative. La comparaison entre les doses calculées par le système de planification de traitement MultiPlan et les doses mesurées a été étudiée en dose absolue. Les distributions de dose provenant des films et des images du système de planification ont été comparées à l’aide de la fonction gamma, paramétrée avec différents couples de tolérance. Résultats: L’étude avec les dosimètres thermoluminescents solides a permis de vérifier la fiabilité du faisceau avec une reproductibilité de 1,7 %. Les mesures de dose absolue dans le fantôme irradié, dans sept centres participants, ont montré, pour le volume cible, une déviation de dose inférieure aux limites autorisées (±5 %) pour la plupart des centres participants. Les mesures de dose relative réalisées à Nancy et par le laboratoire Equal-Estro ont permis de définir les critères de l’indice gamma le plus adaptés (5 %/2mm – avec l’indice gamma≤1 pour au moins 95 % des pixels). Ces critères devaient être indépendants du logiciel d’analyse de films employé. Conclusion: L’étude a permis de définir un contrôle qualité externe basé sur un plan d’irradiation reproductible avec des mesures par dosimètres thermoluminescents et films radiochromiques. Ce protocole devra être validé par une nouvelle série de mesure utilisant les enseignements de cette étude. [ABSTRACT FROM AUTHOR]

Abstract: A survey of gamma exposure in dwellings of Campania region, southern Italy has been performed using Thermo Luminescent Dosimeters (TLD). In each dwelling TLDs were exposed for six months in the room where the inhabitant spent most of their time, generally the bedroom or living room. The arithmetic mean was found to be 264 ± 111 nGy/h, after the subtraction of the cosmic contribution. The effects of building materials and geographic location were also examined. Using UNSCEAR model, the annual effective dose due to indoor gamma radiation was evaluated and it was found to be 1.3 mSv/y, that is higher than Italian national average of 0.4 mSv/y. [Copyright &y& Elsevier]

The objective of this study is to develop nuclear heating measurement methods in Zero Power experimental reactors. This paper presents the analysis of Thermo-Luminescent Detector (TLD) and Optically Stimulated Luminescent Detectors (OSLD) experiments in the \UO2 core of the MINERVE research reactor at the CEA Cadarache. [ABSTRACT FROM AUTHOR]

Abstract: Thermoluminescent (TL) detectors are often used for measurements of radiation doses in space. While space radiation is composed of a mixture of heavy charged particles, the relative TL efficiency depends on ionization density. The question therefore arises: what is the relative efficiency of TLDs to the radiation present in space? In the attempt to answer this question, the relative TL efficiency of two types of lithium fluoride detectors for space radiation has been calculated, based on the theoretical space spectra and the experimental values of TL efficiency to ion beams. The TL efficiency of LiF:Mg,Ti detectors for radiation encountered at typical low-Earth’s orbit was found to be close to unity, justifying a common application of these TLDs to space dosimetry. The TL efficiency of LiF:Mg,Cu,P detectors is significantly lower. It was found that a shielding may have a significant influence on the relative response of TLDs, due to changes caused in the radiation spectrum. In case of application of TLDs outside the Earth’s magnetosphere, one should expect lower relative efficiency than at the low-Earth’s orbit. [Copyright &y& Elsevier]

Abstract: The LiF:Mg,Cu,Si thermoluminescence materials, recently developed at the laboratory, gain uprising popularity because the materials show several outstanding performance results such as high sensitivities for gamma radiation, flat energy responses with little fluctuation for photons, linear responses over the wide ranges of radiation doses and few residual electrons trapped in the holes. In this study, we investigated the impacts of the Mg concentration and the final thermal treatment conditions on the glow curve structure of LiF:Mg,Cu,Si material to enhance the ratio of high-temperature peak to main peak for the extended application of the two peaks in the high LET radiation dosimetry and in the high-temperature environment. Change in Mg concentration did not affect significantly the ratio of TL responses of high and main dosimetric glow peaks. With Mg concentration in the range from 0.35 to 0.45 mol% and a thermal treatment of 10 min in the range from 400 °C to 440 °C followed by the thermal treatment at 260 °C for 10 min (dual-step thermal treatment) resulted in the highest value of the ratio of TL response of high and main dosimetric glow peaks. [Copyright &y& Elsevier]

Abstract: Ideally, dosimeters should measure the dose without their dosimetric properties being affected by the radiation type being measured. Industry-wide occupational radiation workers that can be potentially exposed to neutron radiation fields are routinely monitored by thermoluminescent (TLD) dosimeters. The neutron dose measured by these devices is obtained from the interaction products of thermal (slow) neutrons and 6Li. The number of alpha particle and 3H− ions (tritium) released in the (n, 6Li) reaction is proportional to the dose received by the dosimeter. It is a common practice to evaluate the neutron dose indirectly from these products. In this work we present for the first time direct evidence that the neutron exposure to LiF:Mg,Cu,P (TLD-600H) can have deleterious effects on the dosimetric properties of one of the most commonly utilized dosimeters in the world. The interstitial non-negligible tritium dose contribution to the dosimeter is a result of the beta decay of the tritium nuclei interstitially present in the material. If not accounted for the effect of this self irradiation can directly affect the measured occupational dose to workers. In order to estimate the significance of these effects, tritium dose buildup was measured in the TLD-600H irradiated to different neutron doses from a reactor and a 252Cf source and then calculated in terms of a daily dose buildup rate. The effect of the self irradiation on these dosimeters resulting from tritium decay was extensively studied. The TLD dosimeters that were exposed to neutron doses show a significant dose buildup even after they have been annealed, i.e. even after the signal produced by the incident neutron dose is completely erased from the lower energy trap states of the dosimeter. The other discovered effect of neutron irradiation on TLD-600H is a significant loss in the detection sensitivity (up to 15%). [Copyright &y& Elsevier]

Abstract: LiF thermoluminescent material doped with Mg, Cu and Si recently developed by the Korea Atomic Energy Research Institute (KAERI) has shown very good dosimetric properties. Since the thermoluminescence in LiF was found to be dependent on the proper combination of dopants, the investigation of the concentration and type of dopants is very important in developing and characterisation of new TL materials. The aim of this work was to determine the influence of type and concentration of activators on the glow curve structure, sensitivity, reproducibility and on the photon energy response of LiF:Mg,Cu,Si detectors. The energy response was studied in air and on the ISO water phantom in the range of mean photon energies between 33 keV and 164 keV. The morphology and local chemical composition of LiF:Mg,Cu,Si detectors were examined using high resolution scanning electron microscopy (FE-SEM). The results show that type and concentration of activators influence the glow curve and sensitivity. Different dopant concentrations did not show influence on the photon energy response. The sensitivity of LiF:Mg,Cu,Si detector with dopant concentration of Mg = 0.35 mol%, Cu = 0.025 mol% and Si = 0.9 mol% was very high (up to 65 times higher than that of TLD-100). The photon energy response of LiF:Mg,Cu,Si detectors containing all three dopants in various concentrations is in accordance with the IAEA recommendations for individual monitoring. [Copyright &y& Elsevier]

Abstract: Topaz, a naturally occurring aluminium fluorosilicate mineral, shows thermo-luminescence (TL) after irradiation to gamma rays. The TL characteristics (glow curve, dose response/intensity, sensitivity, energy response, fading, reusability and mechanical stability) of topaz collected from the Sabser mine in the vicinity of Sakardu in northern Pakistan were studied. The purpose of this study was to design and develop a TLD (thermoluminescence dosimeter) based on topaz. The samples of topaz from this mine were cut into square chips of dimensions 3.2×3.2mm with thickness 0.9mm, which are suitable for the TLD reader. Gamma dose was given to the chips from 60Co and/or 137Cs gamma irradiators. The TL glow curves of the chips revealed stable peak at about 260°C. The height of this peak rose linearly with increase of dose levels. The TL response versus dose (calibration curve) showed the linear behaviour between 10−2 and 102 Gy without saturation. Dose response was independent of gamma energies of 60Co and 137Cs. The response of standard sized chips of topaz remained constant within ±11% deviation from initial value after 30 cycles of reuse. The rate of fading of topaz chips of this mine were studied up to four months, which was fast for initial few hours and slowed after a few days. The chips remained mechanically stable during handling in all types of experiments. Standard sized topaz chips of Sabser mine can effectively and efficiently be used as a TLD. [Copyright &y& Elsevier]

Abstract: Radiotherapy with a proton beam of initial energy 55–80MeV is presently the clinically recommended therapy for some cases of intraocular melanoma such as large melanomas or tumours adjacent to critical organs. Evaluation and optimization of radiation doses outside the treatment volume may contribute to reducing undesirable side-effects and decreasing the risk of occurrence of secondary cancers, particularly for paediatric patients. In this work the undesired doses to organs were assessed basing on Monte Carlo calculation of secondary radiation transport and on results of measurements of neutron and γ-ray doses at the proton therapy facility of the Institute of Nuclear Physics at Kraków. Dosimetry was performed using a He-3-based FHT 762 neutron monitor (Wendi II), a FH40G proportional counter (for γ-rays), and MTS-7 (LiF:Mg,Ti) thermoluminescence detectors (TLDs). Organ doses were calculated in the ADAM anthropomorphic phantom using the MCNPX Monte Carlo transport code and partly verified, for γ-ray doses, with TLD measurements in the RANDO Anderson anthropomorphic phantom. The effective dose due to undesired radiation, including exposure from scattered radiation during the entire process of proton radiotherapy and patient positioning using X-rays, does not exceed 1mSv. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To calculate spectra of cobalt-60 beam at water depth and correction factors for absorbed dose measurements obtained with lithium fluoride thermoluminescent dosimeters using Monte Carlo simulation. MATERIALS AND METHODS: The simulations of secondary spectra of clinical cobalt-60 sources were performed with the PENELOPE Monte Carlo code at different water depths. Experimental measurements of deep doses were obtained with thermoluminescent dosimeters and ionization chamber under reference conditions for radiotherapy. Correction factors for the thermoluminescent dosimeters detectors were obtained through the ratio between the relative energy absorption for the low energy spectrum and the total spectrum. RESULTS: Deep spectral analysis has demonstrated the presence of secondary low-energy spectra responsible for a significant portion of the dose deposition. Discrepancies of 3.2% were observed among the doses measured with ionization chamber and thermoluminescent dosimeters. The adoption of correction factors has allowed a reduction in the discrepancy among absorbed doses to a maximum of 0.3%. CONCLUSION: Simulated spectra allow the calculation of correction factors for reading of thermoluminescent dosimeters utilized in the measurement of deep doses, contributing for the reduction of uncertainties associated with quality control of clinical beams in radiotherapy. [ABSTRACT FROM AUTHOR]

Abstract: Thermoluminescence, dose dependences, and EPR of Mn-doped lithium tetraborate are studied. Mn is shown not to change a charge state during energy storage and release. Mn2+ amount decreases only at very high doses. The amount of Mn2+ depends on the sintering temperature and increases with temperature increase due to reduction of Mn from a higher oxidation state. X-irradiation creates optical absorption bands in Li2B4O7:Mn. Optical stimulation in the UV band is effective for OSL-readout and destroys dosimetric TL peaks. The model of energy storage and release is discussed. [Copyright &y& Elsevier]

Abstract: Nanocrystalline LiF:Mg,Cu,P phosphor material of different shapes and sizes (microcrystalline cubic shape, nanorod shape and nanocrystalline cubical shaped) have been prepared by the chemical co-precipitation method. Thermoluminescence (TL) and other dosimetric characteristics of the phosphor are studied and presented here. The formation of the materials was confirmed by the X-ray diffraction (XRD). Its shapes and sizes were also observed using scanning electron microscope (SEM). The TL glow curve of the microcrystalline powder shows a prominent single peak at 408K along with another peak of lesser intensity at around 638K. On the contrary, the nanocrystalline rod shaped particles show a peak of low intensity at 401K and a prominent peak around 700K while the nanocrystalline particles in cubical shapes again show two peaks, one at around 407K and the other at around 617K, of which the lower temperature (407K) peak is more prominent. The glow curve structure changes at very high doses (100kRad) and some new peaks appear at around 525 and 637K also the first peak appearing at around 401K becomes prominent. The observed changes in TL due to the change in the shape and sizes of the nanophosphor have been reported. The PL has also been studied and various excitation and emission peaks observed due to the presence of various impurities are explained. The observed results have been explained in the light of asymmetrical crystal field effects due to asymmetrical shapes of the nanocrystalline phosphor. The comparison of these properties with the microcrystalline material prepared by the same co-precipitation method is also done. [Copyright &y& Elsevier]

Abstract: Lithium fluoride (LiF) doped with proper activators is a highly sensitive phosphor commonly used for radiation dosimetry using thermoluminescence (TL) technique. Nanorods of this material activated with Cu, Mg and P as single dopants are synthesized in our laboratory and exposed to gamma-rays for their thermoluminescence (TL) properties. The induced TL glow curves of the Cu, Mg and P doped samples are similar with a single peak at 410K. Copper doped sample is found to be the most sensitive sample with TL intensity around 65, 7 and 8 times of those of LiF:Mg, LiF:P and LiF:Mg,Cu,P, respectively, indicating that Cu is the luminescence center in the host of LiF nanorods, while Mg and P act as TL quencher particularly when used as codopants. These observations on the nanostructured form of LiF doped with these activators are entirely different from those of the widely studied LiF:Mg,Cu,P and LiF:Mg,Ti single crystals. The nanorods of LiF:Cu might be used for heavy doses measurement as they are sensitive to gamma-rays and have a linear TL response curve in a long span of exposures. [Copyright &y& Elsevier]