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This study presents the development and characterization of a prototype TL/OSL reader for the retrospective dose assessment of individuals in radiological emergencies. The reader is portable, semi-automatic, and capable of accurate measurements. The dimension of the reader is 25×25×37 cm3 and the weight is about 15 kg. The reader consists of a sample moving stage, a heating module, an optical stimulation module, a detection module, a data acquisition (DAQ) unit, a nitrogen gas control module, and a PC with a GUI program. The reader has three measurement modes: TL, CW_OSL, and custom mode. The reader was characterized using commercial thermal luminescence dosimeters (TLD, LiF:Mg,Cu,Si) and optically stimulated dosimeters (OSLD, Al2O3:C), as well as fortuitous materials, such as display glasses and resistors of mobile phone. The results showed that the reader is capable of measuring signals with a detection limit of up to 0.02 mGy using a commercial dosimeter. In the dose recovery test using fortuitous materials, the reconstructed doses obtained three days post-irradiation closely aligned with the initially administered doses. As a result, this study suggests that the developed TL/OSL reader is a promising instrument for emergency dose assessment at accident sites.

For correct assessment of health risks after low-dose irradiation, calculation of radiation exposure estimates is crucial. To verify the calculated absorbed doses, instrumental methods of retrospective dosimetry are used. We compared calculated and instrumental-based estimates of external absorbed doses in the residents of Dolon, Mostik and Cheremushki villages, Kazakhstan, affected by the first nuclear weapon test performed at the Semipalatinsk Nuclear Test Site (SNTS) on August 29, 1949. The 'instrumental' doses were retrospectively estimated using the Luminescence Retrospective Dosimetry (LRD) and Electron Spin Resonance (ESR) methods. Correlation between the calculated individual cumulative external absorbed whole-body doses based on typical input data and ESR-based individual doses in the same people was strong (r = 0.782). It was even stronger between the calculated doses based on individual questionnaires' input data and the ESR-based doses (r = 0.940). Application of the LRD method is useful for validation of the calculated settlement-average cumulated external absorbed dose to air. Reconstruction of external exposure can be supplemented with the data from later measurements of soil contamination with long-lived radionuclides, such as, 137Cs. Our results show the reliability of the calculational method used for the retrospective assessment of individual external doses. [ABSTRACT FROM AUTHOR]

Precise estimation of individual radiation dose utilizing biomaterials (fingernail, bone, and tooth) is very challenging due to their complex sample processing. Despite, tooth enamel, the most mineralized tissue of tooth is used for this purpose due to its high radiation sensitivity and ability to produce radiation induced long lived CO2− radicals. However, human teeth are not always available, and invasive nature of sample collection adds to the complexity making dose estimation difficult. In such cases, animal teeth (goat, cow, and moose) can be used as a substitute for human teeth due to comparable enamel sensitivity. Moreover, separation of enamel from dentine is a crucial step towards accurate dose estimation from irradiated teeth. In this work, Indian goat teeth were used as it was readily available to us and the comparison of goat enamel sensitivity to radiation was found to be within ∼7.4 % that of human. The enamel samples were separated following two chemical methods; (1) density separation using sodium polytungstate, (2) alkaline denaturation using NaOH and the quality was compared based on their purity and radiation sensitivity. Combined results of spectroscopic characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman analysis authenticated the crystallinity and purity of the separated enamel samples. The radiation sensitivity of separated enamel samples was compared by electron paramagnetic resonance (EPR) analysis as a part of dosimetric characterization. The suitability of both the samples for retrospective dosimetry and epidemiological studies was checked by validating the dose estimated from separated enamel samples with standard alanine/EPR dosimeter.

The Korea Retrospective Dosimetry network (KREDOS) performed an inter-laboratory comparison to confirm the harmonization and reliability of the results of retrospective dosimetry using mobile phone. The mobile phones were exposed to 192Ir while attached to the human phantoms in the field experiment, and the exposure doses read by each laboratory were compared. This paper describes the reference dosimetry performed to present the reference values for inter-comparison and to obtain additional information about the dose distribution. Reference dosimetry included both measurement using LiF:Mg,Cu,Si and calculation via MCNP simulation to allow a comparison of doses obtained with the two different methodologies. When irradiating the phones, LiF elements were attached to the phones and phantoms and irradiated at the same time. The comparison results for the front of the phantoms were in good agreement, with an average relative difference of about 10%, while an average of about 16% relative difference occurred for the back and side of the phantom. The differences were attributed to the different characteristics of the physical and simulated phantoms, such as anatomical structure and constituent materials. Nevertheless, there was about 4% of under-estimation compared to measurements in the overall linear fitting, indicating the calculations were well matched to the measurements.

Several studies have shown that certain components of mobile phones, such as electronic components, display or touch screen glass, are suitable as emergency dosimeters in case of radiological incidents. However, so far the methods are frequently destructive and in case of a dose assessment the mobile phone will be destroyed. In order to overcome this problem, alternative materials need to be sought and further research is necessary. Building on results of a previous study, we further investigated protective glasses in this work, which have become an alternative material for dose reconstruction. Protective glasses are easy to sample and cheap, have become very popular to protect the surface of phones, can be easily replaced without complete destruction of an expensive smartphone, thus a dose assessment method based on this material will potentially find much greater public acceptance. The aim of this study was to optimize the detection window by systematically investigating the radiation-induced TL signals and intrinsic zero dose signals. Using two selected detection windows, the long-term and optical stability of the TL signals were investigated. The set of nine different protective glass samples studied fell into two groups with different fading and optical bleaching characteristics. Further research is necessary in order to reduce the zero dose signal, to reinvestigate the dosimetric properties and to verify the final protocol using a realistic irradiation test.

The article presents a summary of the main tasks carried out over the past 20 years at the Dating Laboratory of the Center for Technological Applications and Nuclear Development (CEADEN) in Havana, Cuba. The laboratory focuses on determining the age of formation of sedimentary deposits using the optically stimulated luminescence technique of quartz. The article highlights the background, objectives, and results achieved by the laboratory, as well as the prospects for development. The laboratory has conducted technical and fundamental studies, as well as the training of young specialists. It is expected that in the near future, the analysis of the samples will be completed and studies related to the deposition process will continue. [Extracted from the article]

Investigations of retrospective dosimetry have shown that components of mobile phones are suitable as emergency dosimeters in case of radiological incidents. For physical dosimetry, components can be read out using optically stimulated luminescence (OSL), thermoluminescence (TL) and phototransferred thermoluminescence (PTTL) methods to determine the absorbed dose. This paper deals with a feasibility study of display glass from modern mobile phones that are measured by thermally assisted (Ta) optically stimulated luminescence. Violet (VSL, 405 nm) and infrared (IRSL, 850 nm) LEDs were used for optical stimulation and two protocols (Ta-VSL and Ta-IRSL) were tested. The aim was to systematically investigate the luminescence properties, compare the results to blue stimulated Ta-BSL protocol (458 nm) and to develop a robust measurement protocol for the usage as an emergency dosimeter after an incident with ionizing radiation.First, the native signals were measured to calculate the zero dose signal. Next, the reproducibility and dose response of the luminescence signals were analyzed. Finally, the signal stability was tested after the storage of irradiated samples at room temperature. In general, the developed Ta-IRSL and Ta-VSL protocols indicate usability, however, further research is needed to test the potential of a new protocol for physical retrospective dosimetry.

Electron paramagnetic resonance, thermoluminescence, and optically stimulated luminescence, with biological tissues and inert materials are well established physical methods for retrospective dosimetry in acute accidental exposures. The objective of this article is to provide a view of the questions still open, the current challenges and the needed solutions. As research on emergency response methods is encountering increasing difficulties in terms of financial and human resources in many countries, it is essential to identify the research priorities and pay attention to cost-effective research paths. The intention of the paper is to stimulate discussion in the scientific community and to encourage collaboration among laboratories toward goals that address the real needs in retrospective dosimetry for acute exposures.

The study of new materials for radiation dosimetry is important to improve the present state of the art and to help in cases of accidents for retrospective dosimetry. Sulfites are compounds that contain a sulfur ion, widely used in the food industry. Due to the significant application of these compounds, sulfites are interesting candidates for accidental dosimetry, as fortuitous radiation detectors. The presence of the SO3− anion enables its detection by electron spin resonance (ESR) spectroscopy. The Dose–Response behavior, signal stability and other spectral features were investigated for sodium sulfite, sodium bisulfite, sodium metabisulfite and potassium metabisulfite, all in crystalline forms. The ESR spectrum of salts presented stability and proportional response with dose, presenting potential for dosimetry applications. [ABSTRACT FROM AUTHOR]

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Abstract Purpose Cardiac effects after breast cancer radiation therapy potentially affect more patients as survival improves. The heart’s heterogeneous radiation exposure and composition of functional structures call for establishing individual relationships between structure dose and specific late effects. However, valid dosimetry requires reliable contouring which is challenging for small volumes based on older, lower-quality computed tomography imaging. We developed a heart atlas for robust heart contouring in retrospective epidemiologic studies. Methods and materials The atlas defined the complete heart and geometric surrogate volumes for six cardiac structures: aortic valve, pulmonary valve, all deeper structures combined, myocardium, left anterior myocardium, and right anterior myocardium. We collected treatment planning records from 16 patients from 4 hospitals including dose calculations for 3D conformal tangential field radiation therapy for left-sided breast cancer. Six observers each contoured all patients. We assessed spatial contouring agreement and corresponding dosimetric variability. Results Contouring agreement for the complete heart was high with a mean Jaccard similarity coefficient (JSC) of 89%, a volume coefficient of variation (CV) of 5.2%, and a mean dose CV of 4.2%. The left (right) anterior myocardium had acceptable agreement with 63% (58%) JSC, 9.8% (11.5%) volume CV, and 11.9% (8.0%) mean dose CV. Dosimetric agreement for the deep structures and aortic valve was good despite higher spatial variation. Low spatial agreement for the pulmonary valve translated to poor dosimetric agreement. Conclusions For the purpose of retrospective dosimetry based on older imaging, geometric surrogate volumes for cardiac organs at risk can yield better contouring agreement than anatomical definitions, but retain limitations for small structures like the pulmonary valve.

Featured Application: The L(+)-ascorbic acid treatment prior to radiation dosimetry using fingernails could efficiently remove the disturbing ESR signals caused by heat or UV light exposure. The effects of L(+)-ascorbic acid (AA) (an antioxidant commonly known as vitamin C) on the electron spin resonance (ESR) signals from fingernails were examined in relation to X-ray and UV irradiation. The ESR signal intensity, stability, and sensitivity to radiation were measured under different storage conditions. The experimental results indicated that the behavior of the increase in the ESR intensity of the AA samples varied depending on the storage and location conditions, showing sensitivity to light and signal instability at room temperature. It was found that the AA treatment caused a large increase in the peak-to-peak intensities with continuous signal growth with storage time, which may provide an enhancement to the radiation-dependent signal in fingernails. It was also suggested that the use of AA for pre-treatment could sufficiently remove the disturbing signals induced by heat or UV light exposure, which is expected to improve the reliability of radiation dosimetry using fingernails. Further studies with different antioxidant conditions are needed to better characterize the complex changes of the ESR signals from fingernails. [ABSTRACT FROM AUTHOR]

Screen protector glasses are often used to protect the display screen surface of mobile phones against physical damage. Their dosimetric properties were recently studied by thermoluminescence with the aim of using these items as potential emergency dosimeters in the event of a radiological accident. They are sensitive to ionizing radiation and they could be easily removed and replaced without destroying the phone in case of a dose assessment. However, an intrinsic background signal that partially overlaps with the radiation-induced TL signal is observed. The reconstructed dose could be overestimated if not properly taken into account. The homogeneity of this confounding signal on the surface of several screen protectors was estimated and a chemical treatment with hydrofluoric acid (HF 40%) was tested to minimize its contribution. For most of the samples studied, the intrinsic background signal remained a serious issue for dose reconstruction. Additionally, the TL signals were measured in the red detector range using two different models of red-sensitive photomultiplier tubes. The homogeneity of the intrinsic background signal on the surface of screen protectors was examined and the results of the reduction of this signal by the chemical HF treatment were discussed.

During recovery phases following a nuclear or radiological incident analyses of doses received by members of the public and responders are often required. Several methods have been investigated for use at different timescales after the incident, including assessments based on measurements of materials present at the time of the incident. Common salt has previously been shown to have potential for retrospective dosimetry in the mGy dose range using laboratory instrumentation. This preliminary study investigates the use of portable instruments, with unprepared commercially sourced salt, in dose ranges below 100 μGy. Responses from pulsed IRSL and portable OSL instruments were compared. For OSL measurements, detection limits of 7 μGy have been demonstrated, with detection limits of 30–340 μGy for the other instruments investigated. Dose responses in the 0–500 μGy range were determined for the most sensitive systems, which show a linear response over this dose range with a non-zero intercept representing doses received from environmental sources since manufacture of the salt. For use as a dosimeter, methods of removing or accounting for inherited signals will be required in this low dose range. The results demonstrate that salt has considerable potential for use in retrospective dosimetry below 100 μGy, and that measurements can be conducted with portable OSL instruments.

This study investigates the potential use of dietary supplements and pharmaceuticals containing magnesium, calcium or potassium for emergency dosimetry applications using the phenomenon of optically stimulated luminescence (OSL). Signal measurements were carried out using different stimulation wavelengths, and blue light stimulation was found to be the most efficient. More than half of the samples exhibited a measurable OSL signal and relatively high radiation sensitivity compared to other previously measured emergency detectors. Moreover, samples generally demonstrated a linear dose response. Possible causes of their high zero-dose signal were investigated: mechanical processing and UV light excitation. As variability in sensitivity was observed, the test-dose protocol was used during measurements. Furthermore, the study showed a significant loss of OSL signal intensity within 24 h after irradiation, which suggests the necessity for a fading correction. Finally, a dose recovery test was performed to evaluate the materials and the test-dose protocol under realistic conditions. The findings indicate the potential for using pharmaceuticals and dietary supplements in the event of a radiation emergency due to their dosimetric properties and ease of obtaining. • Most pharmaceuticals and dietary supplements containing magnesium and calcium exhibit an OSL signal. • OSL signals show good reproducibility, but sensitivity changes require test dose normalization. • Mechanical sample preparation or UV exposure may affect initial zero dose signal. • Dietary supplements exhibit radiation-induced luminescence signals, offering potential for emergency dosimetry applications. • Realistic dose recovery tests demonstrate the applicability for emergency dosimetry applications. [ABSTRACT FROM AUTHOR]

A study on retrospective dosimetry was performed using electronic personal dosimeters (EPDs) for reconstructing doses received by radiographic testing workers. The dosimetric properties of the thermoluminescence (TL) peak in the temperature range of 100–200 °C were investigated by measuring the TL of the resistors extracted from the EPDs in a darkroom environment. Results showed that this TL peak exhibited optimal dosimetric properties, with a minimum detectable dose as low as 13 mGy. To calculate the absorbed dose using the resistors, a simplified single aliquot regenerative (SAR) dose method using the TL peak was employed. The zero dose of the commercial EPD (model CLOVER) was determined to be 58 ± 72 mGy through the random selection of six EPDs. Additionally, a dose overestimation correction factor for compensating rapid sensitivity changes after TL measurement of the natural sample was calculated as 1.73 ± 0.09. Furthermore, it was observed that the TL signal faded exponentially to approximately 60% over a period of 12 weeks. Subsequently, retrospective dosimetry was performed by irradiating EPDs with a standard gamma ray dose of 1 Gy. The radiation exposure dose calculated from the TL peak of the resistors was found to be approximately 10% lower. These findings showed that the retrospective dosimetry with EPD can be utilized for accurately estimating the radiation exposure dose. • Retrospective dosimetry was performed using resistors in electronic personal dosimeters. • The thermoluminescence dosimetric properties of resistors were investigated. • Electronic personal dosimeters are potentially suitable for retrospective dosimetry. [ABSTRACT FROM AUTHOR]

One of the major difficulties in using mobile phone screen glass as a retrospective dosimeter is the high intrinsic background signal present in an unirradiated sample. This study aimed to assess the influence of the intrinsic background signal (not erased before readout) on dose estimation using glasses from the touchscreens of Samsung, iPhone, Xiaomi, Huawei, and Realme mobile phones in comparison to readout with prior erasement of the intrinsic background signal (S0). The most critical triage dose of 2 Gy was investigated, and three groups of screens were distinguished based on the value of the S0 signal. Additionally, the dose linearity in the range of 0.5–2 Gy was checked for four models of phones. The results indicate that the estimation of an accidently absorbed dose without prior removal of (S0) from mobile phone screen glass for doses in the range of 0.5–2 Gy with an uncertainty at the level of several percent is possible, even for screens with a high (S0), e.g., the iPhone 6. In an emergency situation, a calibration should be prepared based on data from irradiated samples without removing the intrinsic background signal beforehand in order to minimise the impact of a possible decrease in sensitivity on the results. • Various touchscreen glasses have different intrinsic background signal and different sensitivity to ionising radiation. • Estimation of the retrospective dose without prior removal of background signal from mobile phone screen glass is possible. • The proposed procedure is time-saving. [ABSTRACT FROM AUTHOR]

In the event of natural disasters or technical malfunctions at nuclear sites, the surrounding media, including individuals, may be subject to unforeseen radiation exposure. Thus, it is not possible to determine the precise level of radiation exposure that each person has received in this scenario. To handle such a problem, the use of retrospective dosimetry can offer an accurate evaluation of the radiation dose acquired as a result of such incidents. This information enables the development of suitable remedial actions. Normally, in the region that has been impacted, several artifacts can serve as natural dosimeters. The study involved the utilization of locally available seven different brands of flooring tiles in Malaysia for the possibility of being used in retrospective dosimetry through exposures to 60Co gamma-rays within a range of 10–200 Gy. To understand the luminescence features of this material, a convenient thermoluminescence (TL) technique has been employed. The dosimetric features of the samples were investigated, including their effective atomic numbers (Z eff), reproducibility, glow curve, dose response, sensitivity, linearity index, energy dependency and fading, which is representative of the usual TL method. Additionally, by analyzing the glow curves of the irradiated samples together with the peak shape method and the initial rise methods, several kinetic parameters, including the kinetic orders (b), activation energy (E) or trap depth, frequency factor (s) or escape probability, and trap lifetime (τ) were calculated. Different kinds of tiles exhibit distinct scenarios in terms of kinetic characteristics. T1 sample exhibits the highest degree of sensitivity and a highly linear dose response among the tile samples that were evaluated. Also, T1, T3, and T5 samples show minimal loss of TL intensity (∼38–39%) one year after irradiation, making them ideal for use as a retrospective dosimeter. • This study explores using common tiles for dose evaluation after radiation events. • 7 local tile brands tested for retrospective dosimetry using thermoluminescence (TL). • White House brand (T1) shows the highest sensitivity and linear dose-response. • The tiles (T1, T3, T5) lose minimal TL signal after a year, ideal for retrospective use. [ABSTRACT FROM AUTHOR]

In a large-scale radiation accident, the swift classification of individuals exposed to high levels of radiation is crucial to minimize casualties. In-vivo tooth dosimetry using L-band electron paramagnetic resonance (EPR) spectroscopy is a promising method for this purpose, as it can estimate individual exposure levels rapidly and non-invasively. However, the accuracy of dose estimation associated with this technique remains a great challenge. To enhance the accuracy, digital multiple harmonic detection (MHD) was incorporated into a home-built L-band EPR spectrometer. This approach enabled the utilization of information present in higher harmonics of EPR signals, which has been often discarded in traditional EPR spectroscopy. Acquired multiple harmonic spectra were reconstructed to the first derivative spectrum to merge information and mitigate the signal broadening. The modulation amplitude varied in a range of 0.3–0.7 mT to maximize the accuracy. In a 0.5-min measurement at 0.6 mT, the standard error of inverse prediction (SEIP) was reduced to 0.57 Gy from 0.71 Gy. The statistical significancy of the enhancement was validated. In conclusion, the accuracy enhanced by this MHD can contribute to improving the efficiency of triage systems in the aftermath of a mass radiation accident. • Digital multiple harmonic detection (MHD) was implemented for in-vivo L-band EPR tooth dosimetry. • The modulation amplitude was optimized within a range of 0.3–0.7 mT to maximize the accuracy. • The accuracy of dose estimation was enhanced by 20.1% in terms of the standard error of inverse prediction (SEIP). • This accuracy enhancement can improve the efficiency of the triage system in a large-scale radiological accident. [ABSTRACT FROM AUTHOR]

This study examines the potential use of components from electronic appliances as emergency dosimeters. The research aims to evaluate the accuracy and reliability of these electronic components in providing precise dose estimations during radiological incidents. Surface mounted devices (SMD) resistors were extracted from a previously irradiated CD-ROM and laptop, as well as pieces of the laptop's screen glass. The irradiation was carried out using a Co-60 source and MTS detectors (LiF:Mg,Ti) were used for the reference. The optically stimulated signal from the element samples was measured using a standardized protocol. Accidental dose was reconstructed using elements extracted from printed circuit boards of a CD-ROM and a laptop using the universal signal fading correction of SMDs extracted from mobile phones. The results showed high efficiency even seven days after exposure. Additionally, the results obtained from the tested SMD samples were comparable to those obtained from the MTS detectors. However, the study found that laptop screen glass samples were slightly overestimated, indicating a need for further investigation into their non-radiation induced signals and fading characteristics. In summary, the study demonstrates that certain laptop and CD-ROM components have dosimetric potential as alternative dosimeters in emergency situations compared to mobile phones, emphasizing their replaceability and low cost. The findings support the feasibility of incorporating electronic components for rapid dose assessment and triage in radiological emergencies, thereby contributing to enhanced emergency response preparedness. • Resistors showed high accuracy in dose reconstructions using OSL. • Universal fading correction was sufficient for dose reconstruction. • Signals from the reference detectors confirm the consistency of the results. • Laptop and CD-ROM components may be good alternatives for the emergency dosimetry. [ABSTRACT FROM AUTHOR]

This work investigates the feasibility of yeast-based impedance measurements for retrospective dosimetry applications. The local environment around yeast cells in a previously developed film-badge was modeled using Geant4. A greater dose response was observed when yeast cells were surrounded by an aluminum-polymer structure, which acted as a conversion layer. Bench-top experiments were conducted using a jar-based dosimeter design that directly combined a finely-ground aluminum conversion medium with yeast powder. It was shown when irradiated in the presence of aluminum grains, yeast cells yielded a higher impedance signal, thereby indicating greater radiation-induced damage. Finally, in separate irradiation experiments, lead and aluminum sheets were placed behind yeast samples and the dosimeters were irradiated to 1 Gy. A 2-fold increase in the impedance signal was shown when samples were positioned in close contact with the lead sheet compared to the aluminum sheet. In all experiments, it was shown that the local environment significantly influences radiative energy deposition in yeast cells. • Yeast-based impedance biodosimetry is presented as a retrospective dosimetry technique. • The impact of the local environment around yeast cells in biodosimetry measurements is discussed. • Sample preparation methods and a measurement protocol in evaluating the impedance response of irradiated yeast samples is presented. [ABSTRACT FROM AUTHOR]

Optically stimulated luminescence (OSL) of quartz obtained from ceramics, concrete, and soil has been studied extensively for its use in retrospective dosimetry. The OSL properties of quartz separated from surface soil of different parts of India were investigated for its application as a retrospective dosimeter. Different parameters such as recuperation, recycling ratio, equivalent dose plateau, and relevant to single-aliquot regenerative protocol were investigated. The dose recovery tests were also performed. These studies show that the soil samples can be used for dose evaluation during any radiation accident.

Several common pharmaceuticals such as ibuprofen, paracetamol, aspirin, oral contraceptives, drugs for the prevention of motion sickness and food supplements such as table vitamins and minerals have been studied for the purposes of retrospective dosimetry using optically stimulated luminescence (OSL). The essence is that the tablets with these drug substances contain additive crystalline materials which, after irradiation and stimulation, may exhibit luminescence. For most of the pharmaceuticals and food supplements, a radiation-induced dose-dependent OSL signal was detected. Subsequently, basic dosimetric characteristics of the materials were studied, specifically sensitivity changes during repeated OSL readings, dose response, zero-dose, minimum detectable dose (MDD) and fading. The most radiation sensitive materials were food supplements with Mg providing zero-dose and MDD values at the level of several mGy. For Mg supplements, considerable sensitivity changes in OSL signal were observed. Despite this, they could be corrected using a Single-Aliquot Regenerative-dose (SAR) protocol. The OSL signals of the other materials were relatively weak but they were well reproducible and exhibited linear dose response. The MDD values were variable among the materials and ranged from 0.1 to several Gy. However, for some of the pharmaceuticals, a very high and variable zero-dose of more than 3 Gy was observed that would rule out the possibility of dose reconstruction for triage purposes. The OSL signal exhibited a significant fading rate for most of the materials. The measurements for dose reconstruction should be performed as soon as possible after irradiation, i.e. within a maximum of a few days.

The cohorts of people formerly living at the Techa River shoreline in the Southern Urals, Russia, are widely studied cohorts for the investigation of low-dose radiation effects to human health. The nuclear facilities of the Mayak Production Association (PA) discharged their radioactive effluents into the nearby Techa River, especially in the first years of operation. Health status of cohort member data is constantly being improved and updated. Consequently, there is a need to also improve and verify the underlying dosimetry, which gives information about the dose of cohort members. For the Techa River population, the dosimetry is handled in the Techa River Dosimetry System (TRDS). The present work shows results of a feasibility study to validate the TRDS at the location of the village of Metlino, a village just 7 km downstream from the Mayak PA. For this settlement there were two sources of external exposure, the contaminated banks of the Techa River and the contaminated shoreline of the nearby Metlinsky Pond. In the present study the north-western wall of a granary was used as a dose archive to validate dose estimates. Measurements of doses in brick accumulated over many decades and measurements of the current dose rate in bricks were combined with dose rate measurements in air above ground in front of the granary, historical contamination data and Monte-Carlo simulations. Air kerma estimates for 1949–1956 significantly different from zero could not be reconstructed for the Metlinsky Pond shoreline near the granary, but an upper dose limit could be estimated. Implications for TRDS-2016 are discussed. [ABSTRACT FROM AUTHOR]

This paper presents the results of the first intercomparison exercise performed by the Korea retrospective dosimetry (KREDOS) working group using electron paramagnetic resonance (EPR) spectroscopy. The intercomparison employed the alanine dosimeter, which is commonly used as the standard dosimeter in EPR methods. Four laboratories participated in the dose assessment of blind samples, and one laboratory carried out irradiation of blind samples. Two types of alanine dosimeters (Bruker and Magnettech) with different geometries were used. Both dosimeters were blindly irradiated at three dose levels (0.60, 2.70, and 8.00 Gy) and four samples per dose were distributed to the participating laboratories. Assessments of blind doses by the laboratories were performed using their own measurement protocols. One laboratory did not participate in the measurements of Magnettech alanine dosimeter samples. Intercomparison results were analyzed by calculating the relative bias, En value, and z-score. The results reported by participating laboratories were overall satisfactory for doses of 2.70 and 8.00 Gy but were considerably overestimated with a relative bias range of 10–95% for 0.60 Gy, which is lower than the minimum detectable dose (MDD) of the alanine dosimeter. After the first intercomparison, participating laboratories are working to improve their alanine-EPR dosimetry systems through continuous meetings and are preparing a second intercomparison exercise for other materials.

Purpose: Cardiac effects after breast cancer radiation therapy potentially affect more patients as survival improves. The heart's heterogeneous radiation exposure and composition of functional structures call for establishing individual relationships between structure dose and specific late effects. However, valid dosimetry requires reliable contouring which is challenging for small volumes based on older, lower-quality computed tomography imaging. We developed a heart atlas for robust heart contouring in retrospective epidemiologic studies.Methods and Materials: The atlas defined the complete heart and geometric surrogate volumes for six cardiac structures: aortic valve, pulmonary valve, all deeper structures combined, myocardium, left anterior myocardium, and right anterior myocardium. We collected treatment planning records from 16 patients from 4 hospitals including dose calculations for 3D conformal tangential field radiation therapy for left-sided breast cancer. Six observers each contoured all patients. We assessed spatial contouring agreement and corresponding dosimetric variability.Results: Contouring agreement for the complete heart was high with a mean Jaccard similarity coefficient (JSC) of 89%, a volume coefficient of variation (CV) of 5.2%, and a mean dose CV of 4.2%. The left (right) anterior myocardium had acceptable agreement with 63% (58%) JSC, 9.8% (11.5%) volume CV, and 11.9% (8.0%) mean dose CV. Dosimetric agreement for the deep structures and aortic valve was good despite higher spatial variation. Low spatial agreement for the pulmonary valve translated to poor dosimetric agreement.Conclusions: For the purpose of retrospective dosimetry based on older imaging, geometric surrogate volumes for cardiac organs at risk can yield better contouring agreement than anatomical definitions, but retain limitations for small structures like the pulmonary valve. [ABSTRACT FROM AUTHOR]

For use in electron paramagnetic resonance dosimetry with tooth enamel, in the present study, very detailed mesh-type tooth models composed of 198 individual tooth models (i.e. newborn: 20; 1 year: 28; 5 years: 48; 10 years: 38; 15 years: 32; and adult: 32) were developed for each sex. The developed tooth models were then implanted in the International Commission on Radiological Protection pediatric and adult mesh-type reference computational phantoms and used to calculate tooth enamel doses, by Monte Carlo simulations with Geant4, for external photon exposures in several idealized irradiation geometries. The calculated dose values were then compared to investigate the dependency of the enamel dose on the age and sex of the phantom and the sites of the teeth. The results of the present study generally show that, if the photon energy is low (i.e. <0.1 MeV), the enamel dose is significantly affected by the age and sex of the phantom and also the sites of the teeth used for dose calculation; the differences are frequently greater than a few times or even orders of magnitude. However, with a few exceptions, the enamel dose was hardly affected by these parameters for energies between 0.1 and 3 MeV. For energies >3 MeV, moderate differences were observed (i.e., up to a factor of two), due to the existence of dose build-up in the head of the phantom for high-energy photons. The calculated dose values were also compared with those of the previous studies where voxel and mathematical models were used to calculate the enamel doses. The results again show significant differences at low energies, e.g., up to ∼3500 times at 0.015 MeV, which are mainly due to the differences in the level of tooth-modeling detailedness. [ABSTRACT FROM AUTHOR]

The study of new materials for radiation dosimetry is important to improve the present state of the art and to help in cases of accidents for retrospective dosimetry. Sulfites are compounds that contain a sulfur ion, widely used in the food industry. Due to the significant application of these compounds, sulfites are interesting candidates for accidental dosimetry, as fortuitous radiation detectors. The presence of the SO3− anion enables its detection by electron spin resonance (ESR) spectroscopy. The Dose–Response behavior, signal stability and other spectral features were investigated for sodium sulfite, sodium bisulfite, sodium metabisulfite and potassium metabisulfite, all in crystalline forms. The ESR spectrum of salts presented stability and proportional response with dose, presenting potential for dosimetry applications.

• Porcelain-based materials were investigated using stimulated luminescence methods. • Luminescence dosimetric properties were examined. • The lowest detectable dose limits (LDDL) of the porcelain-based materials were studied. • Luminescence kinetic parameters of both TL and OSL signals were determined. In the present study, different porcelain-based materials including a sugar bowl, an ashtray, a porcelain breaker, an artificial dental implant, an electric fuse and the seal of a porcelain moneybox were investigated via thermally (TL) and optically stimulated luminescence (OSL). For this purpose, luminescence dosimetric properties such as TL and OSL curve shapes, reproducibility, bleachability, along with dose response features such as linearity and lowest detectable dose limits (LDDL) of these materials were compared. A feature that is sample-dependent deals with both quartz and mullite content of each porcelain paste, as it was indicated by XRD analysis. Three dominant peaks in TL glow curves were ubiquitously observed, and OSL decay curves formed in two components (C 1 and C 2) for all samples. It was determined that the LDDL for only two TL peaks (P1 and P2) seem acceptable for accidental retrospective dosimetry applications (0.9–2.2 Gy). On the other hand, the LDDL values obtained according to OSL analysis yielded more promising results in terms of accidental retrospective dosimetry applications as 0.3–0.4 Gy and 0.75–1.35 Gy for C 1 and C 2 components, respectively. TL peaks P1 and P2 indicate the majority of prevalent, if not universal, properties of stimulated luminescence. This latter universality could support an argument towards identification of these two TL peaks directly correlated to quartz mineral. On the other hand, TL P3 could be attributed to a contribution of more than one mineral, such as quartz, kaolinite and mullite, due to the lack of prevalence over all stimulated luminescence features. [ABSTRACT FROM AUTHOR]

During recovery phases following a nuclear or radiological incident, it is crucial to assess the radiation exposure of both the general public and responders. This assessment is vital for directing protective actions and for conducting subsequent analyses of the incident's impact. Several methods have been employed at different timescales after an incident, including assessments based on measurements of materials present at the time of the incident. Common salt has previously been shown to have potential for retrospective dosimetry in the μGy-mGy dose range using portable OSL instruments. This study aims to explore the effects of sample storage under light and dark conditions on OSL signals. The OSL signals indicate a brief decrease in luminescence during the initial days after irradiation, followed by a gradual rise with extended storage. The period from 8 days to 64 days is characterized by relatively stable results, which encompass a significant portion of the timeframe relevant for dose estimation during both the early and later phases of responding to radiological emergencies. Light exposure (simulated daylight) results in an extremely rapid loss of OSL signals. Results are discussed with reference to TL measurements of associated trapping systems which provide insight into potential zeroing mechanisms and the observed fading behaviour. The results are sufficiently favourable to conclude that these characteristics, together with the widespread availability and low cost of household salt, support its use for prompt emergency assessment and as a retrospective dosimeter, below 100 μGy. • Optically stimulated luminescence (OSL) of sodium chloride (NaCl) was studied as emergency OSL dosimeters. • NaCl has a strong radiation-induced OSL signal. • Salt is highly sensitive to optical bleaching. • Requires light and humidity proof covering for dosimeters in the field. • Two peaks at T max = 110 °C unstable (1.47h), at T max = 284 °C stable for emergency dosimetry. [ABSTRACT FROM AUTHOR]

The portable radio (hand-held device) is the preferred means of communication for the first responders from the homeland security forces and is systematically carried during intervention. This electronic device could therefore be a good candidate as a possible fortuitous dosimeter to estimate the dose received by the members of these security forces in the event of a radiological accident. For this purpose, the dosimetric properties of electronic components extracted from the circuit board of portable radios used by a French specialised intervention unit were investigated using the OSL technique. The dosimetric properties of such electronic components were compared to those of resistors extracted from mobile phones to determine whether an OSL protocol developed for mobile phone resistors could be applied also to these electronic components. The OSL dosimetric properties were generally similar and the results of a dose recovery test using these components removed from a portable radio were in good agreement with the nominal dose. Further experiments showed the importance of knowing the storage temperature conditions of these devices to accurately estimate the dose in case of a radiological accident. • Radiation accident dosimetry using electronic components from portable radios was considered. • Their OSL dosimetric properties were generally similar to those of mobile phone resistors. • An OSL protocol developed for mobile phone resistors was successfully applied for dose estimation. • In the event of a radiological accident, these components could be used as fortuitous dosimeters. [ABSTRACT FROM AUTHOR]

Smart chip cards are a promising material in retrospective dosimetry due to their high collectability with low replacement cost. In this study, dose reconstruction using OSL at elevated temperatures for various chip cards was investigated. The approximate spectral emission of the chip cards was determined through a comparison of radiation-induced and intrinsic background TL signals using different detection filters. In the OSL decay curve, a fast component (0.0–0.4 s) was integrated to avoid high intrinsic background signals. To minimize sensitivity changes due to heat treatment, a protocol to measure OSL at 100 °C was developed and the data were compared with those from a similar protocol for OSL measured at room temperature. In the 0.1 - 5 Gy range, linear and power functions were fitted for room temperature and 100 °C OSL protocols, respectively. The minimum detectable dose was evaluated immediately after exposure, with values of 25 mGy for room temperature and 240 mGy for 100 °C OSL being determined. Signal fading was measured up to 30 days after irradiation for the investigated protocols. A dose recovery test was made 10 days after irradiation using various chip cards, and the 100 °C OSL protocol produced more reliable results than the room temperature OSL protocol. As a result, the study emphasizes the necessity of further investigation of OSL at high temperatures using chip cards. • Dose reconstruction using OSL at elevated temperatures for various smart chip cards was investigated. • The correction factors such as sensitivity change, zero dose, and signal stability were estimated. • A dose recovery test showed the necessity of further research into OSL at elevated temperature. [ABSTRACT FROM AUTHOR]

The effects of L(+)-ascorbic acid (AA) (an antioxidant commonly known as vitamin C) on the electron spin resonance (ESR) signals from fingernails were examined in relation to X-ray and UV irradiation. The ESR signal intensity, stability, and sensitivity to radiation were measured under different storage conditions. The experimental results indicated that the behavior of the increase in the ESR intensity of the AA samples varied depending on the storage and location conditions, showing sensitivity to light and signal instability at room temperature. It was found that the AA treatment caused a large increase in the peak-to-peak intensities with continuous signal growth with storage time, which may provide an enhancement to the radiation-dependent signal in fingernails. It was also suggested that the use of AA for pre-treatment could sufficiently remove the disturbing signals induced by heat or UV light exposure, which is expected to improve the reliability of radiation dosimetry using fingernails. Further studies with different antioxidant conditions are needed to better characterize the complex changes of the ESR signals from fingernails.

When a radiological and nuclear (R/N) emergency occurs, the categorization of individuals into those who are unaffected and those requiring medical intervention is a high priority. At times, a professional dosimeter is not available and therefore some common belongings may be used as fortuitous dosimeters. The preparation of these objects for the measurement should be such as to give the most accurate and precise results. This paper focused on the Photo-Stimulated Luminescence (PSL) response of salty crackers confronts the problem of sample preparation (mass, grain size), dose response and signal stability. The dose response was determined for doses up to 5 Gy, which allowed the calculation of the limit of detection. Additionally, the signal stability was investigated for samples irradiated with 0.3 and 3 Gy. The observed decrease of the signal does not prevent the detection in the dose range typical for R/N emergency. The main dosimetric characteristics were investigated by using two different models of PSL readers equipped with single (infrared) or double (infrared, blue light) stimulation. The results indicated that the limit of detection can be improved by applying blue light stimulation. Moreover, strong correlation of the measurements performed in the two different instruments, as well as the rapidity of the analysis and the simplicity of the operations, suggest that this method can be suitable for a rapid radiation triage of a large number of civilians in a mass casualty event. The study was simultaneously conducted by two laboratories (Ruder Bošković Institute, RBI, Croatia and Istituto Superiore di Sanità, ISS, Italy) involved in the BioPhyMeTRE project (grant No. G5684) supported by NATO Science for Peace and Security Programme.

We report the phenomenon whereby the electron spin resonance signal of human nails intensify after irradiation. Forty nail samples from three donors were divided into three groups (X-ray irradiated, γ-ray irradiated, and control). The extent of signal intensified after irradiation was proportional to the given dose under 11% humidity at 20 °C. This result seemed to contradict previous studies, reporting signal fading. Based on literature and our experimental results, we constructed a model taking both the decay and increase into consideration. Our investigation revealed that rapid deterioration in the signal intensity obscured the increase at humidity levels exceeding 40%. [ABSTRACT FROM AUTHOR]

Optically stimulated luminescence (OSL) of quartz obtained from ceramics, concrete, and soil has been studied extensively for its use in retrospective dosimetry. The OSL properties of quartz separated from surface soil of different parts of India were investigated for its application as a retrospective dosimeter. Different parameters such as recuperation, recycling ratio, equivalent dose plateau, and relevant to single-aliquot regenerative protocol were investigated. The dose recovery tests were also performed. These studies show that the soil samples can be used for dose evaluation during any radiation accident. [ABSTRACT FROM AUTHOR]

Precise estimation of individual radiation dose utilizing biomaterials (fingernail, bone, and tooth) is very challenging due to their complex sample processing. Despite, tooth enamel, the most mineralized tissue of tooth is used for this purpose due to its high radiation sensitivity and ability to produce radiation induced long lived CO 2 radicals. However, human teeth are not always available, and invasive nature of sample collection adds to the complexity making dose estimation difficult. In such cases, animal teeth (goat, cow, and moose) can be used as a substitute for human teeth due to comparable enamel sensitivity. Moreover, separation of enamel from dentine is a crucial step towards accurate dose estimation from irradiated teeth. In this work, Indian goat teeth were used as it was readily available to us and the comparison of goat enamel sensitivity to radiation was found to be within ∼7.4 % that of human. The enamel samples were separated following two chemical methods; (1) density separation using sodium polytungstate, (2) alkaline denaturation using NaOH and the quality was compared based on their purity and radiation sensitivity. Combined results of spectroscopic characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman analysis authenticated the crystallinity and purity of the separated enamel samples. The radiation sensitivity of separated enamel samples was compared by electron paramagnetic resonance (EPR) analysis as a part of dosimetric characterization. The suitability of both the samples for retrospective dosimetry and epidemiological studies was checked by validating the dose estimated from separated enamel samples with standard alanine/EPR dosimeter.- radicals. However, human teeth are not always available, and invasive nature of sample collection adds to the complexity making dose estimation difficult. In such cases, animal teeth (goat, cow, and moose) can be used as a substitute for human teeth due to comparable enamel sensitivity. Moreover, separation of enamel from dentine is a crucial step towards accurate dose estimation from irradiated teeth. In this work, Indian goat teeth were used as it was readily available to us and the comparison of goat enamel sensitivity to radiation was found to be within ∼7.4 % that of human. The enamel samples were separated following two chemical methods; (1) density separation using sodium polytungstate, (2) alkaline denaturation using NaOH and the quality was compared based on their purity and radiation sensitivity. Combined results of spectroscopic characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman analysis authenticated the crystallinity and purity of the separated enamel samples. The radiation sensitivity of separated enamel samples was compared by electron paramagnetic resonance (EPR) analysis as a part of dosimetric characterization. The suitability of both the samples for retrospective dosimetry and epidemiological studies was checked by validating the dose estimated from separated enamel samples with standard alanine/EPR dosimeter., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

Featured Application: The technique presented here could be effectively applied for retrospective assessment of the accidental radiation hand exposure of medical workers. While it is recognized that some medical workers could receive significantly higher radiation doses to their hands than the routinely monitored personal doses, accurate retrospective dosimetry of their hand exposure is still challenging. To solve this issue, a combination of electron spin resonance (ESR) measurement and fingernails is worth to be investigated. However, the application of fingernail ESR dosimetry requires establishing an effective protocol to eliminate the background signal (BKG) which changes due to mechanical stress and other unclear factors, so that the radiation doses would be precisely evaluated from the radiation-induced signals (RIS) only. Thus, the authors investigated possible applications of antioxidants to remove or reduce the BKG in fingernails. In the present study, the effectiveness of chemical treatment using the dithiothreitol (DTT) reducing reagent was examined in irradiated and unirradiated fingernails. Chemically and non-chemically treated fingernails were subsequently exposed to 20 Gy of 137Cs γ-rays and the time changes of the BKG and RIS were confirmed in two different storage conditions: vacuum chamber and freezer. The results show that the non-chemically treated fingernails displayed significant intra-individual variations in the peak-to-peak intensities of both BKG and RIS. RIS from chemically and non-chemically treated samples showed correlations after freezer storage; signals were more stable than the samples stored in the vacuum chamber. Moreover, while the BKG of non-chemically treated samples demonstrated higher levels than those chemically treated, the intra-individual variations were further reduced by the DTT treatment. Our results imply that the use of an antioxidant for hand washing of medical workers prior to starting their work could be effective in reducing the pre-existing free radicals in their fingernails. This also suggests a practical application of hand exposure monitoring using fingernails as a part of radiological emergency preparedness in occupations where radiation or radionuclides are used. Research for finding safer and easier-to-handle antioxidants is to be focused on in future studies. [ABSTRACT FROM AUTHOR]

Cars of a variety of brands are usually parked at a fixed but increasing distance in the periphery of nuclear installations. Herein we focus on the potential use of car windscreens for post-accident dose reconstruction from unplanned nuclear events and natural disasters, also in regard to unexpected events arising during large-scale use of radioactive and nuclear materials. The situation requires identification of analytical techniques that could both readily and reliably be used to assess absorbed dose, sufficient to prompt remedial action where necessary. Samples from three widely used car brands—Honda, Toyota and Proton—are studied in respect of their thermoluminescence (TL) yield. Key TL dosimetric features in the gamma-ray dose range of 1–100 Gy are examined. An ERESCO model 200 MF4-RW X-ray machine has also been used for energy response studies; a Harshaw 3500 TLD reader equipped with WinREMS software was used for the luminescence measurements. All brands exhibit linearity of TL yield versus dose, the samples from Honda showing the greatest response followed by that of the Toyota and Proton brands. The marked energy dependence reflects the effect of the strongly Z-dependent photoelectric effect. Signal fading was investigated over a period of 28 days, the Toyota and Proton brand windshield glass showing a relatively low loss at 52.1% and 52.6% respectively compared to a 56.7% loss for that of the Honda samples. This work forms the first such demonstration of the potential of car windshield glass as a retrospective accident dosimeter. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) signals generated by ionizing radiation in touch-screen glasses have been reported as useful for personal dosimetry in people accidently exposed to ionizing radiation. This article describes the effect of light exposure on EPR spectra of various glasses obtained from mobile phones. This effect can lead to significant inaccuracy of the radiation doses reconstructed by EPR. The EPR signals from samples unexposed and exposed to X-rays and/or to natural and artificial light were numerically separated into three model spectra: those due to background (BG), radiation-induced signal (RIS), and light-induced signal (LIS). Although prolonged exposures of mobile phones to UV light are rather implausible, the article indicates errors underestimating the actual radiation doses in dose reconstruction in glasses exposed to UV light even for low fluences equivalent to several minutes of sunshine, if one neglects the effects of light in applied dosimetric procedures. About 5 min of exposure to sunlight or to light from common UV lamps reduced the intensity of the dosimetric spectral components by 20–60% as compared to non-illuminated samples. This effect strongly limits the achievable accuracy of retrospective dosimetry using EPR in glasses from mobile phones, unless their exposure to light containing a UV component can be excluded or the light-induced reduction in intensity of the RIS can be quantitatively estimated. A method for determination of a correction factor accounting for the perturbing light effects is proposed on basis of the determined relation between the dosimetric signal and intensity of the light-induced signal. [ABSTRACT FROM AUTHOR]

Accidents resulting in widespread dispersal of radioactive materials have given rise to a need for materials that are convenient in allowing individual dose assessment. The present study examines natural Dead Sea salt adopted as a model thermoluminescence dosimetry system. Samples were prepared in two different forms, loose-raw and loose-ground, subsequently exposed to 60Co gamma-rays, delivering doses in the range 2–10 Gy. Key thermoluminescence (TL) properties were examined, including glow curves, dose response, sensitivity, reproducibility and fading. Glow curves shapes were found to be independent of given dose, prominent TL peaks for the raw and ground samples appearing in the temperature ranges 361–385 ºC and 366–401 ºC, respectively. The deconvolution of glow curves has been undertaken using GlowFit, resulting in ten overlapping first-order kinetic glow peaks. For both sample forms, the integrated TL yield displays linearity of response with dose, the loose-raw salt showing some 2.5 × the sensitivity of the ground salt. The samples showed similar degrees of fading, with respective residual signals 28 days post-irradiation of 66% and 62% for the ground and raw forms respectively; conversely, confronted by light-induced fading the respective signal losses were 62% and 80%. The effective atomic number of the Dead Sea salt of 16.3 is comparable to that of TLD-200 (Zeff 16.3), suitable as an environmental radiation monitor in accident situations but requiring careful calibration in the reconstruction of soft tissue dose (soft tissue Zeff 7.2). Sample luminescence studies were carried out via Raman and Photoluminescence spectroscopy as well as X-ray diffraction, ionizing radiation dependent variation in lattice structure being found to influence TL response. [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL) properties of NaF and KCl are investigated in order to assess their suitability as radiation dosemeters for retrospective dosimetry. TL measurements were made on samples irradiated to different doses (1–20 Gy) and heated at a rate ranging from 0.4 to 4 °C/s in a TL/OSL reader. The TL glow curves of NaF, readout at 1oCs−1, exhibited six apparent peaks around 38.7 ± 1.4, 63.5 ± 0.5, 105.5 ± 0.4, 237.5 ± 0.8, 299.0 ± 1.0 and 347.5 ± 0.7 °C with a shoulder around 168.0 ± 2.3 °C. Those of KCl have three clearly identifiable peaks around 44.0 ± 0.3, 95.3 ± 0.8 and 160.5 ± 0.7 °C. Glow curve deconvolution, however, revealed that the glow curves of NaF and KCl are best fitted with nine and five glow peaks respectively. In NaF, all the peaks exhibited linearity of dose-response in the entire dose range considered in this study. Only the peaks around 95.3 ± 0.8 and 160.5 ± 0.7 °C exhibited linear dose-response in the entire dose range for KCl. In NaF, there was thermal quenching of the TL responses of the peaks around 63.5 ± 0.5, 105.5 ± 0.4 and 237.5 ± 0.8 °C, and thermal enhancement of responses for peaks around 299.0 ± 1.0 and 347.5 ± 0.7 °C. With respect to KCl, the TL responses of all the peaks exhibited thermal enhancement as heating rate was increased. The activation energies associated with the thermal enhancement and quenching of the peaks' TL responses are presented. The repeated use of an aliquot of NaF five times for dose measurements resulted in an acceptable variation in sensitivity, on the other hand the sensitivity of KCl decreased with increasing number of repeat use. The activation energy of the electron traps associated with the glow peaks in both crystals calculated in this study are comparable to previously published values. Both crystals can be used for retrospective dosimetry however change in sensitivity with repeat use of an aliquot will have to be accounted for in the case of KCl. • Potassium chloride has three clearly identifiable TL peaks. • Sodium fluoride has six clearly identifiable TL peaks. • Peaks in KCl exhibited luminescence thermal enhancement. • Both luminescence thermal quenching and enhancement existed for peaks in NaF. • Luminescence sensitivity of aliquot of NaF is unaffected by reuse. • NaF suitable for dosimetry without correction. [ABSTRACT FROM AUTHOR]

In the event of a radiological accident or attack, it is important to assess and quantify radiation dose to the population. This could be done using materials in the vicinity that are sensitive to ionizing radiation. Common salt (NaCl) is known to be a sensitive thermoluminescence (TL) phosphor. Luminescence properties of common salt (NaCl) used in Nigeria were investigated using an automated luminescence reader Risø TL/OSL-DA-15, with attention focused more on the Optically Stimulated Luminescence (OSL). Strong radiation-induced TL and OSL signals were observed. The TL peaks occurred at about 100 °C, 240 °C and 280 °C. The dose response of both the TL and OSL signals showed a linear relationship. From the OSL pulse anneal curve with TL curve, a preheat temperature of 190 °C for 10 s was found adequate for the OSL measurements. There was no significant difference in the OSL decay for stimulation temperatures of 100 and 120 °C. Fading experiment over a storage period of 14 days showed about 13 and 3% decrease in the OSL signal of sample 1 and sample 2, respectively. The ratios of measured to given dose for dose recovery test were within ±19% of unity. Within the limit of error the samples could be used as a complementary emergency dosimeter in radiological accident situation.

The specification and current status of the dosimetry problems in Ukraine at the late stage of the Chernobyl accident is given. There are: the permanent monitoring of the Chernobyl exposure doses for the inhabitances of the contaminated areas; the improvement of the retrospective dosimetry of whole body exposure at the early stage of the Chernobyl accident; the improvement of the retrospective thyroid dosimetry; dosimetric support of the radioepidemiological studies; the dosimetric maintenance and radiological control of the works for the stabilization and reconstruction of the Object Shelter.