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In this work, we use paramagnetic defects induced by gamma radiation in some modern paper samples to determine their main dosimetric properties in the decontamination dose range (0.5–10 kGy) of ancient papers. Electron spin resonance (ESR) spectra of photo paper, cigarette paper, white paper napkin (napkin), cash register receipt, straw paper and white photocopy paper recorded before and after irradiation with gamma rays were reported. Photo paper, cigarette paper and napkin samples displayed the radiation-induced cellulose-like ESR signals well known from the literature on cellulose-containing foods. Cash register receipt, straw paper, and white photocopy paper are another set of samples where different ESR spectra were recorded. The ESR signals of these three paper samples were shown to originate from carbonate mineral filler grains. Inorganic mineral fillers are commonly used in paper manufacturing. The dose-response curves associated with the radiation-induced sharp ESR signals originating from the CaCO 3 filler of the cash register receipt (g = 2.0027), the straw paper (g = 1.9995), and the white photocopy paper (g = 1.9996) were found to follow a single exponential saturation function. Despite the observed decreases with time in the signal intensities of cash register receipt and white photocopy paper, detectable ESR signals were obtained even 100 days after irradiation for them and straw paper. The radiation-induced free radicals responsible for the ESR spectrum of straw paper were more stable than those of cash register receipt and white photocopy paper. The results indicate that free radicals induced in mineral CaCO 3 filler grains incorporated within papers have the potential to be used for application to retrospective ESR dosimetry in the range of 0.5–10 kGy. • Radiation-induced ESR signals were examined in six types of modern papers. • Cellulose-like and calcite filler origin signals were observed in the papers. • ESR signals originating from calcite filler increased exponentially in the range 0.5–10 kGy. • The fading behaviors of the signals were investigated depending on the dose. • Common modern papers were tested as potential retrospective ESR dosimeters. [ABSTRACT FROM AUTHOR]

Abstract: An essential part of the laboratory procedure associated with optical dating is the irradiation of sample aliquots with known doses of ionizing radiation. Only if laboratory irradiation faithfully reproduces the effects (within the dating sample) of natural irradiation (during burial) will the dates obtained be accurate. Modelling of quartz luminescence suggests that the usual practice of administering laboratory doses at room temperature, and in single exposures, may lead to both equivalent-dose overestimation and increased levels of scatter in individual age estimates for samples with palaeodoses greater than 40Gy. In the model, this effect is due to the large differences between laboratory and natural dose rates. A modification to standard irradiation practices is suggested as a remedy to this problem, whereby laboratory regeneration doses are administered in 10Gy pulses, with the aliquot then being heated to 240°C following each pulse. Empirical measurements of 12 sedimentary samples support the theoretical findings, with significant differences in dose response being observed between single-irradiation and pulsed-irradiation OSL regeneration data. Results are also presented in which the problem of the laboratory dose response failing to reach the level obtained through natural irradiation is remedied by the pulsed-irradiation procedure. It is possible that the application of pulsed-irradiation regeneration may in future lead to a more accurate means of dating the deposition of quaternary sediments, although this remains to be demonstrated empirically by the dating of known-age samples. [Copyright &y& Elsevier]

A theoretical model of quartz luminescence is presented and used to simulate luminescence response to environmental dose rates over geological timescales. Simulations of natural burial and laboratory measurements suggest that dose-rate effects in quartz cause systematic overestimation of absorbed doses when standard dating procedures are applied. Overestimation of absorbed dose (and therefore of age estimates) becomes significant at palaeodoses greater than ∼40 Gy. This effect is due to competition from the relatively thermally unstable R1 recombination centre (the centre that also plays a key role in ‘dose quenching’ of quartz optically stimulated luminescence, and thermoluminescence). Variation in the concentration of R1 centres leads to variation in measured equivalent dose (De) values and may potentially be a significant source of scatter in De estimates from sedimentary quartz samples. Model predictions indicate that by administering laboratory doses either at raised temperature, or in short pulses with intervening thermal treatments, the malign effects of the R1 centre can be removed. Results from laboratory measurements using pulsed-irradiation support the theoretical predictions. Implementation of pulsed irradiation in a single-aliquot regenerative-dose procedure yielded an accurate and more precise age estimate for a last-interglacial age dune deposit from Africa, compared to the overestimate obtained using the standard procedure, as predicted by the model. [Copyright &y& Elsevier]

Narrow spectrum (blue-green) laboratory partial bleaching of aliquots of natural sedimentary quartz has been shown to have a significant effect on equivalent dose (measured using a single aliquot procedure) calculated as a function of measurement time (De(t)). A simple model, based on empirical data, is presented in which the effects of partial bleaching on De(t) are predicted, taking into account the influences of pre- and post-burial doses. The model is applied to the case of heterogeneous populations of partially bleached single grains with various ranges of residual doses. Modelling shows that under realistic conditions, De histogram plots are unable to distinguish between samples having age overestimates and those with correct ages, whereas the proposed De–Z plot is able to make this distinction. Furthermore, modelling shows that De–Z plots can identify sub-populations of grains/aliquots that show most evidence of full bleaching, which can then be used to estimate a correct mean De value. [Copyright &y& Elsevier]

The identification of incomplete signal re-setting of optically stimulated luminescence signals in sedimentary quartz is a vitally important step in the continued improvement of optical dating. It is shown that narrow spectrum (blue-green) laboratory partial bleaching of aliquots of natural sedimentary quartz has a significant effect on equivalent dose (measured using a single aliquot procedure) calculated as a function of measurement time (De(t)). The blue-green stimulation spectrum mimics that found underwater and the results suggest that incomplete re-setting of waterlain sediments may be possible using the De(t) method. [Copyright &y& Elsevier]

Objective of this work is to define method by which sensitivities of CR-39 and LR-115 in diffusion chamber could be determined. Method is based on initial physical processes that occurs in diffusion chamber: diffusion, deposition and decay of radon (isotopes 222Rn and 220Rn) and their progeny. Cylindrical shape of chamber was considered due to availability of experimental data for validation of presented method. The shape was not limitation factor and can be extended to any geometry. Diffusion equations for radon in two mediums (membrane and chamber volume) and their progeny in volume were solved using Finite Difference Method – FEM, and solutions are their spatial distributions inside of diffusion chamber. Calculation of flux towards the chamber walls determine distribution pattern and deposited progeny fractions. It has been shown that volume and deposited distributions are not uniform. Visible tracks on CR-39 for defined etching conditions are determined by considering range of alpha particles in air and empirical critical angle function θ C = θ C (E). For LR-115 mean critical angle of 〈 θ c 〉 = 50 0 and energy window from E min = 1.7 MeV to E max = 4.2 MeV was adopted from literature to determine number of visible tracks. The track density distributions on detector are found to be non-uniform and radially dependent. Thickness of permeable membrane has important influence on presence of thoron and its progeny tracks on detector. Sensitivities of CR-39 and LR-115 in diffusion chamber were determined using method presented in this work and compared with other theoretical models and experiment with good agreement. This shown applicability of the presented method. One of important conclusion is that detector sensitivity, given as one simple number, is not the best parameter for calibration due to the existence of radial variation of track density. For cylindrical chamber with 10 cm length and 4 cm radius, covered with membrane in form of one-layer filter paper 0.25 mm thickness, and for equal concentrations of 222Rn and 220Rn in front of the chamber, contribution of 220Rn and its progeny to total track density is about 3%. • Solution to stationary diffusion of Rn and progeny in diffusion chamber. • Determination of volume and deposited fractions of Rn and progeny in chamber. • Track density distributions on detector at the bottom of chamber were presented. • Model enables determination of detector sensitivity in cylindrical chamber. [ABSTRACT FROM AUTHOR]

The objective of this paper is to provide a comprehensive review of the advancements and techniques in real time two-dimensional (2D) dosimetry for external radiation therapy with emphasis in vivo dosimetry and patient specific quality assurance. External radiation therapy plays a crucial role in cancer treatment, delivering high-energy radiation beams to target tumours while minimizing damage to surrounding healthy tissues. Accurate dosimetry, as both the measurement of the dose and its delivered location, is paramount to ensure effective treatment outcomes and minimize potential side effects. The planned content of this paper encompasses a thorough examination of the advancements made in 2D dosimetry techniques, including solid state and electronic systems. The evolution from traditional passive dosimetry to modern real time detectors, such as portal imaging, has revolutionized the field, offering enhanced precision, efficiency, and convenience. This review will discuss the principles, advantages, and limitations of these systems, along with their practical implementation and calibration procedures. Furthermore, the paper will highlight novel technologies, such as luminescence coatings, for quality assurance (QA) and real-time dose verification during treatment. The use of innovative materials and designs in dosemeters, including high spatial resolution detectors and tissue-equivalent phantoms, will also be explored. Additionally, the incorporation of advanced data analysis techniques, such as machine/deep learning algorithms, for dose reconstruction and QA will be addressed. The review will also explore the application of real time 2D dosimetry in modern clinical and pre-clinical modalities, including intensity-modulated radiation therapy and volumetric modulated arc therapy, stereotactic radiosurgery, image-guided radiation therapy, particle therapy, adaptive radiotherapy, electron and proton ultra-high dose rate therapy and very high energy electrons. By providing an up-to-date overview of the state-of-the-art in real time 2D dosimetry in vivo dosimetry and patient specific quality assurance, this paper aims to inform and guide professionals in the field, facilitating the adoption of cutting-edge techniques and improving the accuracy and safety of external radiotherapy treatments. • Advancements in Real-Time 2D Dosimetry. •Challenges and Limitations of Traditional Dosimetry. •Emerging Technologies and Future Directions: [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of the neutron field characteristics surrounding biological shielding of Russian research nuclear reactors to establish their expected behavior and enhance personnel neutron monitoring. The study covered five nuclear research reactors: IVV-2M, IRT-T, IRT-MEPhI, RBT-6, and SM-3. All reactors are pool-typed; some (RBT-6 and SM-3) have pressurized water, while others (IVV-2M, IRT-T, and IRT-MEPhI) have water under normal pressure. The neutron fields analyzed are located at the tank cover of reactors, in front of the reactor core covered with biological shielding, and in front of the horizontal experimental channel. The spectrum average neutron energy ranges from 0.01 MeV (RBT-6) to 1.0 MeV (SM-3). The fluence-to-ambient dose conversion coefficient varies from 15 pSv ∙ cm2 (RBT-6) to 260 pSv ∙ cm2 (SM-3). The spectra at the other measurement points exhibit the energy distribution characteristics of the neutron radiation flux density behind the biological shielding. • The paper presents the results of a study of the neutron field characteristics surrounding biological shielding of Russian research nuclear reactors to establish their expected behavior and enhance personnel neutron monitoring. • The study covered five nuclear research reactors: IVV-2M, IRT-T, IRT-MEPhI, RBT-6, and SM-3. • The neutron fields analyzed are located at the tank cover of reactors, in front of the reactor core covered with biological shielding, and in front of the horizontal experimental channel. • The spectrum average neutron energy ranges from 0.01 MeV (RBT-6) to 1.0 MeV (SM-3). • The fluence-to-ambient dose conversion coefficient varies from 15 pSv ∙ cm2 (RBT-6) to 260 pSv ∙ cm2 (SM-3). [ABSTRACT FROM AUTHOR]

This paper presents a detailed description of construction and introduction of an assembly for cosmic veto system at the Laboratory for radioecology of the Ruđer Bošković Institute in Zagreb. It is a typical surface laboratory for environmental radioactivity measurements using HPGe detectors. In surface level laboratories a large part of the background signal is caused by radiation produced by cosmic radiation, mostly by muons. It leads to limiting factors for reaching low detection limits, essential in environmental sample measurements, where relatively low activity concentrations are expected. Thus, reduction of cosmic component of background becomes a requirement, but also a challenge and an expense for already set routine gamma spectrometric laboratories. This paper offers a detailed description of materials and steps needed for construction and implementation of such an assembly as a guideline for other laboratories. The homebuilt veto system presented here is based on large scintillator plates covering the existing passive lead shielding. For the easy and rapid characterization of the veto system, a newly acquired digitizer was used. More specifically, the timestamping capabilities of the CAEN DT5781 MCA were used to identify the coincidences caused by muons between the scintillators and the HPGe. With the 3 plates added, a reduction factor of 2.4 was achieved, reducing the count rate between 40 keV and 2700 keV from 0.58 cps to 0.27 cps. After the full characterization of the veto system, the setup was transferred back to the previously used Canberra DSA, more suitable for routine measurements. This step and its description are lacking in the existing literature, while it is very valuable for the laboratories already set up for the environmental measurement. The additional advantages of a homebuilt system are the modularity and multi-purpose of the system which can later be used for different applications. • Home-built cosmic veto was implemented at gamma-spectrometry laboratory • New acquired digital electronics were used for the characterization of the system • Detailed description of implementation for both Canberra and CAEN systems • Reduction factor of 2.4 in background, with detection limits significantly lowered • System is modular and multi-purpose for different applications [ABSTRACT FROM AUTHOR]

This paper presents the evaluation of the fluence-to-ambient dose equivalent response function (referred to as F2D response function) of the Aloka TPS-451C neutron dose equivalent rate meter (hereafter referred to as a neutron meter) based on a singular value decomposition (SVD) approach. Measurements of neutron ambient dose equivalent rates, Ḣ ∗ (10) , using the neutron meter were conducted in various neutron standard fields of 241Am-Be source with different neutron fluence rate spectra. A series of Ḣ ∗ (10) values and corresponding neutron fluence rate spectra were used as the input data for unfolding the F2D response function of the neutron meter. To verify the SVD-based method, the fluence response functions of a well-known Bonner sphere spectrometer system were unfolded using the SVD method, and the results were compared with those provided in the IAEA technical report No. 403. The SVD method was then applied to determine the F2D response function of the Aloka TPS-451C neutron meter with the use of the ICRP-74 F2D response function and that predicted in a previous work as initial guesses. The consistency between initial guesses and the SVD unfolded F2D response function of the Aloka TPS-451C neutron meter implies the reliability of the SVD method for determining the response functions of neutron meters. • SVD-based computer code has been developed. • Fluence-to-ambient dose equivalent response function of a neutron meter was derived. • Standard uncertainties of response functions were discussed in the paper. [ABSTRACT FROM AUTHOR]

The paper is based on experiments within a project to prepare tutorial tasks on a training centre for testing radiation detectors fixed on unmanned aerial vehicles (UAVs) and in unmanned ground vehicles. The paper reports on a small UAV with NaI(Tl) 2" x 2" detector for radiation monitoring in an emergency event and for radioactive source chasing and detection. The paper is focused on some special cases with the possibility to determine local air kerma rates and the activities of point sources. The detector was calibrated for air kerma rates from 5 nGy h−1 to 20 μGy h−1. The verified model of the NaI(Tl) 2″ x 2″ detector including the electronic module assembled on a UAV was designed in a Monte Carlo simulation. The model was used for calculating the air kerma rates at various altitudes above the ground both for a natural background and for selected point sources. The response functions for 137Cs, 131I, 192Ir, 60Co and 99Mo point sources were calculated by the Monte Carlo simulation to estimate their activities. Experiments were carried out with an NaI(Tl) 2" x 2" detector fixed on a Robodrone UAV and flying over 60Co and 137Cs point sources over the airfield area and the local air kerma rates and the activities of the point sources were calculated with the AGAMA post-processing program. In addition, the response functions for 137Cs distributed uniformly on the surface were calculated by Monte Carlo simulation for future emergency purposes. The detection limits of selected man-made nuclides (point sources) were calculated. • Small detectors, for example NaI(Tl) 2" x 2" or 3" x 3", are able to detect changes in air dose rates at the level of natural background. • Air dose rates of natural background and from surface contamination can be well converted from values at flight altitudes to a height of 1 m above the ground. • Use of non-negative least square method using the response matrices of individual nuclides allows estimation of the activity of point sources, "small hot spots" or surface activity. • Detection limits for small detectors NaI(Tl) are usually in a range of tens of MBq for flight level of 10 m for usual sealed point sources, and hundreds of MBq for flight levels higher than 20 m. [ABSTRACT FROM AUTHOR]

The W-MON project goal is to establish an automatic control mechanism of the presence of radioactive material in conventional waste containers at CERN using a distributed network of interconnected low-power radiation sensors. This network facilitates continuous data recording, transfer and storage in a database while allowing online and offline data analysis, in addition to alarm triggering. Data transmission, processing and evaluation is achieved by a centralized IoT end-to-end data architecture that has been developed for real-time monitoring and visualization of the radiation levels in waste containers. In this paper the results of field tests of the W-MON system described in two previous papers are presented for three different types of sensors. Estimation of failure detection probability, long-term stability tests and sensitivity studies carried out using radioactive samples of various activities placed in standard waste containers are described. A comparison between the manual monitoring procedure currently used at CERN and the W-MON system is discussed in detail. • W-MON system is a network of low-power radiation sensors. • Automatic control of radioactive material in waste containers at CERN. • Centralized IoT architecture enables continuous data transmission. • Real-time monitoring and visualization of radiation levels. • Long-term stability tests using radioactive samples in standard containers. • W-MON system can efficiently replace existing manual monitoring procedures. [ABSTRACT FROM AUTHOR]

Enrichment measurements using identiFinder2 ('HM5') detector are performed on two Material Testing Reactor (MTR) fuel assemblies - one with low-enriched uranium plates (LEU) and another with high-enriched uranium plates (HEU). The effectiveness of International Atomic Energy Agency (IAEA) inspection plans for verifying nuclear material strata, in the form of defect detection probability (DP), is evaluated using statistical models. These models use defect identification probability (IP) curves, which represent the probability that a measured item is identified as a defective item. This paper describes a new modeling procedure that converts the experimental measurements into IP curves and employing such experimentally derived IP curves within DP simulations will better represent the experimental conditions like material type, material distribution, and plate configuration. A comparison of experimental performance curves to a simple statistical model (Gaussian, 15% relative standard deviation RSD) shows that the DP results from the modeled response of HM5 measurements better captures the experimental conditions. This result highlights a need for further research into experimental error variables test model development as use of a simple model does not adequately capture true performance in either the LEU or HEU cases. [ABSTRACT FROM AUTHOR]

Household salt, Sodium Chloride (NaCl), has been suggested as an appropriate material for retrospective and prospective optically stimulated luminescence (OSL) radiation dosimetry. The current paper investigates the potential application of NaCl pellets during a radiological and/or nuclear emergency, together with an existing portable reader, for application as a novel tool for in situ screening of individual doses in exposed populations. The evaluation of the portable reader's performance was assessed based on OSL and infra-red stimulated luminescence (IRSL) methods and the results were compared to two research readers, Risø TL/OSL (DA-20 and DA-15). For the studied absorbed dose range (0.63–487 mGy), it was found that five pellets are needed in the portable reader to achieve a similar OSL signal magnitude as using one pellet in the two research readers. The OSL results of the three readers show similar minimum detectable dose (MDD) values and similar linear trends for the obtained OSL dose response curves, within the studied dose range. The IRSL results show a lower IRSL signal for the portable reader, leading to higher MDD values compared to the stationary readers. The MDD can reach down to 2.3 and 47 μGy, respectively, for OSL and IRSL measurements of NaCl with the SUERC portable reader. Furthermore, sensitization tests show a dose dependent increase in the OSL and IRSL signals. In addition, the possibility of reading the same pellets more than once was confirmed through an advanced protocol, which combines multiple read-outs, and a time delay test. If a combination of OSL and IRSL measurements is applied, it is important to adjust the stimulation length if the first is OSL, while in the case that the first measurement is IRSL, the OSL signal is independent of the IRSL stimulation length. • OSL and IRSL studies on NaCl pellets made from household salt. • Benchmarking of a portable OSL/IRSL reader for in situ measurements. • Feasibility of mass-screening with NaCl pellets and a portable OSL/IRSL reader. • Development of an advanced protocol to allow re-assessment of the NaCl pellets. [ABSTRACT FROM AUTHOR]

Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients. Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam. Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response. Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilization of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information. This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MRI-scanner and a clinical linear accelerator create new opportunities for inline polymer gel dosimetry. Likewise, the use of cone beam CT on linear accelerators opens up the possibility to read out gel dosimeters on the linac. Multiple optical CT designs have shown that optical CT gel dosimetry is eminently capable of providing high quality dosimetric information from clinically relevant treatment regimes. As a result, gel dosimetry provides exciting opportunities for 3D radiation dosimetry that were not available even a few years ago. The unique feature set of a properly executed gel dosimetry workflow allows for the extraction of dosimetric information, in 3D, that is not possible with any other dosimetry system and hence gel dosimetry provides exciting opportunities for clinical and research work in the area of radiation dose measurement. • The different gel dosimetry methods and readout techniques are discussed. • 3D gel dosimeters are readout by use of either MRI, X-ray CT or optical CT. • The readout method-of-choice depends on the application and availability. • Sources of readout uncertainty are discussed and optimization strategies are provided. • Key applications and future applications of gel dosimetry are highlighted. [ABSTRACT FROM AUTHOR]

A Nuclear Accident Dosimetry program is a federal requirement for all facilities that have the potential to have a criticality accident. Personnel Nuclear Accident Dosimeter (PNAD) theory and analytical procedures are driven by various scientific needs and interacting regulations. A brief history of the status of USA Department of Energy (DOE) nuclear accident dosimetry regulations, recommendations, and performance testing criteria are given. Then, the history of the Lawrence Livermore National Laboratory (LLNL) PNAD is explored, including changes in the physical dosimeter and adjustments of the analysis method through the last four decades. Finally, the performance of LLNL's PNAD at criticality accident intercomparison training exercises since 2009 is explored. In general, reported neutron doses have been within or close to DOE-STD-1098 performance criteria while reported gamma doses have been outside of DOE-STD-1098 performance criteria. Reported total absorbed doses have varied in meeting ANSI/HPS N13.3 and ANSI/HPS N13.3 (R2019) performance criteria. Dosimetry staff retirement and turnover have left historical knowledge gaps, yet provided opportunities within the NAD program at LLNL. This review paper serves as an overview of the history and status of the NAD program. Brief technical, procedural and programmatic recommendations to improve LLNL's NAD program are given. Technical recommendations include investigating orientation factors through modeling or empirical experimentation, investigating gamma dosimetry methods for high-dose scenarios, and exploring other dosimetric methods for simpler, quicker NAD analysis. Procedural recommendations include better documentation of conversion factor (activity-to-fluence and fluence-to-dose) derivations and spectrum uses, and updated analysis spreadsheets or simple Graphic User Interfaces for dose calculations. Programmatic recommendations include formalized training for NAD analysts, and having multiple SMEs trained on the NAD program. • Requirements for Nuclear Accident Dosimetry programs are reviewed. • Provides an overview of the Lawrence Livermore National Laboratory nuclear accident. • Discussion of technical, procedural and programmatic improvements to the NAD program. [ABSTRACT FROM AUTHOR]

In this paper, Lu 2.97 Al 5–x Ga x O 12 :Ce 0.03 (x = 0, 1, 2, 3) nanophosphors were synthesized using sol-gel method and calcined at 1100 °C for 3 h. The effect of Ga content on the structural, photoluminescence (PL), and notably thermoluminescence (TL) glow curve, dose response, repeatability and fading properties were investigated. X-ray diffraction (XRD) results indicated that all synthesized samples were crystallized in a pure garnet phase. The PL emission spectra exhibited a broad emission band corresponding to the 5 d → 4f (2F 5/2 , 2F 7/2) transition of Ce3+ ions in the garnet lattice. Furthermore, a significant decrease in emission intensity was observed upon increasing Ga content. The TL characteristics of nanopowders irradiated with β-rays revealed a significant effect of Ga content on the peak position, shape and intensities of TL Glow curves, which can be explained by the reduction of the energy gap and the distribution of trap levels. The dose response linearity in the range of 0.125–100 Gy was examined for different Ga content, revealing a good linear behavior for x = 0 and 1 Ga. Additionally, samples prepared with x = 0, 1, and 2 Ga exhibited a high level of repeatability across a batch of 10 samples. Also, fading studies were performed for 128 h and revealed strong fading in samples synthesized with x = 0 and 1 Ga. These results suggest potential applications of Lu 3 Al 5 O 12 :Ce and Lu 3 Al 4 Ga 1 O 12 :Ce in ionizing radiation dosimetry. • Lu 3 Al 5-x Ga x O 12 :Ce3+ (x = 0, 1, 2 and 3) nanophosphors were successfully synthesized using sol–gel method. • Thermoluminescence properties of prepared nanophosphors exhibited a strong dependence on Ga content. • Single garnet phase was obtained for all prepared nanophosphors. • Lu 3 Al 5-x Ga x O 12 :Ce 0.03 demonstrated a good linear behavior within the range 0.125–100 Gy for x = 0 and x = 1. • Nanophosphors prepared with Ga content of x = 0 and x = 1 displayed perfect repeatability and indicated a remarkably strong fading. [ABSTRACT FROM AUTHOR]

Air kerma length product and air kerma area product are special quantities used in diagnostic radiology. They are measured using special measurement devices – CT-chambers and KAP-meters, in order to calculate quantities related to patient exposure. Appropriate calibration of all measurement devices is of vital importance, and comparisons between calibration laboratories are necessary to prove competence. It is usually considered adequate to participate in air kerma comparisons to prove capabilities for special quantities, but the literature shows that some problems in calibration procedure can remain unknown. The comparisons directly in terms of special quantities provide additional burden to laboratories, and require special transfer instruments, but they allow checking the whole calibration procedures. This paper describes a comparison between two calibration laboratories in terms of both air kerma length product and air kerma area product. Both laboratories achieved good results for all radiation qualities, considering the measurement uncertainty. Transfer instruments' linearity, field size dependence and energy dependence were investigated. Even though the metrological properties of the transfer instruments are worse than the ionization chambers, they can be taken into account by introducing additional measurement uncertainty, performing appropriate corrections or choosing calibration points for the comparison for the values of influence quantities where the transfer instrument response is relatively flat. These comparisons provide additional value to calibration laboratories, but there are still several challenges related to their organization and execution. • Comparison of calibration factors for KAP-meters and CT-chambers was organized. • All the results for all radiation qualities were acceptable. • KAP-meters and CT-chambers have significant energy and field-size dependence. • Though hard to organize, comparisons for special quantities provide additional value. • Air kerma comparisons should also be accepted, especially for established laboratories. [ABSTRACT FROM AUTHOR]

This paper describes a method enabling the measurement of the potential alpha energy concentration (PAEC) of thoron decay products based on the determined concentration of lead 212Pb (T 1/2 = 10.64 h) in the air [Lever et al., 2003]. A liquid scintillation spectrometer was used to determine the concentration of the 212Pb isotope, and the sample was taken by pumping air through a filter where thoron decay products were stored. This method can be classified as integrating because the sample takes several hours, and the measurement results in one value for the entire sampling period. Measurements were carried out in laboratory conditions, in a climatic chamber where a constant supply of thoron was maintained, and in environmental conditions, in the basement of the family house and outdoors. Sampling took from 12 to 48 h. This article presents the preliminary results of the study. The obtained results were in the range of 170–195 Bq/m3 in the case of laboratory measurements and from 0.04 to 0.79 Bq/m3 in the case of environmental measurements. Based on the obtained results, the potential alpha energy concentration (PAEC) was calculated. The application of the low-level LS spectrometer allows for the achievement of a lower limit of detection (LLD) at level 0.04–0.05 Bq/m3, while the use of the portable LS spectrometer allows for the measurement of deficient 212Pb concentrations in the range of 0.4–0.5 Bq/m3. The obtained results confirm that the method is suitable for determining the concentration of 212Pb and, consequently, assessing exposure to thoron progeny. • It is possible to use the LSC method for Pb-212 measurements in air. • Application of LSC methods allows easy estimation of PAEC values. • It is a very promising method of thoron hazard monitoring. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a test of a methodology to describe the shape of true and accidental coincidence gamma-ray spectra. The effect of the coincidence summing was enhanced by using a 50 kBq 22Na source in a NaI well counter. The spectra were described by convoluting Monte Carlo simulated spectra in a spreadsheet for true, as well accidental coincidence summing. In this paper we show that applying convolution techniques to the MCNP simulated probability spectra, not only allows a reconstruction of the shape of the true coincidence spectrum, but the simulations also prove to be an invaluable tool to understand the continuum in the spectra made up of double and even triple random coincidences. Each of these summing processes was used to generate so-called standard spectra that may be used in a full-spectrum analysis of the measured spectra to quantitatively derive the contributions of each of the summing processes. For the case presented it is shown that the accidental coincidences can be accounted for to a 0.1% level, a considerable improvement to the precision in previous papers. Highlights • A methodology is tested to describe true and accidental coincidence γ-ray spectra by convoluting MC spectra in a spreadsheet. • The simulations prove to be invaluable to understand the continuum in the spectra by 2nd and triple random coincidences. • Accidental coincidences can be accounted for to a 0.1% level, a considerable improvement in precision. [ABSTRACT FROM AUTHOR]

Thallium Bromide (TlBr) single crystal detector is widely recognized as an excellent semiconductor nuclear radiation detector. And its detection performance has already reached commercial level of the majority semiconductor detector. However, the long-term stability of TlBr detector always exhibited a serious polarization effect and the commercial application of TlBr detector is heavily limited. In this paper, the polarization phenomenon, polarization mechanism and the influence of polarization effect on detection performance are systematic investigated. As the metal-semiconductor interface plays an important role in detector performance, two typical metal-semiconductor-metal structure, Au/TlBr/Au and Ti/TlBr/Ti detectors are designed and fabricated in this paper. The XPS in-situ analysis results reveal that different oxidation/reduction reactions would happen at the metal-semiconductor interface of Au/TlBr/Au and Ti/TlBr/Ti detectors. The serious polarization effect in Au/TlBr/Au detectors resulted from the aggregated [AuBr 4 ]- ion at the Au/TlBr interface. Meanwhile, the relative weaken polarization effect in Ti/TlBr/Ti detectors is ascribed to the combined effects of oxidic titanium ions (Ti3+, Ti4+) and metallic Ti–Tl layer at the Ti/TlBr interface. Thus, the detector Ti/TlBr/Ti has a relative better energy resolution and long-term stability compared to detector Au/TlBr/Au. This paper systematic investigate the polarization mechanism and the influence of polarization effects on TlBr detector performance, and this will provide a potential solution to suppress the polarization problem by electrode architecture designing in the near future. • The polarization phenomenon, polarization mechanism and the influence on detection performance are systematic investigated. • Two typical MSM structure, Au/TlBr/Au and Ti/TlBr/Ti detectors are designed and fabricated in this work. • A XPS in-situ measure technology is used to study the reaction mechanism at the interface of Au/TlBr and Ti/TlBr. • The serious polarization effect in Au/TlBr/Au detectors resulted from the aggregated [AuBr 4 ]- ion at the Au/TlBr interface. • The polarization effect of Ti/TlBr/Ti detectors is ascribed to the combined effects of ions (Ti3+, Ti4+) and Ti-Tl layer. [ABSTRACT FROM AUTHOR]

Abstract Signal stability is a key consideration when using luminescence dating techniques. The stability, or lifetime, of a signal is one of the factors determining the upper age constraint for luminescence dating, and it has been suggested that the signal being used for dating should have a lifetime at least ten times the age being dated in order to limit age underestimation to an upper loss of 5%. Accurate derivations of signal stability and associated kinetic parameters, such as trap depth and frequency factor, are also important parameters for constraining rock cooling histories in thermochronometric techniques. This paper aims to assess the reproducibility of lifetime determinations derived using isothermal decay measurements. Variability arising from changing the isothermal decay protocol used is tested. Simulating Arrhenius plot from fixed trap depth and frequency values shows that whilst trap depth can be relatively well constrained, significant variability in the frequency factor, hence signal lifetime, should be expected. This paper also uses luminescence signals measured using different wavelengths to better understand the impact of signal from non-fast quartz OSL components in lifetime calculations. The presence of contributions from non-fast OSL components in the initial part of the OSL signal can result in the lifetime being calculated from charge contributions from multiple traps, not solely the 325 °C TL peak, as has been previously assumed. This effect can be reduced however by stimulating luminescence signals with longer wavelengths to better isolate signal from the fast component. Highlights • Lifetime determinations made using isothermal decay measurements are tested. • Multiple-trap signal contributions can impact lifetime determinations. • Trap depth can be well constrained, but frequency factor is more variable. • Variations in the isothermal decay protocol can lead to variability in E and s. [ABSTRACT FROM AUTHOR]

Abstract Activated charcoal was widely used in radon researches and mitigation applications because of good adsorption ability. In the paper, a simple model that can predict radon removal efficiency (η) for radon mitigation applications using flow-through activated charcoal system was developed based on the previous works. Experiments were conducted with a flow-through activated charcoal system to validate the model and study the influence of factors on η. The experimental results of η are consistent with the theory to within 4% at the flow rates of 1–3 L/min, but range from 2% to 14% at the flow rates of 4–5 L/min. The equilibrium time of radon linearly decreases with rising flow rate, and η decreases with rising flow rate. With moisture competing with radon for adsorption sites on the activated charcoal, radon reaches the equilibrium concentration more quickly than moisture does. As relative humidity increases, η decreases, but the radon equilibrium concentration increases. The values of η are bigger for those smaller particle sizes with the same type of activated charcoal. The results of this paper are useful for designing activated charcoal systems at indoor environmental conditions and predicting η for radon mitigation applications. Highlights • Prediction of radon removal efficiency for radon mitigation applications with activated charcoal systems. • Characteristics of radon mitigation for the flow-through activated charcoal system. • Evaluation of the effectiveness of radon mitigation for activated charcoal systems. • Enables future application to design activated charcoal systems for radon mitigation. [ABSTRACT FROM AUTHOR]

Abstract This review paper provides a description of direct recombination processes between carriers from traps to luminescent centers, involving the occurrence of a tunneling mechanism between their space-correlated localized electronic levels. The experimental evidences that allow to recognize tunneling recombination in phosphorescence time decay and thermoluminescence experiments are first outlined, and compared with those characteristic of recombination processes involving the transfer of carriers in the delocalized bands prior to their recombination. Simple explanations are also proposed for the phenomenological observations in both athermal and thermally assisted tunneling processes. The importance of such recombinations in three material classes – scintillators, persistent phosphors, and dosimeters, is then outlined and discussed in relation to the material requirements in their distinct application fields. For each application, numerous literature examples are reported. Finally, the paper is complemented by a brief illustration of literature investigations describing experimental evidences of direct trap-center recombination different from tunneling, mostly based on the inspection of emission spectra and thermoluminescence glow curve shapes. Highlights • Decription of localized, tunneling recombinations from an experimental and materials science oriented point of view. • Characteristics of athermal recombinations. • Athermal tunneling versus distribution of trap levels. • The role of temperature: thermally assisted tunneling. • Influence of tunneling processes in several material classes - scintillators, phosphors, dosimeters. [ABSTRACT FROM AUTHOR]

Optically stimulated luminescence detectors (OSLDs) have been utilized for various dosimetry applications for many years. The use of Al 2 O 3 :C OSLDs for proton dosimetry began over a decade ago, taking advantage of the correlation between the ionization density of the radiation field and the ratio of intensities of the material's two emission bands. The correlation allows for determining both linear energy transfer (LET) and dose in proton beams, with corrections for ionization quenching derived from the LET. However, the previous methodology for proton dosimetry and simultaneous LET determination with Al 2 O 3 :C OSLDs was cumbersome and occasionally associated with large uncertainties, while carbon beam dosimetry posed further challenges due to an elevated LET. This paper reviews the recent advancements in ion beam dosimetry and LET determination using OSLDs. Employing Al 2 O 3 :C,Mg OSLDs alongside improved, automatized read-out techniques, and the use of other radiation quality metrics than averaged LET, has removed most of the previous obstacles for ion beam dosimetry with OSLDs. The feasibility of simultaneous LET determination and dosimetry in ion beams is demonstrated through two case studies involving realistic proton and carbon ion therapy scenarios. • Overview of LET assessment with OSLDs. • Examples of LET measurements within anthropomorphic phantoms. • Possibilities for ion beam dosimetry with OSLDs. [ABSTRACT FROM AUTHOR]

The hybrid K-edge/X-ray fluorescence densitometer (HKED) is a combination of K-edge absorption technology (KED) and characteristic X-ray fluorescence (XRF), which has the advantages of direct, fast and non-destructive determination, and is an ideal non-destructive measurement technology for uranium and plutonium concentrations. In this paper, a new HKED was developed, primarily utilizing an X-ray tube from COMET, alongside high-purity germanium (HPGe) and cadmium telluride (CdTe) detectors from AMETEK ORTEC. This manuscript delves into several variables that influence measurement outcomes under predefined experimental conditions and operational prerequisites to pinpoint critical parameters. It was discerned that the adoption of a 160 kV high voltage setting markedly diminishes experimental interferences, while the beam current, optimally set at 2 mA, not only ensures a linear correlation with the count rate but also maximizes the effective count detected. The incorporation of a 2 cm fixed-length iron rod along the trajectory between the sample and the detector, complemented by an additional 3 mm external absorber before the KED detector, effectively mitigates direct X-ray exposure, thereby enhancing transmittance values to attainable extents. Subsequent to the determination of these pivotal parameters, validation of the HKED system's efficacy was conducted via performance evaluation tests on a laboratory-scale HKED setup. Measurements undertaken for both KED and XRF across an interval ranging from 300 to 3000 s fell within the 2σ boundary, affirming the system's stability. Repeated measurements of 50 g/L and 150 g/L uranium solutions yielded KED precision rates of 0.56% and 0.19%, respectively. Moreover, linear regression analyses linking transmittance, characteristic X-ray fluorescence, and uranium concentrations across a spectrum of 0–150 g/L underscored the laboratory HKED instrument's robust analytical capabilities. Notably, the relative discrepancy between theoretical predictions and empirical findings for the 150 g/L uranium sample was minimized to a commendable 0.58%. • A new hybrid K-edge/X-ray fluorescence densitometer (HKED) was developed. • Repeated tests of 50 g/L and 150 g/L uranium solutions showed KED precision rates of 0.56% and 0.19%. • The relative discrepancy for the 150 g/L uranium sample was minimized to 0.58%. • This development has significant guiding value for HKED advancement. [ABSTRACT FROM AUTHOR]

The use of luminescence signals from single mineral grains for optical dating has become a valuable and frequently utilised tool in Quaternary Geochronology. Single grain luminescence dating is particularly beneficial in complex depositional settings, however the ability to measure single grain signals also offers the opportunity to assess intrinsic luminescence properties of individual mineral grains. The use of spatially resolved luminescence technologies such as an electron multiplier charge coupled device is of benefit when making luminescence measurements at single grain scales because they allow stimulation with light emitting diodes, and this offers a number of key benefits related to stimulation power when it comes to the assessment of characteristics such as optically stimulated luminescence (OSL) decay rate and the calculation of parameters such as the fast ratio and photo ionisation cross-sections. In this paper, the intra- and inter-sample variability of sensitised single grain thermoluminescence (TL) and OSL signals is considered. A comparison between TL and OSL signals is undertaken, as well as calculation of the fast ratio, OSL component photo ionisation cross-sections, thermal stability, and characteristic dose for a suite of quartz samples from a range of geographic locations and depositional settings. For these heated signals, key findings include the lack of relationship between OSL signal intensity and dominance of the fast component, the fitting of two components (a fast and slow component) is the most common fit for single grain OSL signals, characteristic doses from fast dominated signals suggesting saturation at c. 150 Gy, and the identification of the ultrafast OSL component. Intra-sample variability across all measured parameters is observed, suggesting that for this suite of samples, variability is the norm rather than the exception, and that the intrinsic luminescence characteristics of quartz are variable and diverse. • EMCCD imaging used for measurement of single grain quartz luminescence signal properties • Photo ionisation cross-section values calculated from single grain quartz OSL signals • Although not common, the ultra-fast component is observed in some quartz OSL signals • Thermal stability measurements suggest general stability of the signals measured • Characteristic dose assessment suggests an upper D0 limit of ∼150 Gy for fast dominated signals [ABSTRACT FROM AUTHOR]

X-rays generated by high-energy pulsed electron sources can be utilized in tumor treatment. The time spectrum measurement of pulsed electron sources enables precise treatment and provides feedback to the design and construction of accelerators. In this paper, silica aerogel samples of different densities and thicknesses were prepared as Cherenkov radiator. The transmittance and refractive index of these samples were measured, then the absorption and scattering lengths were calculated on the basis of the obtained transmittance. The obtained results were input into Geant4 software to get the intrinsic luminescence time of the silica aerogel of different densities and thicknesses. Finally, a measurement system was constructed with the silica aerogel samples, and the rise time of this system and the silica aerogel were measured by using a picosecond electron accelerator. The results demonstrate that the rise time of the measurement system is below 180 ps and that of the silica aerogel is less than 54.32 ps. It is also proved that the silica aerogel can be used as the Cherenkov radiator for the measurement of the time spectrum of high-energy pulsed electron sources. • Built an optical properties and time spectrum measurement system based on silica aerogel. • Measured the system time spectrum with a picosecond pulse electron source and obtained the rise time of silica aerogel. • Measured the optical properties of silica aerogel and simulated the Cherenkov light emission by using Geant4 software. [ABSTRACT FROM AUTHOR]

This paper presents a versatile and cost-effective system for the monitoring of X-ray exposure during dental cone beam computed tomography procedures based on silicon PIN photodiode detectors. The system, developed and implemented at the University of Pisa's School of Engineering, underwent characterization under a range of operational conditions focusing on full field-of-view 3D protocols used in adult patient examinations. This study was facilitated by the Azienda Ospedaliero Universitaria Pisana, which provided access to a Planmeca ProMax 3D Classic scanner for the research. During the investigation, photodiodes were placed both on the surface and inside an Alderson RANDO phantom head to assess the dose delivered to regions near radiation-sensitive areas such as the salivary glands, thyroid, eye lens, and laryngopharynx. The evaluation process spanned a spectrum of tube voltages, ranging from 60 to 90 kVp, and tube currents, extending up to 16 mA, to ensure a broad and thorough analysis. Furthermore, to reinforce the effectiveness of the silicon photodiodes' measurement capabilities, calibrated GR-200 A-type thermoluminescent dosimeters were positioned within the phantom head inserts to serve as a reference point. Complementing this setup, PCXMC Rotation 2.0 simulations were conducted to further the efficacy of the monitoring system, particularly tailored to the specific dental CBCT protocols being investigated. In conclusion, while the research revealed a generally consistent correlation across PCXMC simulations, photodiode readings, and thermoluminescent dosimeter measurements, it is important to note that a direct comparison was not exactly possible due to limitations in the size and positioning of the systems. Variations up to 20–35% were observed, primarily due to the different positioning of the dosimeters and the unique physical and operational traits of the different measurement methods employed. Nevertheless, the development of an affordable, easily deployable, and scalable dosimetry monitoring system may provide a substantial contribution to enhancing patient safety in dental radiology and aid in the optimization of diagnostic X-ray protocols. • Dose monitoring in dental CBCT using cost-effective silicon PIN photodiodes. • Photodiodes' calibration against reference detectors for organ dose assessment in 3D dental imaging. • Integration of PCXMC simulations for radiation exposure assessment during dental imaging protocols. • Comparison of TLD measurements and photodiode data to identify absorbed dose trends in dental CBCT applications. [ABSTRACT FROM AUTHOR]

The paper presents results of on-ground (pre-flight) calibrations and flight tests (cross-calibration and in situ measurements) of the new, Modified PILLE-ISS Dosimeters with reduced shielding, developed for the radiation monitoring of astronauts during their extravehicular activity (EVA) on board the International Space Station (ISS). The smaller dimensions and weight of the modified thermoluminescent dosimeter allows ergonomic and safe use during EVA, when the dosimeter kit is worn in the outer pocket of a spacesuit. The special design of the detector housing makes it possible to estimate the dose to the astronaut's skin during EVA more accurately. Both pre-flight calibration with high-energy protons and on-board cross-calibration at ISS showed that the variability of the relative sensitivities does not exceed (5–10)% for any of the Modified PILLE-ISS Dosimeters. The additional dose received by astronauts during ISS EVAs in 2023 was in the range (0.37–0.75) mGy (in water) based on the measurements. The corresponding dose rate outside ISS is consistent with the previous readings of other dosimetric equipment installed on the outer surface of space station. • The Hungarian PILLE-ISS onboard thermoluminescent system is upgraded for the EVA dose assessment. • Calibration with high-energy protons showed low deviation in dose-response (less than 10%) for any dosimeter. • On-board cross-calibration at ISS showed that variability of relative sensitivities does not exceed 10% for any dosimeter. • The additional dose received by astronauts during ISS EVAs in 2023 was in the range 0.37–0.75 mGy (in water). • The measured dose rate inside and outside ISS is consistent with the readings of other dosimetric equipment. [ABSTRACT FROM AUTHOR]

The ongoing war in Ukraine is associated with unprecedented radiological threats to the public in Ukraine and the neighboring countries. This calls for fundamental revision of the preparedness plans and established approaches to radiological monitoring of the populations affected by potential radiological emergencies. Dosimetric information will be needed for triage of victims and support to decision makers for prioritizing mitigation actions. Retrospective dosimetry methods strive to find a solution that would achieve this and enable fast and accurate feedback with information on individual doses to the concerned public. All known approaches to emergency dosimetry, both in biological and physical (instrumental) dosimetry have limitations, in particular – preventive cost, limited availability of samples for analysis, insufficient sensitivity (high dose threshold) and/or stability of radiation-induced markers (i.e. high fading). At the moment each of considered dose assessment methods possesses some combination of the aforesaid limitations. A suggestion to overcome these deficiencies is to use ordinary table salt (NaCl), read by optically stimulated luminescence (OSL), with well-known good dosimetric properties, and which allows anybody to prepare improvised individual dosemeters at home to be carried like a regular personal dosemeter until readout of the OSL signal is possible. This paper considers pros and cons of the use of NaCl as an OSL dosemeter in an emergency situation, with emphasis on practical aspects of its application for mass dose assessments for individuals among populations affected by radiological emergency situations. • Comparison of dosimetry methods for radiological emergencies. • Applicability criteria for emergency preparedness dosimetry. • Review of the dosimetric properties of table salt (NaCl) as emergency OSL dosemeter. • Outlook of application of NaCl for mass dosimetric screening during radiological or nuclear emergency. [ABSTRACT FROM AUTHOR]

Radiophotoluminescence (RPL) has been a key phenomenon in dosimetry. Most materials exhibiting RPL are inorganic single crystals, glasses, and ceramics. Recently, similar phenomena (i.e., fluorescence after irradiation) have been realized in soft matters, such as liquids, gels, and organic solids, on the basis of the radiation-induced production of fluorescent molecules. Dosimeters showing such phenomena are attractive from the viewpoints of their tissue equivalence, flexibility, scalability, and workability. The objective of this paper is to present an overview of such dosimeters with emphasis on the radiation chemical reactions used in the materials. Moreover, the sensitivity and the measurable range is introduced. • Organic solids, gels, and solutions exhibiting RPL are reviewed. • Radiation chemical reactions involved in RPL are introduced. • Comparison is provided among the materials. [ABSTRACT FROM AUTHOR]

- This paper aims to enhance our understanding of the effects of ionizing radiation using radiobiology and biodosimetry techniques applied to living plant organisms. Plants are particularly suitable for this purpose as they are highly sensitive to detecting potential genotoxic agents in the environment and their use allows us to avoid using animals in research in compliance with the 3R principle. Currently, the onion (Allium cepa) is recognized as a valid model for the analysis of environmental pollutants but has been relatively unexplored as an indicator of radiation exposure. In this study, analyses of the genotoxicity of X and alpha radiation were conducted using the micronucleus test and mitotic index analysis. Our results indicate that Allium cepa can be considered a valid alternative model to animal use for assessing the effects of ionizing radiation. In particular, it was found that alpha radiation caused significant damage, as evidenced by an increased number of micronuclei, which was 20 times higher compared to X-ray radiation. This was further confirmed through the observation of the effective dose parameter, as determined by the analysis of various weight factors associated with different types of radiation. • Onion (Allium cepa) serves as a model for studying the effects of ionizing radiation. • The micronucleus assay evaluates genotoxicity of X and alpha radiation. • The correlation between radiation dose and onion damage is studied. [ABSTRACT FROM AUTHOR]

Dose evaluation and direct measurements are fundamental for radiation protection in non-conventional accelerator facilities, both before and after the primary and secondary shielding. In this paper, we will report about the experimental setup, data acquisition and analysis, together with FLUKA modeling, of the dose measurements test carried out in the Beam Test Facility (BTF) of the INFN - Frascati's National Laboratories (LNF), where an intense mixed field is produced and measured with thermoluminescent dosimeters. BTF is an extraction and transport line of DA Φ NE LINAC (Buonomo et al. 2021; Mazzitelli et al. 2003). It is optimized for electrons and positrons production in a wide range of intensity, energy (30 MeV–800 MeV), beam spot dimensions and divergence, using both primary and secondary beam of the DA Φ NE LINAC. Through the years, the BTF has gained an important role in particle detectors test and development with electron/positron beam. A small fraction of the BTF's shifts have been dedicated to radiation damage test using LINAC electron primary beam up to 5 × 1 0 10 e-/s. As radiation protection group of the LNF, we evaluated the dose when electrons impinging on a Pb target from: (i) photon Bremsstrahlung production; (ii) photoneutron production. Three dedicated tests with 503 MeV electrons impinging on a ∼ 16 cm thick Pb target have been carried out in February, June 2022 and in January 2023, using TLD700 and TLD600, measuring doses at several charge intervals. The aim of this study focuses on evaluating dosimetric quantities produced by the mixed field, air kerma for the photon component, and ambient dose equivalent for the neutron one, using thermoluminescence dosimeters calibrated with low-energy standards: Cs-137 and Am-Be. The approach adopted involves the use of Monte Carlo simulations of the experiment, both to benchmark against experimental measurements and to validate the results obtained for energies higher than those of calibration. The results of this comparison show excellent agreement between measured and simulated quantities in the forward direction, allowing us to conclude and confirm the validity of the calibrations themselves. • Fundamental dose evaluation and measurements in non-conventional accelerator facilities. • Experimental setup, data acquisition, and analysis at LNF-INFN's Beam Test Facility. • Dose measurements up to 500 MeV using TLD700 and neutron detector, calibrated sources. • Evaluation of air kerma for photons and ambient dose equivalent for neutrons. • Validation via FLUKA simulations for energies beyond calibration. • Measured and simulated quantities confirm calibration validity at higher energies. [ABSTRACT FROM AUTHOR]

The Paul Scherrer Institute is a unique Swiss research institute that operates five large-scale research facilities in which different types of particles, such as electrons, protons, neutrons, pions and muons, are accelerated or produced. Depending on the facility and location, the operational radiation protection has to deal with challenging measurements of mixed radiation fields, which can be in addition pulsed and of high-energy. In this article, we provide insight into the associated demands and challenges using two examples with different requirements for the monitoring technology. Using the example of the high-intensity proton accelerator (HIPA), the measurement technology around high-energy accelerators is examined in more detail. On the other hand, the problems of measuring technology for pulsed radiation and its dynamic range are discussed using the example of the Swiss X-ray free electron laser SwissFEL. The aim of this paper is to highlight the different requirements and technical challenges in radiation measurements for such complex facilities and, thus, to raise awareness and provide a stimulus for further developments in measurement technology. • Operational radiation protection must deal with various complex radiation fields. • Ensure the correct radiation protection measurement technology is used. • Not all rem counters are adequate for use around existing high-energy accelerators. • At pulsed radiation fields the actual dose can be underestimated. [ABSTRACT FROM AUTHOR]

Federal Regulations of the United States require that installations possessing sufficient quantities of fissile material to potentially constitute a critical mass, such that the excessive exposure of individuals to radiation from a nuclear accident is possible, shall provide appropriate nuclear accident dosimetry. The American National Standard ANSl/HPS N13.3–2013 Dosimetry for Criticality Accidents provides technical, quality assurance, and performance requirements for nuclear accident dosimeters (NAD). In 2023 the U.S. Navy operated 82 nuclear-powered ships, with the fleet being composed of 11 aircraft carriers, 68 submarines, having a total number of 98 reactors. Since 1968 the U.S. Navy has used fixed nuclear accident dosimeters (FNAD) mounted to the bulkheads surrounding naval nuclear propulsion reactors. Since 1968 the US Navy has used two nuclear accident criticality dosimeters. The first Navy accident dosimeter DT-518/PD was introduced in 1968. It was developed by the Naval Radiological Defense Laboratory in San Francisco, California under leadership of Eugene Tochilin. This dosimeter contains two indium foils for quick dose assessments using shipboard gamma instruments available on nuclear powered vessels and two sulfur pellets/LiF TLD-700 powder for final dose determination at the Naval Dosimetry Center. The newest Navy NAD is the DT-723/PD, which contains indium foil, gold foil, cadmium shielded gold foil, sulfur pellet and a LiF TLD-700 chip. This paper provides a brief description of the measurement procedures, results of the testing of both NADs and comparison of their performance. • United States Navy nuclear fleet and number of nuclear reactors. • History United States Navy accident dosimetry program. • Nuclear accident dosimeter DT-518/PD. • Nuclear accident dosimeter DT-723/PD. [ABSTRACT FROM AUTHOR]

Gamma-ray coded-aperture imaging technology plays an important role in nuclear security, decommissioning of nuclear facilities, and nuclear medicine diagnosis. However, under near-field imaging condition, artifacts in the reconstructed image can interfere with identifying the shape and position of the radioactive source. In this paper, a gamma-ray coded-aperture imaging method based on mask and anti-mask functions was proposed to suppress imaging artifacts and speed up the acquisition of low-noise reconstructed images. Through simulation, the effects of the number of iterations and the thickness of the coded-aperture collimator on the imaging quality were studied, and the range of the optimal correction factor in the method was determined. Imaging experiments were conducted using a compact coded-aperture gamma camera based on CdZnTe detector to verify the applicability of the optimal correction factor range. The limitations of the proposed method were analyzed through complex-shaped source imaging simulations and multi-source imaging experiments. This method has an insufficient suppression effect on random artifacts and requires further improvement in imaging irregular radioactive sources. However, it has good imaging performance for single-point source and multi-point sources, effectively reducing regular cross-shaped and stripe-like artifacts. In the non-uniform radioactive background, it can eliminate a part of artifacts, significantly improving imaging quality. Therefore, this method has potential applications in complex radioactive environments. • Improvement of a coded-aperture imaging method. • Suppress the artifacts of coded-aperture imaging. • Artifact suppression is better than the MLEM method. • Simulation and experimental validation. [ABSTRACT FROM AUTHOR]

This paper describes the development of 3D-printed dosimeters made from radiochromic materials. Incorporating polymethyl methacrylate (PMMA) as a transparent polymer matrix and leuco-crystal violet as a radiochromic dye, these dosimeters exhibit a color change when exposed to radiation. This change provides a way to visualize and measure three-dimensional dose distributions, which is important for the accurate verification of radiation doses in radiotherapy. The use of 3D printing technology allows these dosimeters to approximate human organ geometries, which may contribute to safer and more effective radiotherapeutic applications. The dosimeters can be customized into various shapes and sizes, are lightweight, and cost-effective, making them appropriate for use in both clinical and research settings in radiotherapy. The fabrication process is detailed, and the dosimeters have been tested at doses up to 100 Gy in X-ray irradiation and analyzed for dose distribution. Bragg-peak measurements from carbon beam irradiation illustrate the dosimeters' capability to detect peak radiation doses with a spatial resolution of approximately 1 mm. These findings indicate the potential of these 3D printed dosimeters to improve the accuracy of radiation delivery, which could positively impact patient outcomes in radiotherapy. • Innovative 3D-printed dosimeters using radiochromic materials. • Tailored dosimeter using FDM technology. • Leuco-crystal violet in a PMMA matrix allows for visible color changes upon radiation exposure. • Experimental validation including carbon ion beam irradiation. • Overcame transparency and fidelity challenges in 3D printing. [ABSTRACT FROM AUTHOR]

In the present work, the microdosimetric one-hit detector model is evaluated by calculating the relative energy response of radiographic films. A small sample of typical radiographic films including the covering paper and the polyester base coated on by one emulsion layer is simulated by Geant4 toolkit. Silver bromide grains with the same cubical shape and dimensions of 1 μm randomly positioned in the emulsion are considered as the targets of the model. The relative energy response for eleven photon energies between 20 keV and 1.25 MeV is determined using the microdosimetric distributions of single energy deposition events in the grains. Calculations are performed for a few weight fractions of the silver bromide in the emulsion. The results show that for the weight fraction 13.3% of the silver bromide in the emulsion, calculated values of the relative energy response are in agreement with the experimental data within 20% difference. It can be concluded that the microdosimetric one-hit detector model satisfactorily predicts the energy response of radiographic films. [ABSTRACT FROM AUTHOR]

This paper presents the properties of alpha particle tracks in a polymer, known as Durolon®. The study involves measurements of the time-dependent evolution of etch pit diameters and areal densities for low-energy alpha particles under various etching conditions, including different temperatures and solutions. A time-dependent model was successfully employed to describe the etch pit growth rates. Additionally, optical absorption and Raman spectroscopy techniques were applied to the samples under investigation, complementing the traditional results obtained through optical microscopy. The suitability of Durolon® polymer as a nuclear track detector is discussed based on the results obtained from the aforementioned complementary techniques. In summary, this research represents a critical step toward establishing Durolon® polymer as a viable nuclear track detector. • Durolon Polymer: A robust solid-state nuclear track detector for radiation monitoring. • Characterization of durolon polymer through various chemical etching techniques • Assessing alpha particle-induced damage to durolon polymer structure. • UV–vis spectroscopy investigation using an understudied durolon polymer. • Raman spectroscopy insights into durolon polymer's molecular structure. [ABSTRACT FROM AUTHOR]

Past exposure to indoor thoron poses a significant risk for lung cancer. A method based on home-stored CDs/DVDs allows the estimation of past exposure through retrospective thoron measurements. However, these measurements are significantly affected by the geometry of the CD-case. In this paper, an improved a posteriori calibration procedure is proposed that mitigates the CD-case effect, enabling the estimation of the disk's calibration factor with uncertainty of about 20%. The influence of the temperature, pressure and humidity on the thoron measurements is also studied and no effect is observed. The CD method overcomes a major source of error in evaluating the past thoron exposure related to the yearly changes in indoor thoron that could even reach an order of magnitude. • Prospective measurements introduce bias in Tn dose assessment due to Tn yearly-variations. • Retrospective Tn measurements by home-stored CD/DVDs overcome this bias. • The study investigates environmental factors and CD-case geometry effects on the measurements. • Temperature, air pressure and humidity show no significant influence on the measurements. • A-posteriori calibration procedure is proposed to mitigate the effect of the CD-case. [ABSTRACT FROM AUTHOR]

Background reconstruction stands as a critical technique for diverse domains, such as signal isolation for gamma spectroscopy, pre-testing of radiation shielding designs, and environmental monitoring. Traditional methods aim to seek the optimal intensity of the background source under a fixed spatial distribution. However, their efficacy is often constrained due to the limited number of variable parameters, resulting in inadequate degrees of freedom and suboptimal performance. This paper introduces an innovative method for background reconstruction, aiming to overcome the limitations of existing approaches. The proposed technique involves the simultaneous adjustment of both intensities and shell thicknesses of a series of monoenergetic sources, modeled as spherical shells. The reconstructed spectrum is conceptualized as a superposition of simulated spectra from these sources, with the optimized parameters being the intensity and thickness of each source. The objective is to minimize the disparity in regions of interest (ROIs) between reconstructed and target spectra through a multivariate nonlinear optimization process, incorporating distinct weight factors for each ROI. The efficacy of the proposed method is validated using a simulation-generated theoretical spectrum. Results demonstrate successful reconstruction, with a high overall concordance between reconstructed and target spectra, showcasing reliability of the method. Subsequently, the method is applied to the reconstruction of an experimental spectrum, and a comparative analysis with a fixed spherical shell thickness method reveals the superior agreement of our proposed method with the experimental spectra. • Novel method for gamma spectrum reconstruction. • Spherical shell model optimizes intensity and thickness. • Multivariate nonlinear optimization. • Validation using simulation and experimental data. [ABSTRACT FROM AUTHOR]

We report a preliminary study of phototransferred thermoluminescence (PTTL) induced by 470 nm light source in rose quartz. The glow curve corresponding to 1 Gy consists of five peaks at 76, 115, 180, 290 and 423 °C labelled I through V in that order. In the PTTL experiments employing blue light. PTTL was regenerated at peak I following preheating to remove peak I only and at peaks I and II otherwise. The dependence of the PTTL intensity on duration of illumination is analyzed in terms of a system of one acceptor and two donors in both cases. The mechanisms for the PTTL phenomena in the rose quartz are comprehensively discussed in this paper. • Phototransferred thermoluminescence (PTTL) of rose quartz induced by 470 nm is reported. • The sample presented five TL glow peaks at 76 °C (I), 115 °C (II), 180 °C (III), 290 °C (IV), and 423 °C (V). • Only peaks I and II are reproduced by PTTL using blue light. • The pulse annealing showed peaks I and II likely present one acceptor and two donors in the PTTL signal. • Dependence on illumination time results shows a good fit when using the equation based on one acceptor and two donors (peak I and II), demonstrating a good correlation between pulse annealing prediction and the model. [ABSTRACT FROM AUTHOR]

Quality control and assurance of mammography X-ray generators include the use of solid-state detectors and/or ionization chambers calibrated in standard reference radiation fields. The IEC 61267:2005 standard defines reference mammography radiation fields for Mo/Mo anode/filtration, while various anode/filtration combinations are encountered in clinical mammography X-ray units. Not all Secondary Standard Dosimetry Laboratories have an X-ray generator with Mo/Mo radiation setup. Thus, traceability can be established only for the available anode/filter combinations, commonly limited to W/Al. In this study, W/Al radiation fields were established under laboratory conditions by performing half-value layer measurements. Then, four solid-state detectors were characterized. X-ray multimeter performance was evaluated in terms of energy response in the W/Al radiation fields. In the laboratory conditions, the energy response of the dosimeters had a large deviation from unity for dosimeters without appropriate anode/filter combination selected in the software settings, even though most of the dosimeters had a uniform relative response. The discrepancy in the response was further investigated by examining its variation induced by available detector software settings, and it was determined that the dosimeter response can vary up to 20 %. In a clinical setup, the half-value layer was determined, and detector performance was examined. Dosimeters were tested in clinical fields with Mo/Mo, Mo/Rh, W/Rh, W/Ag anode/filter combinations in the X-ray tube voltage range from 25 kV to 35 kV. For most clinical radiation fields, multi-element detectors had energy response deviation within ±5 %. The single-element detector had one software setting available and exhibited strong energy dependence. Extensive testing of detector response, such as presented in this paper. allows for correction factor interpolation based on the half-value layer. • IEC standard defines mammography reference radiation fields only for Mo/Mo. • Clinical mammography spectra differ due to various anode/filtration materials used. • Non-standard W/Al qualities for laboratory calibration purposes were developed. • Software induced changes in X-ray multimeter response for W/Al fields were examined. • Performance of X-ray multimeters in clinical mammography beams was evaluated. [ABSTRACT FROM AUTHOR]

The thermoluminescent material CaF 2 (Tm), known as TLD-300 (Harshaw/Bicron), shows a remarkable dependence of its glow curve shape on the quality of the radiation field. The quotient of high-temperature (maximum at about 265 °C) and low-temperature peaks (maximum at about 175 °C) depends strongly on LET (ions) and photon energy. The shape of the glow curve is parameterized by the high-to-low-temperature ratio, HLTR, a decreasing function of photon energy. Our goal has been to investigate the TLD-300 glow curve shape for six photon energies between 6 and 28 keV, and to apply this extended HLTR calibration to determine the effective energy of triboluminescence-generated X-rays (TGXs) produced when peeling adhesive tape in vacuum. For calibration, TLD-300 chips were exposed to X-rays from a W-anode tube (9.7–27.7 keV effective energies), X-rays from a Cu-anode tube (8.0 keV) and a 55Fe radioactive source (5.9 keV). The chips were subjected to an annealing protocol designed to improve the stability of the low-temperature peaks. Doses were low and deconvolution into 7 peaks was performed with custom-made software. For the TGXs investigation, TLD-300 chips and TLD-100 microcubes were exposed inside a vacuum chamber to radiation generated by the peeling of adhesive tape from its own backing. The dosimeters, located at different angular positions with respect to the tape, were covered with a 21-μm thick layer of Mylar (Dupont Tejjin Films) to eliminate stray radiation and block any UV light that may be emitted along with the TGXs. TLD-300 were thermally handled as in calibration, and the HLTR indicated the effective energy. Microcubes were used as monitors of a controlled exposure. The new calibration data confirmed the previous trend and showed consistency with existing HLTR measurements above 30 keV (after correcting by the different annealing procedures). The TGXs TLD-300 glow curves showed the presence of a low-temperature peak below those included in the usual deconvolution. The measured HLTR indicated effective energies close to 7 keV and constant over a wide range of observation angles. The extended calibration validates the use of this technique to evaluate photon energies below the limits investigated previously. For the investigation of TGXs, TLDs have been used as passive dosimeters, offering new possibilities in cases where pileup would be a limiting factor for active solid-state active detectors. The difference in glow curve shapes between the TGXs and the calibration photons offers a tool for further investigation of processes induced by surface electrification. • The glow curve shape of CaF 2 (Tm) depends on the incident energy. • The high-to-low-temperature ratio (HLTR) parameter quantifies glow curve shape. • Calibration of HLTR for x-ray energies extended to 5.9 keV–1250 keV. • Triboluminescence X-ray effective energy from peeling-off tape was (7.0 ± 0.9) keV. [ABSTRACT FROM AUTHOR]

The time projection chamber (TPC) is based on detailed recording of particle ionization processes and can achieve three-dimensional measurement of particle tracks. Therefore, it has broad application prospects in fission cross section measurement. This paper introduces a TPC for measuring fission cross sections and tests the particle identification ability of this detector using a252Cf source. The measured branching ratio of α/SF is very close to the standard value, with a relative error of 3.83%. • This work tests the particle identification ability of a new type of TPC detector using a 252Cf source. • This work introduces an algorithm for TPC particle track reconstruction. • We use this detector to measure the α/SF branching ratio of 252Cf , with an error of 3.83 compared to the reference value. [ABSTRACT FROM AUTHOR]

Within the EURADOS (European Radiation Dosimetry Group) self-sustained programme of regular intercomparisons (ICs) for individual monitoring, three campaigns had been performed in 2012, 2017 and 2022 to assess the performance of neutron personal dosemeters routinely used to measure personal dose equivalent, H p (10). The irradiation schemes were established to provide participants with useful information regarding linearity, reproducibility and response of their dosimetry systems at different energies and angles of incidence. Small alterations were made in irradiation plans for subsequent exercises. Combinations of standard calibration fields and simulated workplace fields were employed, using bare and moderated neutron sources as well as monoenergetic and thermal neutron fields. Neutron energies used to evaluate dosemeter performance ranged from thermal to several MeV. Dose values varied between 0.3 mSv and 15 mSv. The number of participating laboratories in the three campaigns was stable: 31 in IC2012n, 32 in IC2017n and 29 in IC2022n. The dosimetry systems could have been categorized according to their detection principle into albedo and track dosemeters, or a combination of both. In 2012, a category 'other' had to be introduced to consider active personal dosemeters and fission track detectors. In 2012, participants were asked to provided results in a two-step procedure: (i) with no information on the radiation fields, and (ii) after receiving additional simplified a priori information on the energy distribution of the neutron fields to enable correction for dosemeter response. In 2017 and 2022, based on a one-step procedure, however, participants might have requested a priori information upon registration, which was reported in the certificate of participation. Intercomparison results were analysed against the acceptance criteria of the ISO 14146:2018 standard, although there were no standardized performance requirements for neutron personal dosemeters at the time of IC2012n. The paper compares the results of the three exercises, identifies major problems for individual monitoring services and shows trends in dosimetric performance. In all three intercomparisons, a few systems had shown problems related to calibration. Data do not allow to draw a universally applicable conclusion with regard to potentially superior performance of one particular dosimetry system. • Results from three EURADOS inter-comparisons on neutron dosimetry for individual monitoring. • Performance of neutron personal dosemeters tested in various radiation fields. • Statistical overview of personal dosemeter responses. [ABSTRACT FROM AUTHOR]

In fibers made from organic plastic scintillators, a combination of extrinsic and intrinsic effects results in the attenuation of light and thus in a position-dependent light yield. The trapping of photons can further be affected if fibers are coated with or wrapped in a light-absorbing or reflecting material to suppress optical cross-talk. These effects have frequently been studied for long (> 0. 5 m) fibers, yet little data is available for shorter ones. We experimentally studied the position-dependent light yield of single-cladded Kuraray SCSF-78 fibers with lengths of < 10 cm and tested the effect of different cross-talk-preventing materials. Contrary to the often acceptable simplification that light is transmitted in the fiber core alone, we found that photons trapped by the protective cladding significantly contribute to the light transmission in short fibers. In this paper, we perform an in-depth characterization of the position-dependent light yield of fibers sputter-coated with aluminum and wrapped in aluminum foil using a double-exponential attenuation function. Finally, we compare our findings to a simple photon transport model. • Attenuation results in a position-dependent light yield in scintillating fibers. • Coating or wrapping fibers to prevent optical cross-talk changes attenuation. • Light yield in short scintillating fibers is strongly position-dependent. • Photon transport in the fiber cladding contributes significantly to light yield. • Sputter-coating with aluminum is best and easiest method for cross-talk prevention. [ABSTRACT FROM AUTHOR]

This paper compares the performance of four different Tissue-Equivalent proportional counters (TEPC) first in standard radiation fields, with gamma and neutron sources, then in the mixed and complex/intense neutron and photon stray radiation field of a scanning proton therapy facility. The paper focuses on the dead time correction and introduces a new spectra processing methodology to enable the comparison of the four TEPCs while accounting for their different gas filling and gain, lineal energy range of the spectrum and the analysis methodology. Measurements with 137 Cs and/or 60 Co gamma sources demonstrate variable low-LET threshold for each TEPC while data acquired with a 252 Cf neutron source show comparable response of the four TEPCs for high-LET particles. Meanwhile, in the scattered field of proton therapy, microdosimetric spectra measured at different positions and orientations around the patient show a majority of high-LET events at the smallest angle with respect to the beam axis while low-LET particles were mainly dominant at 90° from the beam axis. The introduced processing methodology led to good overlapping of microdosimetric spectra for the four systems. [ABSTRACT FROM AUTHOR]

This paper reviews recent research on the application of the physical dosimetry techniques of electron paramagnetic resonance (EPR) and luminescence (optically stimulated luminescence, OSL, and thermoluminescence, TL) to determine radiation dose following catastrophic, large-scale radiological events. Such data are used in dose reconstruction to obtain estimates of dose due to the exposure to external sources of radiation, primarily gamma radiation, by individual members of the public and by populations. The EPR and luminescence techniques have been applied to a wide range of radiological studies, including nuclear bomb detonation (e.g., Hiroshima and Nagasaki), nuclear power plant accidents (e.g., Chernobyl), radioactive pollution (e.g., Mayak plutonium facility), and in the future could include terrorist events involving the dispersal of radioactive materials. In this review we examine the application of these techniques in ‘emergency’ and ‘retrospective’ modes of operation that are conducted on two distinct timescales. For emergency dosimetry immediate action to evaluate dose to individuals following radiation exposure is required to assess deterministic biological effects and to enable rapid medical triage. Retrospective dosimetry, on the other hand, contributes to the reconstruction of doses to populations and individuals following external exposure, and contributes to the long-term study of stochastic processes and the consequential epidemiological effects. Although internal exposure, via ingestion of radionuclides for example, can be a potentially significant contributor to dose, this review is confined to those dose components arising from exposure to external radiation, which in most studies is gamma radiation. The nascent emergency dosimetry measurement techniques aim to perform direct dose evaluations for individuals who, as members of the public, are most unlikely to be carrying a dosimeter issued for radiation monitoring purposes in the event of a radiation incident. Hence attention has focused on biological or physical materials they may have in their possession that could be used as surrogate dosimeters. For EPR measurements, in particular, this includes material within the body (such as bone or tooth biopsy) requiring invasive procedures, but also materials collected non-invasively (such as clippings taken from finger- or toenails) and artefacts within their personal belongings (such as electronic devices of which smart phones are the most common). For luminescence measurements, attention has also focused on components within electronic devices, including smartphones, and a wide range of other personal belongings such as paper and other polymer-based materials (including currency, clothing, bank cards, etc .). The paper reviews progress made using both EPR and luminescence techniques, along with their current limitations. For the longer-established approach of retrospective dosimetry, luminescence has been the most extensively applied method and, by employing minerals found in construction materials, it consequently is employed in dosimetry using structures within the environment. Recent developments in its application to large-scale radiation releases are discussed, including the atomic bomb detonations at Hiroshima and Nagasaki, fallout from the Chernobyl reactor and atmospheric nuclear bomb tests within the Semipalatinsk Nuclear Test Site and fluvially transported pollution within the Techa River basin due to releases from the Mayak facility. The developments made in applying OSL and TL techniques are discussed in the context of these applications. EPR measurements with teeth have also provided benchmark values to test the dosimetry models used for Chernobyl liquidators (clean-up workers), residents of Semipalatinsk Nuclear Tests Sites and inhabitants of the Techa River basin. For both emergency and retrospective dosimetry applications, computational techniques employing radiation transport simulations based on Monte Carlo code form an essential component in the application of dose determinations by EPR and OSL to dose reconstruction problems. We include in the review examples where the translation from the physical quantity of cumulative dose determined in the sampled medium to a dose quantity that can be applied in the reconstruction of dose to individuals and/or populations; these take into account the source terms, release patterns and the movements of people in the affected areas. One role for retrospective luminescence dosimetry has been to provide benchmark dose determinations for testing the models employed in dose reconstruction for exposed populations, notably at Hiroshima and Nagasaki. The discussion is framed within the context of the well-known radiation incidents mentioned above. [ABSTRACT FROM AUTHOR]