On the feasibility of polymer fibers with mineral filler as emergency dosimeters

The objective of this study is to examine the possibility of using the thermoluminescence (TL) of polymer fibers containing ground calcium carbonate (CaCO3 ) mineral fillers as emergency dosimeters. Calcite, consisting mostly of CaCO3 , is a TL material that exhibits two distinct TL peaks that can be exploited for dosimetry and is a naturally occurring mineral that is ubiquitously in use in everyday materials.

Radiation Measurements 153 (2022) 106718 Contents lists available at ScienceDirect Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas On the feasibility of polymer fibers with mineral filler as emergency dosimeters Oskari Ville Pakari a , Eduardo Gardenali Yukihara a , Dariusz Jakub Gawryluk b , Lily Bossin a ,∗ a b Department of Radiation Safety and Security, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland ARTICLE INFO ABSTRACT Keywords: Emergency dosimeter Polymer fiber Mineral filler Calcite Thermoluminescence The objective of this study is to examine the possibility of using the thermoluminescence (TL) of polymer fibers containing ground calcium carbonate (CaCO3 ) mineral fillers as emergency dosimeters Calcite, consisting mostly of CaCO3 , is a TL material that exhibits two distinct TL peaks that can be exploited for dosimetry and is a naturally occurring mineral that is ubiquitously in use in everyday materials Polymer fiber materials with CaCO3 are already produced at scale e.g for common surgical face masks or surgical gowns, opening the possibility of using such materials as fortuitous dosimeter in emergency situations To assess the feasibility of such materials as dosimeters, we examined the TL properties of two CaCO3 powders as well as commercially available surgical face mask samples The results indicate that the TL emissions across all samples stem from calcite and are in principle usable for dosimetry We discuss limitations that arise from the fading properties and the potentially complex TL background As a case example for emergency dosimetry, we examined samples from a commercially available surgical face mask The face mask was found to exhibit a minimum detectable dose to the order of ∼2 Gy, under laboratory conditions We provide an outlook on how the materials and methods can be improved for radiological dose assessment Introduction A fortuitous detector (Bailiff et al., 2016), in the form of an item or material that the average person is likely to have on them during the exposure, could aid in determining such doses The material hereby has to fulfill a range of properties, such as stable proportionality to received dose, a minimum detectable dose (MDD) well below the aforementioned Gy, ubiquity among the population, as well as simplicity and speed of the dose information retrieval For emergency and fortuitous dosimetry is it thus of interest to investigate a wide range of materials for their suitability as radiation dosimeters Previously examined possibilities for this purpose include mobile phones (Inrig et al., 2008; Eakins and Kouroukla, 2015), ibuprofen (Mrozik and Bilski, 2021), or mineral filler containing faux-leather bags (Bossin, 2019; Bossin et al., 2020) using both thermoluminescence (TL) or optically stimulated luminescence (OSL) methods Calcite is an abundantly occurring TL mineral that has found numerous applications e.g as construction materials, fertilizer, and, particularly of interest for this work, as fillers in polymer plastics to improve features such as water resistance, cost, ergonomy and breathability (Katz et al., 1987; Brunner et al., 2019) A typical filler consists of ground CaCO3 processed from calcite Large-scale radiological events can potentially result in the exposure of large numbers of individuals to doses of ionizing radiation that warrant acute medical care to maximize the odds of survival (Coleman et al., 2011) Following events such as an urban nuclear detonation, the number of casualties would quickly exceed local hospital capacities (Knebel et al., 2011) leading to crisis standards of care (Institute of Medicine, 2009) and triage procedures to be implemented (Caro et al., 2011) In such a triage scenario the decision making ought to be guided by objective information to separate the worried-well from those who require immediate care The speed, sensitivity, or specificity of white blood cell counts or other acute radiation syndrome symptoms is estimated to be well below and often insufficient compared to that of direct information on the dose (Jaworska et al., 2014) Based on data of victims of the Chernobyl power plant accident (Guskova et al., 1988) it is estimated that below a received dose of around Gy no immediate care is required (Jaworska et al., 2014) Useful dose information must therefore meet a given sensitivity and specificity around this decision threshold ∗ Corresponding author E-mail addresses: oskari.pakari@psi.ch (O.V Pakari), lily.bossin@psi.ch (L Bossin) https://doi.org/10.1016/j.radmeas.2022.106718 Received 27 November 2021; Received in revised form 19 January 2022; Accepted 30 January 2022 Available online 12 February 2022 1350-4487/© 2022 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/) Radiation Measurements 153 (2022) 106718 O.V Pakari et al Polymer fiber materials with CaCO3 filler are already produced at commercial scale e.g for common surgical face masks or surgical gowns, opening the possibility of using such materials as fortuitous TL dosimeter in emergency situations Due to the ongoing SARS-COV-2 pandemic, many countries mandate the regular use of common surgical face masks (Chua et al., 2020), fulfilling the ubiquity requirement Finally, a polymer plastic may cover a larger area of the body and could be sampled in different locations to also give information on the dose distribution We therefore identified beneficial characteristics ranging from cost, availability, spatial information, as well as widespread fortuitous use Calcite is already a well studied TL material (Medlin, 1959; Calderon et al., 1984; Sunta, 1984; Medlin, 1964) The typical TL glow peak structure contains two prominent peaks at around 110 ◦ C (Peak 1) and 270 ◦ C (Peak 2), see e.g Down et al (1985) The luminescence mechanism is believed to stem from Mg impurities acting as recombination centers Calcite exhibits a native signal in the thermally stable TL peak region that can be used for dating (Debenham, 1983; Ninagawa et al., 1992) With no appreciable OSL response, calcite may thus also prove less light sensitive than other TL materials The objective of this study is to examine the potential of using the TL of polymer fibers containing calcite mineral fillers as emergency dosimeters To achieve this, we compare X-Ray Diffraction and TL characteristics of two different commercial calcite powders and a commercially available face mask We then discuss the minimum detectable dose and the limitations of the case example of the face mask used for emergency dosimetry Fig (a) Scanning electron micrograph of polypropylene fibers that contain 10% Omyafiber 800 b) Scanning electron micrograph of cross section of a single polypropylene fiber containing 10% Omyafiber 800 Both pictures are courtesy of Omya International AG (Brunner et al., 2019) Materials and methods 2.3.1 Coarse calcite powder the literature (Falini et al., 1998; Effenberger et al., 1983; BouletRoblin et al., 2017) Refined parameters were: scale factor, atomic positions, and isotropic thermal factors Due to the powdered crystals’ nature, a preferred orientation correction as a March–Dollase multiaxial phenomenological model (Dollase, 1986) was implemented into the analysis of some patterns 2.3 Samples As a reference for the behavior of natural calcite, the commercial product Nekafill 15 by Kalkfabrik Netstal Switzerland was acquired It is ground calcite powder used e.g as additive for concrete or mortar Sieving analysis showed 0.0% remainder at a mesh size of 0.5 mm, and 18.7% at 0.063 mm The powder furthermore has a manufacturerreported MgCO3 content of about 1.5% Filling the bottom surface of the measurement cups uniformly lead to a use of about 15 mg of powder per sample Hereafter we refer to this powder as coarse calcite powder 2.1 TL measurements TL measurements were performed using the Risø reader (TL/OSLDA-20, DTU Nutech, Denmark) The samples were placed in stainlesssteel cups With a built-in 90 Sr/90 Y source for beta irradiations, the system allows for convenient subsequent TL readout The source’s dose rate was calibrated in air kerma using the OSL response of thin Al2 O3 :C films to a Cs-137 irradiation performed at the Paul Scherrer Institut (PSI) Calibration Laboratory, giving 35 mGy s−1 using the method described in (Yukihara et al., 2005) The TL curves were acquired with a photomultiplier tube (PMT; type ET Enterprises PMD9107Q-AP-TTL; quantum efficiency less than 10% at 600 nm) with no additional filters aside from the built-in silica windows TL spectra were measured using an Andor iXon Ultra 888 EMCCD attached to Andor’s Kymera 193i spectrometer (grating 150 lines/mm with a center wavelength at 500 nm, CCD pre-cooled to −60 ◦ C) A spectral correction obtained with a calibration lamp was applied (See Supplementary Figure A.11) For phototransfer experiments shown in this work we used a UV light emitting diode (385−410 nm primary wavelength, 12 nm full width at half maximum (Lapp et al., 2015), irradiance of 520 mW cm−2 at the sample position (model LZ400UB00, LED Engin, Inc.) 2.3.2 Fine calcite powder As an example of a more finely ground calcite powder that corresponds to a filler product, we used Omyafiber 800 by Omya International AG, Switzerland, a global producer of industrial minerals derived mostly from calcium carbonate, dolomite, and perlite The powder is manufactured from natural calcite that is ground and then surfacetreated with a proprietary chemical agent that improves the properties of the subsequent dispersion into the polymer A scanning electron micrograph (SEM) image of the powder in a polymer fiber is shown in Fig Similarly to the calcite powder, we used about 15 mg of powder per sample Hereafter we refer to this powder as fine calcite powder 2.2 Powder X-Ray Diffraction 2.3.3 Surgical face mask Powder X-Ray Diffraction (XRD) measurements were conducted at room temperature in the Bragg–Brentano geometry using a Bruker AXS D8 Advance diffractometer (Bruker AXS GmbH, Karlsruhe, Germany) equipped with a Ni-filtered Cu K𝛼 radiation and a 1D LynxEye PSD detector Data analysis (Rietveld, 1969) of the diffraction patterns was performed with the package FULLPROF SUITE (Rodríguez-Carvajal, 1993; Roisnel and Rodríguez-carvajal, 2001) (version July-21) using a previously determined instrument resolution function (Gozzo et al., 2006; Courbion and Ferey, 1988) The final Rietveld refinements were then conducted with restrained zero shift, cell, and peak shapes (Thompson–Cox–Hastings pseudoVoigt function) parameters The structural models were taken from As an example for a polymer fiber product we used Zoey Medical disposable face masks (Zoey medical, 2021) Samples with diameter of (6.0 ± 0.5) mm were cut out using a standard paper hole-puncher We note that the product description does not indicate clearly a polymer that necessarily includes CaCO3 filler The mask consists of three layers, an outer blue colored layer and two inner white/transparent layers For the TL measurements the cut-outs were pressed together and the inner-most layer placed facing towards the PMT The minimum detectable dose (MDD) for an emergency situation was estimated in a first approximation as the mean plus three times the standard deviation of the integral signal calculated from 10 unirradiated samples’ TL curves (Currie, 1968) Radiation Measurements 153 (2022) 106718 O.V Pakari et al Fig Typical TL response of a coarse calcite powder sample to the sequence I) TL readout to erase the native signal II) TL readout to observe the background signal III) TL readout after irradiation (50 Gy in this case) to observe the response The heating rate was ◦ C/s and the maximum TL readout temperature 400 ◦ C Fig Comparison of the laboratory powder X-Ray diffraction patterns of the two calcite powder samples (normalized intensities) The strongest lines associated with calcite-like (CaCO3 ) and dolomite-like (CaMg(CO3 )2 ) phases are indicated with black lines Results and discussion 3.1 Sample characterization 3.1.1 XRD Fig shows the raw XRD signal for both calcite powders for a chosen subset of angles In the observed region we qualitatively indicate the known most dominant peaks that are associated with calcite (CaCO3 , ∼29.5◦ ) as well as dolomite (CaMg(CO3 )2 , ∼31◦ ) (Al-Jaroudi et al., 2007) The detailed fitting using the full diffraction pattern’s angular range as described above was used to estimate the volume ratios of calcite, dolomite, and any other potentially present phases (see Supplementary Figure A.12) The determined volume ratio for the coarse calcite powder was: Calcite (SG R3c H; No 167): 79.8(6)%, Dolomite (SG R3H; No 148): 19.1(4)%, and Graphite-like phase (SG P63/mmc; No 194): 1.1(2)% The lattice distribution of CaCO3 polymorphs suggest the presence of small Mg doping into the Ca site The determined volume ratio for the fine calcite powder was: Calcite (SG R3c H; No 167): 91.8(7)%, and Dolomite (SG R3 H; No 148): 8.2(6)% The presence of a third phase, given the experimental resolution, was not found Given the used procedure, we indeed find a higher CaCO3 and lower dolomite volume fraction in the fine powder, lending evidence to our hypothesis of lower luminescence from such samples due to the lower Mg content A set of face mask samples was also measured using XRD, but the results are less conclusive due to the habit of the specimen resulting in diffraction patterns with high background and broad reflections Additionally, the likely low content of calcite in the mask may well be below the detection limit of our laboratory diffractometer (see supplementary Figure A.13) Fig Typical TL response of a fine calcite powder sample to the sequence I) TL readout to erase the native signal II) TL readout to observe the background signal III) TL readout after irradiation (50 Gy in this case) to observe the response The heating rate was ◦ C/s and the maximum TL readout temperature 400 ◦ C A.14, we find that a dose response, e.g using a test dose normalization (Yukihara et al., 2005), shows a linear response for TL peak in the range from 35 mGy to 14 Gy, and a linear response for Peak above 0.3 Gy A 0.7 Gy dose repeatability test showed a TL integral variability of repeated irradiations and readouts below 1% (Supplementary Figure A.14b) In Fig we show the same TL sequence for the fine calcite powder We observe a similar behavior but with an important difference: the background readout shows a significant remaining TL signal in the region above 150 ◦ C The corrected TL curve exhibits a negative signal above 360 ◦ C The background signal changes over repeated heating of the sample as well When repeatedly heating a native erased fine calcite powder sample to 400 ◦ C (i.e reading out a TL), as shown in Fig 5, we observe a non-linear behavior of a decreasing background in the region between 100 ◦ C and 400 ◦ C, and eventually an increase in the region above 350 ◦ C We hypothesize this behavior to stem from the coating agent used in the fine powder that is not stable at the temperatures used to access TL peak Over successive readouts it thus begins to burn out The fact that the coating agent changes the luminescence signal may affect background subtraction reproducibility, which can impact dose recovery protocols This highlights some of the limitations of using TL of the fine calcite powder for dosimetry: the samples are likely to contain a native signal that limits the usability of the TL peak region, as well as a potential non-linear background behavior 3.1.2 TL response Fig illustrates the successive TL readout signal to 400 ◦ C with a heating rate of ◦ C/s of the coarse calcite powder The first readout shows the native signal dominant in the thermally stable region above 200 ◦ C and no detectable signal below By native signal we refer to the signal from accumulated dose in the material due to natural sources of radiation and/or energy causing electron trapping The second readout then shows the background signal (i.e native signal erased) A third TL readout after a 50 Gy dose then shows the dose response, showing both peaks Note that the native signal well exceeds the equivalent signal of TL peak at 50 Gy By subtracting the background signal (readout 2) from the dose response (readout 3) we determine the background reduced signal used for dosimetry As shown in Supplementary Figure Radiation Measurements 153 (2022) 106718 O.V Pakari et al Fig Repeated TL readout of the unirradiated fine calcite powder In the region relevant for dosimetry (room temperature to 400 ◦ C), we find that the background signal changes in a non-linear, overall decreasing manner This ‘‘burn-out’’ of the background indicates that the finer powder has a thermally unstable component that contributes to the TL signal in a potentially interfering manner 3.1.3 TL emission spectra TL spectrum measurements were conducted on all samples to confirm the emission bands, in particular of the face mask samples, to be that of calcite - around 630 nm (Medlin, 1959) We focused on the native and general dose responses of the used materials The samples were heated to 400 ◦ C with a heating rate of ◦ C/s Fig shows the native TL spectra of the coarse calcite powder, fine calcite powder, and a face mask sample The subsequent response (i.e with native signal erased) to 80 Gy of 𝛽 irradiation was recorded as well and is also shown in Fig The shapes of the TL curves in the direction of temperature follow the already introduced pattern: at temperatures below 200 ◦ C no significant emissions are visible This is consistent with the aforementioned thermal fading characteristics of TL peak Above this temperature all samples exhibit a bright native signal (TL peak 2), with the fine powder and face mask showing a much lower brightness The face mask sample TL response to 80 Gy shows a differing peak structure to the calcite powders, notably by a strong emission at 160 ◦ C This coincides with the melting temperature of the polymer (polymerdatabase.com, 2021); we therefore hypothesize that the mineral filler in the fiber is not heated efficiently until the melting point is reached Once the fiber begins to melt, the filler then quickly reaches a higher temperature and the signal increases as observed Another effect could be the change in opacity of the fiber when molten, leading to a higher effective light output We confirm the dominant emission to be indeed in the expected range around 630 nm for all the examined samples We note that the signal at wavelengths shorter than 400 nm suffer from a large efficiency correction (see Appendix, Figure A.11) and are thus likely not a true signal in the case of the low signal recorded from the face mask sample Fig Native and dose response TL spectra of coarse calcite powder (a, d), fine calcite powder (b, e), and the face mask sample (c, f) Note that the calcite native signal was bright enough to cause saturation and the thus incurring plateau shape of the signal with a stretched exponential decay, indicating that the TL peak region consists of a distribution of traps in terms of activation energy (Chen and McKeever, 1997) This implies that, for practical purposes, TL peak could be used for same day dosimetry and emergency situations, with the possibility of using cold storage of samples to mitigate fading and enable retrospective dose assessment 3.1.5 PTTL response Phototransfer (PT) effects could potentially allow for dose recovery or signal enhancement (e.g by accessing deeper traps without heating to the required temperature) by light stimulation of the samples prior to TL readout — or indicate that a sample is light sensitive and thus be subject to optical bleaching We therefore conducted a PTTL quantification experiment to assess the impact of PT in calcite The procedure was as follows: after irradiation, the sample was heated to a temperature 𝑇𝑝ℎ in the range 50-400 ◦ C and held at that temperature for 60 s Thereafter, the sample was illuminated for s using the UV LED of the reader to elicit a PT response The subsequent TL readout should then show signal below 𝑇𝑝ℎ if significant PT occurred As we display in Fig 8, we find no evidence of PTTL to an extent that could aid the dose recovery, as the supposed PTTL signal at 100 ◦ C constitutes less than 1% compared to the reference TL after irradiation The observed signal is nonetheless not trivial compared to a normal TL readout (compare to Fig 3) and indicates a PT or UV induced trapping As no coincident loss of signal in TL peak with appearance of signal in 3.1.4 Fading Fig 7a presents the results of a qualitative fading study conducted by irradiating a calcite samples with 16 Gy and then waiting a time period (sample remained in the reader, i.e in the dark at room temperature) before reading the TL The procedure was then repeated for four other time points with an annealing of the sample performed at 450 ◦ C in-between two measurements Fig 7b shows the average peak integral (60 ◦ C to 190 ◦ C) of four different samples subject to the same experiment, normalized to the respective value at h waiting time Consistent with literature (Singh and Ingotombi, 1995; Bossin et al., 2020), we find that the integral TL signal between 60 ◦ C and 140 ◦ C of TL peak fades more than 50% within h, whilst for TL peak we observe no significant fading The fading in TL peak was best fitted Radiation Measurements 153 (2022) 106718 O.V Pakari et al Fig (a) TL curves of the calcite sample for various intervals after irradiation (b) Integral of Peak (60 ◦ C to 190 ◦ C) of four samples (mean shown as dot with an errorbar to reflect the standard deviation) over time, normalized to the respective value at h Fig (a) Step annealing TL signals in calcite powder acquired after a dose of 16 Gy After irradiation, the sample was heated to temperature T𝑝ℎ and subsequently illuminated using a UV LED to stimulate a PTTL response (b) The same TL curves in logarithmic scale to display that a PTTL effect, if at all present, affects less than 1% of the signal at 100 ◦ C (c) TL peak intensities for TL peak and TL peak over preheat temperature TL peak was observed, we infer that the signal is UV induced trapping rather than PT This result still presents as an advantage with regards to fortuitous dosimetry: a weak PTTL signal indicates little optical mobility of the trapped charges and a resistance to bleaching due to UV light s under the UV LED corresponds in a first approximation to 36 h of UV-index sunlight (neglecting that sunlight reaching the earth’s surface may have significant contributions of UV down to 300 nm Fioletov et al., 2010) We show an explicit experiment for the TL response as a function of UV bleaching time after irradiation in Supplementary Figure A.15 confirming the weak bleachability of calcite The PTTL experiment further shows relevant features of calcite TL: the preheat clearly moves the peak location to higher temperatures in both peaks, lending evidence to the aforementioned hypothesis of a distribution of trap levels rather than a single trap Furthermore, as the higher temperature end of TL peak is more thermally stable, we may thus explain why the fading does not follow an exponential behavior 3.2 Emergency dosimeter case example: Polymer fiber face mask We next display the results of an applied case example for dose assessment using the face mask samples Due to the melting of the polymer fibers above 160 ◦ C a TL measurement up to 400 ◦ C can be considered destructive Therefore, we undertook two experiments: I) the dose response of 23 face mask samples with TL readout to 400 ◦ C to test a destructive readout scenario with doses up to 30 Gy II) the dose response of 23 face mask samples with TL readout to only 150◦ C to test a non-destructive readout with doses up to 42 Gy For both experiments we therefore may encounter inter-sample variability, but the procedure mimics the actual application case of an irradiated mask and allows for more realistic conclusions as to the operational dosimetric usability The results are displayed in Fig The mask samples show proportional response for TL peak above the MDD of about 1.8 Gy TL peak 2, due to the native signal, was Radiation Measurements 153 (2022) 106718 O.V Pakari et al Fig TL dose response of face mask samples using either (a) a destructive readout to 400 ◦ C and (c) a non-destructive readout to 150 ◦ C The resulting integral TL responses over dose with estimated MDD for TL peak are plotted for the destructive case (b) and non-destructive case (d) Discussion Calcite mineral fillers in polymers showed a TL response proportional to dose that could allow for such materials, e.g a face mask, to be used in emergency dosimetry We demonstrated that commercially available calcite powders show the expected TL response The fine powder was shown to display an important background behavior that may lead to reproducibility issues in dose recovery protocols The dominant source of luminescence in the examined samples is indeed centered at around 630 nm, confirming our hypothesis of Mg sites in calcite being the source of luminescence The native signal in the herein examined samples consistently exceed an equivalent dose of >10 Gy Dose assessment using the TL peak region thus requires the material to be annealed at temperatures above 450 ◦ C The favorable thermal stability makes TL peak very relevant for potential retrospective dose assessment applications Currently, the calcite is not exposed to sufficient heat during the manufacturing chain down to the polymer fiber incorporation Whether this change can be easily achieved in the industrial manufacturing process prior to the incorporation into the polymers in the prospect of enabling dosimetry remains an open question The main limitation for TL peak dosimetry is hereby thermal fading, constraining practical applications to acute dosimetry when timing and environmental parameters were well known A procedure of freezing samples after a suspected exposure could improve this, but requires a careful characterization of the reduced fading (Bossin et al., 2020) Phototransfer properties of calcite have previously been shown to be weak (Bruce et al., 1999) and our experiments using the Risø reader’s UV LED showed no significant PTTL signal in the examined samples We conclude that PT cannot be used in calcite to improve dose recovery Looking at the results of an emergency dosimeter case example using a commercially available face mask, we confirm a dosimetric application of TL peak (up too 200 ◦ C) The face mask furthermore fulfills several desired emergency dosimeter characteristics, such as Fig 10 TL curves of nine samples taken from the same surgical face mask (dashed lines), with the tenth sample being irradiated with ∼16 Gy before readout The native signal in this commercially available product is strong enough to completely mask the radiation induced response in the TL peak region TL peak is well discernible as a radiation-induced peak, but fades thermally within days practically indiscernible from background For 10 samples of the same face mask we exemplify the native signal’s relative strength in Fig 10 In the non-destructive TL experiment we find a higher MDD of 2.5 Gy We observe an important few outliers in both destructive and nondestructive readouts that exceed the MDD limit despite having received a much smaller dose The high variability, in particular for the destructive readout case, seems to arise from the melting peak at 160 ◦ , indicating a complex and not necessarily proportional response to dose Such outliers may warrant sampling a given mask multiple times to confirm the signal The test dose normalization method was shown to work for calcite samples (Supplementary Figure A.14), which could potentially be applied to the non-destructive readout The destructive readout may require a more complex calibration procedure Radiation Measurements 153 (2022) 106718 O.V Pakari et al Acknowledgments ubiquitous availability, simplicity of readout method, speed of sampling using a standard hole puncher, speed of readout using TL, as well as a high likelihood of the item being voluntarily yielded to emergency responders (unlike e.g a mobile phone) The main limitation is once more the thermal fading We found that the MDD for either nondestructive or destructive read-outs may be low enough to deliver useful dose information Nonetheless, assuming a decision threshold of Gy, the sensitivity of this setup may not yet be sufficient for triage scenarios The presented results could therefore be improved in the future: Firstly, the complex background term in the fine calcite powder and thus also in the face mask samples could be reduced by introducing a thermally stable particle coating Secondly, if annealed at least 450 ◦ C for 15 before incorporation into the fiber, the used fine powders could allow for a dosimetric use of TL peak Thirdly, an optimized procedure using cold storage of the samples could allow to extend the time frame of usability of a given sample for TL peak dosimetry Finally, the experimental setup could be optimized for detection in the 500 to 700 nm range by using a red sensitive PMT – e.g a Hamamatsu H7421-40 – that could yield a comparative increase of quantum efficiency of a factor or more at 630 nm This last change could improve the MDD, alleviating fading concerns as well as boosting sensitivity and specificity The authors greatly appreciate the help of M Brunner of Omya International AG, both for providing the samples as well as technical details in discussion This work was supported by a Swiss National Science Foundation SPARK grant (project number CRSK-2_196453) The Risø TL/OSL-DA-20 reader (DTU Nutech, Denmark) was acquired with partial support from the Swiss National Science Foundation (R’Equip project 206021_177028) Appendix A Supplementary data Supplementary material related to this article can be found online at https://doi.org/10.1016/j.radmeas.2022.106718 References Al-Jaroudi, S.S., Ul-Hamid, A., Mohammed, A.-R.I., Saner, S., 2007 Use of x-ray powder diffraction for quantitative analysis of carbonate rock reservoir samples Powder Technol 175 (3), 115–121 http://dx.doi.org/10.1016/j.powtec.2007.01.013 Bailiff, I., Sholom, S., McKeever, S., 2016 Retrospective and emergency dosimetry in response to radiological incidents and nuclear mass-casualty events: a review Radiat Meas 94, 83–139 http://dx.doi.org/10.1016/j.radmeas.2016.09.004 Bossin, L., 2019 New Fortuitous Materials for Luminescence Dosimetry Following Radiological Emergencies (Ph.D thesis) Durham University Bossin, L., Bailiff, I., Terry, I., 2020 Radiological 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http://dx.doi.org/10.1016/0735-245x(85)90061-4, (1982) Eakins, J.S., Kouroukla, E., 2015 Luminescence-based retrospective dosimetry using Al2 O3 from mobile phones: a simulation approach to determine the effects of position J Radiol Prot 35 (2), 343–381 http://dx.doi.org/10.1088/0952-4746/ 35/2/343 Effenberger, H., Kirfel, A., Will, G., 1983 Untersuchungen zur elektronendichteverteilung im dolomit CaMg(CO3 )2 TMPM Tschermaks Mineral Petrogr Mitteilungen 31 (1–2), 151–164 http://dx.doi.org/10.1007/bf01084767 Conclusion In this work we investigated the feasibility of polymer fibers with calcite filler as emergency dosimeters We identified the potential of this material both based on the known TL characteristics of the underlying mineral, calcite, as well as the favorable characteristics of the polymer fiber product that is used e.g in face masks or surgical gowns For this purpose, we presented several experiments using commercial calcite powders, as well as a surgical face mask The TL spectral behavior was found to be consistent among the samples and likely stemming from Mg-doped CaCO3 phases The examined samples showed a native TL signal in the thermally stable (peak 2) region, and limits the usability of currently available materials to the lower temperature (peak 1) region Due to the known thermal fading, and the complex TL background in the fine calcite powder, we conclude that currently available calcite powders as well as polymer fibers such as face masks are limited to dosimetry using TL peak In our detection setup, we found that samples taken from a face mask reach minimum detectable doses of the order of Gy On top of the other favorable qualities of the face mask, we conclude that face masks using calcite based mineral fillers may be suitable to deliver useful dose information in emergency situation, depending on the required sensitivity We outlined improvements to the detection setup that likely alleviate these limitations Given the prevalence e.g of the common face mask in both professional and currently also the general population, it is clear that polymer materials with mineral fillers remain an interesting candidate for fortuitous dosimetry Important changes in the manufacturing or dedicated detection equipment may aid in improving the sensitivity and ease the constraints due to the thermal fading CRediT authorship contribution statement Oskari Ville Pakari: Investigation, Methodology, Software, Writing – original draft Eduardo Gardenali Yukihara: Investigation, Conceptualization, Writing – review & editing, Resources Dariusz Jakub Gawryluk: Investigation, Software Lily Bossin: Funding acquisition, Project administration, Conceptualization, Writing – review & editing Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper Radiation Measurements 153 (2022) 106718 O.V Pakari et al Lapp, 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coincides with the melting temperature of the polymer (polymerdatabase.com, 2021); we therefore hypothesize that the mineral filler in the fiber is not heated