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Metal‐halide perovskites have emerged as one of the most promising contenders for the next‐generation X‐ray scintillators on account of their large absorption coefficients, high light yields, and low‐cost fabrication. However, the existing X‐ray scintillators are plagued either by poor stability or high toxicity. Here, highly stable and flexible CsCu2I3@polymethyl methacrylate (PMMA) composite films are fabricated simply by a facile one‐step drop‐coating technique. Benefiting from the reasonable light yields (24 100 photons MeV−1), short photoluminescence decay time (207 ns), and flat surface, a low detection limit of 39 nGyair s−1 and a record‐high resolution of up to 25 lp mm−1 are demonstrated in these CsCu2I3@PMMA composite films. The X‐ray imaging tests show that the CsCu2I3@PMMA composite films display excellent properties in the dynamic and irregular objects imaging. In addition, the CsCu2I3@PMMA composite films exhibit a desirable endurance to the high‐energy X‐ray's irradiation and the water erosion (photoluminescence quantum yield remains up of 90% of its initial value even after submersion in water for 300 h). This work provides a potential to develop eco‐friendly and highly stable halide perovskite materials for high‐resolution X‐ray imaging. [ABSTRACT FROM AUTHOR]

High‐resolution X‐ray imaging is increasingly required for medical diagnosis and large‐area detection. However, the issues of scattering and optical crosstalk are limiting the spatial resolution of the indirect X‐ray imaging. In this study, a feasible and efficient strategy is proposed to in situ synthesize flexible Cs3Cu2I5:2%In+@paper as a superior scintillator film, which can be scaled up to an ultra‐large area of 4800 cm2. The as‐obtained Cs3Cu2I5:2%In+@paper performs a fascinating photoluminescence quantum efficiency up to 88.14%, a steady state light yield of 70169 photons/MeV, and spatial resolution of 15 lp mm−1. Moreover, the suppressed physical scattering and optical crosstalk of the corresponding film are demonstrated. Accordingly, this work explores a feasible fabrication of customizable scintillation films with large area for high‐resolution X‐ray detection. [ABSTRACT FROM AUTHOR]

Metal halide crystals are bright but hygroscopic scintillator materials that are widely used in X‐ray imaging and detectors. Precipitating them in situ in glass to form glass ceramics (GCs) scintillator offers an efficient avenue for large‐scale preparation, high spatial resolution, and excellent stability. However, precipitating a high fraction of metal halide nanocrystals in glass to maintain high light yield remains a challenge. Herein, an ionic‐covalent hybrid network strategy for constructing GCs scintillator with high crystallinity (up to ≈37%) of BaCl2: Eu2+ nanocrystals is presented. Experimental data and simulations of glass structure reveal that the Ba2+‐Cl− clustering promotes the high crystallization of BaCl2 nanocrystals. The ultralow phonon energy (≈200 cm−1) of BaCl2 nanocrystals and good Eu reduction effect enable high photoluminescence inter quantum efficiency (≈80.41%) in GC. GCs with varied crystallinity of BaCl2: Eu2+ nanocrystals demonstrate efficient radioluminescence and tunable scintillator performance. They either outperform Bi4Ge3O14 single crystal by over 132% steady‐state light yield or provide impressive X‐ray imaging resolutions of 20 lp mm−1. These findings provide a new design strategy for developing bright transparent GCs scintillators with a high fraction of metal halide nanocrystals for X‐ray high‐resolution imaging applications. [ABSTRACT FROM AUTHOR]

Copper (I) based halide scintillators have received high attention due to their high light yield. At the same time, researchers are increasingly interested in exploring organic‐inorganic hybrid copper(I) based halides, due to the diversity and tunability of structures. Here, we describe high‐efficiency photoluminescence and X‐ray excited luminescence in (DFPD)3Cu2I5 (1) (DFPD=4,4‐difluoro‐bipiperidinium). 1 is comprised of a unique [Cu2I5]3− cluster, which have typical structure allowing high‐transition‐probability self‐trapped exciton emission (one Cu+ ion adopts the tetrahedral coordination geometry, the other trigonal planar coordination geometry, the Cu−Cu distance (2.574 Å) is short). Accordingly, 1 shows efficient yellow‐green photoluminescence with the maximum at 527 nm, a full‐width at half‐maximum of 99.2 nm, a large Stokes shift of 214 nm (1.6 eV) and a quantum yield of 77.15 %. Polycrystalline 1 can also convert high‐energy X‐ray photons into UV‐visible pulsed fluorescence with the light yield of 5000 photons/MeV. This finding plays a valuable role in the development of organic‐inorganic hybrid copper(I) based scintillators. [ABSTRACT FROM AUTHOR]

Copper (I) based halide scintillators have received high attention due to their high light yield. At the same time, researchers are increasingly interested in exploring organic‐inorganic hybrid copper(I) based halides, due to the diversity and tunability of structures. Here, we describe high‐efficiency photoluminescence and X‐ray excited luminescence in (DFPD)3Cu2I5 (1) (DFPD=4,4‐difluoro‐bipiperidinium). 1 is comprised of a unique [Cu2I5]3− cluster, which have typical structure allowing high‐transition‐probability self‐trapped exciton emission (one Cu+ ion adopts the tetrahedral coordination geometry, the other trigonal planar coordination geometry, the Cu−Cu distance (2.574 Å) is short). Accordingly, 1 shows efficient yellow‐green photoluminescence with the maximum at 527 nm, a full‐width at half‐maximum of 99.2 nm, a large Stokes shift of 214 nm (1.6 eV) and a quantum yield of 77.15 %. Polycrystalline 1 can also convert high‐energy X‐ray photons into UV‐visible pulsed fluorescence with the light yield of 5000 photons/MeV. This finding plays a valuable role in the development of organic‐inorganic hybrid copper(I) based scintillators. [ABSTRACT FROM AUTHOR]

Despite the extraordinary X‐ray scintillation performance of three‐dimensional (3D) lead perovskite nanocrystals (PNCs), the serious biotoxicity of Pb2+ and luminescent instability in water remain insurmountable obstacles for their applications in medical imaging. To address these drawbacks, herein, the study demonstrates one new lead‐free zero‐dimensional (0D) hybrid cuprous halide of single‐crystalline [BzTPP]2Cu2I4 (BzTPP = Benzyltriphenylphosphonium) as a satisfactory X‐ray scintillator. [BzTPP]2Cu2I4 displays broadband yellowish‐green light emission with a high photoluminescent quantum yield (PLQY) of 44.2% and large Stokes shift of 167 nm upon UV light excitation. High PLQY and negligible self‐absorption enable [BzTPP]2Cu2I4 to display impressive scintillation performance excited by X‐ray with a light yield of 27 706 photons MeV‐1 and low detection limit of 0.352 µGy s−1, surpassing typical 3D PNCs. More importantly, [BzTPP]2Cu2I4 represents extraordinary structural and luminescent stability in water for at least one month. The excellent and stable radioluminescence performance as well as solution growth method ensure a [BzTPP]2Cu2I4‐based screen for fine‐resolution X‐ray imaging with potential in radiography and inspection. This work highlights the multiple merits of low‐toxicity and cost, high light yield, and long‐term water‐stability of 0D hybrid cuprous halides as highly desirable X‐ray scintillators. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the performance of an electromagnetic (EM)‐tracked scintillation dosimeter in detecting source positional errors of IVD in HDR brachytherapy treatment. Materials and Methods: Two different scintillator dosimeter prototypes were coupled to 5 degrees‐of‐freedom (DOF) EM sensors read by an Aurora V3 system. The scintillators used were a 0.3 × 0.4 × 0.4 mm3 ZnSe:O and a BCF‐60 plastic scintillator of 0.5 mm diameter and 2.0 mm in length (Saint‐Gobain Crystals). The sensors were placed at the dosimeter's tip at 20.0 mm from the scintillator. The EM sampling rate was 40/s while the scintillator signal was sampled at 100 000/s using two photomultiplier tubes from Hamamatsu (series H10722) connected to a data acquisition board. A high‐pass filter and a low‐pass filter were used to separate the light signal into two different channels. All measurements were performed with an afterloader unit (Flexitron‐Elekta AB, Sweden) in full‐scattered (TG43) conditions. EM tracking was further used to provide distance/angle‐dependent energy correction for the ZnSe:O inorganic scintillator. For the error detection part, lateral shifts of 0.5 to 3 mm were induced by moving the source away from its planned position. Indexer length (longitudinal) errors between 0.5 to 10 mm were also introduced. The measured dose rate difference was converted to a shift distance, with and without using the positional information from the EM sensor. Results: The inorganic scintillator had both a signal‐to‐noise‐ratio (SNR) and signal‐to‐background‐ratio (SBR) close to 70 times higher than those of the plastic scintillator. The mean absolute difference from the dose measurement to the dose calculated with TG‐43U1 was 1.5% ±0.7%. The mean absolute error for BCF‐60 detector was 1.7% ±1.2%$\pm 1.2\%$ when compared to TG‐43 calculations formalism. With the inorganic scintillator and EM tracking, a maximum area under the curve (AUC) gain of 24.0% was obtained for a 0.5‐mm lateral shift when using the EMT data with the ZnSe:O. Lower AUC gains were obtained for a 3‐mm lateral shifts with both scintillators. For the plastic scintillator, the highest gain from using EM tracking information occurred for a 0.5‐mm lateral shift at 20 mm from the source. The maximal gain (17.4%) for longitudinal errors was found at the smallest shifts (0.5 mm). Conclusions: This work demonstrates that integrating EM tracking to in vivo scintillation dosimeters enables the detection of smaller shifts, by decreasing the dosimeter positioning uncertainty. It also serves to perform position‐dependent energy correction for the inorganic scintillator,providing better SNR and SBR, allowing detection of errors at greater distances from the source. [ABSTRACT FROM AUTHOR]

The search for efficient, re-absorption-free scintillators has recently focused the attention on antimony-based halides, which exhibit largely Stokes shifted luminescence due to radiative recombination of excitons self-trapped (STE) in strongly Jahn-Teller distorted Sb3+ color centers. Here, the synthesis of a hybrid structure is reported with chemical formula (C13H14N3)3SbCl6 consisting of spatially isolated [SbCl6]3- octahedra separated by organic N, N'-diphenylguanidinium (Gua) molecules. The optical properties of this material are mainly determined by the inorganic component and are characterized by a pronounced Stokes shift of "1.3 eV and a room-temperature photoluminescence (PL) efficiency of up to 85%. Remarkably, highly efficient radioluminescence (RL) is observed with scintillation light yields of "2000 ph MeV-1 using both soft X-rays and a 124 keV gamma source. Temperature-dependent PL and RL measurements confirm the minor role of non-radiative channels, which are completely suppressed below 100 K. Thermally stimulated luminescence measurements suggest that the traps in Gua3SbCl6 crystals have a significantly large energy depth distribution below the absorbing state. [ABSTRACT FROM AUTHOR]

Lead‐free metal halides have recently received sustained attention because of their nontoxicity, low‐cost, as well as excellent stability and optoelectronic properties. However, most of the reported lead‐free metal halides are synthesized via slow solution‐processing at high temperature in toxic solvents, which may impede their commercial applications. Here, a solvent‐free strategy is proposed to synthesize inorganic rubidium copper halides (Rb2CuX3, X = Cl, Br) at room temperature, which exhibit efficient violet emission dominated by a self‐trapped excitons (STEs) mechanism and attractive stabilities against ultraviolet illumination and heating. Thus, Rb2CuX3 powders are employed as emitters and scintillators applied in wireless light communication and X‐ray imaging technologies. Under orthogonal frequency division multiplexing modulation, emitters demonstrate a broad −3 dB bandwidth of 26.3 MHz and a high received data rate of 205.1 Mbps. Additionally, flexible scintillation films based on as‐prepared powders are fabricated and show outstanding X‐ray scintillation properties, including a high spatial resolution of 18.1 lp mm−1 and a low detection limit of 104 nGyair s−1, as well as promising imaging performance for irregular objects. These results suggest large‐scale production of nontoxic Rb2CuX3 and their potential commercialization in fields of high‐speed light communication and X‐ray radiography. [ABSTRACT FROM AUTHOR]

Eco‐friendly lead‐free organic–inorganic manganese halides (OIMHs) have attracted considerable attention in various optoelectronic applications because of their superior optical properties and flexible solution processibility. Herein, we report a novel pseudo‐2D layered OIMH (MTP)2MnBr4 (MTP: methyltriphenylphosphonium), which exhibits intense green emission under UV/blue or X‐ray excitation, with a near‐unity photoluminescence quantum yield, high resistance to thermal quenching (I150 °C=84.1 %) and good photochemical stability. These features enable (MTP)2MnBr4 as an efficient green phosphor for blue‐converted white light‐emitting diodes, demonstrating a commercial‐level luminous efficiency of 101 lm W−1 and a wide color gamut of 116 % NTSC. Moreover, these (MTP)2MnBr4 crystals showcase outstanding X‐ray scintillation properties, delivering a light yield of 67000 photon MeV−1, a detection limit of 82.4 nGy s−1, and a competitive spatial resolution of 6.2 lp mm−1 for X‐ray imaging. This work presents a new avenue for the exploration of eco‐friendly luminescent OIMHs towards multifunctional light‐emitting applications. [ABSTRACT FROM AUTHOR]

Background: In vivo dosimetry (IVD) is gaining interest for treatment delivery verification in HDR‐brachytherapy. Time resolved methods, including source tracking, have the ability both to detect treatment errors in real time and to minimize experimental uncertainties. Multiprobe IVD architectures holds promise for simultaneous dose determinations at the targeted tumor and surrounding healthy tissues while enhancing measurement accuracy. However, most of the multiprobe dosimeters developed so far either suffer from compactness issues or rely on complex data post‐treatment. Purpose: We introduce a novel concept of a compact multiprobe scintillator detector and demonstrate its applicability in HDR‐brachytherapy. Our fabricated seven‐fiber probing system is sufficiently narrow to be inserted in a brachytherapy needle or in a catheter. Methods: Our multiprobe detection system results from the parallel implementation of six miniaturized inorganic Gd2O2S:Tb scintillator detectors at the end of a bundle of seven fibers, one fiber is kept bare to assess the stem effect. The resulting system, which is narrower than 320 microns, is tested with a MicroSelectron 9.14 Ci Ir‐192 HDR afterloader, in a water phantom. The detection signals from all six probes are simultaneously read with a sCMOS camera (at a rate of 0.06 s). The camera is coupled to a chromatic filter to cancel Cerenkov signal induced within the fibers upon exposure. By implementing an aperiodic array of six scintillating cells along the bundle axis, we first determine the range of inter‐probe spacings leading to optimal source tracking accuracy (first tracking method). Then, three different source tracking algorithms involving all the scintillating probes are tested and compared. In each of these four methods, dwell positions are assessed from dose measurements and compared to the treatment plan. Dwell time is also determined and compared to the treatment plan. Results: The optimum inter‐probe spacing for an accurate source tracking ranges from 15 to 35 mm. The optimum detection algorithm consists of adding the readout signals from all detector probes. In that case, the error to the planned dwell positions is of 0.01 ± 0.14 mm and 0.02 ± 0.29 mm at spacings between the source and detector axes of 5.5 and 40 mm, respectively. Using this approach, the average deviations to the expected dwell time are of −0.006±0.009$-0.006\,\pm \,0.009$ s and −0.008±0.058$-0.008\, \pm 0.058$ s, at spacings between source and probe axes of 5.5 and 20 mm, respectively. Conclusions: Our six‐probe Gd2O2S:Tb dosimeter coupled to a sCMOS camera can perform time‐resolved treatment verification in HDR brachytherapy. This detection system of high spatial and temporal resolutions (0.25 mm and 0.06 s, respectively) provides a precise information on the treatment delivery via a dwell time and position verification of unmatched accuracy. [ABSTRACT FROM AUTHOR]

High‐energy physics community is looking for a hard, fast, and low‐cost scintillation material, and Ce:Lu3Al5O12 (Ce:LuAG) ceramic is one of the competitive candidates. This work presents Ce,Ca:LuAG scintillation ceramics with good optical quality, and the influence of Ce and Ca concentrations on optical and scintillation properties was fully analyzed. At relatively low level of Ce concentration, the less Ca2+ content is needed to achieve a significant intensity increase in fast scintillation component while maintaining a relatively high light yield (LY). The introduction of only 0.1 at% Ca2+ could increase the LY0.5 μs/LY3.0 μs from 79.9% to 96.1% in Ce,Ca:LuAG ceramics of 0.1 at% Ce. First‐principles investigations are further performed to reveal the tuning mechanisms of the scintillation properties of LuAG by Ce and Ca codoping. We show that the Fermi level shifts down with Ca codoping, which increases the Ce4+ content and decreases the depth of the electron traps (VO), resulting to a faster decay. Moreover, the formation preference of Ca‐VO complexes over Ce‐VO leads to the suppression of the non‐radiative decay of Ce via VO. In summary, our study demonstrates the realization of the performance tuning of LuAG via Ce and Ca codoping. [ABSTRACT FROM AUTHOR]

In this study, a new Cs4SrI6:Yb2+,Sm2+ near‐infrared (NIR) emitting scintillator was developed using sensitization strategy. It was found that Yb2+ sensitization significantly enhances the NIR radioluminescence (RL) of Sm2+, providing a new approach of designing highly emissive sensitized NIR scintillators. By studying the optical spectra and decay kinetics of Cs4SrI6:Yb2+,Sm2+, it was revealed that the energy transfer pathways involve both radiative and nonradiative processes. The gamma spectroscopy performance of Cs4SrI6:Yb2+,Sm2+ single crystals was studied by using the high‐quantum‐efficiency avalanche photodiode (APD) as the readout. Our results highlight the importance of using sensitization strategy of achieving NIR emitting scintillators and demonstrate the significant potential for radiation detection applications. [ABSTRACT FROM AUTHOR]

Ferroptosis therapy induced by iron‐catalyzed Fenton reaction has offered enormous opportunities for tumor therapy. Unfortunately, high catalytic activity ferrous (Fe2+)‐based therapeutic agent has remained challenging due to the instability of Fe2+. Herein, an X‐ray‐activated Fe2+ supply platform, termed "PFCN", containing the core of CaWO4 nanoscintillator to emit ultraviolet (UV) light and Fe3O4 decorated on the surface to deliver excessive Fe2+ is proposed. Under X‐ray excitation, the UV light emitted by CaWO4 can catalyze ferric (Fe3+) to generate Fe2+, which further cascades the Fenton reaction to induce highly toxic hydroxyl radicals generation. More importantly, immunogenic cell death‐associated immunotherapy is simultaneously triggered during this process. Experiments conducted in vitro and in vivo revealed that X‐ray‐triggered PFCN shows superior tumor therapeutic efficacy, contributing i) enhanced radiotherapy; ii) X‐ray‐activated ferroptosis therapy; and iii) ferroptosis/radiotherapy‐induced immunotherapy. Besides, PFCN can be utilized as an MR/CT dual‐mode imaging contrast agent for tumor diagnosis and treatment monitoring. The study provides a novel example of an X‐ray‐activated ferrous‐regeneration platform for imaging‐guided augmenting tumor ferroptosis/immunotherapy [ABSTRACT FROM AUTHOR]

Gadolinium scandium aluminum garnet scintillator crystals (GSAG:Ce) with Ca2+, Mg2+, and Li+ co‐dopants are grown by the Bridgman method under reducing atmosphere. Crystals are irradiated with a 60Co gamma‐ray source to 10 kGy and 50 kGy doses for evaluation of the radiation hardness. A wide absorption band peaking at around 620 nm is observed in all as‐grown uncodoped GSAG:Ce crystals. Air annealing at high temperatures and introduction of codopants result in elimination of this absorption band and improvement of transmittance in the visible range. The nature of the color center at ≈620 nm is discussed. GSAG:Ce crystals codoped with Li+ and Mg2+:Li+ combine both high transmission and least radiation damage. [ABSTRACT FROM AUTHOR]

Traditional‐metal‐containing scintillators are widely used in X‐ray imaging due to their efficient X‐ray absorption and output of visible light. However, they suffer from heavy‐metal toxicity, environmental stability, harsh preparation, and afterglow. Metal‐free organic scintillators show a rising momentum, especially organic‐halogen‐containing molecules. Halogens are introduced to improve their X‐ray absorption, but the resulting increase in spin–orbit coupling leads to significant delayed fluorescence or phosphorescence, affecting the response speed to X‐rays. Moreover, there is still insufficient practice in fabricating microstructured organic scintillators for high spatial resolution of imaging. Herein, the preparation of nano organic co‐crystals (t‐Bpe‐IFB co‐crystal, abbreviated as BIC, t‐Bpe for trans‐1,2‐bis(4‐pyridyl)ethylene, and IFB for 1,3,5‐trifluoro‐2,4,6‐triiodobenzene) and its application in X‐ray imaging are explored. In contrast to previous single organic‐halogen‐containing molecules, BIC generates nanosecond‐scale fluorescence through the charge‐transfer state of the donor–acceptor. Its high iodine content ensures large X‐ray absorption, strong radioluminescence, and a low detection limit of 85 nGyair s−1. The composite film made of nano‐sized BICs and polydimethylsiloxane exhibits a high spatial resolution of 16.7 lp mm−1. Herein, the application of organic co‐crystals is expanded and ideas are provided for the development of new scintillators. [ABSTRACT FROM AUTHOR]

Low‐dimensional copper‐based halide single crystals are considered excellent scintillators for indirect X‐ray detection, but their potential in direct X‐ray detection has not been investigated. Herein, high‐quality pure Cs3Cu2I5 and Li‐doped Cs3Cu2I5:Li single crystals are grown by the Bridgman method. The Li+ dopant enhances the photoelectric properties of the Cs3Cu2I5 single crystal by extending the carrier lifetime, improving the carrier mobility from 6.49 to 9.52 cm2 V−1 s−1, and increasing the mobility‐lifetime (µτ) product from 1.4 × 10−4 to 2.9 × 10−4 cm2 V−1. The sensitive direct X‐ray detector with a vertical device configuration of Au/Cs3Cu2I5:Li single crystal/PCBM/Au is fabricated and demonstrated to have a high sensitivity of 831.1 µC Gyair−1 cm−2 and low detection limit of 34.8 nGyair s−1. Furthermore, the detector shows negligible baseline current drift and excellent stability upon X‐ray radiation. [ABSTRACT FROM AUTHOR]

X‐ray imaging technology has achieved important applications in many fields and has attracted extensive attentions. Dynamic X‐ray flexible imaging for the real‐time observation of the internal structure of complex materials is the most challenging type of X‐ray imaging technology, which requires high‐performance X‐ray scintillators with high X‐ray excited luminescence (XEL) efficiency as well as excellent processibility and stability. Here, a macrocyclic bridging ligand with aggregation‐induced emission (AIE) feature was introduced for constructing a copper iodide cluster‐based metal–organic framework (MOF) scintillator. This strategy endows the scintillator with high XEL efficiency and excellent chemical stability. Moreover, a regular rod‐like microcrystal was prepared through the addition of polyvinyl pyrrolidone during the in situ synthesis process, which further enhanced the XEL and processibility of the scintillator. The microcrystal was used for the preparation of a scintillator screen with excellent flexibility and stability, which can be used for high‐performance X‐ray imaging in extremely humid environments. Furthermore, dynamic X‐ray flexible imaging was realized for the first time. The internal structure of flexible objects was observed in real time with an ultrahigh resolution of 20 LP mm−1. [ABSTRACT FROM AUTHOR]

Background: The incorporation of multi‐energy capabilities into radiotherapy flat‐panel detectors offers advantages including enhanced soft tissue visualization by reduction of signal from overlapping anatomy such as bone in 2D image projections; creation of virtual monoenergetic images for 3D contrast enhancement, metal artefact reduction and direct acquisition of relative electron density. A novel dual‐layer on‐board imager offering dual energy processing capabilities is being designed. As opposed to other dual‐energy implementation techniques which require separate acquisition with two different x‐ray spectra, the dual‐layer detector design enables simultaneous acquisition of high and low energy images with a single exposure. A computational framework is required to optimize the design parameters and evaluate detector performance for specific clinical applications. Purpose: In this study, we report on the development of a Monte Carlo (MC) model of the imager including model validation. Methods: The stack‐up of the dual‐layer imager (DLI) was implemented in GEANT4 Application for Tomographic Emission (GATE). The DLI model has an active area of 43×43 cm2, with top and bottom Cesium Iodide (CsI) scintillators of 600 and 800 μm thickness, respectively. Measurement of spatial resolution and imaging of dedicated multi‐material dual‐energy (DE) phantoms were used to validate the model. The modulation transfer function (MTF) of the detector was calculated for a 120 kVp x‐ray spectrum using a 0.5 mm thick tantalum edge rotated by 2.5o. For imaging validation, the DE phantom was imaged using a 140 kVp x‐ray spectrum. For both validation simulations, corresponding measurements were done using an initial prototype of the imager. Agreement between simulations and measurement was assessed using normalized root mean square error (NRMSE) and 1D profile difference for the MTF and phantom images respectively. Further comparison between measurement and simulation was made using virtual monoenergetic images (VMIs) generated from basis material images derived using precomputed look‐up tables. Results: The MTF of the bottom layer of the dual‐layer model shows values decreasing more quickly with spatial frequency, compared to the top layer, due to the thicker bottom scintillator thickness and scatter from the top layer. A comparison with measurement shows NRMSE of 0.013 and 0.015 as well as identical MTF50 of 0.8 mm1 and 1.0 mm1 for the top and bottom layer respectively. For the DE imaging of the DE‐phantom, although a maximum deviation of 3.3% is observed for the 10 mm aluminum and Teflon inserts at the top layer, the agreement for all other inserts is less than 2.2% of the measured value at both layers. Material decomposition of simulated scatter‐free DE images gives an average accuracy in PMMA and aluminum composition of 4.9% and 10.3% for 11–30 mm PMMA and 1–10 mm aluminum objects respectively. A comparison of decomposed values using scatter containing measured and simulated DE images shows good agreement within statistical uncertainty. Conclusion: Validation using both MTF and phantom imaging shows good agreement between simulation and measurements. With the present configuration of the digital prototype, the model can generate material decomposed images and virtual monoenergetic images. [ABSTRACT FROM AUTHOR]

Background: Positron probes can accurately localize malignant tumors by directly detecting positrons emitted from positron‐emitting radiopharmaceuticals that accumulate in malignant tumors. In the conventional method for direct positron detection, multilayer scintillator detection and pulse shape discrimination techniques are used. However, some γ‐rays cannot be distinguished by conventional methods. Accordingly, these γ‐rays are misidentified as positrons, which may increase the error rate of positron detection. Purpose: To analyze the energy distribution in each scintillator of the multilayer scintillator detector to distinguish true positrons and γ‐rays and to improve the positron detection algorithm by discriminating true and false positrons. Methods: We used Autoencoder, an unsupervised deep learning architecture, to obtain the energy distribution data in each scintillator of the multilayer scintillator detector. The Autoencoder was trained to separate the combined signals generated from the multilayer scintillator detector into two signals of each scintillator. An energy window was then applied to the energy distribution obtained using the trained Autoencoder to distinguish true positrons from false positrons. Finally, the performance of the proposed method and conventional positron detection algorithm was evaluated in terms of the sensitivity and error rate for positron detection. Results: The energy distribution map obtained using the trained Autoencoder was proven to be similar to that of the simulated results. Furthermore, the proposed method demonstrated a 29.79% (+0.42%p) increase in positron detection sensitivity compared to the conventional method, both having an equal error rate of 0.48%. However, when both methods were set to have the same sensitivity of 1.83%, the proposed method had an error rate that was 25.0% (−0.16%p) lower than that of the conventional method. Conclusions: We proposed and developed an Autoencoder‐based positron detection algorithm that can discriminate between true and false positrons with a smaller error rate than conventional methods. We verified that the proposed method could increase the positron detection sensitivity while maintaining a low error rate compared to the conventional method. If the proposed algorithm is implemented in handheld positron detection probes or cameras, diseases such as cancers can be more accurately localized in a shorter time compared with using traditional methods. [ABSTRACT FROM AUTHOR]

Single‐component metal halides with white light emission are highly attractive for solid‐state lighting applications, but it is still challenging to develop all‐inorganic lead‐free metal halides with high white‐light emission efficiency. Herein, by rationally introducing silver (Ag) into zero‐dimensional (0D) Cs3Cu2Br5 as new structural building unit, a one‐dimensional (1D) bimetallic halide Cs6Cu3AgBr10 is designed that emits strong warm‐white light with an impressive photoluminescence quantum yield (PLQY) of 94.5% and excellent stability. This structural transformation lowers the conduction band minimum while maintaining the localized nature of the valence band maximum, which is crucial in expanding the excitation spectrum and obtaining efficient self‐trapped excitons (STEs) emission simultaneously. Detailed spectroscopy studies reveal that the white‐light originates from triplet STEs emission, which can be remarkably improved by weakening the strong electron‐phonon coupling and thus suppressing phonon‐induced non‐radiative processes. Moreover, the interesting temperature‐dependent emission behavior, together with self‐absorption‐free property, make Cs6Cu3AgBr10 as sensitive luminescent thermometer and high‐performance X‐ray scintillator, respectively. These findings demonstrate a general approach to achieving effective single‐component white‐light emitters based on lead‐free, all‐inorganic metal halides, thereby opening up a new avenue to explore their versatile applications such as lighting, temperature detection and X‐ray imaging. [ABSTRACT FROM AUTHOR]

Fast neutron and X‐ray imaging are considered complementary nondestructive detection technologies. However, due to their opposite cross‐sections, development of a scintillator that is sensitive to both fast neutrons and X‐rays within a single‐material framework remains challenging. Herein, an organic–inorganic hybrid perovskite (C4H9NH3)2PbBr4 (BPB) is demonstrated as a scintillator that fully meets the requirements for both fast neutron and X‐ray detection. The hydrogen‐rich organic component acts as a fast neutron converter and produces detectable recoil protons. The heavy atom‐rich inorganic fraction efficiently deposits the energy of charged recoil protons and directly provides a large X‐ray cross‐section. Due to the synergy of these organic and inorganic components, the BPB scintillator exhibits high light yields (86% of the brightness of a commercial ZnS (Ag)/6LiF scintillator for fast neutrons; 22 000 photons per MeV for X‐rays) and fast response times (τdecay = 10.3 ns). More importantly, energy‐selective fast neutron and X‐ray imaging are also demonstrated, with high resolutions of ≈1 lp mm−1 for fast neutrons and 17.3 lp mm−1 for X‐rays; these are among the highest resolution levels for 2D perovskite scintillators. This study highlights the potential of 2D perovskite materials for use in combined fast neutron and X‐ray imaging applications. [ABSTRACT FROM AUTHOR]

Transionospheric satellite signals are exposed to perturbation, caused by irregularities generated in the ionosphere. However, the characteristics of the satellite motion can have an additional impact on signal perturbation, in addition to the effects of irregularity structures, that drift from west to east during geomagnetic quiet conditions. This paper reports the effect of Global Positioning System satellite geometry, on tracking loop performance of ground‐based receivers, during occurrence of ionospheric scintillations. Observations are made from station Calcutta (22.58°N, 88.38°E geographic; magnetic dip 34.54°), located near the northern crest of Equatorial Ionization Anomaly, during three different solar activity periods (March 2014, March 2015, and March 2022). Efforts have been made to study the correlation of east‐west component of satellite velocity at Ionospheric Pierce Point (IPP) with duration of loss‐of‐lock and rate of signal fading (<−10 dB), from ground scintillation pattern observations. Results of this study show 75%–78% correlation between duration of loss‐of‐lock and eastward component of satellite velocity, for all three period of observation. Subsequently, shorter duration of loss‐of‐lock has been observed corresponding to satellite velocity being westward. Signal fading rate is found to decrease with increasing satellite velocity, having median value of the fading rate cumulative distribution percentage, corresponding to satellite velocity of 16.69, 31.76, and 19.14 m/s respectively during March 2014, March 2015, and March 2022. Results of this study also indicate direction and component of satellite velocity at IPP to be a dominant cause of signal outage, even during periods of weak to moderate scintillations. Plain Language Summary: Equatorial ionosphere is often characterized with generation of irregularities which are electron density depleted regions in the nighttime F layer, that drift from west to east with an average velocity of 100 m/s. Transionospheric satellite links, when intersected by these irregularities can cause fluctuation in signal amplitude and phase, received on ground. Such fluctuations, commonly known as scintillations, are observed as a regular phenomenon over low‐latitude and equatorial stations, especially during equinoctial period of a high solar activity year. The station Calcutta, being located near the northern crest of Equatorial Ionization Anomaly, witnesses some of the worst cases of signal perturbation due to effect of the medium, sometimes leading to complete outage of signal, termed as loss‐of‐lock. However, occurrence of such events can have contribution from both the motion of irregularities and satellites. Under condition of synchronization of signal motion with irregularity drift, tracking loop of a receiver can result in longer duration of loss‐of‐lock. In this study, efforts have been made to understand the effect of Global Positioning System satellite geometry on such tracking loop performance of ground‐based receivers, in presence of scintillation. Results of this study indicate higher duration of loss‐of‐lock when eastward component of satellite velocity is higher. Key Points: Effect of Global Positioning System satellite geometry on tracking loop performance of ground‐based receivers in presence of scintillationStudy of east‐west component of satellite velocity at Ionospheric Pierce Point and its correlation with occurrence of loss‐of‐lockObservation of signal fading rate, having depth <−10 dB, to study its correlation with synchronization of irregularity structure [ABSTRACT FROM AUTHOR]

Halide perovskites (HPs) recently have emerged as one class of competitive scintillators for X‐ray detection and imaging owing to its high quantum efficiency, short decay time, superior X‐ray absorption capacity, low cost, and ease of crystal growth. The tunable structure and versatile chemical compositions of halide perovskites provide distinguishable advantages over traditional inorganic scintillators for optimizing scintillation performance. Since the first observation of the scintillation phenomenon in HPs, substantial efforts have been devoted to expanding the inventory of HP scintillators and regulating material properties. Understanding the relationship between the structure and scintillation properties of HP scintillators is essential for developing materials with improved X‐ray detection and imaging capacities. This review summarizes strategies for improving the light yield of HP scintillators and provides a roadmap for improving the X‐ray imaging performance. Additionally, methods for controlling the light propagation direction in HP scintillators are highlighted for improving X‐ray imaging resolution. Finally, we highlight the current challenge in HP scintillators and provide a perspective on the future development of this emerging scintillator. [ABSTRACT FROM AUTHOR]

Scintillators, which can convert high‐energy ionizing radiation (e.g., X‐ or γ‐rays) into ultraviolet‐visible light, have been widely applied in medical and industrial fields. Developing new scintillation materials with high performance and low cost is very desirable in order to address the growing application demands. Among them, single‐crystal scintillators of organic‐inorganic hybrid metal halides (OIMHs) have attracted much attention because of their excellent optical transparency, suppressed light scattering, and facile solution preparation methods. Herein, three new centimeter‐sized (2‐DMAP)2MnX4 (2‐DMAP+ = 2‐dimethylaminopyridinium, X = Cl, Br, I) single crystals with high crystal quality are synthesized via the solvent evaporation method. Benefiting from the high optical transparency and remarkable luminescence property, (2‐DMAP)2MnBr4 delivers a high X‐ray light yield of 22 000 photons MeV−1, a low limit of detection of 9.50 nGy s−1, and an excellent X‐ray imaging spatial resolution of 20–25 lp mm−1. Moreover, the regulation of single‐crystal thickness from 0.31 mm to 3.03 mm can be easily achieved via a simple solution post‐treatment method, which has a significant influence on the transmittance, spatial imaging resolution, and detection limit. This work demonstrates a promising single‐crystal scintillator for the application of high‐resolution X‐ray imaging with low preparation cost and tunable thickness. [ABSTRACT FROM AUTHOR]

X‐ray induced photodynamic therapy (X‐PDT) circumvents the poor penetration depth of conventional PDT with minimal radio‐resistance generation. However, conventional X‐PDT typically requires inorganic scintillators as energy transducers to excite neighboring photosensitizers (PSs) to generate reactive oxygen species (ROS). Herein, a pure organic aggregation‐induced emission (AIE) nanoscintillator (TBDCR NPs) that can massively generate both type I and type II ROS under direct X‐ray irradiation is reported for hypoxia‐tolerant X‐PDT. Heteroatoms are introduced to enhance X‐ray harvesting and ROS generation ability, and AIE‐active TBDCR exhibits aggregation‐enhanced ROS especially less oxygen‐dependent hydroxyl radical (HO•−, type I) generation ability. TBDCR NPs with a distinctive PEG crystalline shell to provide a rigid intraparticle microenvironment show further enhanced ROS generation. Intriguingly, TBDCR NPs show bright near‐infrared fluorescence and massive singlet oxygen and HO•− generation under direct X‐ray irradiation, which demonstrate excellent antitumor X‐PDT performance both in vitro and in vivo. To the best of knowledge, this is the first pure organic PS capable of generating both 1O2 and radicals (HO•−) in response to direct X‐ray irradiation, which shall provide new insights for designing organic scintillators with excellent X‐ray harvesting and predominant free radical generation for efficient X‐PDT. [ABSTRACT FROM AUTHOR]

Layered metal halide perovskites have attracted enormous research attention over the last few years, befitting their unique optical and electronic properties. Low‐dimensional layered perovskites demonstrate great potential for various optoelectronic and sensing applications beyond photovoltaics. Herein, the recent progress and opportunities in 2D and quasi‐2D perovskites for light‐emitting diodes (LEDs), lasers, memristors, neuromorphic/synaptic applications, UV–vis photodetection, X‐ray detection, scintillators, and photocatalytic applications are reviewed. First, the crystal structure, characteristics, and fundamental properties of 2D layered perovskites are discussed. Recent efforts and developments of 2D and quasi‐2D metal halide perovskite for light‐emitting applications with excellent luminescence properties are reviewed. Unique properties of 2D perovskites, such as negligible leakage current due to restricted carrier transport, high stability, and hydrophobicity, make them viable for memristor devices. After discussing the memristor and neuromorphic devices using 2D perovskites, the outstanding performance of 2D perovskites in UV–vis photodetection including polarization‐sensitive photodetection is discussed. 2D perovskites recently proved as a superior candidate in X‐ray detection with high stability. Further, the scintillation properties of 2D perovskites for the detection of ionizing radiation are discussed. Finally, some of the very recent achievements and present future outlook, including exciting opportunities in this burgeoning field are highlighted. [ABSTRACT FROM AUTHOR]

Copper metal halides have emerged as a strong contender in the scintillator field due to the self‐trapped excitons (STEs) mechanism. However, their development has been hindered by the preparation process. Single crystals have long growth cycles and cannot achieve large areas and flexibility. Quantum dots have a low yield and can easily cause chemical pollution, and the thickness of films prepared by the spin coating cannot be controlled. To address these challenges, a new method for preparing Cs3Cu2Cl5 using sequential vacuum evaporation is developed. This allows successful preparation of large‐area (≈100 cm2) and flexible films. The STEs mechanism of Cs3Cu2Cl5 gives it unique properties such as a large Stokes shift that reduces self‐absorption effects, and a wide full width at half‐maximum that improves coupling with photodiodes. Therefore, Cs3Cu2Cl5 is applied to X‐ray imaging with a light yield of ≈30 000 photons MeV−1, a spatial resolution of over 10 lp mm−1, and a low detection limit below 0.8 µGyair s−1. In addition, the flexible Cs3Cu2Cl5 film enables effective dynamic imaging and clear imaging on non‐planar objects. It also exhibits good resistance to harsh environments, maintaining good imaging performance after 150 days. It is believed that sequential vacuum evaporation provides an important idea for preparing scintillators. [ABSTRACT FROM AUTHOR]

X‐ray photography plays an important role in the fields of medical treatment, security inspection, and non‐destructive testing. The high image quality depends on X‐ray detectors with excellent properties. To meet the future demand for high‐performance scintillation screens, adding a new luminescent center in Cs3Cu2I5 by doping is considered. The successful incorporation of Mn brought a new luminescence peak at 565 nm. Different excitation modalities such as ultraviolet and X‐rays have the ability to tune luminescence. X‐ray can promote the energy transfer efficiency of self‐trapped excitons and non‐radiative intermediate trap states to doping Mn2+ ions. This results in a higher radioluminescence intensity of a radioluminescence light yield of 65 000 Photons MeV−1. Subsequently, a Cs3Cu2I5: Mn scintillation screen is prepared by anodized aluminum oxide (AAO) template. The array channel structure of the AAO template strongly suppresses the internal scintillation light scattering, allowing more scintillation photons to be emitted efficiently. Under the combined effect of Mn‐enhanced radioluminescence properties and AAO template suppressed light scattering, it obtains the lowest detection limit of 49 nGyair s−1. High X‐ray imaging quality has been achieved for circuit boards, beetles, and ball‐point pens and reached a high X‐ray imaging resolution of 11.8 lp mm−1. [ABSTRACT FROM AUTHOR]

Nanocrystals of CsPbBr3, a colloidal perovskite, are hybridized with silver nanoparticles (Ag NPs) and organic molecules (2,5‐diphenyloxazole, PPO) to improve X‐ray radioluminescence (RL). It is known that charge transfer from the PPO molecules to the CsPbBr3 nanocrystals enhances the RL efficiency of the CsPbBr3 nanocrystals. In this study, Ag NPs are introduced to further enhance the RL efficiency. The plasmonic process of the Ag NPs is activated by the PPO molecules, which contain X‐ray‐induced high‐energy charges. Subsequently, electric fields induced by the plasmonic process of the Ag NPs accelerate the charge transfer from the PPO molecules to the CsPbBr3 nanocrystals. The plasmonic effect of the Ag NPs is demonstrated by the full‐width half maximum (FWHM): the photoluminescence FWHM of the hybridized CsPbBr3 nanocrystals is reduced, whereas the RL FWHM remains unchanged. The Ag‐NP‐induced plasmonic effect improves the RL efficiency of the PPO‐decorated CsPbBr3 nanocrystals by ≈10%. The obtained results demonstrate that a plasmonic process can strengthen the RL of X‐ray scintillators for X‐ray detection and imaging. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskite single crystals (SCs) are promising materials for detecting ionizing radiation owing to their outstanding photoelectric conversion capability and inexpensive solution processability. However, the accuracy and stability of the detectors have been limited due to the charge traps and defects in SCs, especially when operated under high‐precision photon‐counting mode for energy spectrum acquisition. Here, we proposed a trap freezing deactivation route, which obviously suppressed dark current and noise by up to 97% and 92%, respectively. Furthermore, the bulk ion migration effect was essential for the ability to instantly self‐heal defects induced by radiation damage at temperatures down to −30°C. Consequently, the detector exhibits a record high energy resolution of 7.5% at 59.5 keV for 241Am γ‐ray source, which is the best solution‐processed semiconductor radiation detectors at the same energy range. In addition, the detector maintains over 90% of its initial performance after 9 months of storage when tested in the air. Our results will represent a revision of the paradigm that high‐spectral‐resolution and robust radiation detectors can only be realized with high temperature grown inorganic semiconductor single crystals. [ABSTRACT FROM AUTHOR]

X‐ray flat‐panel detectors are widely used for nondestructive detection of internal information in medical radiography and industrial applications. However, a persisting challenge is the application of radiography on highly curved 3D objects to realize flexibility and information storage for the fabrication of flexible large‐area X‐ray detectors. This study demonstrates a halide‐based double perovskite Cs2Na0.9Ag0.1LuCl6:Dy3+ by a hydrothermal reaction. The as‐prepared crystals exhibit afterglow features through a co‐doping strategy of Dy3+ and Ag+ ions. The double perovskite material with doping modification exhibits excellent scintillation properties with high sensitivity, low detection limit, and high radiation stability. In addition, flexible scintillator detectors are fabricated with an area of 8.0 × 6.0 cm2 by the blade‐coating strategy, which has a high spatial resolution of 11.2 lp mm−1@MTF = 0.2. Based on the long afterglow properties, the Cs2Na0.9Ag0.1LuCl6:Dy3+ flexible film exhibits thermoluminescence after turning off the X‐ray, thereby having strong potential for X‐ray imaging of nonflat and irregular objects. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have recently emerged as exceptional scintillator materials for ionizing radiation detection devices. Their chemical composition consists of elements with high atomic numbers, leading them to have a high attenuation coefficient. Their high attenuation coefficient, in combination with their excellent optoelectronic properties, versatile chemical tunability, and facile and low‐cost fabrication processes, makes them the ideal scintillator material. However, existing perovskite‐based scintillators suffer from poor material stability, especially in humid atmospheres. Moreover, current perovskite films have morphologies that have been optimized for photovoltaics, which results in the relatively long charge carrier lifetimes, a property that is detrimental for fast scintillation. Furthermore, existing reports of perovskite‐based scintillators have shown limited spatial resolution due to poor light transmittance that arises from light scattering from large aggregates of perovskite grains. To address these issues, this work introduces a template‐assisted in situ polymerization‐based process to prepare perovskite/polymer composite scintillators that simultaneously reduces afterglow effects, improves perovskite stability, and is industrially scalable. The optimized perovskite scintillators are then incorporated into X‐ray detection devices to investigate detection performance and device stability. Compared with existing commercial scintillators, the perovskite scintillators show superior detection performance metrics for imaging, indicating the great potential of perovskites for next‐generation, large‐area, and flexible scintillation screens. [ABSTRACT FROM AUTHOR]

The development of high‐performance X‐ray detectors requires scintillators with fast decay time, high light yield, stability, and X‐ray absorption capacity, which are difficult to achieve in a single material. Here, we present the first example of a lanthanide chalcogenide of LaCsSiS4 : 1 % Ce3+ that simultaneously integrates multiple desirable properties for an ideal scintillator. LaCsSiS4 : 1 % Ce3+ demonstrates a remarkably low detection limit of 43.13 nGyair s−1 and a high photoluminescence quantum yield of 98.24 %, resulting in a high light yield of 50480±1441 photons/MeV. Notably, LaCsSiS4 : 1 % Ce3+ exhibits a fast decay time of only 29.35±0.16 ns, making it one of the fastest scintillators among all lanthanide‐based inorganic scintillators. Furthermore, this material shows robust radiation and moisture resistance, endowing it with suitability for chemical processing under solution conditions. To demonstrate the X‐ray imaging capacity of LaCsSiS4 : 1 % Ce3+, we fabricated a flexible X‐ray detector that achieved a high spatial resolution of 8.2 lp mm−1. This work highlights the potential of lanthanide chalcogenide as a promising candidate for high‐performance scintillators. [ABSTRACT FROM AUTHOR]

Substitutional lanthanide doping of 2D transition metal dichalcogenides (TMDs) is expected to be a promising strategy to engineer optical, electronic, and optoelectronic properties of TMDs. Understanding the interactions between lanthanide dopants and 2D TMDs host is one of the key problems to be resolved for their profound research studies. Herein, the interactions between Ce dopants and monolayer WS2 in a physical vapor deposition grown Ce‐doped WS2 monolayer are studied by combining scanning tunneling microscopy with optical characterizations with high spatial and temporal resolution. It is found that the highly anisotropic crystal field can effectively split the energy levels of the Ce dopants' f orbital. The electrons in the split energy levels can bind the holes in the valence band maximum of the Ce‐doped WS2, forming optical bright excitons. These excitons collide with the free A excitons when increasing the pump fluences, reducing the A exciton's lifetime. This study may be beneficial for the design and fabrication of optical, electronic, and optoelectronic devices based on lanthanide‐doped TMDs. [ABSTRACT FROM AUTHOR]

Lead‐free metal halides are considered a new generation of optoelectronic materials due to their low toxicity, superior optoelectronic properties, ease of synthesis, structural diversity, and low cost. In particular, Mn2+‐based metal halides have earned intensive attention owing to their high emission quantum efficiency, rich physical properties (e.g., triboluminescence and stimuli‐responsivity), low cost, and toxicity. Due to the different coordination environments of Mn ions, Mn2+‐based metal halides can exhibit green, red, and near‐infrared emissions. This review summarizes the recent progress of Mn2+‐based metal halides in synthesis methods, emission mechanisms, photophysical properties, and representative applications in X‐ray scintillations, white light‐emitting diodes, optical anti‐counterfeiting technologies, and fluorescent sensors. Finally, the challenges and potential research directions toward developing Mn2+‐based metal halides are also predicted. [ABSTRACT FROM AUTHOR]

Gas sensors are useful for monitoring of greenhouse gases. As the move toward complementary metal‐oxide‐semiconductor (CMOS) compatible pyroelectric room temperature detectors is gaining traction due to its scalability to 8‐in./12‐in. wafer area and integrable with CMOS electronics, CMOS compatible aluminum nitride (AlN)‐ and scandium aluminum nitride (ScAlN)‐based pyroelectric detectors are developed for sensing of CO2and CH4gases, which are two of the greenhouse gases that contribute significantly to global warming. Leveraging gas absorption at respective mid‐infrared (IR) wavelengths, CO2 and CH4 gases are detected at various concentrations with fast response time ≈1 s. A compound parabolic collector (CPC) is designed and integrated into the gas sensor to enhance the optical flux received by the detector, which demonstrates ≈10× signal improvement in its presence. Further factors such as the effect of sensing area reduction and response to random gas concentrations are also tested on AlN‐ and ScAlN‐based pyroelectric detectors respectively to observe the gas sensing behaviors of both detectors. The results obtained provide further understanding of the behavior of CMOS AlN‐ and ScAlN‐based pyroelectric detectors as IR gas sensors, which can potentially inspire new design and design selection for various gas sensing applications. [ABSTRACT FROM AUTHOR]

The article discusses recent advancements in various fields of research. One study focuses on the development of a tool for automated interpretation of X-ray CT images of biological samples, which could enable high-throughput analysis of cell volume and cytoplasmic structure. Another study introduces film-like glass-ceramic scintillators for X-ray imaging applications, which have shown promising results in terms of spatial resolution. Additionally, a unique radiation imaging technique inspired by the tetromino shapes in the game Tetris has been developed, allowing for accurate mapping of radiation sources. Lastly, self-driving laboratories are discussed, which utilize AI and robotics technologies to accelerate the development of new materials. [Extracted from the article]

Metal halide scintillators have drawn great interest for X‐ray imaging; however, it remains challenging to simultaneously achieve a high light yield (LY) and highly sensitive detection. Herein, Zn2+ is successfully introduced into [TPPen]2MnBr4 (TPPMB, TPPen = pentyltriphenylphosphonium) and the synthesis of [TPPen]2Mn0.9Zn0.1Br4 (TPPMZB) is designed. The LY increases from 43 000 for TPPMB to 68 000 photons MeV−1 for TPPMZB in virtue of the Zn atom doping. Additionally, the detection limit of TPPMZB is 204.1 nGy s−1, showing great improvement to that of TPPMB with the value of 696.9 nGy s−1. X‐ray imaging is realized by utilizing the large‐scale scintillator film fabricated by mixing polydimethylsiloxane with TPPMZB or TPPMB, and the spatial resolution is enlarged from 4.6 to 11.2 lp mm−1 after Zn2+‐doping. This study provides a design principle by doping engineering for enhancing the LY property of metal halide X‐ray scintillators. [ABSTRACT FROM AUTHOR]

X‐ray imaging technology is critical to numerous different walks of daily life, ranging from medical radiography and security screening all the way to high‐energy physics. Although several organic chromophores are fabricated and tested as X‐ray imaging scintillators, they generally show poor scintillation performance due to their weak X‐ray absorption cross‐section and inefficient exciton utilization efficiency. Here, a singlet fission‐based high‐performance organic X‐ray imaging scintillator with near unity exciton utilization efficiency is presented. Interestingly, it is found that the X‐ray sensitivity and imaging resolution of the singlet fission‐based scintillator are dramatically improved by an efficient energy transfer from a thermally activated delayed fluorescence (TADF) sensitizer, in which both singlet and triplet excitons can be efficiently harnessed. The fabricated singlet fission‐based scintillator exhibits a high X‐ray imaging resolution of 27.5 line pairs per millimeter (lp mm−1), which exceeds that of most commercial scintillators, demonstrating its high potential use in medical radiography and security inspection. [ABSTRACT FROM AUTHOR]

Zero‐dimensional (0D) structure‐based manganese metal halides (MHs) are believed to be the most promising candidates for the next‐generation X‐ray scintillators due to their intense radioluminescence and environmental friendliness. However, low‐temperature (<180 °C), large‐area integration with more efficient X‐ray detection remains a tremendous challenge. Herein, from the perspective of cation (ionic liquids) structure design, the basic physical parameters of 0D MHs are regulated. And the calculations and experimental results demonstrate larger‐size cations that induce lower melting temperatures, larger exciton‐binding energies, larger ion migration energy, and tunable hardness, which are most desirable for MHscintillators. As a result, the champion materialHTP2MnBr4is achieved as glassy transparency wafer by low‐temperature (165 °C) melt‐quenching. Its application to X‐ray imaging features high spatial resolution (17.28 lp mm−1), scalability (>30 × 30 cm2), and integration with strong coupling force. Furthermore, HTP2MnBr4 glass with reproducible properties demonstrates a high light yield (38 000 photon MeV−1), excellent irradiation stability, and low detection limit (0.13 µGy s−1). The authors believe this work will provide guidance for MHscintillators to further commercial applications. [ABSTRACT FROM AUTHOR]

Background: Fiber optic dosimetry (FOD) has emerged as a useful technique that can be used in those cases when intracavitary, real time, high spatial resolution dose assessment is required. Among the several factors characterizing a dosimeter, angular response of FOD probes has to be assessed in order to consider possible clinical application. Purpose: The objective of this study was to characterize the angular response of a FOD probe based on a cylindrical shaped YVO4:Eu3+ scintillator under irradiation with a 6 MV photon beam generated by a linear accelerator (LINAC). Methods: A FOD probe was irradiated inside a plastic phantom using a 6 MV LINAC photon beam at different azimuthal angles (0° to 360°, 15° steps). Scintillation output was measured with a photomultiplier tube. Similar measurements were performed with a second FOD probe having an optical filter interposed between the scintillator and the fiber. Monte Carlo simulations using PENELOPE were carried out in order to interpret the observed results. Results: The FOD output was symmetrical with respect to the scintillator axis. For the unfiltered probe, the signal was maximum at rear incidence (0°) and steadily decreased down to its minimum value at frontal incidence (180°) having a signal ratio of 37%. The output of the filtered probe showed a plateau from 15° up to 115°. The signal was maximum at 60° and minimum at 180° having a signal ratio of 16%. Monte Carlo simulations predicted symmetry of the deposited dose about 0° and 90°, which contrasts with experimental findings. Conclusions: Photoluminescence (PL) of the scintillator induced by the Cherenkov light increases the angular dependence. Radiation attenuation inside the scintillator and partial light collection of the scintillation yield by the optical fiber (OF) are responsible for asymmetrical response. Results from this study should be considered in order to minimize angular dependence in FOD. [ABSTRACT FROM AUTHOR]

Glass scintillators have several benefits compared to the currently used single or polycrystalline scintillators, including non‐hygroscopicity, mechanical ruggedness, ease of producing customizable shapes, and low‐cost synthesis. The combination of the inert glass matrix and the embedded highly scintillating center render them significant materials for medical imaging and therapy, non‐destructive probing, nuclear monitoring, and high‐energy physics. Recently, great progress has been made in exploring new kinds of glass scintillator materials, improving imaging resolution for radiation detection, and developing an enormous range of commercial products. However, the majority of efforts have been devoted to the variation of materials, while rationally designing this new family of scintillators toward expected properties and applications is still lacking. In this review, the focus is specifically on advances in glass scintillators, including the scintillation fundamentals, material designing rule, and current application status, as well as future challenges and future directions. [ABSTRACT FROM AUTHOR]

X‐ray imaging technology has been widely used in the fields of environmental monitoring, safety inspection, nondestructive examination, space exploration, and medical diagnosis, among which scintillation materials play a vital role in indirectly converting X‐ray to visible photons. Here, a zero‐dimensional organic–inorganic hybrid halide C50H44P2SbCl5 crystal is prepared via a facile antisolvent precipitation method at room temperature. The single crystal of C50H44P2SbCl5 displays a strong yellow broadband emission centered at 592 nm with a near‐unity photoluminescence quantum yield of 98.42%. Importantly, C50H44P2SbCl5 crystals show great environmental stability and irradiation stability. Radioluminescence characterization indicates that C50H44P2SbCl5 crystals exhibit a good linear response to X‐ray dose rates along with an excellent light yield of 44 460 photons MeV−1, surpassing that of commercial inorganic LuAG:Ce scintillator. The spatial resolution of the C50H44P2SbCl5‐based scintillating screen is determined to be 8.2 lp mm−1. In conjunction with polymer thin film, the excellent scintillating feature of organic–inorganic hybrid halides offers exciting opportunities for achieving high‐quality flexible X‐ray imaging. [ABSTRACT FROM AUTHOR]

Background: Fiber optic dosimetry (FOD) has emerged as a useful technique that can be used in those cases when intracavitary, real time, high spatial resolution dose assessment is required. Among the several factors characterizing a dosimeter, angular response of FOD probes has to be assessed in order to consider possible clinical application. Purpose: The objective of this study was to characterize the angular response of a FOD probe based on a cylindrical shaped YVO4:Eu3+ scintillator under irradiation with a 6 MV photon beam generated by a linear accelerator (LINAC). Methods: A FOD probe was irradiated inside a plastic phantom using a 6 MV LINAC photon beam at different azimuthal angles (0° to 360°, 15° steps). Scintillation output was measured with a photomultiplier tube. Similar measurements were performed with a second FOD probe having an optical filter interposed between the scintillator and the fiber. Monte Carlo simulations using PENELOPE were carried out in order to interpret the observed results. Results: The FOD output was symmetrical with respect to the scintillator axis. For the unfiltered probe, the signal was maximum at rear incidence (0°) and steadily decreased down to its minimum value at frontal incidence (180°) having a signal ratio of 37%. The output of the filtered probe showed a plateau from 15° up to 115°. The signal was maximum at 60° and minimum at 180° having a signal ratio of 16%. Monte Carlo simulations predicted symmetry of the deposited dose about 0° and 90°, which contrasts with experimental findings. Conclusions: Photoluminescence (PL) of the scintillator induced by the Cherenkov light increases the angular dependence. Radiation attenuation inside the scintillator and partial light collection of the scintillation yield by the optical fiber (OF) are responsible for asymmetrical response. Results from this study should be considered in order to minimize angular dependence in FOD. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) materials hold great promise as next‐generation efficient emitters due to their theoretical 100% internal quantum efficiency. However, such an intriguing photophysical mechanism is extremely rare in perovskites or their derivatives. Herein, the colloidal synthesis of two‐dimensional CsAgCl2 nanocrystals (NCs) with typical TADF feature is reported first. The TADF mechanism is investigated in detail by combining first‐principles calculations with experimental results, including temperature‐dependent spectral analysis and fs‐transient absorption spectra. A small singlet−triplet state splitting energy (0.082 eV) and a large spatial separation of charge density |Ψ|2 of valence band maximum and conduction band minimum are observed, which are prerequisites for TADF. Moreover, these CsAgCl2 NCs deliver an ultralow X‐ray detection limit of 170.5 nGyair s−1 and a high imaging resolution of 11.5 lp mm−1, much superior to the commercial scintillators. [ABSTRACT FROM AUTHOR]

Herein, details on the effect of Ce3+ concentration and annealing temperature on luminescence and scintillation properties of Y3Al5O12:Ce3+ (YAG:Ce3+) nanoscintillator powders, prepared by sol–gel method, have been investigated. Despite extensive research on YAG:Ce3+ single crystal, the behavior of this material at the nanoscale is still not fully understood. The photoluminescence spectra of nanoscintillator powders have been measured and analyzed. To properly assess the scintillation properties, the nanoscintillator sample powders are developed for use as a radiation detector and underwent preparation procedures, including surface homogenization and efficient coupling with a photomultiplier tube window. It is shown that even with nanoscintillator powders, pulse height spectra, with well‐resolved photo‐peak from the Compton edge, and scintillation decay curves are obtained. It is found that 0.5 mol% Ce3+ sample annealed at 1000 °C presents the nonradiative quenching concentration with calculated critical distance of 20.21 Å based on the resonance transfer by electric multipole–multipole interaction. Additionally, the sample detector with 0.5 mol% Ce3+ annealed at 1150 °C exhibits the highest light yield (LY) with value 18 900 ph MeV−1 and a better energy resolution value 10% full‐width and half‐maximum under 662 keV γ‐ray from 137Cs source. [ABSTRACT FROM AUTHOR]

Background: Arrays of thick segmented crystalline scintillators are useful x‐ray converters for image‐guided radiation therapy using electronic portal imaging (EPI) and megavoltage cone‐beam computed tomography (MV‐CBCT). Ionizing‐radiation‐only simulations previously showed relatively low modulation transfer function (MTF) in parallel‐element arrays because of beam divergence. Hence, a focused‐element geometry (matching the beam divergence) has been proposed. The "full" (ionizing and optical) MTF performance of such a focused geometry compared to its radiation‐only MTF has, however, not been fully investigated. Purpose: To study the full MTF performance of such arrays in a more realistic situation in which optical characteristics are also included using an in‐house detector model that supports light transport, and quantify the errors in MTF estimation when the optical stage is ignored. Methods: First, radiation (x‐ray and electron) transport was simulated. Then, transport of the generated optical photons was modeled using ScintSim2, an optical Monte Carlo (MC) code developed in MATLAB for simulation of two‐dimensional (2D) parallel‐ and focused‐element scintillator arrays. The full‐MTF responses of focused‐ and parallel‐element geometries, for a large array of 3 × 3 mm2 CsI:Tl detector elements of 10, 40, and 60 mm thicknesses, were examined. For each configuration, a composite line spread function (LSF) was calculated to obtain the MTF. Results: At the Nyquist frequency, for 10 mm‐thick central elements and 60 mm‐thick peripheral parallel elements, full‐MTF exhibited a drop of up to 15 and 79 times, respectively, compared with radiation‐only MTF. This was found to be partly attributable to the angular distribution of the light emerging from the detector‐element exit face and the dependence on its aspect ratio, since the light exiting thicker scintillators exhibited a more forward‐directed distribution. Focused elements provided an increase of up to nine times in peripheral‐area full MTF values. Conclusions: Full MTF was up to 79 times lower than radiation‐only MTF. Focused arrays preserved full MTF by up to nine times compared to parallel elements. The differences in the results obtained with and without inclusion of optical photons emphasize the need to include light transport when optimizing thick segmented scintillation detectors. Besides their application in detector optimization for radiotherapy megavoltage photon imaging, these findings can also be useful for other segmented‐scintillator‐based imaging systems, for example, in nuclear medicine, or in 2D detection systems for quality assurance of MR‐linacs. [ABSTRACT FROM AUTHOR]

Zero‐dimensional (0D) copper‐based perovskite‐derivative nano‐scintillators (NSs), as a promising non‐toxic alternative to lead‐based halide perovskite, have shown great potential in flexible X‐ray detection and imaging. However, their practical applications are still impeded by low X‐ray imaging resolution associated with inadequate radioluminescence (RL) and poor environmental stability. Herein, for the first time a simple but valid Mn2+‐activation strategy is proposed to highly enhance the RL and stability of 0D Cs3Cu2I5 NSs, where the Mn2+ ions are embedded into the highly localized [Cu2I5]3− units by utilizing a modified hot‐injection method. As such, a newly emerged emission band of Mn2+ ion centered at ≈562 nm coupled with much improved intrinsic self‐trapped excitons (STE) emission of the 0D Cs3Cu2I5 host peaking at ≈445 nm can be achieved in these resultant Mn2+‐activated 0D Cs3Cu2I5 NSs, thereby delivering a light yield of 71 000 photons MeV−1 that is much superior to their lead‐based perovskite counterparts and commercial scintillators. As a consequence, X‐ray detectors made of these Mn2+‐activated NSs implement an ultrahigh X‐ray imaging resolution of 16.2 line pairs mm−1 and an ultra‐low detection limit of 127.5 nGyair s−1, highlighting their potential as promising candidates for flexible X‐ray detection and imaging. [ABSTRACT FROM AUTHOR]

Ionospheric scintillation could seriously disrupt the signal tracking of the global navigation satellite systems (GNSS), further causing positioning accuracy degradation or unavailability. BeiDou navigation satellite system (BDS), a newly developed GNSS by China, has begun to provide global positioning, navigation, and timing service. The objective of the present study is to investigate the effects of ionospheric scintillation on BDS‐2 and BDS‐3 multi‐frequency signals. Ionospheric scintillation monitor receiver data from four monitors in Brazil were collected from October 2021 to May 2022. The results illustrate that S4(B2) and S4(B3) linearly increase with S4(B1) for S4(B1) ≤ 0.6, which is consistent with weak scattering theories, and average experimental ratios of S4(B2)/S4(B1), S4(B3)/S4(B1), and S4(B2)/S4(B3) are less than corresponding theoretical ones by 6.1%, 4.4%, and 1.9%, respectively. Meanwhile, as S4 values increase, lower‐frequency scintillation saturates earlier than higher ones, and the probability of ionospheric scintillation events on B2 and B3 signals is approximately twice (S4 ≥ 0.7) as B1 signals in the equatorial ionization anomaly (EIA) regions. To alleviate the undesirable effects of missing data on GNSS positioning, we first investigate the inter‐frequency relationship and distribution probability of two significant spectral parameters, that is, T (the spectral strength of the phase noise at 1 Hz) and p (the spectral slope of the phase power spectral density) in the tracking jitter model among three BDS frequencies. Results show that the performances among B1, B2, and B3 frequencies have a higher correlation respectively, and their values for B2 and B3 signals are more susceptible to be impacted by ionospheric scintillation. Plain Language Summary: Ionospheric scintillation seriously affects the precision and continuity of the global navigation satellite systems (GNSS) signals and causes positioning accuracy degradation or unavailability. Therefore, it is essential to study the impacts of ionospheric scintillation on the GNSS receiver performance. This study first investigates the inter‐frequency relation of the amplitude scintillation index S4 for B1, B2, and B3 signals from BDS‐2 and BDS‐3 satellites based on the Ionospheric scintillation monitor receiver data at four geomagnetic latitudes in the Brazilian territory. Furthermore, the distribution probability and inter‐frequency relationship of two significant phase spectral parameters of the tracking jitter model, which are widely applied in GNSS positioning solutions, are also presented among three BDS frequencies. All investigations conducted within this contribution show agreement with earlier work in ionospheric scintillation and provide supportive and detailed numerical statements and comparisons. Key Points: The inter‐frequency relation of the amplitude scintillation index for multi‐frequency signals from BDS‐2 and BDS‐3 satellites is displayedThe probability of the ionospheric scintillation events on B2 and B3 signals is approximately twice (S4 ≥ 0.6) as B1 signals in EIA regionsThe spectral parameters p and T of B2 and B3 signals are more susceptible to be affected by ionospheric scintillation [ABSTRACT FROM AUTHOR]