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Scintillating materials that convert ionizing radiation into low‐energy photons hold great potential for radiation detection, nondestructive inspection, medical radiography, and space exploration. However, organic scintillators are characterized by low radioluminescence, while bulky inorganic scintillators are not suitable for the development of flexible detectors. Here, high‐resolution X‐ray imaging using solution‐processable lanthanide‐based metal–organic frameworks as microscale scintillators is demonstrated. Mechanistic studies suggest that lanthanide ions absorb X‐rays to generate high‐density molecular triplet excitons, and excited linkers subsequently sensitize lanthanide ions via nonradiative resonance energy transfer. Furthermore, the crystalline nature offers a delocalized electronic feature rather than isolated subunits, which enables direct trapping of charge carriers by lanthanide emitters. By controlling the concentration ratio between Tb3+ and Eu3+ ions, efficient and color‐tunable radioluminescence of lanthanide ions can be achieved. When coupled with elastic, transparent polymer matrices, these metal–organic framework‐based microscintillators allow the fabrication of flexible X‐ray detectors. Such detectors feature a detection limit of 23 nGy s−1, which is 240 times lower than the typical radiation dose for medical diagnosis. X‐ray imaging with resolution higher than 16.6 line pairs per millimeter is further demonstrated. These findings provide insight into the future design of hybrid scintillators for optoelectronics and X‐ray sensing and imaging. [ABSTRACT FROM AUTHOR]

Organic fluorescence scintillators, owing to the ultrafast response time, versatile chemical structures, low processing temperature, and low cost, are considered as one of the promising materials for medical diagnostics, radiation detection, and X‐ray astronomy. However, the low radioluminescence (RL) intensity and low sensitivity hinder their practical applications. In this work, a highly efficient organic fluorescent scintillator, 4,4′‐bis(9‐carbazolyl)biphenyl (CBP), is presented, exhibiting a high X‐ray RL intensity, narrow full width at half‐maximum of 49 nm, and ultrafast decay time of 1.15 ns. More importantly, it has a low detection limit of 25.5 nGy s−1, which is only 1/215 dose rate compared with the commercial X‐ray diagnostics. Such an excellent scintillation performance is mainly attributed to its high photoluminescence quantum yield (PLQY = 61.92%) and good carrier transport (average hole mobility of 0.094 cm2 V−1 s−1). By mixing the CBP into polydimethylsiloxane, the fabricated large area flexible film can be applied in X‐ray radiography, which exhibits a high spatial resolution of 14.3 lp mm−1 at MTF > 0.2. This work paves a way for the implementation of organic fluorescence dyes with high PLQY, high carrier mobility in efficient X‐ray scintillation and imaging. [ABSTRACT FROM AUTHOR]

The optical, photo, and X-ray luminescence properties of Sm3+ ion-doped Li2O-Al2O3-Gd2O3-B2O3-P2O5 glasses are evaluated. The glasses are fabricated by the melt quenching technique. The absorption spectra exhibit the hypersensitive transitions 6H5/2→6P3/2 and 6H5/2→6F7/2 0at the visible and near-infrared range respectively. The glasses display four major transitions characteristic of Sm3+ ion for photoluminescence and X-ray luminescence, with the most intense one corresponding to the 4G5/2→6H7/2 transition. The best emitting samarium concentration obtained by X-ray excitation is compared to BGO crystals. The integral scintillation efficiency of glass is determined by total area under all of peak spectrum. The results indicate the promising application of these glasses in scintillators and for X-ray sensing devices. [ABSTRACT FROM AUTHOR]

Metal‐halide perovskites, especially for 3D halide perovskite single crystals (SCs), are emerging as the promising scintillators. However, the strong self‐absorption and low light yield of these perovskites restrict their practical applications. Quantum cutting can convert a high energy photon into multiple low energy photons, endowing a large Stokes shift and high photoluminescent quantum yield (PLQY). Here, this work reports a novel quantum cutting material, CsPbClxBr3−x:Yb3+ perovskite SCs, with the PLQY of 149% and a Stokes shift >550 nm, successfully conquering the issues of poor PLQY induced by the thermal quenching and the large self‐absorption in perovskite SCs. Benefiting from the extremely high PLQY and negligible self‐absorption effect, the first high‐performance quantum cutting scintillators based on CsPbClxBr3−x:Yb3+ perovskite SCs are developed, exhibiting high transmittance, large X‐ray absorption/conversion efficiency, outstanding light yield of ≈1.12 × 105 photons MeV−1, and a detection limit as low as 176.5 nGyair s−1. Finally, a single‐pixel X‐ray imaging is achieved by integrating CsPbCl3:Yb3+ SCs with silicon photomultiplier. This work sheds light on exploring highly competitive scintillators beyond the scope of traditional perovskites. [ABSTRACT FROM AUTHOR]

Lead‐halide perovskites have received extensive attention in X‐ray imaging applications recently. However, their poor stability, lead toxicity, and strong light self‐absorption seriously limit the commercial development. Here, we report a vacancy‐ordered Cs2HfCl6 double perovskite for scintillators applications. The Cs2HfCl6 microcrystals (MCs) are characterized by broadband blue emission with a large Stokes shift. Joined experimental‐theoretical characterizations reveal the highly localized charge distribution in Cs2HfCl6 and structural distortion of [HfCl6]2− octahedron in the excited state favor the formation of self‐trapped excitons (STEs), which contribute to the broadband emission. Benefiting from the radioluminescence of STEs with negligible self‐absorption, the light yield of Cs2HfCl6 scintillator reaches 21700 photons/MeV, and the detection limit is 55 nGyair s−1. Additionally, the Cs2HfCl6 scintillator exhibits extremely low hygroscopicity and good resistance to X‐ray irradiation. Further, a large‐area scintillator screen (20×20 cm2) is fabricated by combining scrape‐coating and soft‐pressing techniques, showing a spatial resolution of 11.2 lp mm−1. Given the high spatial resolution and fast light decay of this scintillator screen, static X‐ray imaging of bulky objects is realized, and dynamic X‐ray imaging of a rotating chopping fan is demonstrated without ghosting effects. These results demonstrate the great commercial promise of Cs2HfCl6 scintillation screens for indirect X‐ray detection. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid metal halides are a promising platform for the design of materials for circularly polarized luminescence (CPL) and X‐ray detection applications. Meanwhile, despite the recent progress in this hot field, hybrid metal halides, simultaneously endowed with efficient CPL and high photoluminescence quantum yield (PLQY), are still limited to a few examples. Herein, the efficient, stable, and low‐cost CPL‐active Mn(II) hybrids are developed via blending of luminogenic [MnBr4]2− anions with N/OH‐bond free R/S‐[MBA‐Me3]+ cations in a single ionic structure. The synthesized R/S‐[MBA‐Me3]MnBr4 hybrids display brightly green Mn2+‐centered circularly polarized phosphorescence with near‐unity PLQY and a high glum factor of 0.0045. Single crystals of R/S‐[MBA‐Me3]MnBr4 are used to fabricate UV‐pumped circularly polarized light‐emitting diodes (LEDs) displaying a high optical selectivity upon exposure to right‐handed and left‐handed circular polarization conditions. Moreover, the titled compounds are found to emit strong X‐ray radioluminescence with excellent linear response to X‐ray dose rate that is used for X‐ray imaging demonstration. These findings reveal a great potential of R/S‐[MBA‐Me3]MnBr4 as low‐cost materials for CPL‐LEDs, scintillators, and X‐ray imaging applications. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid copper(I)‐based halides have attracted great interest in the field of optoelectronics due to their low cost, non‐toxicity, large Stokes shift, and high photoluminescence quantum yields (PLQYs). Here, bulk zero‐dimensional (0D) organic‐inorganic hybrid copper(I)‐based (R,S‐2‐mpip)2Cu2I6 (mpip = methylpiperazinium, C5H14N22+) single crystals have been grown with equal stoichiometric ratios of R‐ and S‐2‐mpip ligands by chirality–racemization strategy for the first time. Interestingly, (R,S‐2‐mpip)2Cu2I6 single crystals exhibit strong blue–green photoluminescence (PL) located at 520 nm with large Stokes shift of about 230 nm and high PLQY of about 65.96%, which originates from self‐trapped excitons (STEs). More importantly, (R,S‐2‐mpip)2Cu2I6 single crystals also exhibit the strong radioluminescence (RL) at 520 nm, the fast X‐ray scintillation response with a light yield of about 47 000 photon MeV−1 and low detection limit of 6.48 nGyairs−1 when exposed to X‐ray irradiation condition, which is superior to that of other copper(I) iodide‐based hybrids. Based on the excellent characteristics, X‐ray imaging systems based on (R,S‐2‐mpip)2Cu2I6 single crystals exhibit the clear images of "QFNU" logo and crystal symbol pattern. This work not only deepens the understandings of material design and fundamental properties of these racemate systems, but also provides guidance for the further applications in the multi‐functional optoelectronics. [ABSTRACT FROM AUTHOR]

Converting ionizing radiation into visible light is essential in a wide range of fundamental and industrial applications, such as electromagnetic calorimeters in high‐energy particle detectors, electron detectors, image intensifiers, and X‐ray imaging. These different areas of technology all rely on scintillators or phosphors, i.e., materials that emit light upon bombardment by high‐energy particles. In all cases, the emission is through spontaneous emission. The fundamental nature of spontaneous emission poses limitations on all these technologies, imposing an intrinsic trade‐off between efficiency and resolution in all imaging applications: thicker phosphors are more efficient due to their greater stopping power, which however comes at the expense of image blurring due to light spread inside the thicker phosphors. Here, the concept of inverse‐designed nanophotonic scintillators is proposed, which can overcome the trade‐off between resolution and efficiency by reshaping the intrinsic spontaneous emission. To exemplify the concept, multilayer phosphor nanostructures are designed and these nanostructures are compared to state‐of‐the‐art phosphor screens in image intensifiers, showing a threefold resolution enhancement simultaneous with a threefold efficiency enhancement. The enabling concept is applying the ubiquitous Purcell effect for the first time in a new context—for improving image resolution. Looking forward, this approach directly applies to a wide range of technologies, including X‐ray imaging applications. [ABSTRACT FROM AUTHOR]

Background: Plastic scintillators have been used as radiation detectors for the past few years, as they are water-equivalent and independent of the dose, dose rate, and angle of incidence. In addition, they are also independent of the presence of a magnetic field and could be used for in vivo dosimetry in an MR-Linac. With the advent of a new commercial scintillation detector, Blue Physics Model 10,its characterization has been performed on an MR-Linac with a view to future applications. Purpose: To perform the dosimetric characterization and study potential applications of a novel commercial plastic scintillation detector in a MR-Linac. Methods: Scintillation detector description, calibration procedure, short-term repeatability, dose-response linearity, dose-rate dependence, angular dependence, and temperature dependence have been studied. Percent-depth-dose (PDD) and beam profiles were measured for small fields and a standard field, as well as output factors, for comparison with other PTW detectors: a diamond diode and PinPoint and Semiflex 3D ionization chambers. The suitability of the plastic scintillator for in vivo dosimetry in a magnetic field has also been studied measuring the dose to a point in an anthropomorphic phantom while acquiring MR imaging. This measured dose was compared with that calculated with Monaco planning system and with that measured with a PTW Semiflex 3D chamber, the latter without acquiring MR images. Results: Short-term repeatability presented negligible variations (<0.4%) for 100 and 20 MU. Similar results were obtained for dose-response linearity and dose-rate dependence. A small angular dependence was determined, while the scintillator resulted practically independent of the temperature. PDDs showed excellent agreement except in the build-up region, and calculated penumbras with the profiles given by the scintillator were between the ones obtained with the diamond detector and the PinPoint ionization chamber. Measured OF with the scintillator were the highest between all detectors, 1.26% higher than the value obtained with the microdiamond for the smallest field measured, 0.5 × 0.5 cm2. Finally, the total dose to a point measured with the scintillator was 0.51% higher compared to that calculated by the planning system. Conclusion: The Blue Physics model 10 scintillation system showed excellent dosimetric characteristics. Its response independent of the temperature and the presence of a magnetic field make it suitable for in vivo dosimetry in an MR-Linac while acquiring MR images, which could solve the impossibility of performing a dosimetric QA for each adapted plan. Furthermore, its temporal resolution allows independent radiation pulses to be measured and visualized, which could be used in future applications. [ABSTRACT FROM AUTHOR]

Background: The spatial and temporal dose rate distribution of pencil beam scanning (PBS) proton therapy is important in ultra-high dose rate (UHDR) or FLASH irradiations. Validation of the temporal structure of the dose rate is crucial for quality assurance and may be performed using detectors with high temporal resolution and large dynamic range. Purpose: To provide time-resolved in vivo dose rate measurements using a scintillator-based detector during proton PBS pre-clinical mouse experiments with dose rates ranging from conventional to UHDR. Methods: All irradiations were performed at the entrance plateau of a 250 MeV PBS proton beam. A detector system with four fiber-coupled ZnSe:O inorganic scintillators and 20 μs temporal resolution was used for dose rate measurements.The system was first characterized in terms of precision and stem signal. The detector precision was determined through repeated irradiations with the same field. The stem signal contribution was quantified by irradiating two of the detector probes alongside a bare fiber (fiber without a coupled scintillator). Next, the detector system was calibrated against an ionization chamber (IC) with all four detector probes and the IC placed in a water bath at 2 cm depth. A scan pattern covering 9.6 × 9.6 cm was used. Multiple irradiations with different requested nozzle currents provided instantaneous dose rates at the detector positions in the range of 7–1270 Gy/s. The correspondence of the detector signal (in Volts) to the instantaneous dose rate (in Gy/s) was found.The instantaneous dose rate was calculated from the beam current and the spot-to-detector distance assuming a Gaussian beam profile at distances up to 8 mm from the spot. Afterwards, the calibrated system was used in vivo, in mouse experiments, where mouse legs were irradiated with a constant dose and varying field dose rates of 0.7–87.5 Gy/s. The instantaneous dose rate was measured for each delivered spot and the delivered dose was determined as the integrated instantaneous dose rate. The spot dose profile and PBS dose rate map were calculated. The dose contamination to neighbouring mice were measured together with the upper limit of the dose to the mouse body. Results: The detectors showed high precision with ≤0.4% fluctuations in the measured dose. The stem signal exceeded 10% for spots <5 mm from the optical fiber and >18 mm from the scintillator.It contributed up to 0.2% to the total dose, which was considered negligible. All four detectors showed a non-linear relation between signal and instantaneous dose rate, which was modelled with a polynomial response function. In the mouse experiments, the measured scintillator dose showed 1.8% fluctuations, independent of the field dose rate.The in vivo measured spot dose profile had tails that deviated from a Gaussian profile with measurable dose contributions from spots up to 85 mm from the detector. Neighbour mouse irradiation contributed ∼1% of the total mouse dose. The upper limit of the mouse body dose was 6% of the mouse leg dose. Conclusions: A fiber-coupled inorganic scintillator-based detector system can provide high precision in vivo measurements of the instantaneous dose rate if correction for the non-linear dose rate dependency is applied. [ABSTRACT FROM AUTHOR]

Purpose and objective: To describe a methodology for the dual-material fused deposition modeling (FDM) 3D printing of plastic scintillator arrays, to characterize their light output under irradiation using an sCMOS camera, and to establish a methodology for the dosimetric calibration of planar array geometries. Materials and methods: We have published an investigation into the fabrication and characterization of single element FDM printed scintillators intending to produce customizable dosimeters for radiation therapy applications. ¹ This work builds on previous investigations by extending the concept to the production of a high-resolution (scintillating element size 3 × 3 × 3 mm³) planar scintillator array. The array was fabricated using a BCN3D Epsilon W27 3D printer and composed of polylactic acid (PLA) filament and BCF-10 plastic scintillator. The array's response was initially characterized using a 20 × 20 cm² 6 MV photon field with a source-to-surface (SSD) distance of 100 cm and the beam incident on the top of the array. The light signals emitted under irradiation were imaged using 200 ms exposures from a sCMOS camera positioned at the foot of the treatment couch (210 cm from the array). The collected images were then processed using a purpose-built software to correct known optical artefacts and determine the light output for each scintillating element. The light output was then corrected for element sensitivity and calibrated to dose using Monte Carlo simulations of the array and irradiation geometry based on the array's digital 3D print model. To assess the accuracy of the array calibration both a 3D beam and a clinical VMAT plan were delivered. Dose measurements using the calibrated array were then compared to EBT3 GAFChromic film and OSLD measurements, as well as Monte Carlo simulations and TPS calculations. Results: Our results establish the feasibility of dual-material 3D printing for the fabrication of custom plastic scintillator arrays. Assessment of the 3D printed scintillators response across each row of the array demonstrated a nonuniform response with an average percentage deviation from the mean of 2.1% ± 2.8%. This remains consistent with our previous work on individual 3D printed scintillators which showed an average difference of 2.3% and a maximum of 4.0% between identically printed scintillators.¹ Array dose measurements performed following calibration indicate difficulty in differentiating the scintillator response from ambient background light contamination at low doses (<20–25 cGy) and dose rates (≤100 MU/min). However, when analysis was restricted to exclude dose values less than 10% of the Monte Carlo simulated max dose the average absolute percentage dose difference between Monte Carlo simulation and array measurement was 5.3% ± 4.8% for the fixed beam delivery and 5.4% ± 5.2% for the VMAT delivery Conclusion In this study, we developed and characterized a 3D printed array of plastic scintillators and demonstrated a methodology for the dosimetric calibration of a simple array geometry. [ABSTRACT FROM AUTHOR]

All‐inorganic halide perovskites appear as a promising class of scintillators for radiation detection applications due to their excellent optoelectronic properties. Herein, a self‐activated perovskite CsEuBr3 single crystal is developed as an efficient X‐ and γ‐ray scintillator. Single crystals of CsEuBr3 are grown by the Bridgman method. The phase structure, stability, photophysics properties, and scintillation performance of CsEuBr3 single crystals are studied. Under X‐ray irradiation, its emission peaks at 445 and 510 nm, associated with Eu2+ 5d–4f and defect‐related emission, respectively, are studied. Under 137Cs gamma irradiation, it has a decent light yield of 22 000 ± 2000 photons MeV−1 and an energy resolution of 6.2 ± 0.4% at 662 keV with a scintillation decay of 510 ns. [ABSTRACT FROM AUTHOR]

A bis‐heteroleptic Ru(II) complex, 1[PF6]2 of a benzimidazole substituted pyridyl‐1,2,3‐triazole ligand (BiPT) for highly selective luminescence turn‐on detection of hypochlorous acid (HOCl) is reported. Detection of HOCl is achieved by the Markovnikov addition of HOCl to the C=C bond of 1,2,3‐triazole and a successive highly specific C(sp2)‐H chlorination at the C5 position of 1,2,3‐triazole. The chlorination at C5 in 1,2,3‐triazole is supported by high‐resolution mass spectrometry and 1H NMR study. 1[PF6]2 shows high sensitivity towards HOCl in PBS buffer (pH 7.4) containing 5 % acetonitrile with a 37‐fold luminescence light‐up and a detection limit as low as 7.5 μM. HOCl mediated C(sp2)‐H chlorination increases the 3MC‐3MLCT energy gap as well as the population of the 3MLCT excited state and exhibits the radiative decay from the excited state of 1. The probe showed low cytotoxicity and efficiently permeated the cell membrane. The cell‐imaging experiments revealed rapid staining of the HeLa cells in the presence of exogenous HOCl. [ABSTRACT FROM AUTHOR]

In recent years remarkable progress has been made on developing low‐dimensional perovskite‐related materials. In particular, with the aim of going toward compounds with low toxicity, various low‐dimensional metal halide nanocrystals have been synthesized and investigated. These nanocrystalline compounds crystallize in a plethora of structures and dimensionalities, in many cases with exciting optical properties. Thanks to their photoluminescence emission, which is typically broad and largely Stokes‐shifted, such nanocrystals can find applications in indoor lighting, scintillators and luminescent solar concentrators. In this review, recent developments leading to the improvement/management of light emission from such low‐dimensional metal halide nanocrystals are highlighted and the possible origin of their light emission is discussed. Furthermore, parallels with their bulk counterparts are drawn and an outlook on what is still worth exploring/studying in this field of research is provided. [ABSTRACT FROM AUTHOR]

Scintillators have attracted tremendous attention due to their great potential in radiation detection, industrial non‐destructive testing, and medical theranostic applications. Thermally activated delayed fluorescence (TADF) based scintillators can simultaneously harvest radiation‐induced singlet and triplet excitons for high‐efficient X‐ray excited luminescence. However, pure organic TADF materials composed of light elements exhibit low X‐ray absorption coefficients, resulting in relatively weak X‐ray excited luminescence. Herein, a series of novel high‐performance X‐ray scintillators based on TADF mononuclear Cu(I)‐halide complexes are successfully developed. Together with high X‐ray absorption coefficient of heavy halogen elements and halide‐to‐ligand charge transfer characteristics, these TADF scintillators display excellent performance with high X‐ray relative light yields (as high as 28385 ± 1335 photons MeV−1), good linear response to X‐ray dose rate and high resistance to humidity and radiation. X‐ray imaging tests show that a relatively high spatial resolution of 9.8 lp/mm is realized based on their flexible scintillator films. These features suggest that it is a promising strategy to realize strong X‐ray excited luminescence by incorporating heavy halogen elements in TADF materials, providing more possibilities for exploring new low‐cost and high‐performance scintillators. [ABSTRACT FROM AUTHOR]

The search for color‐tunable, efficient, and robust scintillators plays a vital role in the development of modern X‐ray radiography. The radioluminescence tuning of copper iodide cluster scintillators in the entire visible region by bandgap engineering is herein reported. The bandgap engineering benefits from the fact that the conduction band minimum and valence band maximum of copper iodide cluster crystals are contributed by atomic orbitals from the inorganic core and organic ligand components, respectively. In addition to high scintillation performance, the as‐prepared crystalline copper iodide cluster solids exhibit remarkable resistance toward both moisture and X‐ray irradiation. These features allow copper iodide cluster scintillators to show particular attractiveness for low‐dose X‐ray radiography with a detection limit of 55 nGy s−1, a value ≈100 times lower than a standard dosage for X‐ray examinations. The results suggest that optimizing both inorganic core and organic ligand for the building blocks of metal halide cluster crystals may provide new opportunities for a new generation of high‐performance scintillation materials. [ABSTRACT FROM AUTHOR]

Glass is a group of materials with appealing qualities, including simplicity in fabrication, durability, and high transparency, and they play a crucial role in the optics field. In this paper, a new organic–inorganic metal halide luminescent glass exhibiting >78 % transmittance at 506–800 nm range together with a high photoluminescence quantum yield (PLQY) of 28.5 % is reported through a low‐temperature melt‐quenching approach of pre‐synthesized (HTPP)2MnBr4 (HTPP=hexyltriphenylphosphonium) single crystal. Temperature‐dependent X‐ray diffraction, polarizing microscopy, and molecular dynamics simulations were combined to investigate the glass‐crystal interconversion process, revealing the disordered nature of the glassy state. Benefiting from the transparent nature, (HTPP)2MnBr4 glass yields an outstanding spatial resolution of 10 lp mm−1 for X‐ray imaging. The superb optical properties and facility of large‐scale fabrication distinguish the organic–inorganic metal halide glass as a highly promising class of materials for optical devices. [ABSTRACT FROM AUTHOR]

The toxicity of heavy‐metal Pb and instability of lead‐based halide perovskite nanomaterials are main factors to impede their practical applications in the fields of solar cells, LEDs and scintillators. In this paper, all inorganic lead‐free cesium manganese halide nanocrystals are synthesized in glass for the first time. Red photoluminescence with broad PL band, negligible self‐absorption and a high photoluminescence quantum yield of 41.8% is obtained. In addition, modulating halide component can change the Mn2+ ions coordination environment to obtain tunable photoluminescence from red to green. More importantly, cesium manganese halide nanocrystals embedded glasses exhibit outstanding long‐term stabilities. Theses cesium manganese halide nanocrystals embedded glasses are also highly stable against high energy irradiation and exhibit highly efficient radioluminescence, making them promising for high‐resolution X‐ray imaging. These results demonstrate that cesium manganese halide nanocrystals embedded glasses are promising eco‐friendly candidates for applications in light‐emitting diodes and scintillators. [ABSTRACT FROM AUTHOR]

Copper‐based metal halide scintillators have received increasing attention due to their high light yield and nontoxicity. However, the synthetic methods are still not feasible for actual commercialization for the difficulty in scaling up and the absence of green chemical footprint. Herein, we report a new, simple, aqueous synthetic method for the mass production of highly purified and crystallized Cs3Cu2Cl5 powder by a room‐temperature reaction between a saturated aqueous solution of CsCl and a saturated hydrochloric acid solution of CuCl. The product exhibits a photoluminence peak centering at 527 nm (FWHM = 106.7 nm) and a quantum yield (PLQY) of 97%. A prototype X‐ray imaging detector is fabricated by coupling a large area scintillation screen prepared by blade coating of Cs3Cu2Cl5 powder and a commercial thin‐film transistor (TFT) panel (16 cm × 13 cm, 125 µm pixel size) with readout circuit. The device exhibits a high spatial resolution of 4 lp mm−1, exceeding the theoretical limit of the TFT panel, and an excellent dynamic imaging ability. In short, this work demonstrates an efficient novel synthetic method of Cs3Cu2Cl5 and its application as X‐ray imaging device, providing an applicable solution for its future commercialization. [ABSTRACT FROM AUTHOR]

Mn2+ dopants introduce a new emission center in semiconductor luminescent materials, endowing them promising photoluminescence (PL) properties, such as a wide color tuning range, reversible color change, reduced self‐absorption etc. Recently, rapid development of Mn2+ doped metal halide perovskites (MHPs) promote their promising applications in displays, photovoltaics, scintillators, etc. The emission color, luminous efficiency, and energy transfer pathway of doped perovskites are affected by condition of host lattice that accommodates Mn2+ ions. In this review, the optical properties determined by host materials with diverse geometries involving perovskite nanocrystals and perovskite derivatives is focused on, and the possible energy transfer routes in different doping systems are analyzed. An overview of recent advances of different doped systems with assigned emission channels together with the influence factors, strategies to enhance PL intensity and finally potential applications are summarized. To the end, the underlying challenges and possible solutions for further research in Mn doped perovskites are proposed. [ABSTRACT FROM AUTHOR]

Scintillators with high light yield, low detection limit, large X‐ray attenuation efficiency as well as stable and nontoxic compositions are of great importance for radiation detection applications. Here, 0D (C8H20N)2Cu2Br4 single crystals are obtained and show blue emission peaking at 468 nm with a near‐unity photoluminescence quantum yield of 99.7%, a large Stokes shift of 148 nm (i.e., negligible self‐absorption), and a good environmental stability along with strong X‐ray absorption capability. Moreover, a high light yield of up to ≈ 91 300 photons/MeV and a low detection limit of 52.1 nGyair s−1 are realized, which is more than one hundred times lower than the dose rate of 5.5 µGyair s−1 required for X‐ray medical diagnostics. (C8H20N)2Cu2Br4 ceramic wafer scintillation screen is fabricated by a cold pressing sintering process, and the clear contrast images of opaque metal box and electronic component with a spatial resolution of 9.54 lp mm−1 are realized. This study not only designs a new lead‐free metal halide scintillator, but also develops a universal strategy for the preparation of large‐sized scintillator screen in nondestructive X‐ray imaging. [ABSTRACT FROM AUTHOR]

Scintillators with high light yield, low detection limit, large X‐ray attenuation efficiency as well as stable and nontoxic compositions are of great importance for radiation detection applications. Here, 0D (C8H20N)2Cu2Br4 single crystals are obtained and show blue emission peaking at 468 nm with a near‐unity photoluminescence quantum yield of 99.7%, a large Stokes shift of 148 nm (i.e., negligible self‐absorption), and a good environmental stability along with strong X‐ray absorption capability. Moreover, a high light yield of up to ≈ 91 300 photons/MeV and a low detection limit of 52.1 nGyair s−1 are realized, which is more than one hundred times lower than the dose rate of 5.5 µGyair s−1 required for X‐ray medical diagnostics. (C8H20N)2Cu2Br4 ceramic wafer scintillation screen is fabricated by a cold pressing sintering process, and the clear contrast images of opaque metal box and electronic component with a spatial resolution of 9.54 lp mm−1 are realized. This study not only designs a new lead‐free metal halide scintillator, but also develops a universal strategy for the preparation of large‐sized scintillator screen in nondestructive X‐ray imaging. [ABSTRACT FROM AUTHOR]

The development of metal‐halide perovskite nanocrystals (NCs) that yield bright and stable emission is of great importance. Previous reported perovskite NCs are mostly based on APbX3‐type family fabricated via ligand‐ or surfactant‐assisted chemical approaches. However, realizing bright and stable emission remains a challenge because of desorption of ligands/surfactants during long‐term operation. Herein, Ruddlesden–Popper (RP)‐type (A)2(MA)n‐1PbnBr3n+1 NCs with size less than Bohr radius stabilized in mesoporous silica scaffold, which are prepared in situ via physical approach at low temperature are introduced. The RP NCs in mesoporous silica exhibit the formation of spatially and electronically separated quantum wells, efficient energy funneling between different n phases for bright emission (photoluminescence quantum yields of ≈99%), high irradiation stability (T70 = 110 days), and long‐term stability (T90 = 110 days). These RP NCs have broad potential for bright light‐emitting diodes, high‐resolution PL imaging, and waterproof inks. Importantly, for the first time, stretchable perovskite X‐ray scintillator is demonstrated with excellent X‐ray imaging with resolution greater than 14 line pairs mm−1. These findings offer a paradigm to motivate future research toward stable and efficient perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

Nowadays, high performance (stability, spatial resolution, and optical yield) and multi‐functional application (low‐cost, large‐area, and flexible) are urgently needed for X‐ray detectors in national defense and medical treatment et al. Herein, self‐organizing pixelated zero‐dimensional metal halide Cs4PbBr6 based micro‐disks for low‐cost (0.0238 $ cm−2, 1/37 of CsI(Tl)), large‐area and ultra‐flexible scintillator plates are designed, prepared and applied. The theoretical model describes that the micro‐disks‐based structure being separated from others by air can reduce the transverse optical diffusion within the scintillator, especially when the optical boundary of "pixel" surface is changed by metal coating. Meanwhile, such structure also inhibits the stress generation in the crystal when bent. Further characterization points out that the fabricated scintillator plate possesses high spatial resolution (≈15.9 lp mm−1) and light yield (≈19000 ph Me V−1). Especially, the device shows excellent stability and almost no deterioration of spatial resolution after aging in various extreme environments and in extreme bending tests (folding, keeping bending for a long time). Finally, the good suitability to couple with various photoelectric devices and successful imaging demonstrations of nondestructive measurement are exhibited. It is believed that these findings provide a low‐cost and flexible scintillator preparation scheme and demonstrate a pre‐eminent design paradigm. [ABSTRACT FROM AUTHOR]

X‐Ray‐induced luminescence behavior of Si/Ge‐doped GaN single crystals is observed and analyzed in combination with undoped GaN. Similarities between radioluminescence (RL) and photoluminescence (PL) indicate an analogous physical process. Under X‐Ray irradiation, the gallium nitride (GaN) single crystals doped with Si/Ge elements intensely emit tunable visible light ranging from 1.8 to 2.2 eV, and an ultraviolet (UV) emission of ≈3.3 eV is aroused by the intrinsic direct band‐edge transition of GaN. Due to the difference in the physical properties of excitation source and the self‐absorption effect, the UV signal in RL has a dramatic reduction (especially for undoped GaN) and redshift, which is also considered to be the obvious difference between the two spectra. RL results obtained herein along with PL demonstrate that the visible luminescence of Si/Ge‐doped GaN is mainly attributed to DAP or/and e‐A recombination, which is supported by density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Background: Eye plaque brachytherapy is currently an optimal therapy for intraocular cancers. Due to the lack of an effective and practical technique to measure the seed radioactivity distribution, current quality assurance (QA) practice according to the American Association of Physicists in Medicine TG129 only stipulates that the plaque assembly be visually inspected. Consequently, uniform seed activity is routinely adopted to avoid possible loading mistakes of differential seed loading. However, modulated dose delivery, which represents a general trend in radiotherapy to provide more personalized treatment for a given tumor and patient, requires differential activities in the loaded seeds. Purpose: In this study, a fast and low‐cost radio‐luminescent imaging and dose calculating system to verify the seed activity distribution for differential loading was developed. Methods: A proof‐of‐concept system consisting of a thin scintillator sheet coupled to a camera/lens system was constructed. A seed‐loaded plaque can be placed directly on the scintillator surface with the radioactive seeds facing the scintillator. The camera system collects the radioluminescent signal generated by the scintillator on its opposite side. The predicted dose distribution in the scintillator's sensitive layer was calculated using a Monte Carlo simulation with the planned plaque loading pattern of I‐125 seeds. Quantitative comparisons of the distribution of relative measured signal intensity and that of the relative predicted dose in the sensitive layer were performed by gamma analysis, similar to intensity‐modulated radiation therapy QA. Results: Data analyses showed high gamma (3%/0.3 mm, global, 20% threshold) passing rates for correct seed loadings and low passing rates with distinguished high gamma value area for incorrect loadings, indicating that possible errors may be detected. The measurement and analysis only required a few extra minutes, significantly shorter than the time to assay the extra verification seeds the physicist already must perform as recommended by TG129. Conclusions: Radio‐luminescent QA can be used to facilitate and assure the implementation of intensity‐modulated, customized plaque loading. [ABSTRACT FROM AUTHOR]

Ce3+‐doped 20Gd2O3–20Al2O3–60SiO2 (GAS:xCe3+) glasses (x = 0.3, 0.7, 1.1, 1.5, 1.9 mol%) with Si3N4 as a reducing agent were prepared. The density of the glasses is around 4.2 g/cm3. With the increase in the Ce3+ concentration, both the photoluminescence (PL) and PL excitation peaks of GAS:xCe3+ glasses show a redshift because the 4f–5d energy levels of Ce3+ ions are narrowed. PL quantum yield and PL decay time of GAS:xCe3+ glasses are 28.32–50.59% and 43–64 ns, respectively. In addition, they both first increases and then decreases with the Ce3+ concentration increasing, reached the maximum when x = 1.1 mol%. The integrated X‐ray excited luminescence (XEL) intensity of the GAS:1.1Ce3+ glass is 23.86% of that of Bi4Ge3O12 (BGO) crystal, and the light yield reaches 1200 ph/MeV with an energy resolution of 22.98% at 662 keV when exposed to γ‐rays. The PL and XEL thermal activation energies of GAS:xCe3+ glasses are independent of Ce3+ ions concentration. Scintillating decay time of the glasses exhibits two components consisting of nanosecond and microsecond levels, and the scintillating decay time gradually decreases with the Ce3+ concentration increasing. The difference between PL and scintillating decay time is discussed regarding the different luminescent mechanisms. [ABSTRACT FROM AUTHOR]

Luminescent metal halide perovskites (MHPs) open new avenues for highly efficient radiation detection. To challenge the state‐of‐art technology, fundamental understanding of factors controlling radiation light yield of MHP scintillators is urgent. Herein, a design method is established by simultaneously considering charge‐transfer and recombination efficiencies via band alignment engineering in doped MHPs materials, and this strategy is corroborated experimentally and computationally by applying it to the luminescence of ns2 electron (Sb3+, Bi3+, and Te4+) doped vacancy‐ordered double perovskite Cs2ZrCl6. Alloying Te4+ into Cs2ZrCl6 is optimized and significantly improves the scintillation performance, including a twofold increase in light yield and a threefold increase in detection limit over pristine Cs2ZrCl6, and high‐resolution X‐ray imaging with 20 μm for 2D and 0.2 mm for 3D imaging. It is believed that doping engineering in MHPs enabling band alignment method holds great potential for the development of next‐generation MHP scintillators. [ABSTRACT FROM AUTHOR]

The results of a study aimed at assessing the utility of transionospheric 35 MHz scintillation measurements toward cosmic radio sources for estimating the level of spatial coherence in high frequency (HF) skywave systems are presented. An array of four antennas in southern Maryland called the Deployable Low-band Ionosphere and Transient Experiment was used. Two of the antennas within a ∼350-m north/ south baseline were used to monitor 35-MHz intensity variations of two bright cosmic sources, Cygnus A and Cassiopeia A. The other two antennas, which were within a ∼420-m east/west baseline, recorded the 7.85 MHz skywave from the CHU radio station near Ottawa, Ontario. These HF measurements were used to quantify the level of spatial coherence by measuring the amplitudes of the cross correlation of the two antennas' recorded voltages relative to the received power, which were typically ∼0.5 to 0.9, but occasionally near zero. An approximate scaling method was developed to estimate the expected cross-correlation amplitude based on the 35-MHz scintillations. This method assumes a single layer of irregularities at the reflection height that affects relatively small changes in electron density, the latter of which is generally appropriate for mid-latitudes. It also assumes that the irregularity distribution follows that of the background electron density. These calculations typically captured the day-to-day variations in spatial coherence well (correlation coefficient r ≃ 0.6) while only marginally reproducing hour-to-hour variations (r ≃ 0.2). Thus, this method holds promise as an economical and passive means to assess the spatial coherence expected for skywave propagation within a given mid-latitude region. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the necessity of extending the output factor table (OF Table) of the Varian EclipseTM Treatment Planning System for small field stereotactic radiosurgery (SRS) and stereotactic body radiosurgery (SBRT) treatments. Methods: A new AcurosXB 15.6 beam model was created in the Eclipse Beam Configuration, which is identical to the one that has been used in the clinic with a default 3 × 3 cm to 40 × 40 cm OF Table, except the OF Table in the new model was extended to cover the range from 1 × 1 cm to 40 × 40 cm. 80 small square and rectangular output factors were measured on a Varian TrueBeam utilizing a Standard Imaging Exradin W2‐1×1 scintillator detector, inside a PTW BeamScan water tank with 95 cm SSD at 5 cm depth. Cerenkov contamination was corrected using a rectangular field method (2 cm × 15 cm field). Nine Radiosurgery plans with primary jaw setting ranging from 0.7 cm to 2.0 cm were evaluated by both beam models. The monitor unit (MU) differences between the two beam models were calculated for identical 3‐dimensional (3D) absolute dose distributions. Output factors, measured versus Eclipse calculated, were compared down to 0.5 × 0.5 cm primary jaw setting. Results: For the 6FFF beam, the difference between the two beam models was ∼ 6% for 1 × 1 cm jaw settings and 4% at 1.5 × 1.5 cm, with the extended OF Table requiring higher MUs for the same dose prescription and same 3‐dimensional isodose distribution. For the 6MV beam, the corresponding difference is ∼7.5% for 1 × 1 cm, 5% for 1.5 × 1.5 cm, and 3% for 2 × 2 cm jaw settings, with the extended OF Table requiring higher MUs. For jaw settings smaller than 1 × 1 cm, measured dose can be considerably smaller than Eclipse predicted dose, even with the OF Table extension. This is reflected by the fact that the output factor for 0.5 × 0.5 cm, calculated via Eclipse external beam, was more than 30% greater than that measured for both 6FFF and 6MV beams. Conclusions: Eclipse does a satisfactory job for primary jaw sizes down to 2 cm. For jaw settings smaller than 1.5 cm, the OF Table in Eclipse should be extended to improve the dose calculation accuracy. [ABSTRACT FROM AUTHOR]

Although low‐dimensional hybrid metal halides have emerged as promising light emitters due to their broadband emission originated from self‐trapped exciton (STE), the synthesis of lead‐free halides with high photoluminescence quantum yield remains a challenge. Herein, a series of new luminescent single crystals of antimony‐based metal halides [Na(DMSO)2]3SbBr6−xClx (x = 0, 2, 3, 4, 6) is synthesized. By optimizing the ratio of Br and Cl, [Na(DMSO)2]3SbBr3Cl3 exhibits an ultra‐broadband yellow light emission peaking at 606 nm with a full width at half‐maximum of 160 nm and a high photoluminescence quantum yield of 90.6%. Both experimental characterizations and theoretical calculations indicate that STE emission is responsible for the ultra‐broadband yellow light emission. Furthermore, blue LED chip‐pumped white light‐emitting diodes by using the yellow‐emitting [Na(DMSO)2]3SbBr3Cl3 are demonstrated, showing a correlated color temperature of 3948 K and a color rendering index of 85. Finally, a large‐size and flexible [Na(DMSO)2]3SbBr3Cl3 scintillator used for X‐ray imaging is prepared by a template assembled method, exhibiting a high spatial resolution of 15.5 lp mm−1 and a low detection limit of 285.8 nGyair s−1. This work highlights the potential of Sb‐based halides in solid‐state illumination and X‐ray imaging. [ABSTRACT FROM AUTHOR]

Copper(I) halide perovskite Cs3Cu2I5 has recently attracted tremendous interest and has been considered an exceptionally promising scintillator due to its high quantum yield. However, its slow scintillation decay time, previously considered an intrinsic property, is a significant drawback preventing its practical application and commercialization. But in this work, it is found that the high‐quality Cs3Cu2I5 single‐crystal grown by the designed aqueous solution method surprisingly exhibits a fast scintillation decay time of 39 ns (82%), quite different from previous reports. This subversive change may be due to the high crystal quality with denser 0D structure and low trap density (6.41 × 108 cm–3), changing the excited‐state structural deformation and accelerating the recombination of electrons and holes while directly reducing the prolongation of decay time caused by inherent defects. Moreover, the single‐crystal with a rocking curve FWHM value of only 50.4˝ has a high optical transmittance (85%), a very high absolute photoluminescence quantum yield (PLQY, 97.76%), superior environmental stability, and excellent light‐yield and energy resolution under different γ‐ray sources (241Am, 60Co, 22Na, 137Cs, 152Eu). These extraordinary properties pave the way for the subsequent development of practical applications. [ABSTRACT FROM AUTHOR]

Background: Current clinical positron emission tomography (PET) systems utilize detectors where the scintillator typically contains single elements of 3–6‐mm width and about 20‐mm height. While providing good time‐of‐flight performance, this design limits the spatial resolution and causes radial astigmatism as the depth‐of‐interaction (DOI) remains unknown. Purpose: We propose an alternative, aiming to combine the advantages of current detectors with the DOI capabilities shown for monolithic concepts, based on semi‐monolithic scintillators (slabs). Here, the optical photons spread along one dimension enabling DOI‐encoding with a still small readout area beneficial for timing performance. Methods: An array of eight monolithic LYSO slabs of dimensions 3.9 × 32 × 19 mm3 was read out by a 64‐channel photosensor containing digital SiPMs (DPC3200‐22‐44, Philips Digital Photon Counting). The position estimation in the detector's monolithic and DOI direction was based on a calibration with a fan beam collimator and the machine learning technique gradient tree boosting (GTB). Results: We achieved a positioning performance in terms of mean absolute error (MAE) of 1.44 mm for the monolithic direction and 2.12 mm for DOI considering a wide energy window of 300–700 keV. The energy resolution was determined to be 11.3%, applying a positional‐dependent energy calibration. We established both an analytical and machine‐learning‐based timing calibration approach and applied them for a first‐photon trigger. The analytical timing calibration corrects for electronic and optical time skews leading to 240 ps coincidence resolving time (CRT) for a pair of slab‐detectors. The CRT was significantly improved by utilizing GTB to predict the time difference based on specific training data and applied on top of the analytical calibration. We achieved 209 ps for the wide energy window and 198 ps for a narrow selection around the photopeak (411–561 keV). To maintain the detector's sensitivity, no filters were applied to the data during processing. Conclusion: Overall, the semi‐monolithic detector provides attractive performance characteristics. Especially, a good CRT can be achieved while introducing DOI capabilities to the detector, making the concept suitable for clinical PET scanners. [ABSTRACT FROM AUTHOR]

Herein, the first study on the scintillation properties of CsCu2X3 and Cs3Cu2X5 (where X: Cl−, Br−, I−) is presented, describing their charged particle‐induced luminescence involving electrons, protons, α‐particles, and heavy ions, as well as revealing their capabilities on the timing and spectroscopic evaluation of single‐particle events. The thin layers are prepared with a simple and cost‐effective deposition procedure, without the incorporation of external dopants, exploiting the intrinsic radiative recombination observed in low‐dimensional perovskites. The combined effect of the high binding energy and localized stability of self‐trapped excitons, large Stokes shift, defect tolerance, and the high excitation density along the particle track leads to the emergence of boosted scintillation pulses. The observations demonstrate the first use of inorganic thin‐film scintillators with optical pulse characteristics and light yield competitive with doped single crystal scintillators, while also providing improved structural and functional stability under extreme environmental conditions. [ABSTRACT FROM AUTHOR]

Sol–gel chemistry and nano‐imprint lithography (soft‐NIL) can be combined for the fabrication of nano‐patterns with large vertical aspect ratio over large scales. The possibility to frame via soft‐NIL metal oxides materials featuring a large refractive index and low absorption coefficient, opens new avenues for light management. In spite of its importance, the integration of light emitters in these materials has been mostly investigated in flat layers, limiting their efficiency and versatility. Here it is shown that ZrO2 can be combined with light emitting Eu3+ ions and framed via soft‐NIL to form large arrays of pillars atop a 2D residual layer. The chemical precursor solutions and the nano‐imprint technique are developed for photonic metasurfaces sustaining sharp resonances ascribed to quasi‐guided modes and lattice modes, as accounted for by finite difference time domains simulations. These resonances enable for a record extraction of the Eu3+ forward emission up to ≈200 times with respect to the flat counterpart within a relatively small detection angle (≈ ±16° around the vertical direction). These results are relevant for light‐emitting displays, down‐ and up‐conversion processes for light detection such as scintillators for X‐ray and for light amplifiers based on rare‐earth emitters. [ABSTRACT FROM AUTHOR]

The dependencies of global positioning system (GPS) scintillation indices on ionospheric plasma flow and the rate of change of total electron content (TEC) around the dawn sector for the first time of the polar ionosphere are investigated. The phase scintillation index (σφ) derived from GPS measurements of the Canadian High Arctic Ionospheric Network (CHAIN) shows linear dependencies on both the plasma drift speed measured by the SuperDARN radar and on the rate of change of TEC estimated from the GPS receivers of CHAIN. However, the amplitude scintillation index (S4) does not show any dependence on the plasma flow or the rate of change of TEC. These results further support Wang et al. (2018), https://doi.org/10.1002/2017JA024805 at the noon sector. The dependence of the phase scintillation index on the plasma flow further evidences that the standard phase scintillation index is dominated by refractive variations due to the use of a fixed cut‐off frequency of 0.1 Hz while detrending the phase observable. The dependence of the phase scintillation index on the rate of change of TEC consolidates the dominance of refractive variations inside. Plain Language Summary: In decades, the standard scintillation indices are widely used to represent the strength of scintillations in the ionosphere, which were usually calculated from the sixth order Butterworth filter with a fixed cut‐off frequency of 0.1 Hz by the ground‐based Global Navigation Satellite System (GNSS) receiver automatically. At middle‐to‐low latitudes, the applications of these indices are working very well. However, over the polar ionosphere, the completely different scintillation phenomenon "Phase without Amplitude" occurred when confronting the hazard conditions. Then, in order to explaining this weird, many researchers have carried out a lot of valuable approaches, fundamentally challenging the direct adopt of standard phase scintillation index. Here, for the first time, we present an experimental evidence on the dawn sector to prove the clear positive dependence of phase scintillation index on the convection flow speed and also the TEC variations. It reminds us to be careful when using the standard phase scintillation index over the polar region, in particular with high‐speed flows. Key Points: The dependencies of global positioning system scintillation indices on plasma flow and total electron content (TEC) variation were evaluated around the dawn sector of polar ionosphereThe phase scintillation index depends linearly only on the plasma flow speed and the rate of change of TECHowever, the amplitude scintillation index does not rely on the plasma flow and also the rate of change of TEC [ABSTRACT FROM AUTHOR]

Environmentally friendly metal halides have emerged as emitters in lighting and X‐ray imaging applications. However, the conventional scintillator fabrication process involves high‐temperature sintering or powder grinding, resulting in large bulk crystals or agglomerates, which hamper flexible device integration and processability. Here, large‐area flexible scintillation screen films containing (C24H20P)2MnBr4 nanocrystals are prepared in situ, which prevents the generation of agglomerated powders or large bulk crystals, and the preparation duration and cost are reduced. The film exhibits good mechanical stability and homogeneity, and the photoluminescence quantum yield is over 85%. Moreover, the film presents excellent scintillation performance with detection limit as low as 0.608 μGyair s−1 and 14.5 lp mm−1 X‐ray imaging resolution. This excellent performance and simple preparation method are expected to favor industrial mass production. [ABSTRACT FROM AUTHOR]

Metal clusters with color‐tunable radioluminescence have attracted growing attention as X‐ray detection materials. However, they are generally less scintillation‐efficient due to the coexistence of multiple exciton recombination centers. Herein, two new zero‐dimensional copper(I)‐based clusters (DIET)3Cu3X3 (DIET = 1,3‐Diethyl‐2‐thiourea, X = Cl, Br) are designed, which support the single channel photon emission (Cu cluster centered, CC) to enhance the scintillation performance. Those DIET ligands (L) anchoring with copper(I) ions not only generate direct CuL bonds, but also form a disorder [Cu3X3] cluster, which results in the intense X‐ray absorption. (DIET)3Cu3Br3 with low halogen electronegativity further weakens halogen‐to‐ligand charge transfer (XLCT) emission, enabling enhanced quantum efficiency (≈69%) and scintillation performance comparable to commercially available Lu3Al5O12:Ce. Moreover, the flexible thin film counterpart demonstrates legible X‐ray imaging with high spatial resolution of 11.71 lp mm−1. This study provides a feasible design principle to discover new metal cluster‐based scintillators and to further expand their radiation detection applications. [ABSTRACT FROM AUTHOR]

Scintillators display radioluminescent properties when irradiated by high‐energy photons and therefore play an essential role in radiation detection. The current inventory of scintillators is overwhelmingly represented by achiral structures, where the radioluminescence propagates isotropically after generation. Herein, we demonstrate that chiral perovskites of (R‐3AP)PbBr3Cl⋅H2O (R‐3APP) and (S‐3AP)PbBr3Cl⋅H2O (S‐3APP) emerge as a new type of scintillator displaying a distinct property of circularly polarized radioluminescence (CPRL). A high quantum yield of 27.6 %, high luminescence dissymmetric factors (glum) of 4×10−2, and high X‐ray absorption coefficients were observed for these compounds. As proof of concept, we fabricated a polarized scintillator pair by assembling chiral scintillator crystals, which provides a new strategy to attenuate optical crosstalk between the scintillators by precisely controlling the radioluminescence propagation and improves the X‐ray imaging quality at the boundary region. [ABSTRACT FROM AUTHOR]

Sensitive and fast detection of neutrons and gamma rays is vital for homeland security, high‐energy physics, and proton therapy. Fast‐neutron detectors rely on light organic scintillators, and γ‐ray detectors use heavy inorganic scintillators and semiconductors. Efficient mixed‐field detection using a single material is highly challenging due to their contradictory requirements. Here we report hybrid perovskites (C8H12N)2Pb(Br1−xClx)4 that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed‐field radiation detection. High neutron absorption due to a high density of hydrogen, strong radiative recombination within the highly confined [PbX6]4− layer, and sub‐nanometer distance between absorption sites and radiative centers, enable a light yield of 41 000 photons/MeV, detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons and γ‐rays, outperforming commonly used fast‐neutron scintillators. Neutron energy spectrum, time‐of‐flight based fast‐neutron/γ‐ray discrimination and neutron yield monitoring were all successfully achieved using (C8H12N)2Pb(Br0.95Cl0.05)4 detectors. We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction. We envision that molecular hybridized scintillators open a new avenue for mixed‐field radiation detection and imaging. [ABSTRACT FROM AUTHOR]

Anti‐counterfeiting has become a serious issue around the global world; fluorescence‐based tags are praised for the low‐cost and facile decryption process. However, the high‐level anti‐counterfeiting application requires incorporating multifunctional luminescent materials with response to different excitation sources. Herein, a dimeric Cu(I)‐halide‐clusters‐assembled single‐crystal (AEP)2Cu2I6·2I·2H2O (AEP = N‐aminoethylpiperazinium) concerning a high down‐conversion photoluminescence quantum yield (PLQY) value of near unity is reported (λex = 305 nm), which can also be activated by the near‐infrared light and X‐ray. The ultrafast spectroscopy and density functional theory calculations reveal that the broad‐band emission originates from the recombination of self‐trapped excitons. Remarkably, the high PLQY and excellent attenuation capability for X‐ray confers an outstanding light yield of 55 650 photons MeV−1 to (AEP)2Cu2I6·2I·2H2O, which is 5.25 times higher than the standard bismuth germaniumoxide scintillator. Such multi‐light‐stimulus response endows (AEP)2Cu2I6·2I·2H2O with great application potential in anti‐counterfeiting, solid‐state lighting devices, and digital radiography. [ABSTRACT FROM AUTHOR]

Corundum (α‐Al2O3) is a technologically important material and, in particular, widely used in optical applications such as luminescent radiation dosimeters, cryogenic scintillators, and is being considered as a promising candidate for windows in future fusion reactors. Its optical and mechanical properties are controlled by the presence of radiation‐induced (in particular, by fast neutrons) defects. Herein, the thermal stability and recombination kinetics of primary anion Frenkel defects—the F and F+ electronic centers and oxygen interstitials—in fast‐neutron‐irradiated α‐Al2O3 single crystals are analyzed. Theory is developed considering the formation of both neutral and charged oxygen Frenkel defect pairs; defect migration, interaction and recombination. Based on ab initio calculations and new theoretical kinetics analysis, for the first time, a coexistence is demonstrated, in comparable concentrations, of two interstitial types—neutral O atoms and negatively charged O− ions (with attributed optical absorption band maxima at 6.5 eV and 5.6 eV, respectively); and their diffusion parameters, necessary for the prediction of secondary defect‐induced reactions and defect/material thermal stability, are obtained. [ABSTRACT FROM AUTHOR]

Background: Significant interest has been recently shown for using monolithic scintillation crystals in molecular imaging systems, such as positron emission tomography (PET) scanners. Monolithic‐based PET scanners result in a lower cost and higher sensitivity, in contrast to systems based on the more conventional pixellated configuration. The monolithic design allows one to retrieve depth‐of‐interaction information of the impinging 511 keV photons without the need for additional hardware materials or complex positioning algorithms. However, the so‐called edge‐effect inherent to monolithic‐based approaches worsens the detector performance toward the crystal borders due to the truncation of the light distribution, thus decreasing positioning accuracy. Purpose: The main goal of this work is to experimentally demonstrate the detector performance improvement when machine‐learning artificial neural‐network (NN) techniques are applied for positioning estimation in multiple monolithic scintillators optically coupled side‐by‐side. Methods: In this work, we show the performance evaluation of two LYSO crystals of 33 × 25.4 × 10 mm3 optically coupled by means of a high refractive index adhesive compound (Meltmount, refractive index n = 1.70). A 12 × 12 silicon photomultiplier array has been used as photosensor. For comparison, the same detector configuration was tested for two additional coupling cases: (1) optical grease (n = 1.46) in between crystals, and (2) isolated crystals using black paint with an air gap at the interface (named standard configuration). Regarding 2D photon positioning (XY plane), we have tested two different methods: (1) a machine‐learning artificial NN algorithm and (2) a squared‐charge (SC) centroid technique. Results: At the interface region of the detector, the SC method achieved spatial resolutions of 1.7 ± 0.3, 2.4 ± 0.3, and 2.6 ± 0.4 mm full‐width at half‐maximum (FWHM) for the Meltmount, grease, and standard configurations, respectively. These values improve to 1.0 ± 0.2, 1.2 ± 0.2, and 1.2 ± 0.3 mm FWHM when the NN algorithm was employed. Regarding energy performance, resolutions of 18 ± 2%, 20 ± 2%, and 23 ± 3% were obtained at the interface region of the detector for Meltmount, grease, and standard configurations, respectively. Conclusions: The results suggest that optically coupling together scintillators with a high refractive index adhesive, in combination with an NN algorithm, reduces edge‐effects and makes it possible to build scanners with almost no gaps in between detectors. [ABSTRACT FROM AUTHOR]

Purpose: Experimental measurements of two‐dimensional (2D) dose rate distributions in proton pencil beam scanning (PBS) FLASH radiation therapy (RT) are currently lacking. In this study, we characterize a newly designed 2D strip‐segmented ionization chamber array (SICA) with high spatial and temporal resolution and demonstrate its applications in a modern proton PBS delivery system at both conventional and ultrahigh dose rates. Methods: A dedicated research beamline of the Varian ProBeam system was employed to deliver a 250‐MeV proton PBS beam with nozzle currents up to 215 nA. In the research and clinical beamlines, the spatial, temporal, and dosimetric performances of the SICA were characterized and compared with measurements using parallel‐plate ion chambers (IBA PPC05 and PTW Advanced Markus chamber), a 2D scintillator camera (IBA Lynx), Gafchromic films (EBT‐XD), and a Faraday cup. A novel reconstruction approach was proposed to enable the measurement of 2D dose and dose rate distributions using such a strip‐type detector. Results: The SICA demonstrated a position accuracy of 0.12 ± 0.02 mm at a 20‐kHz sampling rate (50 μs per event) and a linearity of R2 > 0.99 for both dose and dose rate with nozzle beam currents ranging from 1 to 215 nA. The 2D dose comparison to the film measurement resulted in a gamma passing rate of 99.8% (2 mm/2%). A measurement‐based proton PBS 2D FLASH dose rate distribution was compared to simulation results and showed a gamma passing rate of 97.3% (2 mm/2%). Conclusions: The newly designed SICA demonstrated excellent spatial, temporal, and dosimetric performances and is well suited for commissioning, quality assurance, and a wide range of clinical applications in proton PBS clinical and FLASH‐RT. [ABSTRACT FROM AUTHOR]

Low‐dimensional organic–inorganic hybrids have emerged as promising X‐ray scintillators due to efficient radioluminescence properties. Herein, stable and efficient X‐ray scintillator based on 0D (C40H38P2)MnBr4 hybrid single crystals grown by a facile solution‐processing method is reported. Its crystal structure is determined to be triclinic with P1¯ space group. It has good stability against moisture and irradiation. (C40H38P2)MnBr4 with tetrahedrally coordinated Mn2+ exhibits green emission peaking at 518 nm originating from d–d 4T1→6A1 transition of Mn2+ ion with a high photoluminescence quantum yield (PLQY) of 74.2%. Under X‐ray excitation, it shows high scintillation yield of 32 000 photons MeV−1, a decent detection limit of 288 nGyair s−1, and a low afterglow comparable to that of Bi4Ge3O12 (BGO). [ABSTRACT FROM AUTHOR]

Plastic scintillators are gaining attention as alternatives to inorganic scintillator crystals owing to their low fabrication cost, customable shape/size, and substantially lighter weight that make them suitable for various radiation detection technologies. These include scintillation panels for national security and industrial monitoring, radiation screens for medical diagnostics, and calorimeters for high energy physics. Because of their low density, plastic scintillators are typically doped with high atomic number (Z) sensitizers that enhance the interaction probability with ionizing radiation and excite molecular emitters. Although effective, such a two‐component design suffers from incomplete sensitization, intrinsically limited efficiency due to multiple radiative steps with non‐unity quantum yield, detrimental phase segregation effects and the fragility of organic emitters to ionizing radiation. In this work, an alternative single‐component scheme is proposed based on high‐Z reabsorption‐free CdZnS/ZnS semiconductor nanocrystals (NCs) doped with manganese embedded in a polyvinyltoluene (PVT) waveguide. Optical‐grade nanocomposites free from optical reabsorption of the scintillation light and with performance comparable to commercial products are obtained through a post‐synthesis resurfacing procedure that maximizes the compatibility between the NCs and PVT and preserves their optical properties upon curing. [ABSTRACT FROM AUTHOR]

Purpose: Although flash radiation therapy (FLASH‐RT) is a promising novel technique that has the potential to achieve a better therapeutic ratio between tumor control and normal tissue complications, the ultrahigh pulsed dose rates (UHPDR) mean that experimental dosimetry is very challenging. There is a need for real‐time dosimeters in the development and implementation of FLASH‐RT. In this work, we characterize a novel plastic scintillator capable of temporal resolution short enough (2.5 ms) to resolve individual pulses. Methods: We characterized a novel plastic dosimeter for use in a linac converter to deliver 16‐MeV electrons at 100‐Gy/s UHPDR average dose rates. The linearity and reproducibility were established by comparing relative measurements with a pinpoint ionization chamber placed at 10‐cm water‐equivalent depth where the electrometer is not saturated by the high dose per pulse. The accuracy was established by comparing the plastic scintillator dose measurements with EBT‐XD Gafchromic radiochromic films, the current reference dosimeter for UHPDR. Finally, the plastic scintillator was compared against EBT‐XD films for online dosimetry of two in vitro experiments performed at UHPDR. Results: Relative ion chamber measurements were linear with plastic scintillator response within ≤1% over 4–20 Gy and pulse frequencies (18–180 Hz). When characterized under reference conditions with NIST‐traceability, the plastic scintillator maintained its dose response under UHPDR conditions and agreed with EBT‐XD film dose measurements within 4% under reference conditions and 6% for experimental online dosimetry. Conclusion: The plastic scintillator shows a linear and reproducible response and is able to accurately measure the radiation absorbed dose delivered by 16‐MeV electrons at UHPDR. The dose is measured accurately in real time with a greater level of precision than that achieved with a radiochromic film. [ABSTRACT FROM AUTHOR]

Background: There is increased interest in in vivo dosimetry for 192Ir brachytherapy (BT) treatments using high atomic number (Z) inorganic scintillators. Their high light output enables construction of small detectors with negligible stem effect and simple readout electronics. Experimental determination of absorbed‐dose energy dependence of detectors relative to water is prevalent, but it can be prone to high detector positioning uncertainties and does not allow for decoupling of absorbed‐dose energy dependence from other factors affecting detector response. Purpose: To investigate which measurement conditions and detector properties could affect their absorbed‐dose energy dependence in BT in vivo dosimetry. Methods: We used a general‐purpose Monte Carlo (MC) code PENELOPE for the characterization of high‐Z inorganic scintillators with the focus on ZnSe (Z¯=32$\bar{Z}=32$) Z. Two other promising media CsI (Z¯=54$\bar{Z}=54$) and Al2O3 (Z¯=11$\bar{Z}=11$) were included for comparison in selected scenarios. We determined absorbed‐dose energy dependence of crystals relative to water under different scatter conditions (calibration phantom 12 × 12 × 30 cm3, characterization phantoms 20 × 20 × 20 cm3, 30 × 30 × 30 cm3, 40 × 40 × 40 cm3, and patient‐like elliptic phantom 40 × 30 × 25 cm3). To mimic irradiation conditions during prostate treatments, we evaluated whether the presence of pelvic bones and calcifications affect ZnSe response. ZnSe detector design influence was also investigated. Results: In contrast to low‐Z organic and medium‐Z inorganic scintillators, ZnSe and CsI media have substantially greater absorbed‐dose energy dependence relative to water. The response was phantom‐size dependent and changed by 11% between limited‐ and full‐scatter conditions for ZnSe, but not for Al2O3. For a given phantom size, a part of the absorbed‐dose energy dependence of ZnSe is caused not due to in‐phantom scatter but due to source anisotropy. Thus, the absorbed‐dose energy dependence of high‐Z scintillators is a function of not only the radial distance but also the polar angle. Pelvic bones did not affect ZnSe response, whereas large and intermediate size calcifications reduced it by 9% and 5%, respectively, when placed midway between the source and the detector. Conclusions: Unlike currently prevalent low‐ and medium‐Z scintillators, high‐Z crystals are sensitive to characterization and in vivo measurement conditions. However, good agreement between MC data for ZnSe in the present study and experimental data for ZnSe:O by Jørgensen et al. (2021) suggests that detector signal is proportional to the average absorbed dose to the detector cavity. This enables an easy correction for non‐TG43‐like scenarios (e.g., patient sizes and calcifications) through MC simulations. Such information should be provided to the clinic by the detector vendors. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the dosimetric characteristics and applications of a dosimetry system composed of a flexible amorphous silicon thin‐film solar cell and scintillator screen (STFSC‐SS) for therapeutic X‐rays. Methods: The real‐time dosimetry system was composed of a flexible a‐Si thin‐film solar cell (0.2‐mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric characteristics of the developed system were evaluated including its energy dependence, dose linearity, and angular dependence. Calibration factors for the signal measured by the system and absorbed dose‐to‐water were obtained by setting reference conditions. The application and correction accuracy of the developed system were evaluated by comparing the absorbed dose‐to‐water measured using a patient treatment beam with that measured using the ion chamber. Results: The responses of STFSC‐SS to energy, field size, depth, and source‐to‐surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former dependence was due to the scintillator screen, not the solar cell. The signals of STFSC‐SS were also dependent on dose rate, while the responses of solar cell alone and scintillator screen were not dependent on dose rate. The scintillator screen reduced the output of solar cell at 6 and 15 MV by 0.60 and 0.55%, respectively. The different absorbed dose‐to‐water measured using STFSC‐SS for patient treatment beam differed by 0.4% compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8 and 1.7%, respectively, confirming the accuracy and applicability of this system. Conclusions: The thin‐film solar cell‐based detector developed in this study can accurately measure absorbed dose‐to‐water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible, making it applicable to curved surfaces, such as a patient's body, and is cost‐effective. [ABSTRACT FROM AUTHOR]

Purpose: Quantitative in vivo molecular imaging of fine brain structures requires high‐spatial resolution and high‐sensitivity. Positron emission tomography (PET) is an attractive candidate to introduce molecular imaging into standard clinical care due to its highly targeted and versatile imaging capabilities based on the radiotracer being used. However, PET suffers from relatively poor spatial resolution compared to other clinical imaging modalities, which limits its ability to accurately quantify radiotracer uptake in brain regions and nuclei smaller than 3 mm in diameter. Here we introduce a new practical and cost‐effective high‐resolution and high‐sensitivity brain‐dedicated PET scanner, using our depth‐encoding Prism‐PET detector modules arranged in a conformal decagon geometry, to substantially reduce the partial volume effect and enable accurate radiotracer uptake quantification in small subcortical nuclei. Methods: Two Prism‐PET brain scanner setups were proposed based on our 4‐to‐1 and 9‐to‐1 coupling of scintillators to readout pixels using 1.5×1.5×20$1.5 \times 1.5 \times 20$ mm3 and 0.987×0.987×20$0.987 \times 0.987 \times 20$ mm3 crystal columns, respectively. Monte Carlo simulations of our Prism‐PET scanners, Siemens Biograph Vision, and United Imaging EXPLORER were performed using Geant4 application for tomographic emission (GATE). National Electrical Manufacturers Association (NEMA) standard was followed for the evaluation of spatial resolution, sensitivity, and count‐rate performance. An ultra‐micro hot spot phantom was simulated for assessing image quality. A modified Zubal brain phantom was utilized for radiotracer imaging simulations of 5‐HT1A receptors, which are abundant in the raphe nuclei (RN), and norepinephrine transporters, which are highly concentrated in the bilateral locus coeruleus (LC). Results: The Prism‐PET brain scanner with 1.5 mm crystals is superior to that with 1 mm crystals as the former offers better depth‐of‐interaction (DOI) resolution, which is key to realizing compact and conformal PET scanner geometries. We achieved uniform 1.3 mm full‐width‐at‐half‐maximum (FWHM) spatial resolutions across the entire transaxial field‐of‐view (FOV), a NEMA sensitivity of 52.1 kcps/MBq, and a peak noise equivalent count rate (NECR) of 957.8 kcps at 25.2 kBq/mL using 450–650 keV energy window. Hot spot phantom results demonstrate that our scanner can resolve regions as small as 1.35 mm in diameter at both center and 10 cm away from the center of the transaixal FOV. Both 5‐HT1A receptor and norepinephrine transporter brain simulations prove that our Prism‐PET scanner enables accurate quantification of radiotracer uptake in small brain regions, with a 1.8‐fold and 2.6‐fold improvement in the dorsal RN as well as a 3.2‐fold and 4.4‐fold improvement in the bilateral LC compared to the Biograph Vision and EXPLORER, respectively. Conclusions: Based on our simulation results, the proposed high‐resolution and high‐sensitivity Prism‐PET brain scanner is a promising cost‐effective candidate to achieve quantitative molecular neuroimaging of small but important brain regions with PET clinically viable. [ABSTRACT FROM AUTHOR]