Evaluating the Effects of Breaking Vacuum During the Fabrication of Amorphous Selenium Detectors.

Direct conversion X-ray detectors offer high spatial resolution and improved sensitivity over indirect conversion detectors. As interest increases in their applications, including utilization as the top layer in dual-layer detectors for polyenergetic X-ray detection, additional studies on fabrication techniques are required. Amorphous selenium is a well-studied high-Z semiconductor capable of high-resolution and high-sensitivity imaging in direct architectures. It is already commercially available for mammography, and much work has gone into developing it for higher-energy applications (>20 keV.) To fully attenuate energies required for the low energy (<35 keV) top layer in dual-layer detectors, a-Se thicknesses greater than 200 µm must be fabricated. However, evaporation crucibles have limited capacity and require reloading of crucible material to achieve higher thicknesses, which is performed by opening the chamber and breaking vacuum mid-fabrication. We investigate the effects of splitting the fabrication into two depositions - exposing the sample to air in between - on device performance. We find that there is no significant effect on the transport properties, and a small range of performance parameters can be found - suggesting small fluctuations between devices of ± 5%, independent of fabrication technique and thickness. This implies that as we increase our thicknesses to those required for the low-energy layer of the dual-layer detector, we can expect performance to be maintained.

Intercalation Electrode and Grain Reconstruction Induce Significant Sensitivity Enhancement for Perovskite X-ray Detectors.

Organic-inorganic hybrid perovskites have been recognized as potential candidates in direct X-ray detectors and have triggered tremendous interest in the past years. The blade coating method meets the requirements of large area and low cost for perovskite X-ray detectors, while the low compactness resulting from solvent evaporation limits the charge collection efficiency (CCE) and device sensitivity. Most of the reports are focused on the melioration of perovskite films to increase device sensitivity; there are still problems of low CCE. Herein, we introduce an intercalation-electrode device structure and achieve a ∼20-fold sensitivity enhancement. Carrier distribution throughout the thick films is simulated, and the electrode intercalating site can be optimized according to the mobility-lifetime factor to achieve the highest CCE. A methylamine thiocyanate (MASCN) additive-assisted coating strategy is developed, and pinhole free thick films with regrown particles are obtained without frequently used hot/soft pressing. A sensitivity level of ∼105 µC Gyair-1 cm-2 as well as a detection limit of 77 nGyair s-1 is achieved under low bias, which is among the best performance for polycrystalline perovskite direct X-ray detectors. This work provides a universal device structure design to overcome carrier loss through a long transport distance and enhances the CCE for ultrahigh sensitivity.

In Situ Crystal Growth and Fusing-Confined Engineering of Quasi-Monocrystalline Perovskite Thick Junctions for X-ray Detection and Imaging.

Metal halide perovskites exhibit great promise for utilization in X-ray detection owing to their excellent optoelectronic properties and high X-ray attenuation capabilities. However, fabricating large-area thick films for high-performance perovskite X-ray detection remains challenging. This study develops an in situ crystal growth and fusing-confined approach to prepare high-quality, large-scale perovskite quasi-monocrystalline thick junctions. The perovskite crystals are grown in situ using a highly concentrated perovskite colloidal solution in 2-methoxyethanol. Introducing methylammonium chloride enhances grain reorganization during in situ growth and fusing-confined processes, effectively reducing grain boundaries and surface defects. This allows for the preparation of quasi-monocrystalline thick junctions of large grains (>100 µm) with high crystallinity, uniform orientation, and vertical penetration across the film thickness. Additionally, the carrier mobility and lifetime of the thick junctions are significantly enhanced. The optimized MAPbI3 detectors demonstrate an X-ray sensitivity of 2.6 × 104 µC Gyair-1 cm-2 and an exceptionally low detection limit of 1 nGyair s-1. Furthermore, inspired by a honeycomb structure, these detectors realize X-ray imaging in 64 × 64 pixels through a pixelated separation design, effectively reducing the charge-sharing effect. This study offers valuable insights into the preparation of large-scale perovskite quasi-monocrystalline thick junctions for highly sensitive X-ray detection and imaging applications.

Enhancement of Electron Transport Characteristics Using MXene-MnFeO3 Nanocomposite Integration with Fullerene Derivatives for the Perovskite-Based Solar Cells and Detectors.

In this study, we prepared a hybrid film incorporating the MnFeO3-decorated conducting two-dimensional (2D) MXene sheet-suspended [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) electron transfer layer (ETL) for the perovskite solar cells (PSCs) and detectors. The incorporation of MXene-MnFeO3 with the PCBM ETL could drive exceptional conducting features for the PSCs. Moreover, the presence of MXene-MnFeO3 facilitated superior charge transfer pathways, thereby enhancing the electron extraction and collection processes. This enhancement was directed to improve the electron mobility within the device, resulting in high photocurrents. The designed interface engineering with the MXene-MnFeO3 nanocomposite-tuned PCBM ETL has produced a remarkable power conversion efficiency of 17.79% ± 0.27. Moreover, X-ray detectors employing PCBM modulated with the MXene-MnFeO3 ETL achieved notable performance metrics including 18.47 µA/cm2 CCD-DCD, 5.53 mA/Gy·cm2 sensitivity, 7.64 × 10-4 cm2/V·s electron mobility, and 1.51 × 1015 cm2/V·s trap density.

Ion Leakage Current Control for Polycrystalline Metal Halide Perovskite Direct X-ray Detectors.

Metal halide perovskites have emerged as promising materials for X-ray detection due to their high X-ray attenuation coefficients, defect tolerance, and suitability for large-area, low-temperature fabrication. However, the intrinsic high ion conductivity of these materials presents challenges, such as high dark current density and current drift, which impair the stability and sensitivity of perovskite X-ray detectors. This study introduces an approach to mitigating these issues by incorporating 2,2,3,3,3-pentafluoropropylamine hydrochloride (PFH) into polycrystalline MAPbI3-xClx films using a one-step blade-coating method. PFH aggregates at grain boundaries, raising local vacuum energy levels and passivating surface defects, thereby reducing ion conductivity without affecting electron conductivity. As a result, this approach significantly reduces the dark current and enhances sensitivity, achieving a low detection limit of 14.7 nGyair/s. Additionally, it improves signal stability, consistency, and response speed of the detector. These findings suggest that PFH is a promising additive for advancing the performance and practical application of polycrystalline metal halide perovskite-based X-ray detectors.

Micro/Nano Engineering Advances Next-Generation Flexible X-ray Detectors.

The growing demands for X-ray imaging applications impose diverse and stringent requirements on advanced X-ray detectors. Among these, flexibility stands out as the most expected characteristic for next-generation X-ray detectors. Flexible X-ray detectors can spatially conform to nonflat surfaces, substantially improving the imaging resolution, reducing the X-ray exposure dosage, and enabling extended application opportunities that are hardly achievable by conventional rigid flat-panel detectors. Over the past years, indirect- and direct-conversion flexible X-ray detectors have made marvelous achievements. In particular, microscale and nanoscale engineering technologies play a pivotal role in defining the optical, electrical, and mechanical properties of flexible X-ray detectors. In this Perspective, we spotlight recent landmark advancements in flexible X-ray detectors from the aspects of micro/nano engineering strategies, which are broadly categorized into two prevailing modalities: materials-in-substrate and materials-on-substrate. We also discuss existing challenges hindering the development of flexible X-ray detectors, as well as prospective research opportunities to mitigate these issues.

High Sensitivity X-Ray Detectors with Low Degradation Based on Deuterated Halide Perovskite Single Crystals.

Methylammonium lead single crystal (MAPbI3 SC) possesses superior optoelectronic properties and low manufacturing cost, making it an ideal candidate for X-ray detection. However, the ionic migration of the perovskites usually leads to instability, dark current drift, and hysteresis of the detector, limiting their applications in well-established technologies. Here, a series of X-ray detectors of MAPbI3 SCs are reported with different degrees of deuteration (DxMAPbI3, x = 0, 0.15, 0.75, 0.99). By controlling the content of deuterium (D) in organic cations, the sensitivity, detection limits, ion migration, and resistivity of the detector can be controlled, thereby improving its performance. Due to stronger hydrogen bonds (N─D···I), the ion activation energy significantly increases to 886 meV. Consequently, the D0.99MAPbI3 SC detector shows more than five-fold enhancement, achieving a record-high mobility-lifetime (µτ) product of 5.39 × 10-2 cm2 V-1, with an ultrahigh sensitivity of 2.18 × 106 µC Gy-1 cm-2 under 120 keV hard X-ray and a low detection limit of 4.8 nGyair s-1, as well as long-term stability. The study provides a straightforward strategy for constructing ultrasensitive X-ray detection and imaging systems based on perovskite SCs.

Indirect detector for ultra-high-speed X-ray micro-imaging with increased sensitivity to near-ultraviolet scintillator emission.

Ultra-high-speed synchrotron-based hard X-ray (i.e. above 10 keV) imaging is gaining a growing interest in a number of scientific domains for tracking non-repeatable dynamic phenomena at spatio-temporal microscales. This work describes an optimized indirect X-ray imaging microscope designed to achieve high performance at micrometre pixel size and megahertz acquisition speed. The entire detector optical arrangement has an improved sensitivity within the near-ultraviolet (NUV) part of the emitted spectrum (i.e. 310-430 nm wavelength). When combined with a single-crystal fast-decay scintillator, such as LYSO:Ce (Lu2-xYxSiO5:Ce), it exploits the potential of the NUV light-emitting scintillators. The indirect arrangement of the detector makes it suitable for high-dose applications that require high-energy illumination. This allows for synchrotron single-bunch hard X-ray imaging to be performed with improved true spatial resolution, as herein exemplified through pulsed wire explosion and superheated near-nozzle gasoline injection experiments at a pixel size of 3.2 µm, acquisition rates up to 1.4 MHz and effective exposure time down to 60 ps.

Double-Sided Bonding Process Enables X-ray Flat Panel Detectors.

Metal halide perovskites have demonstrated superior sensitivity, lower detection limits, stability, and exceptional photoelectric properties in comparison to existing commercially available X-ray detector materials, showing their potential for shaping the next generation of X-ray detectors. Nevertheless, significant challenges persist in the seamless integration of these materials into pixelated array sensors for large-area X-ray direct detection imaging. In this article, we propose a strategy for fabricating large-scale array devices using a double-sided bonding process. The approach involves depositing a wet film on the surface of a thin-film transistor substrate to establish a robust bond between the substrate and δ-CsPbI3 wafer via van der Waals force, thereby facilitating area-array imaging. Additionally, the freestanding polycrystalline δ-CsPbI3 wafer demonstrated a competitive ultralow detection limit of 3.46 nGyair s-1 under 50 kVP X-ray irradiation, and the δ-CsPbI3 wafer still maintains a stable signal output (signal current drift is 3.5 × 10-5 pA cm-1 s-1 V-1) under the accumulated radiation dose of 234.9 mGyair. This strategy provides a novel perspective for the industrial production of large-area X-ray flat panel detectors utilizing perovskites and their derivatives.

Mitigation of Parasitic and Drift Capacitance-Induced Nonlinear Current Responses for Stable and Sensitive Perovskite X-ray Detectors.

The development of perovskite direct X-ray detectors shows potential for advancing medical imaging and industrial inspection precision. To ensure the optimal energy conversion efficiency of X-rays for reducing radiation doses, it is necessary for perovskites with thicknesses reaching hundreds of micrometers or even several millimeters to be utilized. However, the nonlinear current response becomes uncertain with such high thicknesses. For instance, the prevailing theory regarding the rapid trapping and release of charges by shallow-level defects falls short in explaining the nonlinear current response observed in high-quality single-crystal samples. Moreover, a significant nonlinear current response can degrade the detection performance. Here, we elucidate peculiar parasitic and drift capacitance-induced nonlinear current responses in perovskites, which arise from bulk structural deficiencies and interface junction width variation in addition to shallow-level defects. Both theoretical analysis and experimental findings demonstrate the effective suppression of nonlinear current responses by establishing bulk heterojunctions and refining interface junctions. Consequently, we have successfully developed highly linear current-responsive detectors based on polycrystalline MAPbI3 thick films. Notably, these detectors achieve a record sensitivity of 2.3 × 104 µC·Gyair-1·cm-2 under 100 kVp X-ray irradiation with a low bias of 0.1 V/µm, enabling enduring and high-resolution X-ray imaging for high-density objects. Successful fabrication and testing of a 64 × 64-pixel flat-panel prototype detector affirm the widespread applicability of these strategies in rectifying nonlinear current responses in perovskite-based X-ray detectors.

Lead-Free Bismuth-Based Perovskite X-ray Detector with High Sensitivity and Low Detection Limit.

Bismuth-based halide perovskites have shown great potential for direct X-ray detection, attributable to their nontoxicity and advantages in detection sensitivity and spatial resolution. However, the practical application of such materials still faces the critical challenge of combining both high sensitivity and low detection limits. Here, we report a new type of zero-dimensional (0D) perovskite (HIS)BiI5 (1, where HIS2+ = histamine) with high sensitivity and a low detection limit. Structurally, the strong N-H···I hydrogen bonds between HIS2+ cations and inorganic frameworks enhance the rigidity of the structure and diminish the intermolecular distance between adjacent inorganic [Bi2I10]4- dimers. By virtue of such structural merits, single crystal 1 exhibits excellent physical properties perpendicular to both the (001) and (010) faces. Perpendicular to the (010) face, 1 exhibited a high electrical resistivity (2.31 × 1011 Ω cm) and a large carrier mobility-lifetime product (µτ) (2.81 × 10-4 cm2 V-1) under X-ray illumination. Benefiting from these superior physical properties, it demonstrates an excellent X-ray detection capability with a sensitivity of approximately 103 µC Gyair-1 cm-2 and a detection limit of 36 nGyair s-1 in both directions perpendicular to the (001) and (010) crystal faces. These results provide a promising candidate material for the development of new, lead-free, high-performance X-ray detectors.

Can processed images be used to determine the modulation transfer function and detective quantum efficiency?

Purpose: The modulation transfer function (MTF) and detective quantum efficiency (DQE) of x-ray detectors are key Fourier metrics of performance, valid only for linear and shift-invariant (LSI) systems and generally measured following IEC guidelines requiring the use of raw (unprocessed) image data. However, many detectors incorporate processing in the imaging chain that is difficult or impossible to disable, raising questions about the practical relevance of MTF and DQE testing. We investigate the impact of convolution-based embedded processing on MTF and DQE measurements. Approach: We use an impulse-sampled notation, consistent with a cascaded-systems analysis in spatial and spatial-frequency domains to determine the impact of discrete convolution (DC) on measured MTF and DQE following IEC guidelines. Results: We show that digital systems remain LSI if we acknowledge both image pixel values and convolution kernels represent scaled Dirac δ-functions with an implied sinc convolution of image data. This enables use of the Fourier transform (FT) to determine impact on presampling MTF and DQE measurements. Conclusions: It is concluded that: (i) the MTF of DC is always an unbounded cosine series; (ii) the slanted-edge method yields the true presampling MTF, even when using processed images, with processing appearing as an analytic filter with cosine-series MTF applied to raw presampling image data; (iii) the DQE is unaffected by discrete-convolution-based processing with a possible exception near zero-points in the presampling MTF; and (iv) the FT of the impulse-sampled notation is equivalent to the Z transform of image data.

Framework for evaluating photon-counting detectors under pile-up conditions.

Purpose: While X-ray photon-counting detectors (PCDs) promise to revolutionize medical imaging, theoretical frameworks to evaluate them are commonly limited to incident fluence rates sufficiently low that the detector response can be considered linear. However, typical clinical operating conditions lead to a significant level of pile-up, invalidating this assumption of a linear response. Here, we present a framework that aims to evaluate PCDs, taking into account their non-linear behavior. Approach: We employ small-signal analysis to study the behavior of PCDs under pile-up conditions. The response is approximated as linear around a given operating point, determined by the incident spectrum and fluence rate. The detector response is subsequently described by the proposed perturbation point spread function (pPSF). We demonstrate this approach using Monte-Carlo simulations of idealized direct- and indirect-conversion PCDs. Results: The pPSFs of two PCDs are calculated. It is then shown how the pPSF allows to determine the sensitivity of the detector signal to an arbitrary lesion. This example illustrates the detrimental influence of pile-up, which may cause non-intuitive effects such as contrast/contrast-to-noise ratio inversion or cancellation between/within energy bins. Conclusions: The proposed framework permits quantifying the spectral and spatial performance of PCDs under clinically realistic conditions at a given operating point. The presented example illustrates why PCDs should not be analyzed assuming that they are linear systems. The framework can, for example, be used to guide the development of PCDs and PCD-based systems. Furthermore, it can be applied to adapt commonly used measures, such as the modulation transfer function, to non-linear PCDs.

Vertically Oriented Quasi-2D Perovskite Grown In-Situ by Carbonyl Array-Synergized Crystallization for Direct X-Ray Detectors.

Quasi-2D perovskite quantum wells are increasingly recognized as promising candidates for direct-conversion X-ray detection. However, the fabrication of oriented and uniformly thick quasi-2D perovskite films, crucial for effective high-energy X-ray detection, is hindered by the inherent challenges of preferential crystallization at the gas-liquid interface, resulting in poor film quality. In addressing this limitation, a carbonyl array-synergized crystallization (CSC) strategy is employed for the fabrication of thick films of a quasi-2D Ruddlesden-Popper (RP) phase perovskite, specifically PEA2MA4Pb5I16. The CSC strategy involves incorporating two forms of carbonyls in the perovskite precursor, generating large and dense intermediates. This design reduces the nucleation rate at the gas-liquid interface, enhances the binding energies of Pb2+ at (202) and (111) planes, and passivates ion vacancy defects. Consequently, the construction of high-quality thick films of PEA2MA4Pb5I16 RP perovskite quantum wells is achieved and characterized by vertical orientation and a pure well-width distribution. The corresponding PEA2MA4Pb5I16 RP perovskite X-ray detectors exhibit multi-dimensional advantages in performance compared to previous approaches and commercially available a-Se detectors. This CSC strategy promotes 2D perovskites as a candidate for next-generation large-area flat-panel X-ray detection systems.

Metal-Halide Perovskite Submicrometer-Thick Films for Ultra-Stable Self-Powered Direct X-Ray Detectors.

Metal-halide perovskites are revolutionizing the world of X-ray detectors, due to the development of sensitive, fast, and cost-effective devices. Self-powered operation, ensuring portability and low power consumption, has also been recently demonstrated in both bulk materials and thin films. However, the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours, often reporting degradation of the detection performance. Here it is shown that self-powered direct X-ray detectors, fabricated starting from a FAPbBr3 submicrometer-thick film deposition onto a mesoporous TiO2 scaffold, can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss, demonstrating ultra-high operational stability and excellent repeatability. No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy, revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film. In addition, trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy-1 cm-3 at 0 V, an unprecedented value in the field of thin-film-based photoconductors and photodiodes for "hard" X-rays. Finally, prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.

Interface Engineering of Substrate-Integrated Single-Crystal Perovskite Wafers for Sensitive X-Ray Detection.

Metal halide perovskite single crystals are emerging candidates for X-ray detection, however, it is challenging for growth of thickness-controlled single-crystal wafer on commercial backplanes, limiting their practical imaging application. Herein, integration of micrometer-thick methylammonium lead triiodide (MAPbI3) single-crystal wafer on indium tin oxide (ITO) substrates by methylamine (MA)-induced interface recrystallization is reported. Through selection of hole transport material with rich functional group, intimate interface contact with low trap density can be achieved, leading to superior carrier transport properties and homogeneous photoresponse. The as-fabricated X-ray detectors exhibit high sensitivity of 1.4 × 104 µC Gyair -1 cm-2 and low detection limit of 177 nGyair s-1, which are comparable to previous reports based on free-standing MAPbI3 bulk crystals. This work provides a feasible strategy for constructing substrate-integrated single-crystal perovskite wafers with controlled thickness, which may promote practical imaging application of perovskite X-ray detectors.

HCOO- Doping-Induced Multiexciton Emissions in Cs3Cu2I5 Crystals for Efficient X-Ray Scintillation.

Self-trapped exciton (STE) luminescence, typically associated with structural deformation of excited states, has attracted significant attention in metal halide materials recently. However, the mechanism of multiexciton STE emissions in certain metal halide crystals remains largely unexplored. This study investigates dual luminescence emissions in HCOO- doped Cs3Cu2I5 single crystals using transient and steady-state spectroscopy. The dual emissions are attributed to intrinsic STE luminescence originating from the host lattice and extrinsic STE luminescence induced by external dopants, respectively, each of which can be triggered independently at distinct energy levels. Theoretical calculations reveal that multiexciton emission originates from structural distortion of the host and dopant STEs within the 0D lattice in their respective excited states. By meticulously tuning the excitation wavelength and selectively exciting different STEs, the dynamic alteration of color change in Cs3Cu2I5:HCOO- crystals is demonstrated. Ultimately, owing to an extraordinarily high photoluminescence quantum yield (99.01%) and a diminished degree of self-absorption in Cs3Cu2I5:HCOO- crystals, they exhibit remarkable X-ray scintillation characteristics with light yield being improved by 5.4 times as compared to that of pristine Cs3Cu2I5 crystals, opening up exciting avenues for achieving low-dose X-ray detection and imaging.

Achieving Low-Dose Rate X-Ray Imaging Based on 2D/3D-Mixed Perovskite Films.

X-ray detection and imaging are widely used in medical diagnosis, product inspection, security monitoring, etc. Large-scale polycrystalline perovskite thick films possess high potential for direct X-ray imaging. However, the notorious problems of baseline drift and high detection limit caused by ions migration are still remained. Here, ion migration is reduced by incorporating 2D perovskite into 3D perovskite, thereby increasing the ion activation energy. This approach hinders ion migration within the perovskite film, consequently suppressing baseline drift and reducing the lowest detection limit(LOD) of the device. As a result, the baseline drifting declines by 20 times and the LOD reduces to 21.1 nGy s-1, while the device maintains a satisfactory sensitivity of 5.6 × 103 µC Gy-1 cm-2. This work provides a new strategy to achieve low ion migration in large-scale X-ray detectors and may provide new thoughts for the application of mixed-dimension perovskite.

Exploring Non-Toxic Lower Dimensional Perovskites for Next-Generation X-Ray Detectors.

Owing to their extraordinary photophysical properties, organometal halide perovskites are emerging as a new material class for X-ray detection. However, the existence of toxic lead makes their commercialization questionable and should readily be replaced. Accordingly, several lead alternatives have been introduced into the framework of conventional perovskites, resulting in various new perovskite dimensionalities. Among these, Pb-free lower dimensional perovskites (LPVKs) not only show promising X-ray detecting properties due to their higher ionic migration energy, wider and tunable energy bandgap, smaller dark currents, and structural versatility but also exhibit extended environmental stability. Herein, first, the structural organization of the PVKs (including LPVKs) is summarized. In the context of X-ray detectors (XDs), the outstanding properties of the LPVKs and active layer synthesis routes are elaborated afterward. Subsequently, their applications in direct XDs are extensively discussed and the device performance, in terms of the synthesis method, device architecture, active layer size, figure of merits, and device stability are tabulated. Finally, the review is concluded with an in-depth outlook, thoroughly exploring the present challenges to LPVKs XDs, proposing innovative solutions, and future directions. This review provides valuable insights into optimizing non-toxic Pb-free perovskite XDs, paving the way for future advancements in the field.

Analyzer-free hard x-ray interferometry.

Objective. To enable practical interferometry-based phase contrast CT using standard incoherent x-ray sources, we propose an imaging system where the analyzer grating is replaced by a high-resolution detector. Since there is no need to perform multiple exposures (with the analyzer grating at different positions) at each scan angle, this scheme is compatible with continuous-rotation CT apparatus, and has the potential to reduce patient radiation dose and patient motion artifacts.Approach. Grating-based x-ray interferometry is a well-studied technique for imaging soft tissues and highly scattering objects embedded in such tissues. In addition to the traditional x-ray absorption-based image, this technique allows reconstruction of the object phase and small-angle scattering information. When using conventional incoherent, polychromatic, hard x-ray tubes as sources, three gratings are usually employed. To sufficiently resolve the pattern generated in these interferometers with contemporary x-ray detectors, an analyzer grating is used, and consequently multiple images need to be acquired for each view angle. This adds complexity to the imaging system, slows image acquisition and thus increases sensitivity to patient motion, and is not dose efficient. By simulating image formation based on wave propagation, and proposing a novel phase retrieval algorithm based on a virtual grating, we assess the potential of a analyzer-grating-free system to overcome these limitations.Main results. We demonstrate that the removal of the analyzer-grating can produce equal image contrast-to-noise ratio at reduced dose (by a factor of 5), without prolonging scan duration.Significance.By demonstrating that an analyzer-free CT system, in conjuction with an efficient phase retrieval algorithm, can overcome the prohibitive dose and workflow penalties associated grating-stepping, an alternative path towards realizing clinical inteferometric CT appears possible.