High Resolution X-ray Imaging Detector Research Articles

3D X-ray microscopy with a CsPbBr3 nanowire scintillator

X-ray microscopy is an essential imaging method in many scientific fields, which can be extended to three-dimensional (3D) using tomography. Recently, metal halide perovskite (MHP) nanomaterials have become a promising candidate for X-ray scintillators, due to their high light yield, high spatial resolution, and easy fabrication. Tomography requires many projections and therefore scintillators with excellent stability. This is challenging for MHPs, which often suffer from fast degradation under X-ray irradiation and ambient conditions. Here, we demonstrate that MHP scintillators of CsPbBr3 nanowires (diameter: 60 nm, length: 5–9 µm) grown in anodized aluminum oxide (CsPbBr3 NW/AAO) have sufficient stability for X-ray micro-tomography. A tomogram was taken with a Cu X-ray source over 41 h (dose 4.2 Gyair). During this period the scintillator brightness fluctuated less than 5%, which enabled a successful reconstruction. A long-term study with 2 weeks of continuous X-ray exposure (37.5 Gyair) showed less than 14% fluctuations in brightness and no long-term degradation, despite variations in the ambient relative humidity from 7.4 %RH to 34.2 %RH. The resolution was stable at (180 ± 20) 1pmm−1, i.e., about 2.8 micron. This demonstrates that CsPbBr3 NW/AAO scintillators are promising candidates for high resolution X-ray imaging detectors.

Recent Development in X-Ray Imaging Technology: Future and Challenges.

X-ray imaging is a low-cost, powerful technology that has been extensively used in medical diagnosis and industrial nondestructive inspection. The ability of X-rays to penetrate through the body presents great advances for noninvasive imaging of its internal structure. In particular, the technological importance of X-ray imaging has led to the rapid development of high-performance X-ray detectors and the associated imaging applications. Here, we present an overview of the recent development of X-ray imaging-related technologies since the discovery of X-rays in the 1890s and discuss the fundamental mechanism of diverse X-ray imaging instruments, as well as their advantages and disadvantages on X-ray imaging performance. We also highlight various applications of advanced X-ray imaging in a diversity of fields. We further discuss future research directions and challenges in developing advanced next-generation materials that are crucial to the fabrication of flexible, low-dose, high-resolution X-ray imaging detectors.

Anti-scatter grid artifact elimination for high-resolution x-ray imaging detectors without a prior scatter distribution profile.

Using anti-scatter grids with high-resolution imaging detectors could result in grid-line artifacts, with increasing severity as detector resolution improves. Grid-line mask subtraction can result in residual artifacts that are due to residual scatter penetrating the grid and not subtracted. By subtracting this residual scatter, the grid artifacts can be minimized. In the previous works, an initial residual-scatter estimate was derived by placing lead markers on a test object; however, any change in the object geometry requires a new scatter estimate. Such a method is impractical to implement during a clinical procedure. In this work, we present a new method to derive the initial scatter estimate to eliminate grid-line artifacts during a procedure. A standard stationary Smit-Roentgen x-ray grid (line density - 70 lines/cm, grid ratio - 13:1) was used with a high-resolution CMOS detector (Dexela Model 1207, pixel size - 75 μm) to image an anthropomorphic head phantom. The initial scatter estimate was derived from the image itself and the grid artifacts were eliminated using recursive correction estimation; this result was compared to that with the estimate derived from placing lead markers on the phantom. In both cases, the contrast-to-noise ratio (CNR) was improved compared to the original image with grid artifacts. Percentage differences in CNR's for three regions between the images corrected with the two estimates were less than 5%. With the new method no a priori scatter distribution profiles are needed, eliminating the need to have libraries of pre-calculated scatter profiles and making the implementation more clinically practical.

The high resolution X-ray imaging detector planes for the MIRAX mission

The MIRAX X-ray observatory, the first Brazilian-led astrophysics space mission, is designed to perform an unprecedented wide-field, wide-band hard X-ray (5–200 keV) survey of Galactic X-ray transient sources. In the current configuration, MIRAX will carry a set of four coded-masks telescopeswith high spatial resolution Cadmium Zinc Telluride (CZT) detector planes, each one consisting of an array of 64 closely tiled CZT pixelated detectors. Taken together, the four telescopes will have a total detection area of 959 cm2, a large field of view (60° × 60° FWHM), high angular resolution for this energy range (6 arcmin) and very good spectral resolution ( ∼ 2 keV @ 60 keV). A stratospheric balloon-borne prototype of one of the MIRAX telescopes has been developed, tested and flown by the Harvard-Smithsonian Center for Astrophysics (CfA) as part of the ProtoEXIST program. In this paper we show results of validation and calibration tests with individual CZT detectors of the ProtoEXIST second generation experiment (P2). Each one of 64 detector units of the P2 detector plane consists of an ASIC, developed by Caltech for the NuSTAR telescope, hybridized to a CZT crystal with 0.6 mm pixel size. The performance of each detector was evaluated using radioactive sources in the laboratory. The calibration results show that the P2 detectors have average energy resolution of ∼ 2.1 keV @ 60 keV and 2.3 @ 122 keV. P2 was also successfully tested on near-space environment on a balloon flight, demonstrating the detector unit readiness for integration on a space mission telescope, as well as satisfying all MIRAX mission requirements.

Meeting Report: Workshop on Beamline Integration and Data Formatting

A two-day workshop on beamline integration and data formatting (HDF5/NeXus) of the EIGER detector was held in Baden, Switzerland, January 24–25, 2013. Its aim was to discuss the technical challenges inherent with the next generation of high-frame-rate, high-resolution X-ray imaging detectors, and specifically with the EIGER detector. EIGER is a photon-counting hybrid pixel detector developed at the Paul Scherrer Institute (PSI) and DECTRIS Ltd. With even higher spatial resolution and frame rates than its predecessor, the PILATUS detector, it will be able to continuously produce up to 3000 images per second. The corresponding extreme data rates generated by this and future detectors present a significant challenge for beamline integration of the detectors, for data handling by the users, and for data processing software. Efficient data flow, storage, and processing must be achieved to handle the huge data sets that will be produced in seconds by these devices.

Synthesis and scintillation characterization of nanocrystalline Lu2O3(Eu) powder for high-resolution X-ray imaging detectors

Lu2O3:Eu(CEu:5mol%) powder scintillators with nanocrystalline structures were successfully synthesized via a precipitation method and subsequent calcination treatment as a conversion material for X-ray imaging detectors. In this work, a homogeneous precipitation process was carried out using DEA(diethanolamine) as a precipitant to prepare nanocrystalline Eu-doped Gd2O3 powders. The microstructures, crystal structure and scintillation properties such as luminescent spectra, decay time and light intensity were measured as a function of calcination temperature in heat-treatment of the synthesized powder. The sample prepared at 1200°C calcination temperature showed the highest light intensity. And the scintillator showed a strong red emission light at near 611nm under photo- and X-ray luminescence for its potential X-ray imaging detector applications.

Characterization and imaging performance of nanoscintillator screen for high resolution X-ray imaging detectors

We have synthesized europium-doped gadolinium oxide (Gd 2O 3:Eu) scintillators by a precipitation method with advantages of simple process and low-temperature calcinations for high resolution X-ray imaging detectors. The powders with about 15–30 nm particle sizes were obtained by subsequent calcinations of the precursor at a different temperature of 600–800 °C for 10 h. The wavelength of the main emission peak was about 610 nm and as temperature increased, light intensity of the scintillator increased in the X-ray luminescence case. Imaging performance such as X-ray linearity and spatial resolution of both commercial bulk and nanocrystalline-Gd 2O 3:Eu scintillator screens was measured and compared with the X-ray imaging system after coupling these to a CCD image sensor.

Submicrometer-resolution three-dimensional imaging with hard x-ray imaging microtomography

An x-ray microtomography method combined with hard x-ray imaging microscopy was developed that has a potential spatial resolution of the order of 10–100 nm. The system consists of a high-brilliance undulator source of SPring-8, a beam diffuser plate to reduce the coherence of the illumination, a high-precision rotating sample stage, a Fresnel zone plate objective, and a high-resolution x-ray imaging detector. The three-dimensional images of several samples were observed and successfully reconstructed with a pitch pattern of 0.6 μm.

A new high resolution X-ray imaging detector with fast read-out

A new silicon detector design suitable for X-ray imaging is presented. The new detector features energy and position resolution comparable with a fully depleted pn-charge coupled device and read-out times of few tens of microseconds.