Conventional X-ray Tube Research Articles

Nanoscale X-ray detectors based on individual CdS, SnO[formula omitted] and ZnO nanowires

The development of nanoscale X-ray sensors is of crucial importance to achieve higher spatial resolution in many X-ray-based techniques playing a key role in materials science, healthcare, and security. Here, we demonstrate X-ray detection using individual CdS, SnO2, and ZnO nanowires (NWs). The NWs were produced via vapor–liquid–solid technique and characterized using X-ray diffraction, scanning, and transmission electron microscopy. Electrical measurements were performed under ambient conditions while exposing two-terminal NW-based devices to X-rays generated by a conventional tungsten anode X-ray tube. Fast and stable nanoampere-range X-ray beam induced current (XBIC) in response to X-ray illumination was observed. The high XBIC measured in the NW devices could be attributed to the efficient transport and collection of generated charge carriers due to the single-crystalline nature of NWs and the short NW length. Such fast-response and high-sensitivity nanoscale X-ray detectors can find applications in sub-micron resolution imaging and nanofocused beam shape measurements.

Comparison of the X-ray tube spectrum measurement using BGO, NaI, LYSO, and HPGe detectors in a preclinical mini-CT scanner: Monte Carlo simulation and practical experiment

BackgroundIn diagnostic X-ray computed tomography (CT) imaging, some applications, such as dose measurement using the Monte Carlo method and material decomposition using dual/multi-energy approaches, rely on accurate knowledge of the energy spectrum of the X-ray beam. In this regard, X-ray detectors providing an accurate estimation of the X-ray spectrum could greatly impact the quality of dual/multi-energy CT imaging and patient-specific dosimetry. PurposeThe aim of this study is to estimate the intrinsic efficiency and energy resolution of different types of solid-state gamma-ray detectors in order to generate a precise dual-energy X-ray beam from the conventional x-ray tube using external X-ray filters. Materials and methodsThe X-ray spectrum of a clinical X-ray tube was experimentally measured using a high purity Germanium detector (HPGe) and the obtained spectrum validated by Monte Carlo (MC) simulations. The obtained X-ray spectrum from the experiment was employed to assess the energy resolution and detection efficiency of different inorganic scintillators and semiconductor-based solid-state detectors, namely HPGe, BGO, NaI, and LYSO, using MC simulations. The best performing detector was employed to experimentally create and measure a dual-energy X-ray spectrum through applying attenuating filters to the original X-ray beam. ResultsThe simulation results indicated 9.16% energy resolution for the HPGe detector wherein the full width-at-half-maximum (FWHM) of the energy resolution for the HPGe detector was about 1/3rd of the other inorganic detectors. The X-ray spectra estimated from the various source energies exhibited a good agreement between experimental and simulation results with a maximum difference of 6%. Owing to the high-energy discrimination power of the HPGe detector, a dual-energy X-ray spectrum was created and measured from the original X-ray spectrum using 0.5 and 4.5 mm Aluminum external filters, which involves 70 and 140 keV energy peaks with 8% overlap. ConclusionThe experimental measurements and MC simulations of the HPGe detector exhibited close agreement in high-energy resolution estimation of the X-ray spectrum. Given the accurate measurement of the X-ray spectrum with the HPGe detector, a dual-energy X-ray spectrum was generated with minimal energy overlap using external X-ray filters.

Light-controlled pulsed x-ray tube with photocathode* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61901470 and U1931138), the Strategic Pioneer Program on Space Science, Chinese Academy of Sciences (Grant No. XDA15020501-04), the CAS “Light of West China” Program (Grant No. XAB2018A07), and the Foundation of State Key Laboratory of China (Grant No. SKLIPR2021).

Unstable mechanical structure, low energy efficiency, and cooling requirements limit the application of conventional x-ray tubes based on filament as cathode in several academic areas. In this paper, we demonstrate a light-controlled pulsed x-ray tube using multialkali cathode as electron generator. The photocathode active area of the light controlled x-ray tube is 13.2 cm2 (41 mm in diameter), which provides high photoelectron-emitting efficiency up to 0.288 mA/lm in 460-nm LED and 2.37-mA maximum tube current. Furthermore, the modulation ability from 1 kHz to 100 kHz of the x-ray tube is tested. The results suggest that the light-controlled pulsed x-ray tube has easy modulation and short x-ray pulse properties and is promising to be the next generation x-ray tube with wide applications in medical radiationtherapy as well as the calibration for detectors and scintillators.

Dose-response of Fricke- and PAGAT-dosimetry gels in kilovoltage and megavoltage photon beams: Impact of LET on sensitivity.

Dosimetry of ionizing radiation quantifies the energy deposited by an incident beam to the medium. This study presents the relative response of two types of gel dosimeters describing their differences by estimating radiation chemical yields produced in water radiolysis. Two types of gel dosimeter were used, namely an acid ferrous ion solution infused with xylenol orange known as Fricke gel and a polymer gel based on acrylamide and N,N'-methylenebis(acrylamide) known as PAGAT. Samples were irradiated using two photon beam energies, one from a conventional X-ray tube operated at 44kV and the other one from a LINAC operated at 6 MV. The dosimeters were analyzed by optical absorbance and magnetic resonance imaging. Additionally, the linear energy transfer of each beam was calculated using Monte Carlo simulations for further estimation of the radiation chemical yields produced during water radiolysis. Obtained results for both gel dosimeters indicate that their response at 44kV and 6 MV are different, regardless of the read-out technique. On average, the sensitivity at 44kV was found to be 65 % of the response at 6 MV. The calculated radiation chemical yields are in agreement with the observed experimental results. The main reason for the difference in the response of the dosimeters may be related to the linear energy transfer of each photon beam, which varies the production of primary chemical species during water radiolysis.

First characterization of chemical environments using energy dispersive inelastic x-ray scattering induced by an x-ray tube.

Energy Dispersive Inelastic X-ray Scattering (EDIXS) is a reliable technique for the discrimination and characterization of local chemical environments. By means of this methodology, the speciation of samples has been attained in a variety of samples and experimental conditions, such as total reflection, grazing incidence, and confocal setups. Until now, due to the requirement of a monochromatic and intense exciting beam, this tool had been applied using exclusively synchrotron radiation sources. We present, for the first time, results of test measurements using EDIXS for chemical characterization implemented in a conventional x-ray tube based laboratory. The results show good discrimination between different iron compounds under study, suggesting the real possibility of rutinary chemical state characterizations of samples by means of EDIXS using a conventional x-ray tube.

Enhanced Tomographic Sensing Multimodality with a Crystal Analyzer

This article demonstrates how a combination of well-known tools—a standard 2D detector (CCD (charge-coupled device) camera) and a crystal analyzer—can improve the multimodality of X-ray imaging and tomographic sensing. The use of a crystal analyzer allowed two characteristic lines of the molybdenum anode— and —to be separated from the polychromatic radiation of the conventional X-ray tube. Thus, as a result of one measurement, three radiographic projections (images) were simultaneously recorded. The projection images at different wavelengths were separated in space and registered independently for further processing, which is of interest for the spectral tomography method. A projective transformation to compensate for the geometric distortions that occur during asymmetric diffraction was used. The first experimental results presented here appear promising.

External beam radiation therapy with kilovoltage x-rays.

Kilovoltage (kV) x-rays are most commonly used for diagnostic imaging due to their sensitivity to tissue composition. In radiation therapy (RT), due to their fast attenuation, kV x-rays are typically only used for superficial irradiation of skin cancer and for intra-operative RT (IORT). Recently, however, a number of kV RT techniques have emerged. In this review article, we provide a brief overview of the use of kV x-rays for RT. Various kV x-ray source technologies suitable for RT, such as conventional x-ray tubes as well as novel x-ray sources, are first described. This x-ray source section is then followed by a section on their implementation in terms of clinical, veterinary and preclinical applications. Specifically, IORT, superficial RT and dose enhancement with iodine and gold nanoparticles, as well as microbeam RT and FLASH RT are discussed in this context. Then, a number of kV x-ray RT applications in modeling and proof-of-principle stages, such as breast external beam RT with rotational sources, kilovoltage arc therapy and the BriXS Compton pulsed x-ray sources, are reviewed. Finally, some clinical and economic considerations for the development of kV RT techniques are discussed.

X-ray phase imaging reaching clinical uses.

X-ray phase imaging that uses the phenomena of X-ray refraction and scattering to generate image contrast has the potential to overcome the drawback of conventional X-ray radiography in observing biological soft tissues. After its dawn at synchrotron radiation facilities 30years ago, the development of X-ray phase imaging is expanding to hospitals by grating-based phase-imaging approaches available with a conventional X-ray tube. In this review, after introducing the physical advantages and methodological details of X-ray phase imaging, recent trials of instrumentation in hospitals for diagnoses of rheumatoid arthritis and chronic obstructive pulmonary disease are introduced.

Spectroscopic imaging at compact inverse Compton X-ray sources.

While K-edge subtraction (KES) imaging is a commonly applied technique at synchrotron sources, the application of this imaging method in clinical imaging is limited although results have shown its superiority to conventional clinical subtraction imaging. Over the past decades, compact synchrotron X-ray sources, based on inverse Compton scattering, have been developed to fill the gap between conventional X-ray tubes and synchrotron facilities. These so called inverse Compton sources (ICSs) provide a tunable, quasi-monochromatic X-ray beam in a laboratory setting with reduced spatial and financial requirements. This allows for the transfer of imaging techniques that have been limited to synchrotrons until now, like KES imaging, into a laboratory environment. This review article presents the first studies that have successfully performed KES at ICSs. These have shown that KES provides improved image quality in comparison to conventional X-ray imaging. The results indicate that medical imaging could benefit from monochromatic imaging and KES techniques. Currently, the clinical application of KES is limited by the low K-edge energy of available iodine contrast agents. However, several ICSs are under development or already in commissioning which will provide monochromatic X-ray beams with higher X-ray energies and will enable KES using high-Z elements as contrast media. With these developments, KES at an ICS has the ability to become an important tool in pre-clinical research and potentially advancing existing clinical imaging techniques.

Dual-energy crystal-analyzer scheme for spectral tomography.

In the present work, a method for adjusting a crystal analyzer to separate two characteristic lines from the spectrum of a conventional X-ray tube for simultaneous registration of tomographic projections is proposed. The experimental implementation of this method using radiation of a molybdenum anode (Kα1, Kβ lines) and a silicon Si(111) crystal analyzer in Laue geometry is presented. Projection images at different wavelengths are separated in space and can be recorded independently for further processing. Potential uses of this scheme are briefly discussed.

Resonant inelastic X-ray scattering using a miniature dispersive Rowland refocusing spectrometer.

X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In such cases, each beamline must match the choice of emission spectrometer to the scientific mission of its users. Previous work has recently reported a miniature tender X-ray spectrometer using a dispersive Rowland refocusing (DRR) geometry that functions with high energy resolution even with a large X-ray spot size on the sample [Holden et al. (2017). Rev. Sci. Instrum. 88, 073904]. This instrument has been used in the laboratory in multiple studies of non-resonant X-ray emission spectroscopy using a conventional X-ray tube, though only for preliminary measurements at a low-intensity microfocus synchrotron beamline. This paper reports an extensive study of the performance of a miniature DRR spectrometer at an unfocused wiggler beamline, where the incident monochromatic flux allows for resonant studies which are impossible in the laboratory. The results support the broader use of the present design and also suggest that the DRR method with an unfocused beam could have important applications for materials with low radiation damage thresholds and that would not survive analysis on focused beamlines.

Grating-based phase-contrast CT (PCCT): histopathological correlation of human liver cirrhosis and hepatocellular carcinoma specimen

AimsTo correlate signal intensities in grating-based phase-contrast CT (PCCT) images obtained at a synchrotron light source and a conventional X-ray source with tissue components in human liver cirrhosis and hepatocellular...

The true spectrum of tribo-generated X-rays from peeling tape

X-rays generated through tribological processes differ from those obtained with conventional X-ray tubes in that a substantial portion of the total energy is emitted in pulses of order 10 ns in duration. The short duration of these pulses usually causes solid-state detectors to register pileup events that can make the corresponding spectrum unreliable as a characterization tool. In this work, we find that a solid angle subtended by the detector of 5×10−6 is necessary to obtain the true spectra of X-rays generated from peeling adhesive tape in a moderate vacuum. The maximum individual photon energy is found to be 30 keV, which is about half of that reported in previous studies that overlook the effects of pileup. Being able to obtain a reliable spectrum may help us understand the physical processes behind this phenomenon so that it can be optimized for present and future applications.

Focusing Properties of Bent Micro-Channel Plates in the X-Ray Range

Compact and flexible Micro-Channel Plate (MCP) devices are versatile optical systems suitable to condense and shape intense X-ray beams. Studies on propagation of both soft and hard X-ray radiations through these devices are of continuous interests because of increasing demand of synchrotron radiation X‑ray sources, in particular, to enhance the spot stability and to optimize the beam for specific experiments. In this work synchrotron radiation sources as well as a conventional X-ray tube coupled to polycapillary lenses have been used to characterize the transmission and the angular distribution of thin flat or spherically bent MCPs with different curvature radii. It is shown that the radiation beam from both synchrotron radiation and conventional X-ray sources can be efficiently condensed by thin spherically bent MCPs.

A proof of principle experiment for microbeam radiation therapy at the Munich compact light source.

Microbeam radiation therapy (MRT), a preclinical form of spatially fractionated radiotherapy, uses an array of microbeams of hard synchrotron X-ray radiation. Recently, compact synchrotron X-ray sources got more attention as they provide essential prerequisites for the translation of MRT into clinics while overcoming the limited access to synchrotron facilities. At the Munich compact light source (MuCLS), one of these novel compact X-ray facilities, a proof of principle experiment was conducted applying MRT to a xenograft tumor mouse model. First, subcutaneous tumors derived from the established squamous carcinoma cell line FaDu were irradiated at a conventional X-ray tube using broadbeam geometry to determine a suitable dose range for the tumor growth delay. For irradiations at the MuCLS, FaDu tumors were irradiated with broadbeam and microbeam irradiation at integral doses of either 3Gy or 5Gy and tumor growth delay was measured. Microbeams had a width of 50µm and a center-to-center distance of 350µm with peak doses of either 21Gy or 35Gy. A dose rate of up to 5Gy/min was delivered to the tumor. Both doses and modalities delayed the tumor growth compared to a sham-irradiated tumor. The irradiated area and microbeam pattern were verified by staining of the DNA double-strand break marker γH2AX. This study demonstrates for the first time that MRT can be successfully performed in vivo at compact inverse Compton sources.

On the capabilities of conventional x-ray tubes to deliver ultra-high (FLASH) dose rates.

By means of Monte Carlo (MC) simulations and indirect measurements, we have evaluated the maximum dose rates achievable with conventional x-ray tubes and related them to FLASH therapy dose rates of >40Gy/s. Monte Carlo models of two 160kV x-ray tubes, the 3-kW MXR-160/22 and the 6-kW MXR-165, were built in the EGSnrc/BEAMnrc code. The dose rate in a water phantom placed against the x-ray tube surface, located at 3.7 and 3.5cm from the focal spot for the MXR-160/22 and MXR-165 x-ray tube, respectively, was calculated with DOSXYZnrc. Dose delivered with the 120-kV beam in a plastic water phantom for the MXR-160/22 was measured and calculated. Gafchromic EBT3 films were placed at 15 and 18mm depths in the plastic water phantom that was irradiated with a low tube current of 0.2mA for 30s. The maximum 160-kV phantom surface dose rate was determined to be FLASH capable, calculated as (114.3±0.6)Gy/s and (160.0±0.8)Gy/s for the MXR-160/22 and MXR-165 x-ray tubes, respectively. The dose rate in a 1-cm diameter region was found to be (110.6±2.8)Gy/s and (151.9±2.6)Gy/s and remained FLASH capable to depths of 1.4 and 2.0mm for the MXR-160/22 and MXR-165 x-ray tube, respectively. The 120-kV dose profiles measured with EBT3 films agreed with MC simulations to within 3.6% for regions outside of heel effect and at both measurement depths; this presented a good validation data set for the simulations of phantom surface dose rate using the 160-kV beam. We have indirectly determined that, with a careful experimental design, conventional x-ray tubes can be made suitable for use in FLASH radiotherapy and dosimetry experiments.

Investigation of conventional diagnostic X-ray tube housing leakage radiation using ion chamber survey meter in Mizoram, India

Leakage radiation that transmitted the protected X-ray tube housing was measured and compared with national and international safety standard. To the best of the authors’ knowledge, no tube housing leakage measurement has been done so far in the present study area. The authors considered all the conventional diagnostic X-ray units in Mizoram, India. Ion chamber survey meter was used to measure leakage radiation and it was placed at 5 different positions (left, right, front, back, top) of the X-ray tube. Measurements were done at 1 m focus-to-detector distance by projecting X-ray tube vertically downward with collimator diaphragms closed completely. SPSS statistics for windows, version 17.0 (SPSS, Inc., Chicago, IL, USA) was used to derived mean, standard error of the mean etc. The tube housing leakage exposure rates ranged between 0.03 mRh-1 and 500 mR h-1; among the 5 positions, rate measured in the front direction has the highest mean at 41.61±8.63 mR h-1; whereas the top has the lowest 4.57±1.16 mRh-1. Tube housing radiation level ranged from 0.01 to 58 mR in one hour. Leakage radiation was minimum at the top position of the tube and maximum in the front direction. All the equipment were in compliance with national and international standard norms, the highest leakage radiation level was 50.43% of the safety limit.

Archaeo-ceramic 2.0: investigating ancient ceramics using modern technological approaches

Since the first attempts to the petrographic analysis on pottery, a multitude of archaeometric studies have been carried out to solve important issues on provenance, production technology, dating, functionality and conservation state of ancient ceramic materials. According to the scientists’ background, the period when the investigations were done, destructive versus non-destructive analyses (also in relation to the unicity of the studied objects), as well as the purpose of the research, numerous analytical methods, typically used in various disciplines such as geology, physics and chemistry, have been applied. This contribution focuses on the use of innovative approaches to solve archaeological issues on pottery provenance, production technology and post-depositional alteration, reporting some examples of new methods applied to perform mineralogical, petrographic and chemical analyses. The traditional microscopic characterisation of ceramic pastes, for instance, can now be easily coupled with quantitative analysis of abundance and size distribution of their textural features, through the application of digital image analysis. This method, applied to images acquired by polarised transmitted light microscope, scanning electron microscope in back-scattered mode and microchemical mapping, can quantitatively and quickly describe production recipes, contributing to the definition of the pottery production choices and changes over time. As for the mineralogical analysis, the possibility of simultaneously processing numerous X-ray diffraction patterns by statistical tools, such as cluster analysis on raw data, is another example of a modern way to analyse ancient pottery and interpreting, with an objective comparison method, possible differences or analogies in the production recipes and/or firing technology of groups of ceramics. Moreover, modern microdiffraction techniques, both using conventional (X-ray tubes) and advanced sources (synchrotron radiation), also coupled with micro-Raman spectroscopy, allow the determination of mineralogical composition of small-sized phases both in ceramic bodies and slips/glazes, supplying important information on the production technology and possible post-deposition processes. As for the provenance issue, especially on fine ware, constraining relationships between far away communities/societies can now be evaluated not only on the basis of conventional bulk chemistry but also by isotope analysis. These new methodological approaches give rise to the new concept of archaeometric analysis on ancient ceramic materials that can be defined as “archaeo-ceramic 2.0”.

New-Age Pyroelectric Radiographic X-Ray Generators

Medical imaging history has begun with the discovery of X-rays. X-rays that are widely used since
 their invention in different areas from projectional radiography to computed tomography. Year by
 year their technology is improved in many aspects especially for their generation of which tubes
 are changed to get the most efficient rays. Nowadays different mechanisms are studied to obtain
 X-rays; one of them is pyroelectricity phenomena. Pyroelectricity is a material’s electricity
 generation from temperature changes. The output spectra of the pyroelectric X-ray generator is
 quite similar to traditional X-ray tubes, which gives a chance for replacing low-voltage pyroelectric
 X-ray generators instead of high-voltage conventional X-ray tubes. The results of conducted
 experiments and continued studies show us that the use of pyroelectricity for X-ray generation has
 great advantages. More portable X-ray devices may be available in the near future, and these new
 designs offer safer and easier to operate since they use only 12 Volts instead of kiloVolts. In
 conclusion, healthcare technologies require high budges in general, this low-cost alternative might
 make the radiological imaging available for low-income countries. In this paper, the fundamentals
 of X-ray generation from pyroelectric material is reviewed, a device on the market, COOL-X, is
 investigated, and both conventional method and pyroelectricity methods are compared.

Quantitative Imaging of Gd Nanoparticles in Mice Using Benchtop Cone-Beam X-ray Fluorescence Computed Tomography System.

Nanoparticles (NPs) are currently under intensive research for their application in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) is considered a promising non-invasive imaging technique to obtain the bio-distribution of nanoparticles which include high-Z elements (e.g., gadolinium (Gd) or gold (Au)). In the present work, a set of experiments with quantitative imaging of GdNPs in mice were performed using our benchtop XFCT device. GdNPs solution which consists of 20 mg/mL NaGdF4 was injected into a nude mouse and two tumor-bearing mice. Each mouse was then irradiated by a cone-beam X-ray source produced by a conventional X-ray tube and a linear-array photon counting detector with a single pinhole collimator was placed on one side of the beamline to record the intensity and spatial information of the X-ray fluorescent photons. The maximum likelihood iterative algorithm with scatter correction and attenuation correction method was applied for quantitative reconstruction of the XFCT images. The results show that the distribution of GdNPs in each target slice (containing liver, kidney or tumor) was well reconstructed and the concentration of GdNPs deposited in each organ was quantitatively estimated, which indicates that this benchtop XFCT system provides convenient tools for obtaining accurate concentration distribution of NPs injected into animals and has potential for imaging of nanoparticles in vivo.