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Sample records for high dose x-ray

  1. A Simple Low-dose X-ray CT Simulation from High-dose Scan.

    PubMed

    Zeng, Dong; Huang, Jing; Bian, Zhaoying; Niu, Shanzhou; Zhang, Hua; Feng, Qianjin; Liang, Zhengrong; Ma, Jianhua

    2015-10-01

    Low-dose X-ray computed tomography (CT) simulation from high-dose scan is required in optimizing radiation dose to patients. In this study, we propose a simple low-dose CT simulation strategy in sinogram domain using the raw data from high-dose scan. Specially, a relationship between the incident fluxes of low- and high- dose scans is first determined according to the repeated projection measurements and analysis. Second, the incident flux level of the simulated low-dose scan is generated by properly scaling the incident flux level of high-dose scan via the determined relationship in the first step. Third, the low-dose CT transmission data by energy integrating detection is simulated by adding a statistically independent Poisson noise distribution plus a statistically independent Gaussian noise distribution. Finally, a filtered back-projection (FBP) algorithm is implemented to reconstruct the resultant low-dose CT images. The present low-dose simulation strategy is verified on the simulations and real scans by comparing it with the existing low-dose CT simulation tool. Experimental results demonstrated that the present low-dose CT simulation strategy can generate accurate low-dose CT sinogram data from high-dose scan in terms of qualitative and quantitative measurements.

  2. High-dose-rate stroboscopic x-ray generator with a hot-cathode triode

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Ichimaru, Toshio; Sakamaki, Kimio; Takayama, Kazuyoshi; Tamakawa, Yoshiharu

    1997-12-01

    The construction and the fundamental studies of a high-dose- rate stroboscopic x-ray generator utilizing a hot-cathode radiation tube for high-speed radiography are described. This generator consists of the following essential components: a constant high-voltage power supply, an energy-storage oil condenser of about 0.1 (mu) F, a grid pulser, a dc power supply for the filament, and an x-ray tube. The x-ray tube is a glass-enclosed hot-cathode triode and is composed of the following major parts: an anode rod made of copper, a tungsten plate target, an iron focusing electrode, a tungsten hot- cathode (filament), a tungsten grid, and a glass tube body. The electron beams from the cathode are accelerated by both the grid and anode electrodes and are roughly converged to the target by the focusing electrode. In the present work, the storage condenser is charged up to 70 kV by the power supply, and the electric charges in the condenser are discharged repetitively to the x-ray tube by the grid pulser. Because the cathode current is increased by increasing the positive grid voltage, high-dose-rate repetitive x-rays are then produced. In this generator, the cathode current which is almost equivalent to the tube current is primarily regulated by the filament temperature (fulminate voltage). The pulse widths of x-rays were about 600 ns, and the maximum repetition rate was about 50 kHz. The cathode current was less than 3.1 angstrom, and the x-ray intensity had a value of 35.2 nC/kg at 0.5 m per pulse with a charging voltage of 70 kV and a filament voltage of 12 V.

  3. Study of high-dose x-ray radiation damage of silicon sensors

    NASA Astrophysics Data System (ADS)

    Schwandt, Joern; Fretwurst, Eckhart; Klanner, Robert; Pintilie, Ioana; Zhang, Jiaguo

    2013-05-01

    The high intensity and high repetition rate of the XFEL, the European X-ray Free-Electron Laser presently under construction in Hamburg, results in X-ray doses of up to 1 GGy in silicon sensors for 3 years of operation. Within the AGIPD Collaboration the Hamburg group has systematically studied X-ray-radiation damage using test structures and segmented sensors fabricated on high-ohmic n-type silicon. MOS Capacitors and Gate- Controlled Diodes from 4 vendors with different crystal orientations and different technological parameters, as well as strip sensors have been irradiated in the dose range between 10 kGy and 1 GGy. Current-Voltage, Capacitance/Conductance-Voltage and Thermal Dielectric Relaxation Current measurements were used to extract oxide-charge densities, interface-trap densities and surface-current densities as function of dose and annealing conditions. The results have been implemented into TCAD simulations, and the radiation performance of strip sensors and guard-ring structures simulated and compared to experimental results. Finally, with the help of detailed TCAD simulations, the layout and technological parameters of the AGIPD pixel sensor have been optimized. It is found that the optimization for sensors exposed to high X-ray doses is significantly different than for non-irradiated sensors, and that the specifications of the AGIPD sensor can be met. In 2012 sensors have been ordered, the first batch has been delivered recently, and first results on a comparison between simulations and measurements will be presented.

  4. [Differential dose albedo for high-energy X-rays on concrete slab].

    PubMed

    Kato, Hideki

    2006-08-20

    We computed the differential dose albedo (alpha(D)) for high-energy X-rays on a concrete slab when the incident angle, reflection angle, and azimuth angle were changed, by means of Monte Carlo simulation. We found that alpha(D) changed with incident, reflection, and azimuth angles to the concrete slab. On the whole, the larger the incident angle, the larger alpha(D) tended to become. If the incident angle and reflection angle were the same, the larger the azimuth angle, the smaller alpha(D) tended to become. When the incident, reflection, and azimuth angles were the same, the smaller the X-ray energy was, the larger alpha(D) became, in the order of 10 MV, 6 MV, and 4 MV X-rays.

  5. Effect of high-energy X-ray doses on bone elastic properties and residual strains.

    PubMed

    Singhal, A; Deymier-Black, Alix C; Almer, J D; Dunand, D C

    2011-11-01

    Bone X-ray irradiation occurs during medical treatments, sterilization of allografts, space travel and in vitro studies. High doses are known to affect the post-yield properties of bone, but their effect on the bone elastic properties is unclear. The effect of such doses on the mineral-organic interface has also not been adequately addressed. Here, the evolution of elastic properties and residual strains with increasing synchrotron X-ray dose (5-3880 kGy) is examined on bovine cortical bone. It is found that these doses affect neither the degree of nanometer-level load transfer between the hydroxyapatite (HAP) platelets and the collagen up to stresses of -60 MPa nor the microscopic modulus of collagen fibrils (both measured by synchrotron X-ray scattering during repeated in situ loading and unloading). However, the residual elastic strains in the HAP phase decrease markedly with increased irradiation, indicating damage at the HAP-collagen interface. The HAP residual strain also decreases after repeated loading/unloading cycles. These observations can be explained by temporary de-bonding at the HAP/collagen interface (thus reducing the residual strain), followed by rapid re-bonding (so that load transfer capability is not affected). Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Dose estimation and shielding calculation for X-ray hazard at high intensity laser facilities

    NASA Astrophysics Data System (ADS)

    Qiu, Rui; Zhang, Hui; Yang, Bo; James, C. Liu; Sayed, H. Rokni; Michael, B. Woods; Li, Jun-Li

    2014-12-01

    An ionizing radiation hazard produced from the interaction between high intensity lasers and solid targets has been observed. Laser-plasma interactions create “hot” electrons, which generate bremsstrahlung X-rays when they interact with ions in the target. However, up to now only limited studies have been conducted on this laser-induced radiological protection issue. In this paper, the physical process and characteristics of the interaction between high intensity lasers and solid targets are analyzed. The parameters of the radiation sources are discussed, including the energy conversion efficiency from laser to hot electrons, hot electron energy spectrum and electron temperature, and the bremsstrahlung X-ray energy spectrum produced by hot electrons. Based on this information, the X-ray dose generated with high-Z targets for laser intensities between 1014 and 1020 W/cm2 is estimated. The shielding effects of common shielding items such as the glass view port, aluminum chamber wall and concrete wall are also studied using the FLUKA Monte Carlo code. This study provides a reference for the dose estimation and the shielding design of high intensity laser facilities.

  7. Bystander effect between zebrafish embryos in vivo induced by high-dose X-rays.

    PubMed

    Choi, V W Y; Ng, C Y P; Kobayashi, A; Konishi, T; Suya, N; Ishikawa, T; Cheng, S H; Yu, K N

    2013-06-18

    We employed embryos of the zebrafish, Danio rerio, for our studies on the in vivo bystander effect between embryos irradiated with high-dose X-rays and naive unirradiated embryos. The effects on the naive whole embryos were studied through quantification of apoptotic signals at 25 h post fertilization (hpf) through the terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay followed by counting the stained cells under a microscope. We report data showing that embryos at 5 hpf subjected to a 4-Gy X-ray irradiation could release a stress signal into the medium, which could induce a bystander effect in partnered naive embryos sharing the same medium. We further demonstrated that this bystander effect (induced through partnering) could be successfully suppressed through the addition of the nitric oxide (NO) scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) into the medium but not through the addition of the CO liberator tricarbonylchloro(glycinato)ruthenium(II) (CORM-3). This shows that NO was involved in the bystander response between zebrafish embryos induced through X-ray irradiation. We also report data showing that the bystander effect could be successfully induced in naive embryos by introducing them into the irradiated embryo conditioned medium (IECM) alone, i.e., without partnering with the irradiated embryos. The IECM was harvested from the medium that had conditioned the zebrafish embryos irradiated at 5 hpf with 4-Gy X-ray until the irradiated embryos developed into 29 hpf. NO released from the irradiated embryos was unlikely to be involved in the bystander effect induced through the IECM because of the short life of NO. We further revealed that this bystander effect (induced through IECM) was rapidly abolished through diluting the IECM by a factor of 2× or greater, which agreed with the proposal that the bystander effect was an on/off response with a threshold.

  8. REDUCTION OF BIOLOGICAL EFFECTIVENESS OF X-RAYS AT VERY HIGH DOSE RATES,

    DTIC Science & Technology

    It has been observed that relative biological effectiveness (RBE) of X-rays or gamma rays is independent of dose rate provided that their delivery ... time is short compared to the recuperation time of the organism. At higher dose rates, however, several effects may modify the RBE. One possible

  9. A method for high-energy, low-dose mammography using edge illumination x-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Diemoz, Paul C.; Bravin, Alberto; Sztrókay-Gaul, Anikó; Ruat, Marie; Grandl, Susanne; Mayr, Doris; Auweter, Sigrid; Mittone, Alberto; Brun, Emmanuel; Ponchut, Cyril; Reiser, Maximilian F.; Coan, Paola; Olivo, Alessandro

    2016-12-01

    Since the breast is one of the most radiosensitive organs, mammography is arguably the area where lowering radiation dose is of the uttermost importance. Phase-based x-ray imaging methods can provide opportunities in this sense, since they do not require x-rays to be stopped in tissue for image contrast to be generated. Therefore, x-ray energy can be considerably increased compared to those usually exploited by conventional mammography. In this article we show how a novel, optimized approach can lead to considerable dose reductions. This was achieved by matching the edge-illumination phase method, which reaches very high angular sensitivity also at high x-ray energies, to an appropriate image processing algorithm and to a virtually noise-free detection technology capable of reaching almost 100% efficiency at the same energies. Importantly, while proof-of-concept was obtained at a synchrotron, the method has potential for a translation to conventional sources.

  10. Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging.

    PubMed

    Arvanitis, C D; Bohndiek, S E; Royle, G; Blue, A; Liang, H X; Clark, A; Prydderch, M; Turchetta, R; Speller, R

    2007-12-01

    Monolithic complementary metal oxide semiconductor (CMOS) active pixel sensors with high performance have gained attention in the last few years in many scientific and space applications. In order to evaluate the increasing capabilities of this technology, in particular where low dose high resolution x-ray medical imaging is required, critical electro-optical and physical x-ray performance evaluation was determined. The electro-optical performance includes read noise, full well capacity, interacting quantum efficiency, and pixels cross talk. The x-ray performance, including x-ray sensitivity, modulation transfer function, noise power spectrum, and detection quantum efficiency, has been evaluated in the mammographic energy range. The sensor is a 525 x 525 standard three transistor CMOS active pixel sensor array with more than 75% fill factor and 25 x 25 microm pixel pitch. Reading at 10 f/s, it is found that the sensor has 114 electrons total additive noise, 10(5) electrons full well capacity with shot noise limited operation, and 34% interacting quantum efficiency at 530 nm. Two different structured CsI:Tl phosphors with thickness 95 and 115 microm, respectively, have been optically coupled via a fiber optic plate to the array resulting in two different system configurations. The sensitivity of the two different system configurations was 43 and 47 electrons per x-ray incident on the sensor. The MTF at 10% of the two different system configurations was 9.5 and 9 cycles/mm with detective quantum efficiency of 0.45 and 0.48, respectively, close to zero frequency at approximately 0.44 microC/kg (1.72 mR) detector entrance exposure. The detector was quantum limited at low spatial frequencies and its performance was comparable with high resolution a: Si and charge coupled device based x-ray imagers. The detector also demonstrates almost an order of magnitude lower noise than active matrix flat panel imagers. The results suggest that CMOS active pixel sensors when coupled

  11. X-ray photoelectron spectroscopy characterization of high dose carbon-implanted steel and titanium alloys

    NASA Astrophysics Data System (ADS)

    Viviente, J. L.; García, A.; Alonso, F.; Braceras, I.; Oñate, J. I.

    1999-04-01

    A study has been made of the depth dependence of the atomic fraction and chemical bonding states of AISI 440C martensitic stainless steel and Ti-6Al-4V alloy implanted with 75 keV C + at very high doses (above 10 18 ions cm -2), by means of X-ray photoelectron spectroscopy combined with an Ar + sputtering. A Gaussian-like carbon distribution was observed on both materials at the lowest implanted dose. More trapezoidal carbon depth-profiles were found with increasing implanted doses, and a pure carbon layer was observed only on the titanium alloy implanted at the highest dose. The implanted carbon was combined with both base metal and carbon itself to form metallic carbides and graphitic carbon. Furthermore, carbon-enriched carbides were also found by curve fitting the C 1s spectra. The titanium alloy showed a higher carbidic contribution than the steel implanted at the same C + doses. A critical carbon concentrations of about 33 at.% and 23 at.% were measured for the formation of C-C bonds in Ti-6Al-4V and steel samples, respectively. The carbon atoms were bound with metal to form carbidic compounds until these critical concentrations were reached; when this C concentration was exceeded the proportion of C-C bonds increased and resulted in the growth of carbonaceous layers.

  12. Image quality and dose efficiency of high energy phase sensitive x-ray imaging: phantom studies.

    PubMed

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

    2014-01-01

    The goal of this preliminary study was to perform an image quality comparison of high energy phase sensitive imaging with low energy conventional imaging at similar radiation doses. The comparison was performed with the following phantoms: American College of Radiology (ACR), contrast-detail (CD), acrylic edge and tissue-equivalent. Visual comparison of the phantom images indicated comparable or improved image quality for all phantoms. Quantitative comparisons were performed through ACR and CD observer studies, both of which indicated higher image quality in the high energy phase sensitive images. The results of this study demonstrate the ability of high energy phase sensitive imaging to overcome existing challenges with the clinical implementation of phase contrast imaging and improve the image quality for a similar radiation dose as compared to conventional imaging near typical mammography energies. In addition, the results illustrate the capability of phase sensitive imaging to sustain the image quality improvement at high x-ray energies and for breast simulating phantoms, both of which indicate the potential to benefit fields such as mammography. Future studies will continue to investigate the potential for dose reduction and image quality improvement provided by high energy phase sensitive imaging.

  13. Low Dose X-Ray Sources and High Quantum Efficiency Sensors: The Next Challenge in Dental Digital Imaging?

    PubMed Central

    Mistry, Arnav R.; Yang, Jie

    2014-01-01

    Objective(s). The major challenge encountered to decrease the milliamperes (mA) level in X-ray imaging systems is the quantum noise phenomena. This investigation evaluated dose exposure and image resolution of a low dose X-ray imaging (LDXI) prototype comprising a low mA X-ray source and a novel microlens-based sensor relative to current imaging technologies. Study Design. A LDXI in static (group 1) and dynamic (group 2) modes was compared to medical fluoroscopy (group 3), digital intraoral radiography (group 4), and CBCT scan (group 5) using a dental phantom. Results. The Mann-Whitney test showed no statistical significance (α = 0.01) in dose exposure between groups 1 and 3 and 1 and 4 and timing exposure (seconds) between groups 1 and 5 and 2 and 3. Image resolution test showed group 1 > group 4 > group 2 > group 3 > group 5. Conclusions. The LDXI proved the concept for obtaining a high definition image resolution for static and dynamic radiography at lower or similar dose exposure and smaller pixel size, respectively, when compared to current imaging technologies. Lower mA at the X-ray source and high QE at the detector level principles with microlens could be applied to current imaging technologies to considerably reduce dose exposure without compromising image resolution in the near future. PMID:25574389

  14. Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates

    NASA Astrophysics Data System (ADS)

    Fournier, P.; Crosbie, J. C.; Cornelius, I.; Berkvens, P.; Donzelli, M.; Clavel, A. H.; Rosenfeld, A. B.; Petasecca, M.; Lerch, M. L. F.; Bräuer-Krisch, E.

    2016-07-01

    Microbeam radiation therapy (MRT) is a new radiation treatment modality in the pre-clinical stage of development at the ID17 Biomedical Beamline of the European synchrotron radiation facility (ESRF) in Grenoble, France. MRT exploits the dose volume effect that is made possible through the spatial fractionation of the high dose rate synchrotron-generated x-ray beam into an array of microbeams. As an important step towards the development of a dosimetry protocol for MRT, we have applied the International Atomic Energy Agency’s TRS 398 absorbed dose-to-water protocol to the synchrotron x-ray beam in the case of the broad beam irradiation geometry (i.e. prior to spatial fractionation into microbeams). The very high dose rates observed here mean the ion recombination correction factor, k s , is the most challenging to quantify of all the necessary corrections to apply for ionization chamber based absolute dosimetry. In the course of this study, we have developed a new method, the so called ‘current ramping’ method, to determine k s for the specific irradiation and filtering conditions typically utilized throughout the development of MRT. Using the new approach we deduced an ion recombination correction factor of 1.047 for the maximum ESRF storage ring current (200 mA) under typical beam spectral filtering conditions in MRT. MRT trials are currently underway with veterinary patients at the ESRF that require additional filtering, and we have estimated a correction factor of 1.025 for these filtration conditions for the same ESRF storage ring current. The protocol described herein provides reference dosimetry data for the associated Treatment Planning System utilized in the current veterinary trials and anticipated future human clinical trials.

  15. Distinct Sets of lncRNAs are Differentially Modulated after Exposure to High and Low Doses of X Rays.

    PubMed

    Terradas, Mariona; Martín, Marta; Repullès, Joan; Huarte, Maite; Genescà, Anna

    2016-12-01

    High- and low-dose X rays are used in medicine as therapeutic and diagnostic tools, respectively. While the cellular response to high-dose radiation is well known, studies on the effects of low-dose radiation and its ability to trigger a proper DNA damage response have had contradictory results. The functions of many signaling and effector proteins of the DNA damage response (DDR) have been described, and are attributed to well-known DDR pathways. However, there has been little known about the contribution of long noncoding RNAs (lncRNAs) to DDR, although there is recent evidence that lncRNAs may be associated with almost all biological functions, including DDR. In this work, we investigated the participation of lncRNAs in the response to different X-ray doses. By microarray analysis, we observed that in human breast epithelial cells, distinct sets of coding and noncoding transcripts are differentially regulated after moderate- and high-dose irradiation compared to those regulated after low-dose irradiation. While the modulated coding and noncoding genes at low doses relate to cell signaling pathways, those affected by moderate and high doses are mostly enriched for cell cycle regulation and apoptotic pathways. Quantification using qPCR of the lncRNAs identified by microarrays allowed the validation of 75% of those regulated at the higher doses. These results indicate that lncRNA expression is regulated by ionizing radiation and that this expression is dose dependent.

  16. Dose measurement using Al2O3 dosimeter in comparison to LiF:Mg,Ti dosimeter and ionization chamber at low and high energy x-ray

    NASA Astrophysics Data System (ADS)

    Yusof, Mohd Fahmi Mohd; Yahya, Muhammad Hadzmi; Rosnan, Muhammad Syazwan; Abdullah, Reduan; Kadir, Ahmad Bazlie Abdul

    2017-01-01

    The dose measurement using Al2O3 OSL dosimeter (OSLD) was carried out at low and high energy x-ray. The dose at low energy x-ray was measured at 40, 71 and 125 kVp x-ray energies. The dose ar high energy x-ray was measured at 6 and 10 MV x-ray energies measured at the depth of maximum dose (Zmax). The results were compared to that in ionization chamber and LiF: Mg,Ti thermoluminescent dosimeters (TLD100). The results showed that the dose of OSLD were less in agreement to ionization chamber compared to that in TLD100. The dose of OSLD however was in good agreement to that in ionization chamber at high energy x-ray. The dose measured using OSLD were found to be more consistence at high energy x-ray shown by the standard deviation of the readings. The measurement of x2 showed that the readings of OSLD were close to that in ionization chamber with values of 2.21 and 4.63 for 6 and 10 MV respectively. The results indicated that OSLD is more suitable for dose measurement at high energy x-ray.

  17. High-resolution, low-dose phase contrast X-ray tomography for 3D diagnosis of human breast cancers

    PubMed Central

    Zhao, Yunzhe; Brun, Emmanuel; Coan, Paola; Huang, Zhifeng; Sztrókay, Aniko; Diemoz, Paul Claude; Liebhardt, Susanne; Mittone, Alberto; Gasilov, Sergei; Miao, Jianwei; Bravin, Alberto

    2012-01-01

    Mammography is the primary imaging tool for screening and diagnosis of human breast cancers, but ∼10–20% of palpable tumors are not detectable on mammograms and only about 40% of biopsied lesions are malignant. Here we report a high-resolution, low-dose phase contrast X-ray tomographic method for 3D diagnosis of human breast cancers. By combining phase contrast X-ray imaging with an image reconstruction method known as equally sloped tomography, we imaged a human breast in three dimensions and identified a malignant cancer with a pixel size of 92 μm and a radiation dose less than that of dual-view mammography. According to a blind evaluation by five independent radiologists, our method can reduce the radiation dose and acquisition time by ∼74% relative to conventional phase contrast X-ray tomography, while maintaining high image resolution and image contrast. These results demonstrate that high-resolution 3D diagnostic imaging of human breast cancers can, in principle, be performed at clinical compatible doses. PMID:23091003

  18. Dose and detectability improvements with high energy phase sensitive x-ray imaging in comparison to low energy conventional imaging

    PubMed Central

    Wong, Molly Donovan; Yan, Aimin; Ghani, Muhammad; Li, Yuhua; Fajardo, Laurie; Wu, Xizeng; Liu, Hong

    2014-01-01

    The objective of this study was to demonstrate the potential benefits of using high energy x-rays for phase sensitive breast imaging through a comparison with conventional mammography imaging. We compared images of a contrast-detail (CD) phantom acquired on a prototype phase sensitive x-ray imaging system with images acquired on a commercial flat panel digital mammography unit. The phase contrast images were acquired using a micro-focus x-ray source with a 50 μm focal spot at 120 kVp and 4.5 mAs, with a magnification factor of 2.46 and a 50 μm pixel pitch. A phase attenuation duality (PAD)-based phase retrieval algorithm that requires only a single phase contrast image was applied. Conventional digital mammography images were acquired at 27 kVp, 131 mAs and 28 kVp, 54 mAs. For the same radiation dose, both the observer study and SNR/FOM comparisons indicated a large improvement by the phase retrieved image as compared to the clinical system for the larger disk sizes, but the improvement was not enough to detect the smallest disks. Compared to the double dose image acquired with the clinical system, the observer study also indicated that the phase retrieved image provided improved detection capabilities for all disk sizes except the smallest disks. Thus the SNR improvement provided by phase contrast imaging is not yet enough to offset the noise reduction provided by the clinical system at the doubled dose level. However, the potential demonstrated by this study for high energy phase sensitive x-ray imaging to improve lesion detection and reduce radiation dose in mammography warrants further investigation of this technique. PMID:24732108

  19. Dose and detectability improvements with high energy phase sensitive x-ray imaging in comparison to low energy conventional imaging.

    PubMed

    Wong, Molly Donovan; Yan, Aimin; Ghani, Muhammad; Li, Yuhua; Fajardo, Laurie; Wu, Xizeng; Liu, Hong

    2014-05-07

    The objective of this study was to demonstrate the potential benefits of using high energy x-rays for phase sensitive breast imaging through a comparison with conventional mammography imaging. We compared images of a contrast-detail phantom acquired on a prototype phase sensitive x-ray imaging system with images acquired on a commercial flat panel digital mammography unit. The phase contrast images were acquired using a micro-focus x-ray source with a 50 µm focal spot at 120 kVp and 4.5 mAs, with a magnification factor of 2.46 and a 50 µm pixel pitch. A phase attenuation duality-based phase retrieval algorithm that requires only a single phase contrast image was applied. Conventional digital mammography images were acquired at 27 kVp, 131 mAs and 28 kVp, 54 mAs. For the same radiation dose, both the observer study and signal-to-noise ratio (SNR)/figure of merit comparisons indicated a large improvement by the phase retrieved image as compared to the clinical system for the larger disc sizes, but the improvement was not enough to detect the smallest discs. Compared to the double dose image acquired with the clinical system, the observer study also indicated that the phase retrieved image provided improved detection capabilities for all disc sizes except the smallest discs. Thus the SNR improvement provided by phase contrast imaging is not yet enough to offset the noise reduction provided by the clinical system at the doubled dose level. However, the potential demonstrated by this study for high energy phase sensitive x-ray imaging to improve lesion detection and reduce radiation dose in mammography warrants further investigation of this technique.

  20. Use of the DBD-FISH technique for detecting DNA breakage in response to high doses of X-rays.

    PubMed

    Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; Cerda-Flores, Ricardo M; Fernández, José Luis; López-Fernández, Carmen; Gosálvez, Jaime

    2014-11-01

    The aim of this study was to generate a dose-response curve using the DNA breakage detection-fluorescent in situ hybridization (DBD-FISH) test as a biomarker of initial genetic effects induced by high doses of X-rays. A dose-response curve was obtained by measuring the ex vivo responses to increasing doses (0-50 Gy) of X-rays in the peripheral blood lymphocytes of ten healthy donors. The overall dose-response curve was constructed using integrated density (ID; area × fluorescence intensity) as a measure of genetic damage induced by irradiation. The correlation coefficient was high (r = 0.934, b(0) = 10.408, and b(1) = 0.094). One-way ANOVA with the Student-Newman-Keuls test for multiple comparisons showed significant differences among the average ln ID values according to dose. Our results suggest the usefulness of the DBD-FISH technique for measuring intrinsic individual cellular radio sensitivity ex vivo.

  1. Dose in x-ray computed tomography.

    PubMed

    Kalender, Willi A

    2014-02-07

    Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (CTDI) are discussed in detail. A review of approaches to patient dose assessment presently in practice, of the dose levels encountered and options for further dose optimization are also given and discussed. Patient dose assessment remains a topic for further improvement and for international consensus. All approaches presently in use are based on Monte Carlo (MC) simulations. Estimates for effective dose are established, but they are crude and not patient-specific; organ dose estimates are rarely available. Patient- and organ-specific dose estimates can be provided with adequate accuracy and independent of CTDI phantom measurements by fast MC simulations. Such information, in particular on 3D dose distributions, is important and helpful in optimization efforts. Dose optimization has been performed very successfully in recent years and even resulted in applications with effective dose values of below 1 mSv. In general, a trend towards lower dose values based on technical innovations has to be acknowledged. Effective dose values are down to clearly below 10 mSv on average, and there are a number of applications such as cardiac and pediatric CT which are performed routinely below 1 mSv on modern equipment.

  2. Scintillator avalanche photoconductor with high resolution emitter readout for low dose x-ray imaging: lag.

    PubMed

    Lia, Dan; Zhao, Wei; Nanba, Masakazu; Egami, Norifomi

    2009-09-01

    A new concept of indirect conversion flat-panel imager with avalanche gain and field emitter array (FEA) readout is being investigated. It is referred to as scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The present work investigates the temporal performance, i.e., lag, of SAPHIRE. Since the temporal performance of the x-ray detection materials, i.e., the structured scintillator and avalanche amorphous selenium (a-Se) photoconductor, has been studied previously, the investigation is focused on lag due to the FEA readout method. The principle of FEA readout is similar to that of scanning electron beam readout used in camera tubes, where the dominant source of lag is the energy spread of electrons. Since the principles of emission and beam focusing methods for FEA are different from thermionic emission used in camera tubes, its electron beam energy spread and hence lag is expected to be different. In the present work, the energy spread of the electrons emitted from a FEA was investigated theoretically by analyzing different contributing factors due to the FEA design and operations: The inherent energy spread of field emission, the FEA driving pulse delay, and the angular distribution of emitted electrons. The electron energy spread determined the beam acceptance characteristic curve of the photoconductive target, i.e., the accepted beam current (I(a)) as a function of target potential (V(t)), from which lag could be calculated numerically. Lag calculation was performed using FEA parameters of two prototype HARP-FEA image sensors, and the results were compared with experimental measurements. Strategies for reducing lag in SAPHIRE were proposed and analyzed. The theoretical analysis shows that the dominant factor for lag is the angular distribution of electrons emitted from the FEA. The first frame lags for two prototype sensors with 4 and 25 microm HARP layer thicknesses were 62.1% and 9.1%, respectively. A lag clearance

  3. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: Spatial resolution.

    PubMed

    Li, Dan; Zhao, Wei

    2008-07-01

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator/HARP (SHARP) combination is read out by the electron beams emitted from the FEA. The proposed detector is called scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The programmable avalanche gain of HARP can improve the low dose performance of indirect FPI while the FEA can be made with pixel sizes down to 50 μm. Because of the avalanche gain, a high resolution type of CsI (Tl), which has not been widely used in indirect FPI due to its lower light output, can be used to improve the high spatial frequency performance. The purpose of the present article is to investigate the factors affecting the spatial resolution of SAPHIRE. Since the resolution performance of the SHARP combination has been well studied, the focus of the present work is on the inherent resolution of the FEA readout method. The lateral spread of the electron beam emitted from a 50 μm×50 μm pixel FEA was investigated with two different electron-optical designs: mesh-electrode-only and electrostatic focusing. Our results showed that electrostatic focusing can limit the lateral spread of electron beams to within the pixel size of down to 50 μm. Since electrostatic focusing is essentially independent of signal intensity, it will provide excellent spatial uniformity. © 2008 American Association of Physicists in Medicine.

  4. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: Spatial resolution

    PubMed Central

    Li, Dan; Zhao, Wei

    2008-01-01

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator∕HARP (SHARP) combination is read out by the electron beams emitted from the FEA. The proposed detector is called scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The programmable avalanche gain of HARP can improve the low dose performance of indirect FPI while the FEA can be made with pixel sizes down to 50 μm. Because of the avalanche gain, a high resolution type of CsI (Tl), which has not been widely used in indirect FPI due to its lower light output, can be used to improve the high spatial frequency performance. The purpose of the present article is to investigate the factors affecting the spatial resolution of SAPHIRE. Since the resolution performance of the SHARP combination has been well studied, the focus of the present work is on the inherent resolution of the FEA readout method. The lateral spread of the electron beam emitted from a 50 μm×50 μm pixel FEA was investigated with two different electron-optical designs: mesh-electrode-only and electrostatic focusing. Our results showed that electrostatic focusing can limit the lateral spread of electron beams to within the pixel size of down to 50 μm. Since electrostatic focusing is essentially independent of signal intensity, it will provide excellent spatial uniformity. PMID:18697540

  5. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: spatial resolution.

    PubMed

    Li, Dan; Zhao, Wei

    2008-07-01

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator/HARP (SHARP) combination is read out by the electron beams emitted from the FEA. The proposed detector is called scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The programmable avalanche gain of HARP can improve the low dose performance of indirect FPI while the FEA can be made with pixel sizes down to 50 microm. Because of the avalanche gain, a high resolution type of CsI (Tl), which has not been widely used in indirect FPI due to its lower light output, can be used to improve the high spatial frequency performance. The purpose of the present article is to investigate the factors affecting the spatial resolution of SAPHIRE. Since the resolution performance of the SHARP combination has been well studied, the focus of the present work is on the inherent resolution of the FEA readout method. The lateral spread of the electron beam emitted from a 50 microm x 50 microm pixel FEA was investigated with two different electron-optical designs: mesh-electrode-only and electrostatic focusing. Our results showed that electrostatic focusing can limit the lateral spread of electron beams to within the pixel size of down to 50 microm. Since electrostatic focusing is essentially independent of signal intensity, it will provide excellent spatial uniformity.

  6. SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) for low dose x-ray imaging: Spatial resolution

    SciTech Connect

    Li Dan; Zhao Wei

    2008-07-15

    An indirect flat panel imager (FPI) with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose and high resolution x-ray imaging. It is made by optically coupling a structured x-ray scintillator, e.g., thallium (Tl) doped cesium iodide (CsI), to an amorphous selenium (a-Se) avalanche photoconductor called high-gain avalanche rushing amorphous photoconductor (HARP). The charge image created by the scintillator/HARP (SHARP) combination is read out by the electron beams emitted from the FEA. The proposed detector is called scintillator avalanche photoconductor with high resolution emitter readout (SAPHIRE). The programmable avalanche gain of HARP can improve the low dose performance of indirect FPI while the FEA can be made with pixel sizes down to 50 {mu}m. Because of the avalanche gain, a high resolution type of CsI (Tl), which has not been widely used in indirect FPI due to its lower light output, can be used to improve the high spatial frequency performance. The purpose of the present article is to investigate the factors affecting the spatial resolution of SAPHIRE. Since the resolution performance of the SHARP combination has been well studied, the focus of the present work is on the inherent resolution of the FEA readout method. The lateral spread of the electron beam emitted from a 50 {mu}mx50 {mu}m pixel FEA was investigated with two different electron-optical designs: mesh-electrode-only and electrostatic focusing. Our results showed that electrostatic focusing can limit the lateral spread of electron beams to within the pixel size of down to 50 {mu}m. Since electrostatic focusing is essentially independent of signal intensity, it will provide excellent spatial uniformity.

  7. An indirect flat-panel detector with avalanche gain for low dose x-ray imaging: SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout)

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Li, Dan; Rowlands, J. A.; Egami, N.; Takiguchi, Y.; Nanba, M.; Honda, Y.; Ohkawa, Y.; Kubota, M.; Tanioka, K.; Suzuki, K.; Kawai, T.

    2008-03-01

    An indirect flat-imager with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose x-ray imaging with high resolution. It is made by optically coupling a structured x-ray scintillator CsI (Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The charge image created by HARP is read out by electron beams generated by the FEA. The proposed detector is called SAPHIRE (Scintillator Avalanche Photoconductor with HIgh Resolution Emitter readout). The avalanche gain of HARP depends on both a-Se thickness and applied electric field E Se. At E Se of > 80 V/μm, the avalanche gain can enhance the signal at low dose (e.g. fluoroscopy) and make the detector x-ray quantum noise limited down to a single x-ray photon. At high exposure (e.g. radiography), the avalanche gain can be turned off by decreasing E Se to < 70 V/μm. In this paper the imaging characteristics of the FEA readout method, including the spatial resolution and noise, were investigated experimentally using a prototype optical HARP-FEA image sensor. The potential x-ray imaging performance of SAPHIRE, especially the aspect of programmable gain to ensure wide dynamic range and x-ray quantum noise limited performance at the lowest exposure in fluoroscopy, was investigated.

  8. Early effects comparison of X-rays delivered at high-dose-rate pulses by a plasma focus device and at low dose rate on human tumour cells.

    PubMed

    Virelli, A; Zironi, I; Pasi, F; Ceccolini, E; Nano, R; Facoetti, A; Gavoçi, E; Fiore, M R; Rocchi, F; Mostacci, D; Cucchi, G; Castellani, G; Sumini, M; Orecchia, R

    2015-09-01

    A comparative study has been performed on the effects of high-dose-rate (DR) X-ray beams produced by a plasma focus device (PFMA-3), to exploit its potential medical applications (e.g. radiotherapy), and low-DR X-ray beams produced by a conventional source (XRT). Experiments have been performed at 0.5 and 2 Gy doses on a human glioblastoma cell line (T98G). Cell proliferation rate and potassium outward currents (IK) have been investigated by time lapse imaging and patch clamp recordings. The results showed that PFMA-3 irradiation has a greater capability to reduce the proliferation rate activity with respect to XRT, while it does not affect IK of T98G cells at any of the dose levels tested. XRT irradiation significantly reduces the mean IK amplitude of T98G cells only at 0.5 Gy. This work confirms that the DR, and therefore the source of radiation, is crucial for the planning and optimisation of radiotherapy applications.

  9. High-resolution wide-angle X-ray scattering of protein solutions: effect of beam dose on protein integrity.

    PubMed

    Fischetti, Robert F; Rodi, Diane J; Mirza, Ahmed; Irving, Thomas C; Kondrashkina, Elena; Makowski, Lee

    2003-09-01

    Wide-angle X-ray scattering patterns from proteins in solution contain information relevant to the determination of protein fold. At relevant scattering angles, however, these data are weak, and the degree to which they might be used to categorize the fold of a protein is unknown. Preliminary work has been performed at the BioCAT insertion-device beamline at the Advanced Photon Source which demonstrates that one can collect X-ray scattering data from proteins in solution to spacings of at least 2.2 A (q = 2.8 A(-1)). These data are sensitive to protein conformational states, and are in good agreement with the scattering predicted by the program CRYSOL using the known three-dimensional atomic coordinates of the protein. An important issue in the exploitation of this technique as a tool for structural genomics is the extent to which the high intensity of X-rays available at third-generation synchrotron sources chemically or structurally damage proteins. Various data-collection protocols have been investigated demonstrating conditions under which structural degradation of even sensitive proteins can be minimized, making this technique a viable tool for protein fold categorization, the study of protein folding, unfolding, protein-ligand interactions and domain movement.

  10. Calculation of dose conversion factors for posterior-anterior chest radiography of adults with a relatively high-energy X-ray spectrum.

    PubMed

    Schultz, F W; Geleijns, J; Zoetelief, J

    1994-08-01

    In a survey of X-ray units as applied for thorax examinations considerable variations were observed in entrance dose among different hospitals in the Leyden region. For the median exposure conditions, i.e. 125 kVp, heavy filtering and large focus-to-skin distance (177.5 cm), absorbed dose distributions have been derived using mathematical phantoms of a standard male or female adult. For relatively high-energy X-rays, back scatter factors were calculated by Monte Carlo simulation. In addition, conversion factors were obtained, relating organ doses to air kerma, free in air. Effective dose equivalent and effective dose were calculated according to ICRP-26 and ICRP-60 recommendations, respectively. The computational procedures were compared with results reported in the literature for a similar exposure configuration but using lower-energy X-rays. Causes of relative differences ranging from -56% to +34% were analysed. In addition to the photon energy spectrum and filtering, the exposure geometry appears to be a very important parameter which can be optimized for the purpose of dose reduction.

  11. High resolution X-ray scattering measurements

    NASA Technical Reports Server (NTRS)

    Zombeck, M. V.; Braeuninger, H.; Ondrusch, A.; Predehl, P.

    1982-01-01

    The results of high angular resolution grazing incidence scattering measurements of highly polished, coated optical flats in the X-ray spectral range of 1.5 to 6.4 keV are reported. The interpretation of these results in terms of surface microtopography is presented and the implications for grazing incidence X-ray imaging are discussed.

  12. Photoneutron depth dose equivalent distributions in high-energy X-ray medical accelerators by a novel position-sensitive dosimeter.

    PubMed

    Hakimi, Amir; Sohrabi, Mehdi

    2017-04-01

    The purpose of this study was to; (1) investigate employing a novel position-sensitive mega-size polycarbonate (MSPC) dosimeter for photoneutron (PN) depth, profile and dose equivalent distributions studies in a multilayer polyethylene phantom in a Siemens ONCOR accelerator, and (2) develop depth dose equivalent distribution matrix data at different depths and positions of the phantom for patient PN dose equivalent determination and in particular for PN secondary cancer risk estimation. Position-sensitive MSPC dosimeters were successfully exposed at 9 different depths of the phantom in a 10×10cm(2) X-ray field. The dosimeters were processed in mega-size electrochemical chambers at optimum conditions. Each MSPC dosimeter was placed at a known phantom depth for PN depth dose equivalents and profiles on transverse, longitudinal and diagonal axes and isodose equivalent distribution studies in and out of the X-ray beam. PN dose equivalent distributions at any depth showed the highest value at the beam central axis and decreases as the distance increases. PN dose equivalent at any position studied in the axes has a maximum value on the phantom surface which decreases as depth increases due to flux reduction by multi-elastic scattering interactions. Extensive PN dose equivalent matrix data at different depths and positions in the phantom were determined. The position-sensitive MSPC dosimeters proved to be highly efficient for PN depth, profile and isodose equivalent distribution studies. The extensive data obtained highly assists for determining PN dose equivalent of a patient undergoing high-energy X-ray therapy and for PN secondary cancer risk estimation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. High Resolution X-ray-Induced Acoustic Tomography

    PubMed Central

    Xiang, Liangzhong; Tang, Shanshan; Ahmad, Moiz; Xing, Lei

    2016-01-01

    Absorption based CT imaging has been an invaluable tool in medical diagnosis, biology, and materials science. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. In this letter, we report a new imaging modality, X-ray Induced Acoustic Tomography (XACT), which takes advantages of high sensitivity to X-ray absorption and high ultrasonic resolution in a single modality. A single projection X-ray exposure is sufficient to generate acoustic signals in 3D space because the X-ray generated acoustic waves are of a spherical nature and propagate in all directions from their point of generation. We demonstrate the successful reconstruction of gold fiducial markers with a spatial resolution of about 350 μm. XACT reveals a new imaging mechanism and provides uncharted opportunities for structural determination with X-ray. PMID:27189746

  14. High Resolution X-ray-Induced Acoustic Tomography.

    PubMed

    Xiang, Liangzhong; Tang, Shanshan; Ahmad, Moiz; Xing, Lei

    2016-05-18

    Absorption based CT imaging has been an invaluable tool in medical diagnosis, biology, and materials science. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. In this letter, we report a new imaging modality, X-ray Induced Acoustic Tomography (XACT), which takes advantages of high sensitivity to X-ray absorption and high ultrasonic resolution in a single modality. A single projection X-ray exposure is sufficient to generate acoustic signals in 3D space because the X-ray generated acoustic waves are of a spherical nature and propagate in all directions from their point of generation. We demonstrate the successful reconstruction of gold fiducial markers with a spatial resolution of about 350 μm. XACT reveals a new imaging mechanism and provides uncharted opportunities for structural determination with X-ray.

  15. High Resolution X-ray-Induced Acoustic Tomography

    NASA Astrophysics Data System (ADS)

    Xiang, Liangzhong; Tang, Shanshan; Ahmad, Moiz; Xing, Lei

    2016-05-01

    Absorption based CT imaging has been an invaluable tool in medical diagnosis, biology, and materials science. However, CT requires a large set of projection data and high radiation dose to achieve superior image quality. In this letter, we report a new imaging modality, X-ray Induced Acoustic Tomography (XACT), which takes advantages of high sensitivity to X-ray absorption and high ultrasonic resolution in a single modality. A single projection X-ray exposure is sufficient to generate acoustic signals in 3D space because the X-ray generated acoustic waves are of a spherical nature and propagate in all directions from their point of generation. We demonstrate the successful reconstruction of gold fiducial markers with a spatial resolution of about 350 μm. XACT reveals a new imaging mechanism and provides uncharted opportunities for structural determination with X-ray.

  16. Low Dose High Energy X-ray In-Line Phase Sensitive Imaging Prototype: Investigation of Optimal Geometric Conditions and Design Parameters

    PubMed Central

    Ghani, Muhammad. U.; Yan, Aimin; Wong, Molly. D.; Li, Yuhua; Ren, Liqiang; Wu, Xizeng; Liu, Hong

    2016-01-01

    The objective of this study was to investigate the optimization of a high energy in-line phase sensitive x-ray imaging prototype under different geometric and operating conditions for mammography application. A phase retrieval algorithm based on phase attenuation duality (PAD) was applied to the phase contrast images acquired by the prototype. Imaging performance was investigated at four magnification values of 1.67, 2, 2.5 and 3 using an acrylic edge, an American College of Radiology (ACR) mammography phantom and contrast detail (CD) phantom with tube potentials of 100, 120 and 140 kVp. The ACR and CD images were acquired at the same mean glandular dose (MGD) of 1.29 mGy with a computed radiography (CR) detector of 43.75 µm pixel pitch at a fixed source to image distance (SID) of 170 cm. The x-ray tube focal spot size was kept constant as 7 µm while a 2.5 mm thick aluminum (Al) filter was used for beam hardening. The performance of phase contrast and phase retrieved images were compared with computer simulations based on the relative phase contrast factor (RPF) at high x-ray energies. The imaging results showed that the x-ray tube operated at 100 kVp under the magnification of 2.5 exhibits superior imaging performance which is in accordance to the computer simulations. As compared to the phase contrast images, the phase retrieved images of the ACR and CD phantoms demonstrated improved imaging contrast and target discrimination. We compared the CD phantom images acquired in conventional contact mode with and without the anti-scatter grid using the same prototype at 1.295 mGy and 2.59 mGy using 40 kVp, a 25 µm rhodium (Rh) filter. At the same radiation dose, the phase sensitive images provided improved detection capabilities for both the large and small discs, while compared to the double dose image acquired in conventional mode, the observer study also indicated that the phase sensitive images provided improved detection capabilities for the large discs. This

  17. Low dose high energy x-ray in-line phase sensitive imaging prototype: Investigation of optimal geometric conditions and design parameters.

    PubMed

    Ghani, Muhammad U; Yan, Aimin; Wong, Molly D; Li, Yuhua; Ren, Liqiang; Wu, Xizeng; Liu, Hong

    2015-01-01

    The objective of this study was to investigate the optimization of a high energy in-line phase sensitive x-ray imaging prototype under different geometric and operating conditions for mammography application. A phase retrieval algorithm based on phase attenuation duality (PAD) was applied to the phase contrast images acquired by the prototype. Imaging performance was investigated at four magnification values of 1.67, 2, 2.5 and 3 using an acrylic edge, an American College of Radiology (ACR) mammography phantom and contrast detail (CD) phantom with tube potentials of 100, 120 and 140 kVp. The ACR and CD images were acquired at the same mean glandular dose (MGD) of 1.29 mGy with a computed radiography (CR) detector of 43.75 μm pixel pitch at a fixed source to image distance (SID) of 170 cm. The x-ray tube focal spot size was kept constant as 7 μm while a 2.5 mm thick aluminum (Al) filter was used for beam hardening. The performance of phase contrast and phase retrieved images were compared with computer simulations based on the relative phase contrast factor (RPF) at high x-ray energies. The imaging results showed that the x-ray tube operated at 100 kVp under the magnification of 2.5 exhibits superior imaging performance which is in accordance to the computer simulations. As compared to the phase contrast images, the phase retrieved images of the ACR and CD phantoms demonstrated improved imaging contrast and target discrimination. We compared the CD phantom images acquired in conventional contact mode with and without the anti-scatter grid using the same prototype at 1.295 mGy and 2.59 mGy using 40 kVp, a 25 μm rhodium (Rh) filter. At the same radiation dose, the phase sensitive images provided improved detection capabilities for both the large and small discs, while compared to the double dose image acquired in conventional mode, the observer study also indicated that the phase sensitive images provided improved detection capabilities for the large discs. This

  18. Linear accelerator x-ray sources with high duty cycle

    SciTech Connect

    Condron, Cathie; Brown, Craig; Gozani, Tsahi; Langeveld, Willem G. J.; Hernandez, Michael

    2013-04-19

    X-ray cargo inspection systems typically use a several-MV pulsed linear accelerator (linac) to produce a bremsstrahlung spectrum of x rays by bombarding a target with electrons. The x rays traverse the cargo and are detected by a detector array. Spectroscopy of the detected x rays is very desirable: if one can determine the spectrum of the transmitted x rays, one can determine the Z of the material they traversed. Even in relatively low-dose modes of operation, thousands of x rays arrive at each detector element during each pulse, unless the x rays are heavily absorbed or scattered by the cargo. For portal or fixed-site systems, dose rates, and therefore x-ray count rates, are even higher. Because of the high x-ray count rate, spectroscopy is impractical in conventional cargo inspection systems, except in certain special cases. For a mobile system, typical pulse durations are a few microseconds, and the number of pulses is on the order of 100 per second, leading to a duty factor of about 0.04%. Clearly, a linear accelerator x-ray source with much higher duty factor would be useful, since then the same number of x rays could be spread out over time, reducing the x-ray count rate. In this paper, we explore the possibility of designing a linear accelerator system, using more or less Conventional Off the Shelf (COTS) components, capable of duty cycles of 1% or greater. A survey was conducted of available linac RF source options and, given the possibilities, calculations were performed for suitable beam centerline designs. Keeping in mind that the size and cost of the accelerator system should be practical for use in a mobile cargo inspection system, only a few options are shown to be reasonably feasible, both requiring the use of klystrons instead of the magnetrons used in conventional systems. An S-Band design appears clearly possible, and there is also a promising X-Band design.

  19. High accuracy gaseous x-ray detectors

    SciTech Connect

    Smith, G.C.

    1983-11-01

    An outline is given of the design and operation of high accuracy position-sensitive x-ray detectors suitable for experiments using synchrotron radiation. They are based on the gas proportional detector, with position readout using a delay line; a detailed examination is made of factors which limit spatial resolution. Individual wire readout may be used for extremely high counting rates.

  20. [Effective dose transmission of diagnostic X-rays through concrete and lead shields].

    PubMed

    Kato, Hideki

    2003-08-01

    When computing the amount of leakage from a diagnostic X-ray room, the transmission data of X-ray beams through the shielding material, which are used in the computation, must agree with the conditions of use of the X-ray equipment. Even if the tube potential is the same, the energy spectrum of generated X-rays depends on conditions such as high voltage rectification and total filtration, and transmission through the shielding material, too, is subject to change. In this paper, we propose a new method of calculation, which uses transmission data of mono-energetic photon beams computed by means of a Monte Carlo simulation, for obtaining effective dose transmission data through the shielding material of an X-ray beam with spectral distribution. We also present effective dose transmission data of primary X-ray beams and 90 degrees scattered X-ray beams through concrete and lead shields as determined by this method. This method, which can calculate the transmission data of X-ray beams with any spectral distribution, is useful in evaluating the leakage dose of diagnostic X-ray facilities.

  1. Treatment of foods with high-energy X rays

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Meissner, J.; Herer, A. S.; Beers, E. W.

    2001-07-01

    The treatment of foods with ionizing energy in the form of gamma rays, accelerated electrons, and X rays can produce beneficial effects, such as inhibiting the sprouting in potatoes, onions, and garlic, controlling insects in fruits, vegetables, and grains, inhibiting the growth of fungi, pasteurizing fresh meat, poultry, and seafood, and sterilizing spices and food additives. After many years of research, these processes have been approved by regulatory authorities in many countries and commercial applications have been increasing. High-energy X rays are especially useful for treating large packages of food. The most attractive features are product penetration, absorbed dose uniformity, high utilization efficiency and short processing time. The ability to energize the X-ray source only when needed enhances the safety and convenience of this technique. The availability of high-energy, high-power electron accelerators, which can be used as X-ray generators, makes it feasible to process large quantities of food economically. Several industrial accelerator facilities already have X-ray conversion equipment and several more will soon be built with product conveying systems designed to take advantage of the unique characteristics of high-energy X rays. These concepts will be reviewed briefly in this paper.

  2. Feasibility study for application of the compressed-sensing framework to interior computed tomography (ICT) for low-dose, high-accurate dental x-ray imaging

    NASA Astrophysics Data System (ADS)

    Je, U. K.; Cho, H. M.; Cho, H. S.; Park, Y. O.; Park, C. K.; Lim, H. W.; Kim, K. S.; Kim, G. A.; Park, S. Y.; Woo, T. H.; Choi, S. I.

    2016-02-01

    In this paper, we propose a new/next-generation type of CT examinations, the so-called Interior Computed Tomography (ICT), which may presumably lead to dose reduction to the patient outside the target region-of-interest (ROI), in dental x-ray imaging. Here an x-ray beam from each projection position covers only a relatively small ROI containing a target of diagnosis from the examined structure, leading to imaging benefits such as decreasing scatters and system cost as well as reducing imaging dose. We considered the compressed-sensing (CS) framework, rather than common filtered-backprojection (FBP)-based algorithms, for more accurate ICT reconstruction. We implemented a CS-based ICT algorithm and performed a systematic simulation to investigate the imaging characteristics. Simulation conditions of two ROI ratios of 0.28 and 0.14 between the target and the whole phantom sizes and four projection numbers of 360, 180, 90, and 45 were tested. We successfully reconstructed ICT images of substantially high image quality by using the CS framework even with few-view projection data, still preserving sharp edges in the images.

  3. Monochromatic x-rays for low-dose digital mammography: preliminary results.

    PubMed

    Yoon, Kwon-Ha; Kwon, Young Man; Choi, Byoung-Jung; Son, Hyun Hwa; Ryu, Cheol Woo; Chon, Kwon Su; Park, Seong Hoon; Juhng, Sun Kwan

    2012-12-01

    The feasibility of using monochromatic x-ray imaging generated from an x-ray tube and a multilayer reflector for digital mammography with a low radiation dose was examined. A multilayer mirror was designed to select the x-ray peak with an energy of 21.5 keV generated from an x-ray tube with a tungsten target and was fabricated by the ion-beam sputtering deposition system. Monochromatic x-ray images were obtained from an experimental digital mammography setup with a scanning stage. The performance of the system was evaluated using a breast phantom, a spectrometer, and a radiation dosimeter. We measured the contrast-to-noise ratio and performed the 10% modulation function test to determine image quality and resolution. The monochromatic beam from the multilayer reflector had a full-width-at-half-maximum of 0.9 keV at 21.5 keV, and the reflectivity was 0.70, which was 90% of the designed value. The polychromatic and monochromatic x-rays showed radiation doses of 0.497 and 0.0415 mGy, respectively. The monochromatic x-ray image shows fibers, calcifications, and masses more clearly than the polychromatic x-ray images do. The image contrast of the monochromatic x-rays was 1.85 times higher than that of the polychromatic x-rays. The experimental mammography setup had a spatial resolution of 7 lp/mm with both x-rays. Monochromatic x-rays generated using a multilayer mirror may be a useful diagnostic tool for breast examination by providing high contrast imaging with a low radiation dose.

  4. Miniaturized, High-Speed, Modulated X-Ray Source

    NASA Technical Reports Server (NTRS)

    Gendreau, Keith; Arzoumanian, Zaven; Kenyon, Steve; Spartana, Nick

    2013-01-01

    A low-cost, miniature x-ray source has been developed that can be modulated in intensity from completely off to full intensity on nanosecond timescales. This modulated x-ray source (MXS) has no filaments and is extremely rugged. The energy level of the MXS is adjustable from 0 to more than 100 keV. It can be used as the core of many new devices, providing the first practical, arbitrarily time-variable source of x-rays. The high-speed switching capability and miniature size make possible many new technologies including x-ray-based communication, compact time-resolved x-ray diffraction, novel x-ray fluorescence instruments, and low- and precise-dose medical x-rays. To make x-rays, the usual method is to accelerate electrons into a target material held at a high potential. When the electrons stop in the target, x-rays are produced with a spectrum that is a function of the target material and the energy to which the electrons are accelerated. Most commonly, the electrons come from a hot filament. In the MXS, the electrons start off as optically driven photoelectrons. The modulation of the x-rays is then tied to the modulation of the light that drives the photoelectron source. Much of the recent development has consisted of creating a photoelectrically-driven electron source that is robust, low in cost, and offers high intensity. For robustness, metal photocathodes were adopted, including aluminum and magnesium. Ultraviolet light from 255- to 350-nm LEDs (light emitting diodes) stimulated the photoemissions from these photocathodes with an efficiency that is maximized at the low-wavelength end (255 nm) to a value of roughly 10(exp -4). The MXS units now have much higher brightness, are much smaller, and are made using a number of commercially available components, making them extremely inexpensive. In the latest MXS design, UV efficiency is addressed by using a high-gain electron multiplier. The photocathode is vapor-deposited onto the input cone of a Burle Magnum

  5. Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma x-ray source.

    PubMed

    Tillman, C; Grafström, G; Jonsson, A C; Jönsson, B A; Mercer, I; Mattsson, S; Strand, S E; Svanberg, S

    1999-12-01

    To determine whether intense laser-produced x rays have an increased radiation hazard. Mammalian cells were exposed to x rays from a laser-produced plasma that produced ultrahigh peak absorbed dose rates, up to a factor of 10(10) higher than those produced by conventional x rays used in imaging. The cell survival was studied as a function of the absorbed dose. The survival of mammalian cells exposed to high peak absorbed dose rates with laser-produced x rays was compared with the survival of cells exposed to standard absorbed dose rates with conventional x-ray sources. Comparative survival studies were performed by using a conventional x-ray tube and a cobalt 60 source. The absorbed doses in the irradiation field were measured with thermoluminescent dosimeters. Cell survival following irradiation by filtered, laser-produced x rays with a high dose rate was not markedly different from the survival following irradiation by conventional sources. There was, however, a notable difference between the survival after exposure to filtered, laser-produced x rays and the survival after exposure to unfiltered laser-produced x rays. Exposure to filtered, laser-produced x rays with a high dose rate does not lead to increased harm to mammalian cells exposed in vitro compared with the harm from exposure to x rays from conventional sources, which indicates that the use of high-power laser facilities for medical imaging is justified.

  6. Assessment of targeted and non-targeted responses in cells deficient in ATM function following exposure to low and high dose X-rays.

    PubMed

    Kiuru, Anne; Kämäräinen, Meerit; Heinävaara, Sirpa; Pylkäs, Katri; Chapman, Kim; Koivistoinen, Armi; Parviainen, Teuvo; Winqvist, Robert; Kadhim, Munira; Launonen, Virpi; Lindholm, Carita

    2014-01-01

    Radiation sensitivity at low and high dose exposure to X-rays was investigated by means of chromosomal aberration (CA) analysis in heterozygous ATM mutation carrier and A-T patient (biallelic ATM mutation) lymphoblastoid cell lines (LCLs). Targeted and non-targeted responses to acutely delivered irradiation were examined by applying a co-culture system that enables study of both directly irradiated cells and medium-mediated bystander effects in the same experimental setting. No indication of radiation hypersensitivity was observed at doses of 0.01 Gy or 0.1 Gy for the ATM mutation carrier LCL. The A-T patient cells also did not show low-dose response. There was significant increase in unstable CA yields for both ATM mutation carrier and A-T LCLs at 1 and 2 Gy, the A-T cells displaying more distinct dose dependency. Both chromosome and chromatid type aberrations were induced at an increased rate in the irradiated A-T cells, whereas for ATM carrier cells, only unstable chromosomal aberrations were increased above the level observed in the wild type cell line. No bystander effect could be demonstrated in any of the cell lines or doses applied. Characteristics typical for the A-T cell line were detected, i.e., high baseline frequency of CA that increased with dose. In addition, dose-dependent loss of cell viability was observed. In conclusion, CA analysis did not demonstrate low-dose (≤100 mGy) radiosensitivity in ATM mutation carrier cells or A-T patient cells. However, both cell lines showed increased radiosensitivity at high dose exposure.

  7. Assessment of Targeted and Non-Targeted Responses in Cells Deficient in ATM Function following Exposure to Low and High Dose X-Rays

    PubMed Central

    Heinävaara, Sirpa; Pylkäs, Katri; Chapman, Kim; Koivistoinen, Armi; Parviainen, Teuvo; Winqvist, Robert; Kadhim, Munira; Launonen, Virpi; Lindholm, Carita

    2014-01-01

    Radiation sensitivity at low and high dose exposure to X-rays was investigated by means of chromosomal aberration (CA) analysis in heterozygous ATM mutation carrier and A-T patient (biallelic ATM mutation) lymphoblastoid cell lines (LCLs). Targeted and non-targeted responses to acutely delivered irradiation were examined by applying a co-culture system that enables study of both directly irradiated cells and medium-mediated bystander effects in the same experimental setting. No indication of radiation hypersensitivity was observed at doses of 0.01 Gy or 0.1 Gy for the ATM mutation carrier LCL. The A-T patient cells also did not show low-dose response. There was significant increase in unstable CA yields for both ATM mutation carrier and A-T LCLs at 1 and 2 Gy, the A-T cells displaying more distinct dose dependency. Both chromosome and chromatid type aberrations were induced at an increased rate in the irradiated A-T cells, whereas for ATM carrier cells, only unstable chromosomal aberrations were increased above the level observed in the wild type cell line. No bystander effect could be demonstrated in any of the cell lines or doses applied. Characteristics typical for the A-T cell line were detected, i.e., high baseline frequency of CA that increased with dose. In addition, dose-dependent loss of cell viability was observed. In conclusion, CA analysis did not demonstrate low-dose (≤100 mGy) radiosensitivity in ATM mutation carrier cells or A-T patient cells. However, both cell lines showed increased radiosensitivity at high dose exposure. PMID:24681528

  8. High-Resolution X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Brissenden, Roger J.; Davis, William; Elsner, Ronald F.; Elvis, Martin; Freeman, Mark; Gaetz, Terry; Gorenstein, Paul; Gubarev, Mikhail V.

    2010-01-01

    Fundamental needs for future x-ray telescopes: a) Sharp images => excellent angular resolution. b) High throughput => large aperture areas. Generation-X optics technical challenges: a) High resolution => precision mirrors & alignment. b) Large apertures => lots of lightweight mirrors. Innovation needed for technical readiness: a) 4 top-level error terms contribute to image size. b) There are approaches to controlling those errors. Innovation needed for manufacturing readiness. Programmatic issues are comparably challenging.

  9. Enhancement of X-ray dose absorption for medical applications

    NASA Astrophysics Data System (ADS)

    Lim, Sara; Nahar, S.; Pradhan, A.; Barth, R.

    2013-05-01

    A promising technique for cancer treatment is radiation therapy with high-Z (HZ) nanomoities acting as radio-sensitizers attached to tumor cells and irradiated with X-rays. But the efficacy of radiosenstization is highly energy dependent. We study the physical effects in using platinum (Pt) as the radio-sensitizing agent, coupled with commonly employed broadband x-ray sources with mean energies around 100 keV, as opposed to MeV energies produced by clinical linear accelerators (LINAC) used in radiation therapy. Numerical calculations, in vitro, and in vivo studies of F98 rat glioma (brain cancer) demonstrate that irradiation from a medium energy X-ray (MEX) 160 kV source is far more effective than from a high energy x-ray (HEX) 6 MV LINAC. We define a parameter to quantify photoionization by an x-ray source, which thereby provides a measure of subsequent Auger decays. The platinum (Z = 78) results are also relevant to ongoing studies on x-ray interaction with gold (Z = 79) nanoparticles, widely studied as an HZ contrast agent. The present study should be of additional interest for a combined radiation plus chemotherapy treatment since Pt compounds such cis-Pt and carbo-Pt are commonly used in chemotherapy.

  10. High frequency x-ray generator basics.

    PubMed

    Sobol, Wlad T

    2002-02-01

    The purpose of this paper is to present basic functional principles of high frequency x-ray generators. The emphasis is put on physical concepts that determine the engineering solutions to the problem of efficient generation and control of high voltage power required to drive the x-ray tube. The physics of magnetically coupled circuits is discussed first, as a background for the discussion of engineering issues related to high-frequency power transformer design. Attention is paid to physical processes that influence such factors as size, efficiency, and reliability of a high voltage power transformer. The basic electrical circuit of a high frequency generator is analyzed next, with focus on functional principles. This section investigates the role and function of basic components, such as power supply, inverter, and voltage doubler. Essential electronic circuits of generator control are then examined, including regulation of voltage, current and timing of electrical power delivery to the x-ray tube. Finally, issues related to efficient feedback control, including basic design of the AEC circuitry are reviewed.

  11. Dose optimization in pediatric cardiac x-ray imaging

    SciTech Connect

    Gislason, Amber J.; Davies, Andrew G.; Cowen, Arnold R.

    2010-10-15

    Purpose: The aim of this research was to explore x-ray beam parameters with intent to optimize pediatric x-ray settings in the cardiac catheterization laboratory. This study examined the effects of peak x-ray tube voltage (kVp) and of copper (Cu) x-ray beam filtration independently on the image quality to dose balance for pediatric patient sizes. The impact of antiscatter grid removal on the image quality to dose balance was also investigated. Methods: Image sequences of polymethyl methacrylate phantoms approximating chest sizes typical of pediatric patients were captured using a modern flat-panel receptor based x-ray imaging system. Tin was used to simulate iodine-based contrast medium used in clinical procedures. Measurements of tin detail contrast and flat field image noise provided the contrast to noise ratio. Entrance surface dose (ESD) and effective dose (E) measurements were obtained to calculate the figure of merit (FOM), CNR{sup 2}/dose, which evaluated the dose efficiency of the x-ray parameters investigated. The kVp, tube current (mA), and pulse duration were set manually by overriding the system's automatic dose control mechanisms. Images were captured with 0, 0.1, 0.25, 0.4, and 0.9 mm added Cu filtration, for 50, 55, 60, 65, and 70 kVp with the antiscatter grid in place, and then with it removed. Results: For a given phantom thickness, as the Cu filter thickness was increased, lower kVp was favored. Examining kVp alone, lower values were generally favored, more so for thinner phantoms. Considering ESD, the 8.5 cm phantom had the highest FOM at 50 kVp using 0.4 mm of Cu filtration. The 12 cm phantom had the highest FOM at 55 kVp using 0.9 mm Cu, and the 16 cm phantom had highest FOM at 55 kVp using 0.4 mm Cu. With regard to E, the 8.5 and 12 cm phantoms had the highest FOM at 50 kVp using 0.4 mm of Cu filtration, and the 16 cm phantom had the highest FOM at 50 kVp using 0.25 mm Cu. Antiscatter grid removal improved the FOM for a given set of x-ray

  12. Order of magnitude reduction of fluoroscopic x-ray dose

    NASA Astrophysics Data System (ADS)

    Bal, Abhinav; Robert, Normand; Machan, Lindsay; Deutsch, Meir; Kisselgoff, David; Babyn, Paul; Rowlands, John A.

    2012-03-01

    The role of fluoroscopic imaging is critical for diagnostic and image guided therapy. However, fluoroscopic imaging can require significant radiation leading to increased cancer risk and non-stochastic effects such as radiation burns. Our purpose is to reduce the exposure and dose to the patient by an order of magnitude in these procedures by use of the region of interest method. Method and Materials: Region of interest fluoroscopy (ROIF) uses a partial attenuator. The central region of the image has full exposure while the image periphery, there to provide context only, has a reduced exposure rate. ROIF using a static partial attenuator has been shown in our previous studies to reduce the dose area product (DAP) to the patient by at least 2.5 times. Significantly greater reductions in DAP would require improvements in flat panel detectors performance at low x-ray exposures or a different x-ray attenuation strategy. Thus we have investigated a second, dynamic, approach. We have constructed an x-ray shutter system allowing a normal x-ray exposure in the region of interest while reducing the number of x-ray exposures in the periphery through the rapid introduction, positioning and removal of an x-ray attenuating shutter to block radiation only for selected frames. This dynamic approach eliminates the DQE(0) loss associated with the use of static partial attenuator applied to every frame thus permitting a greater reduction in DAP. Results: We have compared the two methods by modeling and determined their fundamental limits.

  13. High-spatial-resolution nanoparticle x-ray fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Larsson, Jakob C.; Vâgberg, William; Vogt, Carmen; Lundström, Ulf; Larsson, Daniel H.; Hertz, Hans M.

    2016-03-01

    X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 μm), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.

  14. Dual-gate photo thin-film transistor: a “smart” pixel for high- resolution and low-dose X-ray imaging

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Ou, Hai; Chen, Jun

    2015-06-01

    Since its emergence a decade ago, amorphous silicon flat panel X-ray detector has established itself as a ubiquitous platform for an array of digital radiography modalities. The fundamental building block of a flat panel detector is called a pixel. In all current pixel architectures, sensing, storage, and readout are unanimously kept separate, inevitably compromising resolution by increasing pixel size. To address this issue, we hereby propose a “smart” pixel architecture where the aforementioned three components are combined in a single dual-gate photo thin-film transistor (TFT). In other words, the dual-gate photo TFT itself functions as a sensor, a storage capacitor, and a switch concurrently. Additionally, by harnessing the amplification effect of such a thin-film transistor, we for the first time created a single-transistor active pixel sensor. The proof-of-concept device had a W/L ratio of 250μm/20μm and was fabricated using a simple five-mask photolithography process, where a 130nm transparent ITO was used as the top photo gate, and a 200nm amorphous silicon as the absorbing channel layer. The preliminary results demonstrated that the photocurrent had been increased by four orders of magnitude due to light-induced threshold voltage shift in the sub-threshold region. The device sensitivity could be simply tuned by photo gate bias to specifically target low-level light detection. The dependence of threshold voltage on light illumination indicated that a dynamic range of at least 80dB could be achieved. The "smart" pixel technology holds tremendous promise for developing high-resolution and low-dose X-ray imaging and may potentially lower the cancer risk imposed by radiation, especially among paediatric patients.

  15. The superslow pulsation X-ray pulsars in high mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    2013-03-01

    There exists a special class of X-ray pulsars that exhibit very slow pulsation of P spin > 1000 s in the high mass X-ray binaries (HMXBs). We have studied the temporal and spectral properties of these superslow pulsation neutron star binaries in hard X-ray bands with INTEGRAL observations. Long-term monitoring observations find spin period evolution of two sources: spin-down trend for 4U 2206+54 (P spin ~ 5560 s with Ṗ spin ~ 4.9 × 10-7 s s-1) and long-term spin-up trend for 2S 0114+65 (P spin ~ 9600 s with Ṗ spin ~ -1 × 10-6 s s-1) in the last 20 years. A Be X-ray transient, SXP 1062 (P spin ~ 1062 s), also showed a fast spin-down rate of Ṗ spin ~ 3 × 10-6 s s-1 during an outburst. These superslow pulsation neutron stars cannot be produced in the standard X-ray binary evolution model unless the neutron star has a much stronger surface magnetic field (B > 1014 G). The physical origin of the superslow spin period is still unclear. The possible origin and evolution channels of the superslow pulsation X-ray pulsars are discussed. Superslow pulsation X-ray pulsars could be younger X-ray binary systems, still in the fast evolution phase preceding the final equilibrium state. Alternatively, they could be a new class of neutron star system - accreting magnetars.

  16. X-ray and radioiodine dose to thyroid follicular cells

    SciTech Connect

    Faw, R.E. . Dept. of Nuclear Engineering); Eckerman, K.F.; Ryman, J.C. )

    1991-01-01

    Radiation doses to the epithelial cells of thyroid follicles have been calculated for internal exposure by radionuclides of iodine and by secondary radiations created as a result of interactions of externally administered x rays with iodine naturally occurring in the thyroid. Calculations were performed for the thyroids of subjects ranging from the newborn to the adult male. Results for internal radionuclides are reported as the dose rate to follicular-cell nuclei per unit specific activity of the radionuclide in the thyroid as a whole, i.e., as the specific S value'' as used in the MIRD method for internal dosimetry. Results for x rays are reported as the response function, i.e., the absorbed dose per unit fluence of primary x rays. Dose rates are subdivided into internal and external components, the former from radiations emitted within the colloid volume of any one follicle, and the latter from radiations emitted throughout the thyroid in follicles surrounding that one follicle. 37 refs., 5 figs., 3 tabs.

  17. An investigation of dose changes for therapeutic kilovoltage X-ray beams with underlying lead shielding.

    PubMed

    Hill, Robin; Healy, Brendan; Holloway, Lois; Baldock, Clive

    2007-07-01

    Kilovoltage x-ray beams are used to treat cancer on or close to the skin surface. Many clinical cases use high atomic number materials as shielding to reduce dose to underlying healthy tissues. In this work, we have investigated the effect on both the surface dose and depth doses in a water phantom with lead shielding at depth in the phantom. The EGSnrc Monte Carlo code was used to simulate the water phantom and to calculate the surface doses and depth doses using primary x-ray beam spectra derived from an analytical model. The x-ray beams were in the energy range of 75-135 kVp with field sizes of 2, 5 and 8 cm diameter. The lead sheet was located beneath the water surface at depths ranging from 0.5-7.5 cm. The surface dose decreased as the lead was positioned closer to the water surface and as the field size was increased. The variation in surface dose as a function of x-ray beam energy was only small but the maximum reduction occurred for the 100 kVp x-ray beam. For the 8 cm diameter field with the lead at 1 cm depth and using the 100 kVp x-ray beam, the surface dose was reduced to 0.898 of the surface dose in the water phantom only. Measured surface dose changes, using a Farmer-type ionization chamber, agreed with the Monte Carlo calculated doses. Calculated depth doses in water with a lead sheet positioned below the surface showed that the dose fall-off increased as the lead was positioned closer to the water surface as compared to the depth dose in the water phantom only. Monte Carlo calculations of the total x-ray beam spectrum at the water surface showed that the total fluence decreased due to a reduction in backscatter from within the water and very little backscatter from the lead. The mean energy of the x-ray spectrum varied less than 1 keV, with the lead at 1 cm beneath the water phantom surface. As the Monte Carlo calculations showed good agreement with the measured results, this method can be used to verify surface dose changes in clinical situations

  18. Absorbed dose assessment in newborns during x-ray examinations

    NASA Astrophysics Data System (ADS)

    Taipe, Patricia K.; Berrocal, Mariella J.; Carita, Raúl F.

    2012-02-01

    Often a newborn presents breathing problems during the early days of life, i.e. bronchopneumonia, wich are caused in most of cases, by aspirating a mixture of meconium and amniotic fluid. In these cases, it is necessary to make use of a radiograph, requested by the physician to reach a diagnosis. This paper seeks to evaluate the absorbed doses in neonates undergoing a radiograph. For this reason we try to simulate the real conditions in a X-ray room from Lima hospitals. With this finality we perform a simulation made according a questionnaire related to technical data of X-ray equipment, distance between the source and the neonate, and its position to be irradiated. The information obtained has been used to determine the absorbed dose by infants, using the MCNP code. Finally, the results are compared with reference values of international health agencies.

  19. Gold nanoparticles as dose-enhancement agent for kilovoltage X-ray therapy of melanoma.

    PubMed

    Kim, So-Ra; Kim, Eun-Hee

    2017-05-01

    Melanoma is mainly treated by surgery and rarely with radiation because of the high radioresistance of this tumor. Nevertheless, radiotherapy is the preferred treatment modality for unresectable lesions and avoiding cosmetic disfigurement caused by surgical excision. This study investigated the therapeutic advantage of gold nanoparticles (AuNPs) for kilovoltage X-ray treatment of melanoma. Commercial AuNPs were evaluated for cytotoxicity and cellular internalization. The sensitivity of human skin melanoma cells to 150 and 450 kVp X-ray exposure was assessed in terms of clonogenicity with or without spherical AuNP treatment. AuNP treatment elicited dose enhancement effect on melanoma cells exposed to kilovoltage X-rays. Treatment with 320 μM 50 nm AuNPs before exposure to 150 kVp X-rays at 2 Gy resulted in clonogenic cell death equivalent to that caused by 4.3 Gy X-rays without AuNP treatment. AuNPs of 50 nm in size can regulate melanoma cells in kilovoltage X-ray treatment by functioning as dose-enhancement agent and thus improving radioresponse of the cells. Melanomas of stages T1-T3 gain therapeutic benefits from 150 kVp X-ray treatment.

  20. Evaluation of the medical exposure doses regarding dental examinations with different X-ray instruments

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Chi; Chuang, Keh-Shih; Yu, Cheng-Ching; Chao, Jiunn-Hsing; Hsu, Fang-Yuh

    2015-11-01

    Modern dental X-ray examination that consists of traditional form, panorama, and cone-beamed 3D technologies is one of the most frequent diagnostic applications nowadays. This study used the Rando Phantom and thermoluminescence dosimeters (TLD) to measure the absorbed doses of radiosensitive organs recommended by International Commission on Radiological Protection (ICRP), and whole body effective doses which were delivered due to dental X-ray examination performed with different types of X-ray instrument. Besides, enamel samples which performed reading with Electronic Paramagnetic Resonance (EPR) procedure were also used to estimate the tooth doses. EPR is a dose reconstruction method of measuring free radicals induced by radiation exposure to the calcified tissue (mainly in the tooth enamel or bone) to evaluate the accepted high dose. The tooth doses estimated by TLD and EPR methods were compared. Relationships between the tooth doses and effective doses by dental X-ray examinations with different types of X-ray equipment were investigated in this work.

  1. Dose-rate plays a significant role in synchrotron radiation X-ray-induced damage of rodent testes

    PubMed Central

    Chen, Heyu; Wang, Ban; Wang, Caixia; Cao, Wei; Zhang, Jie; Ma, Yingxin; Hong, Yunyi; Fu, Shen; Wu, Fan; Ying, Weihai

    2016-01-01

    Synchrotron radiation (SR) X-ray has significant potential for applications in medical imaging and cancer treatment. However, the mechanisms underlying SR X-ray-induced tissue damage remain unclear. Previous studies on regular X-ray-induced tissue damage have suggested that dose-rate could affect radiation damage. Because SR X-ray has exceedingly high dose-rate compared to regular X-ray, it remains to be determined if dose-rate may affect SR X-ray-induced tissue damage. We used rodent testes as a model to investigate the role of dose-rate in SR X-ray-induced tissue damage. One day after SR X-ray irradiation, we determined the effects of the irradiation of the same dosage at two different dose-rates, 0.11 Gy/s and 1.1 Gy/s, on TUNEL signals, caspase-3 activation and DNA double-strand breaks (DSBs) of the testes. Compared to those produced by the irradiation at 0.11 Gy/s, irradiation at 1.1 Gy/s produced higher levels of DSBs, TUNEL signals, and caspase-3 activation in the testes. Our study has provided the first evidence suggesting that dose-rate could be a significant factor in SR X-ray-induced tissue damage, which may establish a valuable base for utilizing this factor to manipulate the tissue damage in SR X-ray-based medical applications. PMID:28078052

  2. Dose-rate plays a significant role in synchrotron radiation X-ray-induced damage of rodent testes.

    PubMed

    Chen, Heyu; Wang, Ban; Wang, Caixia; Cao, Wei; Zhang, Jie; Ma, Yingxin; Hong, Yunyi; Fu, Shen; Wu, Fan; Ying, Weihai

    2016-01-01

    Synchrotron radiation (SR) X-ray has significant potential for applications in medical imaging and cancer treatment. However, the mechanisms underlying SR X-ray-induced tissue damage remain unclear. Previous studies on regular X-ray-induced tissue damage have suggested that dose-rate could affect radiation damage. Because SR X-ray has exceedingly high dose-rate compared to regular X-ray, it remains to be determined if dose-rate may affect SR X-ray-induced tissue damage. We used rodent testes as a model to investigate the role of dose-rate in SR X-ray-induced tissue damage. One day after SR X-ray irradiation, we determined the effects of the irradiation of the same dosage at two different dose-rates, 0.11 Gy/s and 1.1 Gy/s, on TUNEL signals, caspase-3 activation and DNA double-strand breaks (DSBs) of the testes. Compared to those produced by the irradiation at 0.11 Gy/s, irradiation at 1.1 Gy/s produced higher levels of DSBs, TUNEL signals, and caspase-3 activation in the testes. Our study has provided the first evidence suggesting that dose-rate could be a significant factor in SR X-ray-induced tissue damage, which may establish a valuable base for utilizing this factor to manipulate the tissue damage in SR X-ray-based medical applications.

  3. The intrinsic collective X-ray spectrum of luminous high-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Sazonov, S.; Khabibullin, I.

    2017-06-01

    Using a sample of 200 luminous (LX, unabs > 1038 erg s-1, where LX, unabs is the unabsorbed 0.25-8 keV luminosity) high-mass X-ray binary (HMXB) candidates found with Chandra in 27 nearby galaxies, we have constructed the collective X-ray spectrum of HMXBs in the local Universe per unit star formation rate, corrected for observational biases associated with intrinsic diversity of HMXB spectra and X-ray absorption in the interstellar medium. This spectrum is well fit by a power law with a photon index Γ = 2.1 ± 0.1 and is dominated by ultraluminous X-ray sources with LX, unabs > 1039 erg s-1. Hard sources (those with the 0.25-2 to 0.25-8 keV flux ratio of <0.6) dominate above ˜2 keV, while soft and supersoft sources (with the flux ratios of 0.6-0.95 and >0.95, respectively) at lower energies. The derived spectrum probably represents the angle-integrated X-ray emission of the near- and supercritically accreting stellar mass black holes and neutron stars in the local Universe. It provides an important constraint on supercritical accretion models and can be used as a reference spectrum for calculations of the X-ray preheating of the Universe by the first generations of X-ray binaries.

  4. Computational Simulations of High Intensity X-Ray Matter Interaction

    SciTech Connect

    London, R A; Rionta, R; Tatchyn, R; Roessler, S

    2001-08-02

    Free electron lasers have the promise of producing extremely high-intensity short pulses of coherent, monochromatic radiation in the 1-10 keV energy range. For example, the Linac Coherent Light Source at Stanford is being designed to produce an output intensity of 2 x 10{sup 14} W/cm{sup 2} in a 230 fs pulse. These sources will open the door to many novel research studies. However, the intense x-ray pulses may damage the optical components necessary for studying and controlling the output. At the full output intensity, the dose to optical components at normal incidence ranges from 1-10 eV/atom for low-Z materials (Z < 14) at photon energies of 1 keV. It is important to have an understanding of the effects of such high doses in order to specify the composition, placement, and orientation of optical components, such as mirrors and monochromators. Doses of 10 eV/atom are certainly unacceptable since they will lead to ablation of the surface of the optical components. However, it is not precisely known what the damage thresholds are for the materials being considered for optical components for x-ray free electron lasers. In this paper, we present analytic estimates and computational simulations of the effects of high-intensity x-ray pulses on materials. We outline guidelines for the maximum dose to various materials and discuss implications for the design of optical components.

  5. High speed x-ray beam chopper

    DOEpatents

    McPherson, Armon; Mills, Dennis M.

    2002-01-01

    A fast, economical, and compact x-ray beam chopper with a small mass and a small moment of inertia whose rotation can be synchronized and phase locked to an electronic signal from an x-ray source and be monitored by a light beam is disclosed. X-ray bursts shorter than 2.5 microseconds have been produced with a jitter time of less than 3 ns.

  6. [Absorbed dose conversion factors obtained from X-ray spectra measured at water phantom surface].

    PubMed

    Aoki, Kiyoshi; Koyama, Masaki

    2005-03-20

    The absorbed dose conversion factor for X-rays at the water phantom surface has been obtained from the measured spectra. These measurements have been made at tube voltages of 60 kV to 120 kV and field sizes ranging from 5 x 5 cm(2) to 30 x 30 cm(2) with and without additional 2 mm aluminium filtration. A small silicon diode detector with little angular dependence was used for this measurement. The absorbed dose conversion factor obtained was 0.03-0.43% smaller than that obtained from the primary X-ray spectrum. The difference was large for high-voltage and heavily filtered X-rays. As field size increases, the conversion factor decreases, but the decrease is slight when field size exceeds 20 x 20 cm(2). The absorbed dose conversion factor obtained from the primary or surface X-ray spectrum is 0.4-1.8% larger than that obtained from the effective energy of primary X-rays. The difference is large in high-voltage X-rays and decreases slightly with increases in field size.

  7. SU-D-BRF-02: In Situ Verification of Radiation Therapy Dose Distributions From High-Energy X-Rays Using PET Imaging

    SciTech Connect

    Zhang, Q; Kai, L; Wang, X; Hua, B; Chui, L; Wang, Q; Ma, C

    2014-06-01

    Purpose: To study the possibility of in situ verification of radiation therapy dose distributions using PET imaging based on the activity distribution of 11C and 15O produced via photonuclear reactions in patient irradiated by 45MV x-rays. Methods: The method is based on the photonuclear reactions in the most elemental composition {sup 12}C and {sup 16}O in body tissues irradiated by bremsstrahlung photons with energies up to 45 MeV, resulting primarily in {sup 11}C and {sup 15}O, which are positron-emitting nuclei. The induced positron activity distributions were obtained with a PET scanner in the same room of a LA45 accelerator (Top Grade Medical, Beijing, China). The experiments were performed with a brain phantom using realistic treatment plans. The phantom was scanned at 20min and 2-5min after irradiation for {sup 11}C and {sup 15}, respectively. The interval between the two scans was 20 minutes. The activity distributions of {sup 11}C and {sup 15}O within the irradiated volume can be separated from each other because the half-life is 20min and 2min for {sup 11}C and {sup 15}O, respectively. Three x-ray energies were used including 10MV, 25MV and 45MV. The radiation dose ranged from 1.0Gy to 10.0Gy per treatment. Results: It was confirmed that no activity was detected at 10 MV beam energy, which was far below the energy threshold for photonuclear reactions. At 25 MV x-ray activity distribution images were observed on PET, which needed much higher radiation dose in order to obtain good quality. For 45 MV photon beams, good quality activation images were obtained with 2-3Gy radiation dose, which is the typical daily dose for radiation therapy. Conclusion: The activity distribution of {sup 15}O and {sup 11}C could be used to derive the dose distribution of 45MV x-rays at the regular daily dose level. This method can potentially be used to verify in situ dose distributions of patients treated on the LA45 accelerator.

  8. X-RAY POLARIZATION FROM HIGH-MASS X-RAY BINARIES

    SciTech Connect

    Kallman, T.; Blondin, J.

    2015-12-10

    X-ray astronomy allows study of objects that may be associated with compact objects, i.e., neutron stars or black holes, and also may contain strong magnetic fields. Such objects are categorically nonspherical, and likely noncircular when projected on the sky. Polarization allows study of such geometric effects, and X-ray polarimetry is likely to become feasible for a significant number of sources in the future. Potential targets for future X-ray polarization observations are the high-mass X-ray binaries (HMXBs), which consist of a compact object in orbit with an early-type star. In this paper we show that X-ray polarization from HMXBs has a distinct signature that depends on the source inclination and orbital phase. The presence of the X-ray source displaced from the star creates linear polarization even if the primary wind is spherically symmetric whenever the system is viewed away from conjunction. Direct X-rays dilute this polarization whenever the X-ray source is not eclipsed; at mid-eclipse the net polarization is expected to be small or zero if the wind is circularly symmetric around the line of centers. Resonance line scattering increases the scattering fraction, often by large factors, over the energy band spanned by resonance lines. Real winds are not expected to be spherically symmetric, or circularly symmetric around the line of centers, owing to the combined effects of the compact object gravity and ionization on the wind hydrodynamics. A sample calculation shows that this creates polarization fractions ranging up to tens of percent at mid-eclipse.

  9. X-Ray Polarization from High Mass X-Ray Binaries

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Dorodnitsyn, A.; Blondin, J.

    2015-01-01

    X-ray astronomy allows study of objects which may be associated with compact objects, i.e. neutron stars or black holes, and also may contain strong magnetic fields. Such objects are categorically non-spherical, and likely non-circular when projected on the sky. Polarization allows study of such geometric effects, and X-ray polarimetry is likely to become feasible for a significant number of sources in the future. A class of potential targets for future X-ray polarization observations is the high mass X-ray binaries (HMXBs), which consist of a compact object in orbit with an early type star. In this paper we show that X-ray polarization from HMXBs has a distinct signature which depends on the source inclination and orbital phase. The presence of the X-ray source displaced from the star creates linear polarization even if the primary wind is spherically symmetric whenever the system is viewed away from conjunction. Direct X-rays dilute this polarization whenever the X-ray source is not eclipsed; at mid-eclipse the net polarization is expected to be small or zero if the wind is circularly symmetric around the line of centers. Resonance line scattering increases the scattering fraction, often by large factors, over the energy band spanned by resonance lines. Real winds are not expected to be spherically symmetric, or circularly symmetric around the line of centers, owing to the combined effects of the compact object gravity and ionization on the wind hydrodynamics. A sample calculation shows that this creates polarization fractions ranging up to tens of percent at mid-eclipse.

  10. Editorial: Focus on X-ray Beams with High Coherence

    NASA Astrophysics Data System (ADS)

    Robinson, Ian; Gruebel, Gerhard; Mochrie, Simon

    2010-03-01

    This editorial serves as the preface to a special issue of New Journal of Physics, which collects together solicited papers on a common subject, x-ray beams with high coherence. We summarize the issue's content, and explain why there is so much current interest both in the sources themselves and in the applications to the study of the structure of matter and its fluctuations (both spontaneous and driven). As this collection demonstrates, the field brings together accelerator physics in the design of new sources, particle physics in the design of detectors, and chemical and materials scientists who make use of the coherent beams produced. Focus on X-ray Beams with High Coherence Contents Femtosecond pulse x-ray imaging with a large field of view B Pfau, C M Günther, S Schaffert, R Mitzner, B Siemer, S Roling, H Zacharias, O Kutz, I Rudolph, R Treusch and S Eisebitt The FERMI@Elettra free-electron-laser source for coherent x-ray physics: photon properties, beam transport system and applications E Allaria, C Callegari, D Cocco, W M Fawley, M Kiskinova, C Masciovecchio and F Parmigiani Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy Anders Madsen, Robert L Leheny, Hongyu Guo, Michael Sprung and Orsolya Czakkel The Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) Sébastien Boutet and Garth J Williams Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy Andrei Fluerasu, Pawel Kwasniewski, Chiara Caronna, Fanny Destremaut, Jean-Baptiste Salmon and Anders Madsen Exploration of crystal strains using coherent x-ray diffraction Wonsuk Cha, Sanghoon Song, Nak Cheon Jeong, Ross Harder, Kyung Byung Yoon, Ian K Robinson and Hyunjung Kim Coherence properties of the European XFEL G Geloni, E Saldin, L Samoylova, E Schneidmiller, H Sinn, Th Tschentscher and M Yurkov Fresnel coherent diffractive imaging: treatment and analysis of data G J

  11. Image quality based x-ray dose control in cardiac imaging

    NASA Astrophysics Data System (ADS)

    Davies, Andrew G.; Kengyelics, Stephen M.; Gislason-Lee, Amber J.

    2015-03-01

    An automated closed-loop dose control system balances the radiation dose delivered to patients and the quality of images produced in cardiac x-ray imaging systems. Using computer simulations, this study compared two designs of automatic x-ray dose control in terms of the radiation dose and quality of images produced. The first design, commonly in x-ray systems today, maintained a constant dose rate at the image receptor. The second design maintained a constant image quality in the output images. A computer model represented patients as a polymethylmetacrylate phantom (which has similar x-ray attenuation to soft tissue), containing a detail representative of an artery filled with contrast medium. The model predicted the entrance surface dose to the phantom and contrast to noise ratio of the detail as an index of image quality. Results showed that for the constant dose control system, phantom dose increased substantially with phantom size (x5 increase between 20 cm and 30 cm thick phantom), yet the image quality decreased by 43% for the same thicknesses. For the constant quality control, phantom dose increased at a greater rate with phantom thickness (>x10 increase between 20 cm and 30 cm phantom). Image quality based dose control could tailor the x-ray output to just achieve the quality required, which would reduce dose to patients where the current dose control produces images of too high quality. However, maintaining higher levels of image quality for large patients would result in a significant dose increase over current practice.

  12. The high energy X-ray universe

    PubMed Central

    Giacconi, Riccardo

    2010-01-01

    Since its beginning in the early 1960s, the field of X-ray astronomy has exploded, experiencing a ten-billion-fold increase in sensitivity, which brought it on par with the most advanced facilities at all wavelengths. I will briefly describe the revolutionary first discoveries prior to the launch of the Chandra and XMM-Newton X-ray observatories, present some of the current achievements, and offer some thoughts about the future of this field. PMID:20404148

  13. Reference dose levels for patients undergoing common diagnostic X-ray examinations in Irish hospitals.

    PubMed

    Johnston, D A; Brennan, P C

    2000-04-01

    Wide variations in patient dose for the same type of X-ray examination have been evident from various international dose surveys. Reference dose levels provide a framework to reduce this variability and aid in the optimization of radiation protection. The aim of this study was to establish, for the first time, a baseline for national reference dose levels in Ireland for four of the most common X-ray examinations: chest, abdomen, pelvis and lumbar spine. Measurements of entrance surface dose using thermoluminescent dosemeters (TLDs) for these four X-ray examinations were performed on 10 patients in each of 16 randomly selected hospitals. This represented 42% of Irish hospitals applicable to this study. Results have shown wide variation of mean hospital doses, from a factor of 3 for an anteroposterior lumbar spine to a factor of 23 for the chest X-ray. The difference between maximum and minimum individual patient dose values varied up to a factor of 75. Reasons for these dose variations were complex but, in general, low tube potential, high mAs and low filtration were associated with high-dose hospitals. This study also demonstrated lower reference dose levels of up to 40% when compared with those established by the UK and the Commission of the European Communities for four out of six projections. Only the chest X-ray exhibited a similar reference level to those established elsewhere. This emphasizes the importance of each country establishing its own reference dose levels that are appropriate to their own radiographic techniques and practices in order to optimize patient protection.

  14. Nanoparticle location and material dependent dose enhancement in X-ray radiation therapy

    PubMed Central

    Hossain, Mainul

    2012-01-01

    Nanoparticles of high atomic number (Z) materials can act as radiosensitizers to enhance radiation dose delivered to tumors. An analytical approach is used to calculate dose enhancements to tumor endothelial cells and their nuclei for a series of nanoparticles (bismuth, gold and platinum) located at different locations relative to nuclei by considering contributions from both photoelectrons and Auger electrons. The ratio of the dose delivered to cells with and without the nanoparticles is known as the dose enhancement factor (DEF). DEFs depend on material composition, size and location of nanoparticles with respect to the cell and the nucleus. Energy of irradiating X-ray beam affects X-ray absorption by nanoparticles and plays an important role in dose enhancements. For diagnostic X-ray sources, bismuth nanoparticles provide higher dose enhancements than gold and platinum nanoparticles for a given nanoparticle size, concentration and location. The highest DEFs are achieved for nanoparticles located closest to the nucleus where energy depositions from short range Auger electrons are maximum. With nanoparticles ranging in diameter between 2-400 nm, the dose enhancement increases with decrease in particle size. The results are useful in finding optimized conditions for nanoparticle enhanced X-ray radiation therapy of cancer. PMID:23393610

  15. Reabsorption of Soft X-Ray Emission at High X-Ray Free-Electron Laser Fluences

    NASA Astrophysics Data System (ADS)

    Schreck, Simon; Beye, Martin; Sellberg, Jonas A.; McQueen, Trevor; Laksmono, Hartawan; Kennedy, Brian; Eckert, Sebastian; Schlesinger, Daniel; Nordlund, Dennis; Ogasawara, Hirohito; Sierra, Raymond G.; Segtnan, Vegard H.; Kubicek, Katharina; Schlotter, William F.; Dakovski, Georgi L.; Moeller, Stefan P.; Bergmann, Uwe; Techert, Simone; Pettersson, Lars G. M.; Wernet, Philippe; Bogan, Michael J.; Harada, Yoshihisa; Nilsson, Anders; Föhlisch, Alexander

    2014-10-01

    We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime.

  16. Reabsorption of soft x-ray emission at high x-ray free-electron laser fluences.

    PubMed

    Schreck, Simon; Beye, Martin; Sellberg, Jonas A; McQueen, Trevor; Laksmono, Hartawan; Kennedy, Brian; Eckert, Sebastian; Schlesinger, Daniel; Nordlund, Dennis; Ogasawara, Hirohito; Sierra, Raymond G; Segtnan, Vegard H; Kubicek, Katharina; Schlotter, William F; Dakovski, Georgi L; Moeller, Stefan P; Bergmann, Uwe; Techert, Simone; Pettersson, Lars G M; Wernet, Philippe; Bogan, Michael J; Harada, Yoshihisa; Nilsson, Anders; Föhlisch, Alexander

    2014-10-10

    We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime.

  17. High resolution, large area, high energy x-ray tomography

    SciTech Connect

    Trebes, J.E.; Dolan, K.W.; Haddad, W.S.; Haskins, J.J.; Lerche, R.A.; Logan, C.M.; Perkins, D.E.; Schneberk, D.J.; Rikard, R.D.

    1997-08-01

    An x-ray tomography system is being developed for high resolution inspection of large objects. The goal is to achieve 25 micron resolution over object sizes that are tens of centimeters in extent. Typical objects will be metal in composition and therefore high energy, few MeV x-rays will be required. A proof-of-principle system with a limited field of view has been developed. Preliminary results are presented.

  18. High Resolution X-ray Imaging

    NASA Technical Reports Server (NTRS)

    Cash, Webster

    2002-01-01

    NAG5-5020 covered a period of 7.5 years during which a great deal of progress was made in x-ray optical techniques under this grant. We survived peer review numerous times during the effort to keep the grant going. In 1994, when the grant started we were actively pursuing the application of spherical mirrors to improving x-ray telescopes. We had found that x-ray detectors were becoming rapidly more sophisticated and affordable, but that x-ray telescopes were only being improved through the intense application of money within the AXAF program. Clearly new techniques for the future were needed. We were successful in developing and testing at the HELSTF facility in New Mexico a four reflection coma-corrected telescope made from spheres. We were able to demonstrate 0.3 arcsecond resolution, almost to the diffraction limit of the system. The community as a whole was, at that time, not particularly interested in looking past AXAF (Chandra) and the effort needed to evolve. Since we had reached the diffraction limit using non-Wolter optics we then decided to see if we could build an x-ray interferometer in the laboratory. In the lab the potential for improved resolution was substantial. If synthetic aperture telescopes could be built in space, then orders of magnitude improvement would become feasible. In 1998 NASA, under the direction of Dr. Nick White of Goddard, started a study to assess the potential and feasibility of x-ray interferometry in space. My work became of central interest to the committee because it indicated that such was possible. In early 1999 we had the breakthrough that allowed us build a practical interferometer. By using flats and hooking up with the Marshall Space Flight Center facilities we were able to demonstrate fringes at 1.25keV on a one millimeter baseline. This actual laboratory demonstration provided the solid proof of concept that NASA needed.

  19. Multiwavelength Anomalous Diffraction at High X-Ray Intensity

    NASA Astrophysics Data System (ADS)

    Son, Sang-Kil; Chapman, Henry N.; Santra, Robin

    2011-11-01

    The multiwavelength anomalous diffraction (MAD) method is used to determine phase information in x-ray crystallography by employing anomalous scattering from heavy atoms. X-ray free-electron lasers (FELs) show promise for revealing the structure of single molecules or nanocrystals, but the phase problem remains largely unsolved. Because of the ultrabrightness of x-ray FEL, samples experience severe electronic radiation damage, especially to heavy atoms, which hinders direct implementation of MAD with x-ray FELs. Here, we propose a generalized version of MAD phasing at high x-ray intensity. We demonstrate the existence of a Karle-Hendrickson-type equation in the high-intensity regime and calculate relevant coefficients with detailed electronic damage dynamics of heavy atoms. The present method offers a potential for ab initio structural determination in femtosecond x-ray nanocrystallography.

  20. Multiwavelength anomalous diffraction at high x-ray intensity.

    PubMed

    Son, Sang-Kil; Chapman, Henry N; Santra, Robin

    2011-11-18

    The multiwavelength anomalous diffraction (MAD) method is used to determine phase information in x-ray crystallography by employing anomalous scattering from heavy atoms. X-ray free-electron lasers (FELs) show promise for revealing the structure of single molecules or nanocrystals, but the phase problem remains largely unsolved. Because of the ultrabrightness of x-ray FEL, samples experience severe electronic radiation damage, especially to heavy atoms, which hinders direct implementation of MAD with x-ray FELs. Here, we propose a generalized version of MAD phasing at high x-ray intensity. We demonstrate the existence of a Karle-Hendrickson-type equation in the high-intensity regime and calculate relevant coefficients with detailed electronic damage dynamics of heavy atoms. The present method offers a potential for ab initio structural determination in femtosecond x-ray nanocrystallography.

  1. High Resolution X-ray Imaging

    NASA Technical Reports Server (NTRS)

    Cash, Webster

    2002-01-01

    NAG5-5020 covered a period of 7.5 years during which a great deal of progress was made in x-ray optical techniques under this grant. We survived peer review numerous times during the effort to keep the grant going. In 1994, when the grant started we were actively pursuing the application of spherical mirrors to improving x-ray telescopes. We had found that x-ray detectors were becoming rapidly more sophisticated and affordable, but that x-ray telescopes were only being improved through the intense application of money within the AXAF program. Clearly new techniques for the future were needed. We were successful in developing and testing at the HELSTF facility in New Mexico a four reflection coma-corrected telescope made from spheres. We were able to demonstrate 0.3 arcsecond resolution, almost to the diffraction limit of the system. The community as a whole was, at that time, not particularly interested in looking past AXAF (Chandra) and the effort needed to evolve. Since we had reached the diffraction limit using non-Wolter optics we then decided to see if we could build an x-ray interferometer in the laboratory. In the lab the potential for improved resolution was substantial. If synthetic aperture telescopes could be built in space, then orders of magnitude improvement would become feasible. In 1998 NASA, under the direction of Dr Nick White of Goddard, started a study to assess the potential and feasibility of x-ray interferometry in space. My work became of central interest to the committee because it indicated that such was possible. In early 1999 we had the breakthrough that allowed us build a practical interferometer. By using flats and hooking up with the Marshall Space Flight Center facilities we were able to demonstrate fringes at 1.25keV on a one millimeter baseline. This actual laboratory demonstration provided the solid proof of concept that NASA needed. As the year progressed the future of x-ray astronomy jelled around the Maxim program. Maxim is a

  2. [High-Performance Active Pixel X-Ray Sensors for X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Bautz, Mark; Suntharalingam, Vyshnavi

    2005-01-01

    The subject grants support development of High-Performance Active Pixel Sensors for X-ray Astronomy at the Massachusetts Institute of Technology (MIT) Center for Space Research and at MIT's Lincoln Laboratory. This memo reports our progress in the second year of the project, from April, 2004 through the present.

  3. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism

    DOE PAGES

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; ...

    2015-11-03

    Here, we demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantummore » trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.« less

  4. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

    PubMed

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

    2015-11-17

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

  5. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism

    PubMed Central

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D.; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J.; Mancuso, Christopher A.; Hogle, Craig W.; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L.; Dorney, Kevin M.; Chen, Cong; Shpyrko, Oleg G.; Fullerton, Eric E.; Cohen, Oren; Oppeneer, Peter M.; Milošević, Dejan B.; Becker, Andreas; Jaroń-Becker, Agnieszka A.; Popmintchev, Tenio; Murnane, Margaret M.; Kapteyn, Henry C.

    2015-01-01

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform. PMID:26534992

  6. Development of high resolution imaging detectors for x ray astronomy

    NASA Technical Reports Server (NTRS)

    Murray, S. S.; Schwartz, D. A.

    1992-01-01

    This final report summarizes our past activities and discusses the work performed over the period of 1 April 1990 through 1 April 1991 on x-ray optics, soft x-ray (0.1 - 10 KeV) imaging detectors, and hard x-ray (10 - 300 KeV) imaging detectors. If microchannel plates (MCPs) can be used to focus x-rays with a high efficiency and good angular resolution, they will revolutionize the field of x-ray optics. An x-ray image of a point source through an array of square MCP pores compared favorably with our ray tracing model for the MCP. Initial analysis of this image demonstrates the feasibility of MCPs for soft x-rays. Our work continues with optimizing the performance of our soft x-ray MCP imaging detectors. This work involves readout technology that should provide improved MCP readout devices (thin film crossed grid, curved, and resistive sheets), defect removal in MCPs, and photocathode optimization. In the area of hard x-ray detector development we have developed two different techniques for producing a CsI photocathode thickness of 10 to 100 microns, such that it is thick enough to absorb the high energy x-rays and still allow the photoelectrons to escape to the top MCP of a modified soft x-ray imaging detector. The methods involve vacuum depositing a thick film of CsI on a strong back, and producing a converter device that takes the place of the photocathode.

  7. High energy resolution off-resonant X-ray spectroscopy

    SciTech Connect

    Wojciech, Blachucki

    2015-10-16

    This work treats of the high energy resolution off-resonant X-ray spectroscopy (HEROS) method of determining the density of unoccupied electronic states in the vicinity of the absorption edge. HEROS is an alternative to the existing X-ray absorption spectroscopy (XAS) methods and opens the way for new studies not achievable before.

  8. Medical x-ray exposure doses as contaminants of atomic bomb doses

    SciTech Connect

    Yamamoto, O.; Antoku, S.; Russell, W.J.; Fujita, S.; Sawada, S.

    1988-03-01

    Since 1967 at the times of their biennial ABCC/RERF radiological examinations, all Adult Health Study (AHS) subjects have been interviewed to determine the exposures to medical x-rays they experienced in institutions other than RERF in order to estimate the numbers of examinations and corresponding doses which they received. These data have been stored on computer tapes together with the doses these subjects received during their radiological examinations in the ABCC/RERF Department of Radiology. Thus, their medical x-ray doses are available along with their atomic bomb doses (tentative 1965 doses revised, T65DR) for assessment of the role of ionizing radiation in the development of diseases. The medical x-ray doses incurred at RERF were assessed by means of phantom dosimetry. Those at other institutions were determined using phantom dosimetry data and results of surveys for trends in radiological examinations in Hiroshima and Nagasaki. By the end of 1982, the average medical x-ray doses to the active bone marrow were 12.04 mGy for A-bomb exposed groups and 8.92 mGy for control groups (not-in-cities); to the male gonads, 2.26 mGy and 1.89 mGy, respectively; and to the female gonads, 17.45 mGy and 12.58 mGy, respectively. Results for Hiroshima and Nagasaki were similar. The main impact of medical x-ray doses was in the lowest T65DR group. Medical x-ray active bone marrow doses ranged from 0.05-500% (mean, 35%) of A-bomb doses in the 10-99 mGy T65DR group. In the 100-999 mGy T65DR group, medical x-ray active bone marrow doses ranged from 0.005-50% (mean, 5%) of their T65DR. In the greater than 1000-mGy T65DR group, medical x-ray exposures were proportionally less. Medical x-ray exposures produced smaller doses to the gonads of males than to those of the females.

  9. Advanced High Brilliance X-Ray Source

    NASA Technical Reports Server (NTRS)

    Gibson, Walter M.

    1998-01-01

    The possibility to dramatically increase the efficiency of laboratory based protein structure measurements through the use of polycapillary X-ray optics was investigated. This project initiated April 1, 1993 and concluded December 31, 1996 (including a no cost extension from June 31, 1996). This is a final report of the project. The basis for the project is the ability to collect X-rays from divergent electron bombardment laboratory X-ray sources and redirect them into quasiparallel or convergent (focused) beams. For example, a 0.1 radian (approx. 6 deg) portion of a divergent beam collected by a polycapillary collimator and transformed into a quasiparallel beam of 3 millradian (0.2 deg) could give a gain of 6(exp 2)/0.2(exp 2) x T for the intensity of a diffracted beam from a crystal with a 0.2 deg diffraction width. T is the transmission efficiency of the polycapillary diffraction optic, and for T=0.5, the gain would be 36/0.04 x O.5=45. In practice, the effective collection angle will depend on the source spot size, the input focal length of the optic (usually limited by the source spot-to-window distance on the x-ray tube) and the size of the crystal relative to the output diameter of the optic. The transmission efficiency, T, depends on the characteristics (fractional open area, surface roughness, shape and channel diameter) of the polycapillary optic and is typically in the range 0.2-0.4. These effects could substantially reduce the expected efficiency gain. During the course of this study, the possibility to use a weakly focused beam (0.5 deg convergence) was suggested which could give an additional 10-20 X efficiency gain for small samples . Weakly focused beams from double focusing mirrors are frequently used for macromolecular crystallography studies. Furthermore the crystals are typically oscillated by as much as 2 deg during each X-ray exposure in order to increase the reciprocal space (number of crystal planes) sampled and use of a slightly convergent

  10. Measurements of X-ray doses and spectra produced by picosecond laser-irradiated solid targets.

    PubMed

    Yang, Bo; Qiu, Rui; Yu, Minghai; Jiao, Jinlong; Lu, Wei; Yan, Yonghong; Zhang, Bo; Zhang, Zhimeng; Zhou, Weimin; Li, Junli; Zhang, Hui

    2017-05-01

    Experiments have shown that high-intensity laser interaction with a solid target can generate significant X-ray doses. This study was conducted to determine the X-ray doses and spectra produced for picosecond laser-irradiated solid targets. The photon doses and X-ray spectra in the laser forward and side directions were measured using an XG III ps 300 TW laser system. For laser intensities of 7×10(18)-4×10(19)W/cm(2), the maximum photon dose was 16.8 mSv at 50cm with a laser energy of ~153J on a 1-mm Ta target. The photon dose in the forward direction increased more significantly with increasing laser intensity than that in the side direction. For photon energies >300keV, the X-ray spectrum can be fit with an effective temperature distribution of the exponential form, dN/dE = k× exp(-E/Tx). The X-ray temperature Tx increased with the laser intensity in the forward direction with values of 0.46-0.75MeV. Tx was less strongly correlated with the laser intensity in the side direction with values of 0.29-0.32MeV. The escaping electron spectrum was also measured. The measured electron temperature was correlated with the electron temperature predicted by the ponderomotive law. The observations in this experiment were also investigated numerically. A good agreement was observed between the experimental and simulation results.

  11. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, Eric H.; Legros, Mark; Madden, Norm W.; Goulding, Fred; Landis, Don

    1998-01-01

    A broad bandwidth high resolution x-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces x-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available x-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for x-ray microanalysis or in research applications such as laboratory and astrophysical x-ray and particle spectroscopy.

  12. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, E.H.; Legros, M.; Madden, N.W.; Goulding, F.; Landis, D.

    1998-07-07

    A broad bandwidth high resolution X-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces X-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available X-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for X-ray microanalysis or in research applications such as laboratory and astrophysical X-ray and particle spectroscopy. 6 figs.

  13. Miniaturized High-Speed Modulated X-Ray Source

    NASA Technical Reports Server (NTRS)

    Gendreau, Keith C. (Inventor); Arzoumanian, Zaven (Inventor); Kenyon, Steven J. (Inventor); Spartana, Nick Salvatore (Inventor)

    2015-01-01

    A miniaturized high-speed modulated X-ray source (MXS) device and a method for rapidly and arbitrarily varying with time the output X-ray photon intensities and energies. The MXS device includes an ultraviolet emitter that emits ultraviolet light, a photocathode operably coupled to the ultraviolet light-emitting diode that emits electrons, an electron multiplier operably coupled to the photocathode that multiplies incident electrons, and an anode operably coupled to the electron multiplier that is configured to produce X-rays. The method for modulating MXS includes modulating an intensity of an ultraviolet emitter to emit ultraviolet light, generating electrons in response to the ultraviolet light, multiplying the electrons to become more electrons, and producing X-rays by an anode that includes a target material configured to produce X-rays in response to impact of the more electrons.

  14. A ROSAT high resolution x ray image of NGC 1068

    NASA Technical Reports Server (NTRS)

    Halpern, J.

    1993-01-01

    The soft x ray properties of the Seyfert 2 galaxy NGC 1068 are a crucial test of the 'hidden Seyfert 1' model. It is important to determine whether the soft x rays come from the nucleus, or from a number of other possible regions in the circumnuclear starburst disk. We present preliminary results of a ROSAT HRI observation of NGC 1068 obtained during the verification phase. The fraction of x rays that can be attributed to the nucleus is about 70 percent so the 'soft x ray problem' remains. There is also significant diffuse x ray flux on arcminute scales, which may be related to the 'diffuse ionized medium' seen in optical emission lines, and the highly ionized Fe K(alpha) emission seen by BBXRT.

  15. X-ray characterization of CMOS imaging detector with high resolution for fluoroscopic imaging application

    NASA Astrophysics Data System (ADS)

    Cha, Bo Kyung; Kim, Cho Rong; Jeon, Seongchae; Kim, Ryun Kyung; Seo, Chang-Woo; Yang, Keedong; Heo, Duchang; Lee, Tae-Bum; Shin, Min-Seok; Kim, Jong-Boo; Kwon, Oh-Kyung

    2013-12-01

    This paper introduces complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS)-based X-ray imaging detectors with high spatial resolution for medical imaging application. In this study, our proposed X-ray CMOS imaging sensor has been fabricated by using a 0.35 μm 1 Poly 4 Metal CMOS process. The pixel size is 100 μm×100 μm and the pixel array format is 24×96 pixels, which provide a field-of-view (FOV) of 9.6 mm×2.4 mm. The 14.3-bit extend counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. Both thallium-doped CsI (CsI:Tl) and Gd2O2S:Tb scintillator screens were used as converters for incident X-rays to visible light photons. The optical property and X-ray imaging characterization such as X-ray to light response as a function of incident X-ray exposure dose, spatial resolution and X-ray images of objects were measured under different X-ray energy conditions. The measured results suggest that our developed CMOS-based X-ray imaging detector has the potential for fluoroscopic imaging and cone-beam computed tomography (CBCT) imaging applications.

  16. HIgh Rate X-ray Fluorescence Detector

    SciTech Connect

    Grudberg, Peter Matthew

    2013-04-30

    The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with

  17. Development of high throughput X-ray telescopes for X-ray imaging and dispersive spectrometers

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.

    1986-01-01

    During the past year the technical approach to the realization of a high throughput Kirkpatrick-Baez X-ray mirror became better defined in terms of construction methodology and factors which affect maximum size. More progress was made than anticipated in the area of automatic figure formation. However, effort to improve the resolution of float glass by simple techniques were not successful. Mirror development, spectroscopy, all sky telescope, and explorer concept studies are discussed.

  18. High spatial resolution x-ray spectroscopy with the XM-1 X-ray microscope

    NASA Astrophysics Data System (ADS)

    Johnson, Lewis E.; Denbeaux, Greg; Meyer-Ilse, Werner

    2000-06-01

    The XM-1 x-ray microscope was built to obtain high-resolution transmission images from a wide variety of thick (< 10 micron) samples. Modeled after a "conventional" full-field microscope, XM-1 makes use of zone plates (ZP) for the condenser and objective elements. The XM-1 x-ray microscope has been shown to have a spatial resolution of 36 nm by doing a 10%-90% edge scan across a knife edge. Moreover, the condenser ZP and pinhole combination yields good spectral resolution to λ/Δλ of 700. We have shown that with this energy resolution we can distinguish between different elements and some chemical states. We can see spectra with adequate signal to noise even for individual 36nm pixels. With these capabilities, we are beginning work on various experiments in which we will distinguish different chemical species of specific elements within a sample.

  19. Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Petre, R.; Mushotzky, R. F.; Krolik, J. H.; Holt, S. S.

    1983-01-01

    Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The averager spectral index alpha is 0.66 + or - .36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N(H) 10 to the 22nd power/sq cm; the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0175-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium.

  20. Resonant Auger Effect at High X-Ray Intensity

    SciTech Connect

    Rohringer, N; Santra, R

    2008-03-27

    The resonant Auger effect of atomic neon exposed to high-intensity x-ray radiation in resonance with the 1s {yields} 3p transition is discussed. High intensity here means that the x-ray peak intensity is sufficient ({approx} 10{sup 18} W/cm{sup 2}) to induce Rabi oscillations between the neon ground state and the 1s{sup -1}3p ({sup 1}P) state within the relaxation lifetime of the inner-shell vacancy. For the numerical analysis presented, an effective two-level model, including a description of the resonant Auger decay process, is employed. Both coherent and chaotic x-ray pulses are treated. The latter are used to simulate radiation from x-ray free-electron lasers based on the principle of self-amplified spontaneous emission. Observing x-ray-driven atomic population dynamics in the time domain is challenging for chaotic pulse ensembles. A more practical option for experiments using x-ray free-electron lasers is to measure the line profiles in the kinetic energy distribution of the resonant Auger electron. This provides information on both atomic population dynamics and x-ray pulse properties.

  1. Construction of an ionization chamber for the measurement of dose of low energy x-rays

    SciTech Connect

    Perez, Y. B. Alcantara; Jimenez, F. J. Ramirez

    2008-08-11

    We designed and constructed the prototype of an ionization chamber to measure the dose of an X-ray tube with Molybdenum anode. This X-ray tube is located in the Physics department at CINVESTAV and is used for medical physics purposes in the imaging area. The ionization chamber is designed to measure doses on biological samples exposed to X-rays and will be applied in radiation protection studies.

  2. Compton spectra of atoms at high x-ray intensity

    NASA Astrophysics Data System (ADS)

    Son, Sang-Kil; Geffert, Otfried; Santra, Robin

    2017-03-01

    Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL–matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

  3. X-ray emission from high temperature plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.

    1977-01-01

    The physical processes occurring in plasma focus devices were investigated with particular emphasis on X-ray emission. Topics discussed include: trajectories of high energy electrons; detection of ion trajectories; spatial distribution of neutron emission; space and time resolved emission of hard X-rays from a plasma focus; the staged plasma focus as a variation of the hypocloidal pinch; formation of current sheets in a staged plasma focus; and X-ray and neutron emission from a staged plasma focus. The possibility of operating dense plasma-focus type devices in multiple arrays beyond the scaling law for a single gun is discussed.

  4. X-ray dose reduction by adaptive source equalization and electronic region-of-interest control

    NASA Astrophysics Data System (ADS)

    Burion, Steve; Sandman, Anne; Bechtel, Kate; Solomon, Edward; Funk, Tobias

    2011-03-01

    Radiation dose is particularly a concern in pediatric cardiac fluoroscopy procedures, which account for 7% of all cardiac procedures performed. The Scanning-Beam Digital X-ray (SBDX) fluoroscopy system has already demonstrated reduced dose in adult patients owing to its high-DQE photon-counting detector, reduced detected scatter, and the elimination of the anti-scatter grid. Here we show that the unique flexible illumination platform of the SBDX system will enable further dose area product reduction, which we are currently developing for pediatric patients, but which will ultimately benefit all patients. The SBDX system has a small-area detector array and a large-area X-ray source with up to 9,000 individually-controlled X-ray focal spots. Each focal spot illuminates a small fraction of the full field of view. To acquire a frame, each focal spot is activated for a fixed number of 1-microsecond periods. Dose reduction is made possible by reducing the number of activations of some of the X-ray focal spots during each frame time. This can be done dynamically to reduce the exposure in areas of low patient attenuation, such as the lung field. This spatially-adaptive illumination also reduces the dynamic range in the full image, which is visually pleasing. Dose can also be reduced by the user selecting a region of interest (ROI) where full image quality is to be maintained. Outside the ROI, the number of activations of each X-ray focal spot is reduced and the image gain is correspondingly increased to maintain consistent image brightness. Dose reduction is dependent on the size of the ROI and the desired image quality outside the ROI. We have developed simulation software that is based on real data and can simulate the performance of the equalization and ROI filtration. This software represents a first step toward real-time implementation of these dose-reduction methods. Our simulations have shown that dose area product reductions of 40% are possible using equalization

  5. X-ray emission from high temperature plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.

    1976-01-01

    The physical processes occurring in plasma focus devices were studied. These devices produce dense high temperature plasmas, which emit X rays of hundreds of KeV energy and one to ten billion neutrons per pulse. The processes in the devices seem related to solar flare phenomena, and would also be of interest for controlled thermonuclear fusion applications. The high intensity, short duration bursts of X rays and neutrons could also possibly be used for pumping nuclear lasers.

  6. A New High Heat Load X-Ray Tube

    NASA Astrophysics Data System (ADS)

    Iversen, Arthur H.; Whitaker, Stephen

    1984-06-01

    A new class of internally liquid cooled rotating anode x-ray tubes capable of high average and high peak power is proposed for medical applications. The principles of this new tube design are discussed and estimated performance levels are compared to levels attainable with conventional solid rotating anode medical x-ray tubes and with existing liquid cooled rotating anode x-ray tubes. Performance improvements of the proposed tube include essentially unlimited anode Heat Unit loading, and anode cooling rates, peak and continuous, that are more than an order of magnitude greater than is currently available. The new tube would enable present high average power demanding procedures such as CT and digital and conventional vascular angiography to be performed more efficiently and with higher patient throughput. New imaging techniques requiring even higher average power levels such as energy subtraction, slit scanning, x-ray spectrum optimization and special scatter rejection methods would become more clinically practical.

  7. Low dose hard x-ray contact microscopy assisted by a photoelectric conversion layer

    SciTech Connect

    Gomella, Andrew; Martin, Eric W.; Lynch, Susanna K.; Wen, Han; Morgan, Nicole Y.

    2013-04-15

    Hard x-ray contact microscopy provides images of dense samples at resolutions of tens of nanometers. However, the required beam intensity can only be delivered by synchrotron sources. We report on the use of a gold photoelectric conversion layer to lower the exposure dose by a factor of 40 to 50, allowing hard x-ray contact microscopy to be performed with a compact x-ray tube. We demonstrate the method in imaging the transmission pattern of a type of hard x-ray grating that cannot be fitted into conventional x-ray microscopes due to its size and shape. Generally the method is easy to implement and can record images of samples in the hard x-ray region over a large area in a single exposure, without some of the geometric constraints associated with x-ray microscopes based on zone-plate or other magnifying optics.

  8. Low dose hard x-ray contact microscopy assisted by a photoelectric conversion layer

    PubMed Central

    Gomella, Andrew; Martin, Eric W.; Lynch, Susanna K.; Morgan, Nicole Y.; Wen, Han

    2013-01-01

    Hard x-ray contact microscopy provides images of dense samples at resolutions of tens of nanometers. However, the required beam intensity can only be delivered by synchrotron sources. We report on the use of a gold photoelectric conversion layer to lower the exposure dose by a factor of 40 to 50, allowing hard x-ray contact microscopy to be performed with a compact x-ray tube. We demonstrate the method in imaging the transmission pattern of a type of hard x-ray grating that cannot be fitted into conventional x-ray microscopes due to its size and shape. Generally the method is easy to implement and can record images of samples in the hard x-ray region over a large area in a single exposure, without some of the geometric constraints associated with x-ray microscopes based on zone-plate or other magnifying optics. PMID:23837131

  9. X-ray Methods in High-Intensity Discharges and Metal-Halide Lamps: X-ray Induced Fluorescence

    SciTech Connect

    Curry, John J.; Lapatovich, Walter P.; Henins, Albert

    2011-12-09

    We describe the use of x-ray induced fluorescence to study metal-halide high-intensity discharge lamps and to measure equilibrium vapor pressures of metal-halide salts. The physical principles of metal-halide lamps, relevant aspects of x-ray-atom interactions, the experimental method using synchrotron radiation, and x-ray induced fluorescence measurements relevant to metal-halide lamps are covered.

  10. Diagnostic Spectrometers for High Energy Density X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Hudson, L. T.; Henins, A.; Seely, J. F.; Holland, G. E.

    2007-08-01

    A new generation of advanced laser, accelerator, and plasma confinement devices are emerging that are producing extreme states of light and matter that are unprecedented for laboratory study. Examples of such sources that will produce laboratory x-ray emissions with unprecedented characteristics include megajoule-class and ultrafast, ultraintense petawatt laser-produced plasmas; tabletop high-harmonic-generation x-ray sources; high-brightness zeta-pinch and magnetically confined plasma sources; and coherent x-ray free electron lasers and compact inverse-Compton x-ray sources. Characterizing the spectra, time structure, and intensity of x rays emitted by these and other novel sources is critical to assessing system performance and progress as well as pursuing the new and unpredictable physical interactions of interest to basic and applied high-energy-density (HED) science. As these technologies mature, increased emphasis will need to be placed on advanced diagnostic instrumentation and metrology, standard reference data, absolute calibrations and traceability of results. We are actively designing, fabricating, and fielding wavelength-calibrated x-ray spectrometers that have been employed to register spectra from a variety of exotic x-ray sources (electron beam ion trap, electron cyclotron resonance ion source, terawatt pulsed-power-driven accelerator, laser-produced plasmas). These instruments employ a variety of curved-crystal optics, detector technologies, and data acquisition strategies. In anticipation of the trends mentioned above, this paper will focus primarily on optical designs that can accommodate the high background signals produced in HED experiments while also registering their high-energy spectral emissions. In particular, we review the results of recent laboratory testing that explores off-Rowland circle imaging in an effort to reclaim the instrumental resolving power that is increasingly elusive at higher energies when using wavelength

  11. The High Energy X-ray Probe (HEX-P)

    NASA Astrophysics Data System (ADS)

    Harrison, Fiona; HEX-P Collaboration Collaboration

    2017-01-01

    The High-Energy X-ray Probe (HEX-P) is a probe-class ( 500M) next-generation high-energy X-ray observatory with broadband (2-200 keV) response and 40 times the sensitivity of any previous mis-sion in the 10-80 keV band, and >500 times the sensitivity of any previous mission in the 80-200 keV band. Intended to launch contemporaneously with Athena, HEX-P will provide fundamental new discoveries that range from resolving 90% of the X-ray background at its peak, to measuring the cosmic evolution of black hole spin, to studying faint X-ray populations in nearby galaxies. Based on NuSTAR heritage, HEX-P requires only modest technology development, and could easily be executed within the next decade.

  12. Whole-body CT with high heat-capacity X-ray tube and automated tube current modulation--effect of tube current limitation on contrast enhancement, image quality and radiation dose.

    PubMed

    Kanematsu, Masayuki; Kondo, Hiroshi; Miyoshi, Toshiharu; Goshima, Satoshi; Noda, Yoshifumi; Tanahashi, Yukichi; Bae, Kyongtae T

    2015-05-01

    To evaluate the effect of tube current limitation on contrast enhancement, image quality, and radiation dose in whole-body 64-detector CT with a high heat-capacity X-ray tube and automated tube current modulation. One hundred eighteen patients were randomized into three whole-body CT protocols: tube current limitation at 210 mA, 450 mA, and no limitation. Signal-to-noise ratio (SNR), dose-length product (DLP), estimated effective dose (ED), and image quality were assessed. Mean SNR of aorta was comparable among protocols, but that of liver was somewhat lower in 210-mA than in 450-mA and no-limitation protocols (p<0.05). Mean DLP with 210-mA (533.8 mGy cm) was reduced by 31% from that with 450-mA (768.4 mGy cm) and by 38% from that with no-limitation protocol (861.3 mGy cm), respectively. Image quality was slightly degraded (p<0.017) with 210 mA relative to the others in thorax and pelvis, but no difference was found in diagnostic acceptability. For whole-body CT using multidetector CT mounted with a high heat-capacity X-ray tube, an appropriate tube current limitation setting may help reduce excessive radiation dose without significant compromise in diagnostic acceptability. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. The Radiation Dose Determination of the Pulsed X-ray Source

    NASA Astrophysics Data System (ADS)

    Miloichikova, I.; Stuchebrov, S.; Zhaksybayeva, G.; Wagner, A.

    2014-10-01

    In this paper the radiation dose measurement technique of the pulsed X-ray source RAP-160-5 is described. The dose rate measurement results from the pulsed X-ray beams at the different distance between the pulsed X-ray source focus and the detector obtained with the help of the thermoluminescent detectors DTL-02, the universal dosimeter UNIDOS E equipped with the plane-parallel ionization chamber type 23342, the dosimeter-radiometer DKS-96 and the radiation dosimeter AT 1123 are demonstrated. The recommendations for the dosimetry measurements of the pulsed X-ray generator RAP-160-5 under different radiation conditions are proposed.

  14. High performance x-ray anti-scatter grid

    DOEpatents

    Logan, C.M.

    1995-05-23

    Disclosed are an x-ray anti-scatter grid for x-ray imaging, particularly for screening mammography, and method for fabricating same, x-rays incident along a direct path pass through a grid composed of a plurality of parallel or crossed openings, microchannels, grooves, or slots etched in a substrate, such as silicon, having the walls of the microchannels or slots coated with a high opacity material, such as gold, while x-rays incident at angels with respect to the slots of the grid, arising from scatter, are blocked. The thickness of the substrate is dependent on the specific application of the grid, whereby a substrate of the grid for mammography would be thinner than one for chest radiology. Instead of coating the walls of the slots, such could be filed with an appropriate liquid, such as mercury. 4 Figs.

  15. Towards high-resolution ptychographic x-ray diffraction microscopy

    SciTech Connect

    Takahashi, Yukio; Suzuki, Akihiro; Yamauchi, Kazuto; Zettsu, Nobuyuki; Kohmura, Yoshiki; Ishikawa, Tetsuya; Senba, Yasunori; Ohashi, Haruhiko

    2011-06-01

    Ptychographic x-ray diffraction microscopy is a lensless imaging technique with a large field of view and high spatial resolution, which is also useful for characterizing the wavefront of an x-ray probe. The performance of this technique is degraded by positioning errors due to the drift between the sample and illumination optics. We propose an experimental approach for correcting the positioning errors and demonstrate success by two-dimensionally reconstructing both the wavefront of the focused x-ray beam and the complex transmissivity of the weakly scattering objects at the pixel resolution of better than 10 nm in the field of view larger than 5 {mu}m. This method is applicable to not only the observation of organelles inside cells or nano-mesoscale structures buried within bulk materials but also the characterization of probe for single-shot imaging with x-ray free electron lasers.

  16. High performance x-ray anti-scatter grid

    DOEpatents

    Logan, Clinton M.

    1995-01-01

    An x-ray anti-scatter grid for x-ray imaging, particularly for screening mammography, and method for fabricating same, x-rays incident along a direct path pass through a grid composed of a plurality of parallel or crossed openings, microchannels, grooves, or slots etched in a substrate, such as silicon, having the walls of the microchannels or slots coated with a high opacity material, such as gold, while x-rays incident at angels with respect to the slots of the grid, arising from scatter, are blocked. The thickness of the substrate is dependent on the specific application of the grid, whereby a substrate of the grid for mammography would be thinner than one for chest radiology. Instead of coating the walls of the slots, such could be filed with an appropriate liquid, such as mercury.

  17. Progress in high-resolution x-ray holographic microscopy

    SciTech Connect

    Jacobsen, C.; Kirz, J.; Howells, M.; McQuaid, K.; Rothman, S.; Feder, R.; Sayre, D.

    1987-07-01

    Among the various types of x-ray microscopes that have been demonstrated, the holographic microscope has had the largest gap between promise and performance. The difficulties of fabricating x-ray optical elements have led some to view holography as the most attractive method for obtaining the ultimate in high resolution x-ray micrographs; however, we know of no investigations prior to 1987 that clearly demonstrated submicron resolution in reconstructed images. Previous efforts suffered from problems such as limited resolution and dynamic range in the recording media, low coherent x-ray flux, and aberrations and diffraction limits in visible light reconstruction. We have addressed the recording limitations through the use of an undulator x-ray source and high-resolution photoresist recording media. For improved results in the readout and reconstruction steps, we have employed metal shadowing and transmission electron microscopy, along with numerical reconstruction techniques. We believe that this approach will allow holography to emerge as a practical method of high-resolution x-ray microscopy. 30 refs., 4 figs.

  18. Low dose digital X-ray imaging with avalanche amorphous selenium

    NASA Astrophysics Data System (ADS)

    Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

    2015-03-01

    Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

  19. Optimizing abdominal CT dose and image quality with respect to x-ray tube voltage

    NASA Astrophysics Data System (ADS)

    Huda, Walter; Ogden, Kent M.

    2004-05-01

    , where 140 kV offers the best imaging performance. For high Z lesions of bone and iodine, imaging performance generally degrades with increasing kV for all patient sizes, with the degree of degradation largest for the smallest patients. We conclude that 80 kV is optimal with respect to radiation dose in abdominal CT for all pediatric patients. For adults, 80 kV is the x-ray voltage of choice for high Z lesions, whereas 140 kV would generally be the voltage of choice of lesions that have an atomic number similar to that of water.

  20. Performance of high spatial frequency X-ray transmission gratings

    NASA Technical Reports Server (NTRS)

    Fischbach, K. F.; Levine, A. M.; Schattenburg, M. L.; Dewey, D.; Renshaw, R. L.

    1988-01-01

    The performance of high spatial frequency 'phased' X-ray transmission gratings developed for the High Energy Transmission Grating Spectrometer on the Advanced X-ray Astrophysics FAcility (AXAF) is examined. The gratings tested here nominally consist of 1-micron-thick gold lines of 0.2 micron period covering approximately 5 sq cm of a polyimide membrane. A table-top setup at MIT employs the gratings in reflection to diffract UV (325 nm) laser light. It is used to measure grating periods and indicates that period variations within and between gratings are a few parts in 10,000. Tests performed at the Marshall Space Flight Center 304 m X-ray Facility using 1.5 keV X-rays in transmission corroborate the UV measurements and demonstrate geometrically-limited resolving powers of E/Delta E about 750. Finally, X-ray transmission tests performed in the MIT 25 m X-ray facility provide measurements of period, line thickness, space-to-period ratio, tilt of grating lines, and efficiency.

  1. The High Energy X-ray Imager Technology (HEXITEC) for Solar Hard X-ray Observations

    NASA Astrophysics Data System (ADS)

    Christe, Steven; Shih, Albert Y.; Gaskin, Jessica; Wilson-Hodge, Colleen; Seller, Paul; Wilson, Matthew

    2015-04-01

    High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For current high resolution X-ray mirrors, the HPD is about 25 arcsec. Over a 6-m focal length this converts to 750 µm, the optimum pixel size is around 250 µm. Annother requirement are that the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage. For solar observations, the ability to handle high counting rates is also extremely desirable. The Rutherford Appleton Laboratory (RAL) in the UK has been developing the electronics for such a detector. Dubbed HEXITEC, for High Energy X-Ray Imaging Technology, this Application Specific Integrated Circuit (ASIC), can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT), to create a fine (250 µm pitch) HXR detector. The NASA Marshall Space Flight CenterMSFC and the Goddard Space Flight Center (GSFC) has been working with RAL over the past few years to develop these detectors to be used with HXR focusing telescopes. We present on recent results and capabilities as applied to solar observations.

  2. Low Mass X-ray Binary 4U1705-44 Exiting an Extended High X-ray State

    NASA Astrophysics Data System (ADS)

    Phillipson, Rebecca; Boyd, Patricia T.; Smale, Alan P.

    2017-09-01

    The neutron-star low-mass X-ray binary 4U1705-44, which exhibited high amplitude long-term X-ray variability on the order of hundreds of days during the 16-year continuous monitoring by the RXTE ASM (1995-2012), entered an anomalously long high state in July 2012 as observed by MAXI (2009-present).

  3. A High Efficiency Grazing Incidence Pumped X-ray Laser

    SciTech Connect

    Dunn, J; Keenan, R; Price, D F; Patel, P K; Smith, R F; Shlyaptsev, V N

    2006-08-31

    The main objective of the project is to demonstrate a proof-of-principle, new type of high efficiency, short wavelength x-ray laser source that will operate at unprecedented high repetition rates (10Hz) that could be scaled to 1kHz or higher. The development of a high average power, tabletop x-ray laser would serve to complement the wavelength range of 3rd and future 4th generation light sources, e.g. the LCLS, being developed by DOE-Basic Energy Sciences. The latter are large, expensive, central, synchrotron-based facilities while the tabletop x-ray laser is compact, high-power laser-driven, and relatively inexpensive. The demonstration of such a unique, ultra-fast source would allow us to attract funding from DOE-BES, NSF and other agencies to pursue probing of diverse materials undergoing ultrafast changes. Secondly, this capability would have a profound impact on the semiconductor industry since a coherent x-ray laser source would be ideal for ''at wavelength'' {approx}13 nm metrology and microscopy of optics and masks used in EUV lithography. The project has major technical challenges. We will perform grazing-incidence pumped laser-plasma experiments in flat or groove targets which are required to improve the pumping efficiency by ten times. Plasma density characterization using our existing unique picosecond x-ray laser interferometry of laser-irradiated targets is necessary. Simulations of optical laser propagation as well as x-ray laser production and propagation through freely expanding and confined plasma geometries are essential. The research would be conducted using the Physics Directorate Callisto and COMET high power lasers. At the end of the project, we expect to have a high-efficiency x-ray laser scheme operating below 20 nm at 10Hz with a pulse duration of {approx}2 ps. This will represent the state-of-the-art in x-ray lasers and would be a major step forward from our present picosecond laser-driven x-ray lasers. There is an added bonus of creating

  4. High-Resolution and Lightweight X-ray Optics for the X-Ray Surveyor

    NASA Astrophysics Data System (ADS)

    Zhang, William

    Envisioned in "Enduring Quest, Daring Visions" and under study by NASA as a potential major mission for the 2020s, the X-ray Surveyor mission will likely impose three requirements on its optics: (1) high angular resolution: 0.5 PSF, (2) large effective area: e10,000 cm2 or more, and (3) affordable production cost: $500M. We propose a technology that can meet these requirements by 2020. It will help the X-ray Surveyor secure the endorsement of the coming decadal survey and enable its implementation following WFIRST. The technology comprises four elements: (1) fabrication of lightweight single crystal silicon mirrors, (2) coating these mirrors with iridium to maximize effective area without figure degradation, (3) alignment and bonding of these mirrors to form meta-shells that will be integrated to make a mirror assembly, and (4) systems engineering to ensure that the mirror assembly meet all science performance and spaceflight environmental requirements. This approach grows out of our existing approach based on glass slumping. Using glass slumping technology, we have been able to routinely build and test mirror modules of 10half-power diameter (HPD). While comparable in HPD to XMM-Newtons electroformed nickel mirrors, these mirror modules are 10 times lighter. Likewise, while comparable in weight to Suzakus epoxy-replicated aluminum foil mirrors, these modules have 10 times better HPD. These modules represent the current state of the art of lightweight X-ray optics. Although both successful and mature, the glass slumping technology has reached its limit and cannot achieve sub-arc second HPD. Therefore, we are pursuing the new approach based on polishing single crystal silicon. The new approach will enable the building and testing of mirror modules, called meta-shells, capable of 3HPD by 2018 and 1HPD by 2020, and has the potential to reach diffraction limits ( 0.1) in the 2020s.

  5. Development toward high-resolution X-ray phase imaging.

    PubMed

    Momose, Atsushi

    2017-06-01

    Since the 1990s, the use of X-ray phase contrast has been extensively studied for imaging weakly absorbing objects consisting of low-Z elements such as biological soft tissues and polymers. The development of X-ray microscopy was also progressing during this time, although absorption contrast was only available. It was straightforward and important to develop phase-contrast X-ray microscopy. One characteristic in the development is that quantitative phase measurement is possible through the acquisition of phase-contrast images under a specific procedure, thanks to digital X-ray image detectors. Therefore, such a technique is called 'phase imaging' rather than phase-contrast imaging in this review. Highly sensitive three-dimensional phase imaging is feasible in combination with tomography. This article reviews the progress in X-ray phase imaging, especially with regards to X-ray microscopy. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. A nanovehicle developed for treating deep-seated bacteria using low-dose X-ray.

    PubMed

    Pan, Chien-Lin; Chen, Ming-Hong; Tung, Fu-I; Liu, Tse-Ying

    2017-01-01

    Many non-antibiotic strategies, such as photocatalysis and photodynamic therapy, have been proposed to inhibit and/or kill bacteria. However, these approaches still have drawbacks such as insufficient bacterial specificity and the limited penetration depth of ultraviolet and near-infrared light. To overcome these limitations, we developed a bacteria-specific anti-bacterial technique via using low-dose X-ray. Graphene oxide quantum dots (GQDs, a multifunctional vehicle) conjugated with vancomycin (Van, a bacteria-targeting ligand) were assembled with Protoporphyrin IX (PpIX, a photo/radiation sensitizer) to yield a novel Van-GQDs/PpIX complex that specifically attached to Escherichia coli and efficiently generated intracellular reactive oxygen species following X-ray activation. Delivery using GQDs increased the PpIX/Van ratio in the target bacterial cell, damaged bacterial cell wall, and enhanced X-ray-induced PpIX activation. Hence, this approach allowed for the use of a low-dose X-ray to efficiently activate the Van-GQDs/PpIX complex to exert its bactericidal effects on Escherichia coli without damaging normal cells. Furthermore, the E. coli did not develop resistance to the proposed approach for at least 7 rounds of repeated administration during one week. Thus, this proposed vehicle exhibiting bacteria-specific X-ray-triggered toxicity is a promising alternative to antibiotics for treating serious bacterial infections occurring in deep-seated tissues/organs (e.g., osteomyelitis and peritonitis). Administration of antibiotics is the most common treatment modality for bacterial infections. However, in some cases, patient attributes such as age, health, tolerance to antibiotics do not allow for the use of high-dose antibiotics. In addition, some bacteria develop resistance to antibiotics because of improper and long-term use of these agents. Therefore, non-antibiotic strategies to treat deeply situated bacterial infections, such as osteomyelitis, are urgently

  7. Superiority of Low Energy 160 KV X-Rays Compared to High Energy 6 MV X-Rays in Heavy Element Radiosensitization for Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Lim, Sara N.; Pradhan, Anil K.; Nahar, Sultana N.; Barth, Rolf F.; Yang, Weilian; Nakkula, Robin J.; Palmer, Alycia; Turro, Claudia

    2013-06-01

    High energy X-rays in the MeV range are generally employed in conventional radiation therapy from linear accelerators (LINAC) to ensure sufficient penetration depths. However, lower energy X-rays in the keV range may be more effective when coupled with heavy element (high-Z or HZ) radiosensitizers. Numerical simulations of X-ray energy deposition for tumor phantoms sensitized with HZ radiosensitizers were performed using the Monte Carlo code Geant4. The results showed enhancement in energy deposition to radiosensitized phantoms relative to unsensitized phantoms for low energy X-rays in the keV range. In contrast, minimal enhancement was seen using high energy X-rays in the MeV range. Dose enhancement factors (DEFs) were computed and showed radiosensitization only in the low energy range < 200 keV, far lower than the energy of the majority of photons in the LINAC energy range. In vitro studies were carried to demonstrate the tumoricidal effects of HZ sensitized F98 rat glioma cells following irradiation with both low energy 160 kV and high energy 6 MV X-ray sources. The platinum compound, pyridine terpyridine Pt(II) nitrate, was initially used because it was 7x less toxic that an equivalent amount of carboplatin in vitro studies. This would allow us to separate the radiotoxic and the chemotoxic effects of HZ sensitizers. Results from this study showed a 10-fold dose dependent reduction in surviving fractions (SF) of radiosensitized cells treated with low energy 160 kV X-rays compared to those treated with 6 MV X-rays. This is in agreement with our simulations that show an increase in dose deposition in radiosensitized tumors for low energy X-rays. Due to unforeen in vivo toxicity, however, another in vitro study was performed using the commonly used, Pt-based chemotherapeutic drug carboplatin which confirmed earlier results. This lays the ground work for a planned in vivo study using F98 glioma bearing rats. This study demonstrates that while high energy X-rays are

  8. High-energy x-ray imaging diagnostics of nanosecond pulse accelerators

    NASA Astrophysics Data System (ADS)

    Smith, Graham W.; Hohlfelder, Robert J.; Tribe, Alun J.; Beutler, David E.; Gallegos, Roque R.; Seymour, Calvin L. G.; Thompson, Jon A.

    2007-01-01

    X-ray imaging has been undertaken on Sandia National Laboratories' radiation effects x-ray simulators. These simulators typically yield a single very short (<20ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad (Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.5 to 1.8MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and an evaluation of the capability of the spectrometer are presented.

  9. Examination frequency and population dose from medical X-ray examinations in Sudan in 2010.

    PubMed

    Suliman, I I; Ibraheem, S B; Youssif, B E; Abdelgabar, M I; Gafar, R; Elshiekh, E; Ahmed, Nada A; Sulieman, A

    2015-07-01

    This study was performed to estimate examination frequency and collective and per caput effective doses arising from medical X-ray procedures in Sudan, 2010. Information was collected from 30 hospitals performing radiography, computed tomography (CT), fluoroscopy and interventional radiology (IR) procedures. The estimated annual number of examinations was 33 million radiographic X-ray procedures (99 %), 0.34 million CT exams per year (14 % paediatrics CT), 0.02 million fluoroscopy and IR procedures. The estimated annual number of examinations was 326 per 1000 people. The estimated annual collective and per caput effective doses from medical X-ray procedures mount 7197 man Sv and 0.18 mSv, respectively. The study offered the first projection of frequency and population dose from medical X-ray examinations in Sudan and provides estimates of the impact of the medical X-ray procedures at the national level.

  10. Focal construct geometry for high intensity energy dispersive x-ray diffraction based on x-ray capillary optics

    NASA Astrophysics Data System (ADS)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Jiang, Bowen; Zhu, Yu

    2016-03-01

    We presented a focal construct geometry (FCG) method for high intensity energy dispersive X-ray diffraction by utilizing a home-made ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL). The ESBC was employed to focus the X-rays from a conventional laboratory source into a small focal spot and to produce an annular X-ray beam in the far-field. Additionally, diffracted polychromatic X-rays were confocally collected by the PPXRL attached to a stationary energy-resolved detector. Our FCG method based on ESBC and PPXRL had achieved relatively high intensity diffraction peaks and effectively narrowed the diffraction peak width which was helpful in improving the potential d-spacing resolution for material phase analysis.

  11. Focal construct geometry for high intensity energy dispersive x-ray diffraction based on x-ray capillary optics.

    PubMed

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Jiang, Bowen; Zhu, Yu

    2016-03-14

    We presented a focal construct geometry (FCG) method for high intensity energy dispersive X-ray diffraction by utilizing a home-made ellipsoidal single-bounce capillary (ESBC) and a polycapillary parallel X-ray lens (PPXRL). The ESBC was employed to focus the X-rays from a conventional laboratory source into a small focal spot and to produce an annular X-ray beam in the far-field. Additionally, diffracted polychromatic X-rays were confocally collected by the PPXRL attached to a stationary energy-resolved detector. Our FCG method based on ESBC and PPXRL had achieved relatively high intensity diffraction peaks and effectively narrowed the diffraction peak width which was helpful in improving the potential d-spacing resolution for material phase analysis.

  12. Simultaneous X-ray and optical observations of GX 339-4 in an X-ray high state

    NASA Technical Reports Server (NTRS)

    Makishima, K.; Mitsuda, K.; Maejima, Y.; Bradt, H. V.; Remillard, R. A.

    1986-01-01

    Optical emission, soft X-rays, and hard X-rays have been observed simultaneously from the black hole candidate GX 3339-4 in a typical high state. Each of these components is interpreted as arising from a characteristic region of the accretion disk. Considered as a black hole, GX 339-4 lacks the variable 2 keV blackbody component that would be emitted from the 'solid' surface of a neutron star in the low-mass neutron star binaries. The X-ray emission in the high state is therefore extremely soft and stable in time. The intermediate disk region is optically thick and geometrically thin. The observed soft X-ray component with a 'disk blackbody' spectrum comes from this region. The innermost disk region is dynamically unstable due to the effect of general relativity and possibly due to radiation pressure. This region is responsible for the generation of the hard X-ray tail through Comptonization.

  13. The Astro-E High Resolution X-Ray Spectrometer

    NASA Technical Reports Server (NTRS)

    Kelley, Richard L.; Audley, Michael D.; Boyce, Kevin R.; Breon, Susan R.; Fujimoto, Ryuichi; Gendreau, Keith C.; Holt, Stephen S.; Ishisaki, Yoshitaka; McCammon, Dan; Mihara, Tatehiro

    1999-01-01

    The Astro-E High Resolution X-ray Spectrometer (XRS) was developed jointly by the NASA/Goddard Space Flight Center and the Institute of Space and Astronautical Science in Japan. The instrument is based on a new approach to spectroscopy, the X-ray microcalorimeter. This device senses the energies of individual X-ray photons as heat with extreme precision. A 32 channel array of microcalorimeters is being employed, each with an energy resolution of about 12 eV at 6 keV (the Fe-K region). This will provide spectral resolving power 10 times higher than any other non-dispersive X-ray spectrometer. The instrument incorporates a three stage cooling system capable of operating the array at 60 mK for about two years in orbit. The array sits at the focus of a grazing incidence conical mirror. The quantum efficiency of the microcalorimeters and the reflectivity of the X-ray mirror system combine to give high throughput over the 0.3-12 keV energy band. This new capability will enable the study of a wide range of high-energy astrophysical sources with unprecedented spectral sensitivity. This paper presents the basic design requirements and implementation of the XRS, and also describes the instrument parameters and performance.

  14. X-ray security scanners for personnel and vehicle control: dose quantities and dose values.

    PubMed

    Hupe, Oliver; Ankerhold, Ulrike

    2007-08-01

    After the security related occurrences in the past few years, there is an increasing need for airport security and border controls. In the combat against terror and smuggling, X-rays are used for the screening of persons and vehicles. The exposure of humans to ionising radiation raises the question of justification. To solve this question, reliable and traceable dose values are needed. A research project of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety was initiated. Its task is to measure the ambient dose equivalent, H*(10), and the personal dose equivalent, H(p)(10), for typical types of personnel and vehicle X-ray scanners, using the transmission and/or backscatter method. In the following, the measuring quantities which are to be used for these investigations will be discussed and the measuring instruments will be presented. Furthermore, the experimental set-up is described. For the personnel X-ray scanners investigated, the obtained dose values are in the range from 0.07 to 6 microSv. These values will be compared to the dose values of the natural environmental radiation and some exposures in the field of medicine.

  15. EUV spectroscopy of high-redshift x-ray objects

    NASA Astrophysics Data System (ADS)

    Kowalski, M. P.; Wolff, M. T.; Wood, K. S.; Barbee, T. W., Jr.; Barstow, M. A.

    2010-07-01

    As astronomical observations are pushed to cosmological distances (z>3) the spectral energy distributions of X-ray objects, AGN for example, will be redshifted into the EUV waveband. Consequently, a wealth of critical spectral diagnostics, provided by, for example, the Fe L-shell complex and the O VII/VIII lines, will be lost to future planned X-ray missions (e.g., IXO, Gen-X) if operated at traditional X-ray energies. This opens up a critical gap in performance located at short EUV wavelengths, where critical X-ray spectral transitions occur in high-z objects. However, normal-incidence multilayer-grating technology, which performs best precisely at such wavelengths, together with advanced nanolaminate replication techniques have been developed and are now mature to the point where advanced EUV instrument designs with performance complementary to IXO and Gen-X are practical. Such EUV instruments could be flown either independently or as secondary instruments on these X-ray missions. We present here a critical examination of the limits placed on extragalactic EUV measurements by ISM absorption, the range where high-z measurements are practical, and the requirements this imposes on next-generation instrument designs. We conclude with a discussion of a breakthrough technology, nanolaminate replication, which enables such instruments.

  16. High-sensitivity CCD-based X-ray detector.

    PubMed

    Phillips, Walter C; Stewart, Alexander; Stanton, Martin; Naday, Istvan; Ingersoll, Charles

    2002-01-01

    The detector is designed for imaging measurements requiring relatively high sensitivity and high spatial resolution. The detector can discriminate single X-ray photons, yet has the wide dynamic range ( approximately 10000:1) associated with integrating detectors. A GdO2S2 phosphor screen converts the incoming X-ray image into an optical image. The optical image is coupled (without demagnification) to the CCD image sensor using a fiber optic faceplate. The CCD (Philips Semiconductors) has an area of 4.9 x 8.6 cm with 4000 x 7000 12 microm pixels. A single 12 keV X-ray photon produces a signal of 100 e-. With 2 x 2 pixel binning, the total noise per 24 microm pixel in a 100 s image is approximately 30 e- the detective quantum efficiency is >0.6 at 1 X-ray photon per pixel, and the full image can be read out in <4 s. The spatial resolution is 50 microm. The CCD readout system is fully computer-controlled, allowing flexible operation in time-resolved experiments. The detector has been characterized using visible-light images, X-ray images and time-resolved muscle diffraction measurements.

  17. X-ray Thomson scattering in high energy density plasmas

    SciTech Connect

    Glenzer, Siegfried H.; Redmer, Ronald

    2009-10-15

    Accurate x-ray scattering techniques to measure the physical properties of dense plasmas have been developed for applications in high energy density physics. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines, allowing spectrally resolved x-ray scattering measurements from these plasmas. The backscattering spectrum accesses the noncollective Compton scattering regime which provides accurate diagnostic information on the temperature, density, and ionization state. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions and quantum effects. Dense matter theory relates scattering spectra with the dielectric function and structure factors that determine the physical properties of matter. Applications to radiation-heated and shock-compressed matter have demonstrated accurate measurements of compression and heating with up to picosecond temporal resolution. The ongoing development of suitable x-ray sources and facilities will enable experiments in a wide range of research areas including inertial confinement fusion, radiation hydrodynamics, material science, or laboratory astrophysics.

  18. High-Energy Diffraction-Enhanced X-ray Imaging

    SciTech Connect

    Yoneyama, Akio; Ueda, Kazuhiro; Takeda, Tohoru; Yamazaki, Takanori; Hyodo, Kazuyuki

    2010-06-23

    In order to apply the diffraction-enhanced X-ray imaging (DEI) method for much wider variety of samples, we have developed the high-energy DEI system. The energy of X-ray was increased up to 70 keV to achieve high permeability for heavy elements. The diffraction of Si(440) was used to keep large field of view. Demonstrative observation of an electrical cable was performed using the X-ray emitted from the vertical wiggler. The obtained images visualized not only the core and ground wire made of copper but also the isolator and outer jacket made of polymer clearly. The comparison of images obtained by the DEI and the absorption-contrast imaging showed that the sensitivity of DEI is about 10 times higher than that of the absorption method for light elements, and 3 times for heavy elements.

  19. Sub-Picosecond, High Flux, Thomson X-Ray Sources

    SciTech Connect

    James Boyce; David Douglas; Hiroyuki Toyokawa; Winthrop J. Brown; Fred Hartemann

    2003-05-12

    With the advent of high average power FELs, the idea of using such a device to produce x-rays via the Thomson scattering process is appealing, if sufficient flux and/or brightness can be generated. Such x-rays are produced simultaneously with FEL light, offering unprecedented opportunities for pump-probe studies. We discuss non-invasive modifications to the Jefferson Lab's FEL that would meet the criteria of high flux, sub-picosecond, x-ray source. One allows proof-of-principle experiments, is relatively inexpensive, but is not conducive as a ''User-facility.'' Another is a User facility configuration but requires FEL facility modifications. For all sources, we present Thomson scattering flux calculations and potential applications.

  20. Therapy of locally unresectable pancreatic carcinoma: a randomized comparison of high dose (6000 rads) radiation alone, moderate dose radiation (4000 rads + 5-fluorouracil), and high dose radiation + 5-fluorouracil: the Gastrointestinal Tumor Study Group. [X ray

    SciTech Connect

    Moertel, C.G.; Frytak, S.; Hahn, R.G.

    1981-10-15

    One-hundred-ninety-four eligible and evaluable patients with histologically confirmed locally unresectable adenocarcinoma of the pancreas were randomly assigned to therapy with high-dose (6000 rads) radiation therapy alone, to moderate-dose (4000 rads) radiation + 5-fluorouracil (5-FU), and to high-dose radiation plus 5-FU. Median survival with radiation alone was only 5 1/2 months from date of diagnosis. Both 5-FU-containing treatment regimens produced a highly significant survival improvement when compared with radiation alone. Survival differences between 4000 rads plus 5-FU and 6000 rads plus 5-FU were not significant with an overall median survival of ten months. Significant prognostic variables, in addition to treatment, were pretreatment performance status and pretreatment CEA level. The toxic reactions related to the treatment are discussed.

  1. High resolution collimator system for X-ray detector

    DOEpatents

    Eberhard, Jeffrey W.; Cain, Dallas E.

    1987-01-01

    High resolution in an X-ray computerized tomography (CT) inspection system is achieved by using a collimator/detector combination to limit the beam width of the X-ray beam incident on a detector element to the desired resolution width. In a detector such as a high pressure Xenon detector array, a narrow tapered collimator is provided above a wide detector element. The collimator slits have any desired width, as small as a few mils at the top, the slit width is easily controlled, and they are fabricated on standard machines. The slit length determines the slice thickness of the CT image.

  2. A MEMS-based high frequency x-ray chopper.

    PubMed

    Siria, A; Dhez, O; Schwartz, W; Torricelli, G; Comin, F; Chevrier, J

    2009-04-29

    Time-resolved x-ray experiments require intensity modulation at high frequencies (advanced rotating choppers have nowadays reached the kHz range). We here demonstrate that a silicon microlever oscillating at 13 kHz with nanometric amplitude can be used as a high frequency x-ray chopper. We claim that using micro-and nanoelectromechanical systems (MEMS and NEMS), it will be possible to achieve higher frequencies in excess of hundreds of megahertz. Working at such a frequency can open a wealth of possibilities in chemistry, biology and physics time-resolved experiments.

  3. Biphasic and triphasic dose responses in zebrafish embryos to low-dose 150 kV X-rays with different levels of hardness

    PubMed Central

    Kong, Eva Yi; Cheng, Shuk Han; Yu, Kwan Ngok

    2016-01-01

    The in vivo low-dose responses of zebrafish (Danio rerio) embryos to 150 kV X-rays with different levels of hardness were examined through the number of apoptotic events revealed at 24 h post fertilization by vital dye acridine orange staining. Our results suggested that a triphasic dose response was likely a common phenomenon in living organisms irradiated by X-rays, which comprised an ultra-low-dose inhibition, low-dose stimulation and high-dose inhibition. Our results also suggested that the hormetic zone (or the stimulation zone) was shifted towards lower doses with application of filters. The non-detection of a triphasic dose response in previous experiments could likely be attributed to the use of hard X-rays, which shifted the hormetic zone into an unmonitored ultra-low-dose region. In such cases where the subhormetic zone was missed, a biphasic dose response would be reported instead. PMID:26951078

  4. X-ray dose reduction through adaptive exposure in fluoroscopic imaging.

    PubMed

    Burion, Steve; Funk, Tobias

    2011-09-11

    X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high, and this is a significant concern, particularly in pediatric applications. Pediatrics procedures are in general much more complex than those performed on adults and thus are on average four to eight times longer. Furthermore, children can undergo up to 10 fluoroscopic procedures by the age of 10, and have been shown to have a three-fold higher risk of developing fatal cancer throughout their life than the general population. We have shown that radiation dose can be significantly reduced in adult cardiac procedures by using our scanning beam digital x-ray (SBDX) system-- a fluoroscopic imaging system that employs an inverse imaging geometry (Figure 1, Movie 1 and Figure 2). Instead of a single focal spot and an extended detector as used in conventional systems, our approach utilizes an extended X-ray source with multiple focal spots focused on a small detector. Our X-ray source consists of a scanning electron beam sequentially illuminating up to 9,000 focal spot positions. Each focal spot projects a small portion of the imaging volume onto the detector. In contrast to a conventional system where the final image is directly projected onto the detector, the SBDX uses a dedicated algorithm to reconstruct the final image from the 9,000 detector images. For pediatric applications, dose savings with the SBDX system are expected to be smaller than in adult procedures. However, the SBDX system allows for additional dose savings by implementing an electronic adaptive exposure technique. Key to this method is the multi-beam scanning technique of the SBDX system: rather than exposing every part of the image with the same radiation dose, we can dynamically vary the exposure depending on the opacity of the region exposed. Therefore, we can significantly reduce exposure in radiolucent areas and maintain exposure in more opaque regions. In our

  5. High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

    SciTech Connect

    Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; Shapiro, David; Kirz, Janos; Marchesini, Stephano; Neiman, Aaron M.; Turner, Joshua J.; Jacobsen, Chris

    2010-04-20

    X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane and freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.

  6. High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

    DOE PAGES

    Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; ...

    2010-04-20

    X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane andmore » freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.« less

  7. High Resolution X-Ray Phase Contrast Imaging with Acoustic Tissue-Selective Contrast Enhancement

    DTIC Science & Technology

    2005-06-01

    microfocus x - ray source. Rev. Sci. Instr. 68, 2774 (1997). 8. Krol, A. et al. Laser-based microfocused x - ray ...high spatial coherence, such as synchrotrons 46, microfocus x - ray tubes 7, or laser plasma x - ray sources 8,9are employed is the phase contrast component...imaging apparatus to determine the deflection of the bead as a function of acoustic pressure. The x - rays , generated by a microfocus x - ray tube

  8. High spatial resolution soft-x-ray microscopy

    SciTech Connect

    Meyer-Ilse, W.; Medecki, H.; Brown, J.T.

    1997-04-01

    A new soft x-ray microscope (XM-1) with high spatial resolution has been constructed by the Center for X-ray Optics. It uses bending magnet radiation from beamline 6.1 at the Advanced Light Source, and is used in a variety of projects and applications in the life and physical sciences. Most of these projects are ongoing. The instrument uses zone plate lenses and achieves a resolution of 43 nm, measured over 10% to 90% intensity with a knife edge test sample. X-ray microscopy permits the imaging of relatively thick samples, up to 10 {mu}m thick, in water. XM-1 has an easy to use interface, that utilizes visible light microscopy to precisely position and focus the specimen. The authors describe applications of this device in the biological sciences, as well as in studying industrial applications including structured polymer samples.

  9. X-ray radiography with highly charged ions

    DOEpatents

    Marrs, Roscoe E.

    2000-01-01

    An extremely small (1-250 micron FWHM) beam of slow highly charged ions deexciting on an x-ray production target generates x-ray monochromatic radiation that is passed through a specimen and detected for imaging. The resolution of the x-ray radiograms is improved and such detection is achieved with relatively low dosages of radiation passing through the specimen. An apparatus containing an electron beam ion trap (and modifications thereof) equipped with a focusing column serves as a source of ions that generate radiation projected onto an image detector. Electronic and other detectors are able to detect an increased amount of radiation per pixel than achieved by previous methods and apparati.

  10. Highly porous nanoberyllium for X-ray beam speckle suppression

    PubMed Central

    Goikhman, Alexander; Lyatun, Ivan; Ershov, Petr; Snigireva, Irina; Wojda, Pawel; Gorlevsky, Vladimir; Semenov, Alexander; Sheverdyaev, Maksim; Koletskiy, Viktor; Snigirev, Anatoly

    2015-01-01

    This paper reports a special device called a ‘speckle suppressor’, which contains a highly porous nanoberyllium plate squeezed between two beryllium windows. The insertion of the speckle suppressor in an X-ray beam allows manipulation of the spatial coherence length, thus changing the effective source size and removing the undesirable speckle structure in X-ray imaging experiments almost without beam attenuation. The absorption of the nanoberyllium plate is below 1% for 1 mm thickness at 12 keV. The speckle suppressor was tested on the ID06 ESRF beamline with X-rays in the energy range from 9 to 15 keV. It was applied for the transformation of the phase–amplitude contrast to the pure amplitude contrast in full-field microscopy. PMID:25931099

  11. Radiation processing with high-energy X-rays

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.; Stichelbaut, Frédéric

    2013-03-01

    The radiation processing of materials and commercial products with high-energy X-rays, which are also identified by the German term bremsstrahlung, can produce beneficial changes that are similar to those obtained by irradiation with nuclear gamma rays emitted by cobalt-60 sources. Both X-rays and gamma rays are electromagnetic radiations with short wavelengths and high photon energies that can stimulate chemical reactions by creating ions and free radicals in irradiated materials. Nevertheless, there are some physical differences in these energy sources that can influence the choice for practical applications. The English translation of bremsstrahlung is braking radiatiorn or deceleration radiation. It is produced when energetic electrons are deflected by the strong electric field near an atomic nucleus. The efficiency for producing this kind of electromagnetic energy increases with the kinetic energy of the electrons and the atomic number of the target material. The energy spectrum of the emitted X-ray photons is very broad and extends up to the maximum energy of the incident electrons. In contrast, a cobalt-60 nucleus emits two gamma rays simultaneously, which have well-defined energies. Another significant difference is the angular distribution of the radiation. Nuclear gamma rays are emitted in all directions, but high-energy bremsstrahlung photons are concentrated in the direction of the incident electrons when they strike the target material. This property enables an X-ray processing facility to be more compact than a gamma-ray processing facility with similar throughput capacity, and it increases the penetration and the efficiency for absorbing the emitted X-ray energy in the irradiated material. Recent increases in the electron energy and the electron beam power from modern industrial accelerators have increased the throughput rates in X-ray processing facilities, so that this irradiation method is now economically competitive with large cobalt-60

  12. Electron-beam-pinch experiment at Harry Diamond Laboratories: Providing for a high-dose-rate flash x-ray facility for transient radiation effects on electronics (TREE) testing of pieceparts. Final report, May-Jul 90

    SciTech Connect

    Robertson, D.N.; Litz, M.S.; Blomquist, S.M.; Blackburn, J.C.; Ovrebo, G.K.

    1991-08-01

    The peak photon-radiation dose rate of the High-Intensity Flash X-Ray facility has been increased by at least a factor of five through the use of custom beam-pinching hardware. With this hardware, the facility can now routinely provide a dose rate of 2.7 times 10 to the 11th power rads(Si)/s, at a distance of 1/4 in. from the drift-tube face, while providing excellent radial drop-off to minimized irradiation of items surrounding the device under test. The experimental results show the optimum operating parameters of the beam-pinching hardware to be a drift-tube length equal to 6 cm with an internal nitrogen gas pressure of 0.1 Torr.

  13. Shielding for neutron scattered dose to the fetus in patients treated with 18 MV x-ray beams.

    PubMed

    Roy, S C; Sandison, G A

    2000-08-01

    Neutrons are associated with therapeutic high energy x-ray beams as a contaminant that contributes significant unwanted dose to the patient. Measurement of both photon and neutron scattered dose at the position of a fetus from chest irradiation by a large field 18 MV x-ray beam was performed using an ionization chamber and superheated drop detector, respectively. Shielding construction to reduce this scattered dose was investigated using both lead sheet and borated polyethylene slabs. A 7.35 cm lead shield reduced the scattered photon dose by 50% and the scattered neutron dose by 40%. Adding 10 cm of 5% borated polyethylene to this lead shield reduced the scattered neutron dose by a factor of 7.5 from the unshielded value. When the 5% borated polyethylene was replaced by the same thickness of 30% borated polyethylene there was no significant change in the reduction of neutron scatter dose. The most efficient shield studied reduced the neutron scatter dose by a factor of 10. The results indicate that most of the scattered neutrons present at the position of the fetus produced by an 18 MV x-ray beam are of low energy and in the thermal to 0.57 MeV range since lead is almost transparent to neutrons with energies lower than 0.57 MeV. This article constitutes the first report of an effective shield to reduce neutron dose at the fetus when treating a pregnant woman with a high energy x-ray beam.

  14. High repetition rate laser produced soft x-ray source for ultrafast x-ray absorption near edge structure measurements.

    PubMed

    Fourmaux, S; Lecherbourg, L; Harmand, M; Servol, M; Kieffer, J C

    2007-11-01

    Recent progress in high intensity ultrafast laser systems provides the opportunity to produce laser plasma x-ray sources exhibiting broad spectrum and high average x-ray flux that are well adapted to x-ray absorption measurements. In this paper, the development of a laser based x-ray absorption near edge structure (XANES) beamline exhibiting high repetition rate by using the Advanced Laser Light Source (ALLS) facility 100 Hz laser system (100 mJ, 35 fs at 800 nm) is presented. This system is based on a broadband tantalum solid target soft x-ray source and a grazing incidence grating spectrometer in the 1-5 nm wavelength range. To demonstrate the high potential of this laser based XANES technique in condensed matter physics, material science, or biology, measurements realized with several samples are presented: VO2 vanadium L edge, Si3N4 nitrogen K edge, and BPDA/PPD polyimide carbon K edge. The characteristics of this laser based beamline are discussed in terms of brightness, signal to noise ratio, and compared to conventional synchrotron broadband x-ray sources which allow achieving similar measurements. Apart from the very compact size and the relative low cost, the main advantages of such a laser based soft x-ray source are the picosecond pulse duration and the perfect synchronization between this x-ray probe and a laser pulse excitation which open the way to the realization of time resolved x-ray absorption measurements with picosecond range time resolution to study the dynamics of ultrafast processes and phase transition.

  15. High repetition rate laser produced soft x-ray source for ultrafast x-ray absorption near edge structure measurements

    SciTech Connect

    Fourmaux, S.; Lecherbourg, L.; Harmand, M.; Servol, M.; Kieffer, J. C.

    2007-11-15

    Recent progress in high intensity ultrafast laser systems provides the opportunity to produce laser plasma x-ray sources exhibiting broad spectrum and high average x-ray flux that are well adapted to x-ray absorption measurements. In this paper, the development of a laser based x-ray absorption near edge structure (XANES) beamline exhibiting high repetition rate by using the Advanced Laser Light Source (ALLS) facility 100 Hz laser system (100 mJ, 35 fs at 800 nm) is presented. This system is based on a broadband tantalum solid target soft x-ray source and a grazing incidence grating spectrometer in the 1-5 nm wavelength range. To demonstrate the high potential of this laser based XANES technique in condensed matter physics, material science, or biology, measurements realized with several samples are presented: VO{sub 2} vanadium L edge, Si{sub 3}N{sub 4} nitrogen K edge, and BPDA/PPD polyimide carbon K edge. The characteristics of this laser based beamline are discussed in terms of brightness, signal to noise ratio, and compared to conventional synchrotron broadband x-ray sources which allow achieving similar measurements. Apart from the very compact size and the relative low cost, the main advantages of such a laser based soft x-ray source are the picosecond pulse duration and the perfect synchronization between this x-ray probe and a laser pulse excitation which open the way to the realization of time resolved x-ray absorption measurements with picosecond range time resolution to study the dynamics of ultrafast processes and phase transition.

  16. Very high X-ray efficiency from a blazed grating

    NASA Technical Reports Server (NTRS)

    Cash, W.; Kohnert, R.

    1982-01-01

    The efficiency of X-ray diffraction from reflection gratings has been investigated experimentally using a gold-coated plane grating of 25 x 120 mm with a nominal blaze angle of 21 deg in a conical diffraction mount. Results show that conical diffraction is capable of producing very high dispersion efficiencies. The peak of first order at 13.3 A is 40%; at 44 A, the peak is 34%. The most immediate application of this result is to X-ray astronomy where sources are weak.

  17. [Measurement of area of surplus X-ray radiation by dose-area product meter at image intensifier in angiography X-ray units].

    PubMed

    Seguchi, Shigenobu; Saijou, Takaya; Nagao, Tatsuji; Ishikawa, Yoshinobu; Mizuno, Shouta; Nakamura, Akirou

    2006-07-20

    The aim of this study was to assess the area of surplus X-ray radiation (surplus area) of three image intensifiers (I.I.) of two angiography X-ray units. Surplus area refers to an area surrounded with a circular collimator and effective field of view (FOV). Dose-area product (DAP) was used to measure surplus X-rays. A ratio of surplus area when based on each FOV showed an 8% to 39.3% increase with expansion of FOV, surplus area showed an 18 cm(2) to 95 cm(2) decrease with FOV. When the circular collimator was narrowed to a degree that could be confirmed partially in effective FOV, the rate of surplus area was decreased almost as much as the rate of scattered radiation. Surface dose was almost unchanged. The radiation exposure of the physician as well as that of the patient was reduced by the reduction of surplus area. The DAP meter, while a tool for patient radiation exposure management, is also highly useful for machinery management such as the measurement of surplus area at the I.I. system.

  18. Suitability of resin-coated photographic paper for skin dose measurement during fluoroscopically-guided X-ray procedures.

    PubMed

    Guibelalde, E; González, L; Vañó, E

    2004-10-01

    The need for mapping skin doses during fluoroscopically-guided X-ray procedures has been described by a number of institutions and experts. Different large photographic or X-ray films placed on the patient's skin have been found to be useful for recording doses up to 1.0-2.0 Gy - depending on the film - and up to 15 Gy using radiochromic films. Though the upper limit of the film sensitivity is seldom exceeded during interventional procedures, the main disadvantage of the X-ray films is still the excessive sensitivity for long, high dose procedures. Radiochromic films show poor definition for doses below 0.5 Gy and are expensive. The goal of the present paper is to analyse the possibilities of using common resin-coated photographic paper for this purpose. Sensitometric curves obtained with different paper types processed in conventional X-ray film automatic processors demonstrate that some of them can be used with better results than X-ray films at a very low cost. Doses from about 10 mGy to near 3.0 Gy can be measured with good accuracy using a variety of glossy photographic papers.

  19. 20 percent lower lung cancer mortality with low-dose CT vs chest X-ray

    Cancer.gov

    Scientists have found a 20 percent reduction in deaths from lung cancer among current or former heavy smokers who were screened with low-dose helical computed tomography (CT) versus those screened by chest X-ray.

  20. High-Frequency X-Ray Oscillations and X-Ray Spectral Evolution in Galactic Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Remillard, R. A.; Morgan, E. H.; Muno, M.

    2002-12-01

    There are now 5 Galactic black hole candidates that have exhibited quasi-periodic oscillations (QPO) in X-rays in the range of 67 to 300 Hz. The rms amplitudes are near 1 % of the average flux, and in two cases there are significant changes in the QPO frequency. The short timescales and origin in X-rays suggest that these QPOs signify inner accretion disk oscillations rooted in General Relativity, but the particular mechanism is uncertain. For two of these cases, GRO J1655-40 and GRS 1915+105, we trace the conditions under which these QPOs appear in terms of the division of luminosity between the X-ray components due to the accretion disk and the hard X-ray power law. In this context, the fast QPOs are most likely to occur when there is high luminosity in both the disk and the X-ray power-law component. On the other hand, the QPOs are not seen when the X-ray spectrum resembles either a pure disk or a dominant power-law component associated with a radio jet. The results imply a closer kinship for these QPOs than might be concluded from considerations of the gross shape of the X-ray spectrum.

  1. High resolution projection X-ray microscope equipped with fluorescent X-ray analyzer and its applications

    NASA Astrophysics Data System (ADS)

    Minami, K.; Saito, Y.; Kai, H.; Shirota, K.; Yada, K.

    2009-09-01

    We have newly developed an open type fine-focus X-ray tube "TX-510" to realize a spatial resolution of 50nm and to radiate low energy characteristic X-rays for giving high absorption contrast to images of microscopic organisms. The "TX-510" employs a ZrO/W(100) Schottky emitter and an "In-Lens Field Emission Gun". The key points of the improvements are (1) reduced spherical aberration coefficient of magnetic objective lens, (2) easy and accurate focusing, (3) newly designed astigmatism compensator, (4) segmented thin film target for interchanging the target materials by electron beam shift and (5) fluorescent X-ray analysis system.

  2. EUV Spectroscopy of High-redshift X-ray Objects

    NASA Astrophysics Data System (ADS)

    Kowalski, Michael Paul; Wolff, M. T.; Wood, K. S.; Barbee, T. W., Jr.

    2010-03-01

    As astronomical observations are pushed to cosmological distances (z>3) the spectral energy distributions of X-ray objects, AGNs for example, will have their maxima redshifted into the EUV waveband ( 90-912 Å/0.1-0.01 keV). Consequently, a wealth of spectral diagnostics, provided by, for example, the Fe L-shell complex ( 60-6 Å/0.2-2.0 keV) and the O VII/VIII lines ( 20 Å/0.5 keV), will be lost to X-ray instruments operating at traditional ( 0.5-10 keV) and higher X-ray energies. There are precedents in other wavebands. For example, HST evolutionary studies will become largely the province of JWST. Despite the successes of EUVE, the ROSAT WFC, and the Chandra LETG, the EUV continues to be unappreciated and under-utilized, partly because of a preconception that absorption by neutral galactic Hydrogen in the ISM prevents any useful extragalactic measurements at all EUV wavelengths and, until recently, by a lack of a suitable enabling technology. Thus, if future planned X-ray missions (e.g., IXO, Gen-X) are optimized again for traditional X-ray energies, their performance (effective area, resolving power) will be cut off at ultrasoft X-ray energies or at best be radically reduced in the EUV. This opens up a critical gap in performance located right at short EUV wavelengths, where the critical X-ray spectral transitions occur in high-z objects. However, normal-incidence multilayer-grating technology, which performs best precisely at such wavelengths, together with advanced nano-laminate fabrication techniques have been developed and are now mature to the point where advanced EUV instrument designs with performance complementary to IXO and Gen-X are practical. Such EUV instruments could be flown either independently or as secondary instruments on these X-ray missions. We present here a critical examination of the limits placed on extragalactic EUV measurements by ISM absorption, the range where high-z measurements are practical, and the requirements this imposes on

  3. Calculation of x-ray scattering patterns from nanocrystals at high x-ray intensity

    PubMed Central

    Abdullah, Malik Muhammad; Jurek, Zoltan; Son, Sang-Kil; Santra, Robin

    2016-01-01

    We present a generalized method to describe the x-ray scattering intensity of the Bragg spots in a diffraction pattern from nanocrystals exposed to intense x-ray pulses. Our method involves the subdivision of a crystal into smaller units. In order to calculate the dynamics within every unit, we employ a Monte-Carlo-molecular dynamics-ab-initio hybrid framework using real space periodic boundary conditions. By combining all the units, we simulate the diffraction pattern of a crystal larger than the transverse x-ray beam profile, a situation commonly encountered in femtosecond nanocrystallography experiments with focused x-ray free-electron laser radiation. Radiation damage is not spatially uniform and depends on the fluence associated with each specific region inside the crystal. To investigate the effects of uniform and non-uniform fluence distribution, we have used two different spatial beam profiles, Gaussian and flattop. PMID:27478859

  4. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera

    NASA Astrophysics Data System (ADS)

    Boone, Matthieu N.; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P.; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2014-01-01

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques.

  5. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera.

    PubMed

    Boone, Matthieu N; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2014-01-21

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques.

  6. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera

    PubMed Central

    Boone, Matthieu N.; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P.; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2013-01-01

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques. PMID:24357889

  7. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV.

    PubMed

    Seidenbusch, M; Harder, D; Regulla, D

    2014-05-01

    The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual

  8. Bubble technique for evaluating effective dose of diagnostic X-rays: a feasibility study.

    PubMed

    Chen, Chien Yi; Yang, Kai Chun; Pan, Lung Kwang

    2009-09-01

    This study examined the feasibility of applying the bubble technique to evaluate effective dose for diagnostic X-rays. A BTI-GAMMA bubble detector from Bubble Technology Industries was used for gamma detection. A multi-slab acrylic (PMMA) phantom was fabricated to quantify the effective dose E based on an ICRP-60 report. Accordingly, the bubble detectors were evaluated through preliminary tests to ascertain both the reproducibility of specific X-ray doses and the linearity of multiple X-ray doses. Qualified bubble detectors were then inserted into a multi-slab acrylic phantom. The positions of the inserted bubbles closely corresponded with the position of represented organs or tissues. The effective dose E of X-ray was determined in 12 organ and tissue samples. The bubble detector was maintained at either 21.5 degrees C (for abdomen AP) or 22 degrees C (for chest PA) to optimize counting, and the assessed effective doses for males and females were 66.75 +/- 10.23 microSv and 66.47 +/- 9.89 microSv, respectively, for each chest PA X-ray exposure. The abdominal AP X-ray exposure doses were 1183.73 +/- 124.29 microSv and 976.70 +/- 120.13 microSv for males and females, respectively. Controlling and holding the bubble detector at an optimal ambient temperature during X-ray exposure was the most important issue in practical application, and the optimal temperature had to be adjusted slightly with incident X-ray to effectively suppress the largest bubbles to enable easy reading.

  9. Nanoplasma Formation by High Intensity Hard X-rays

    PubMed Central

    Tachibana, T.; Jurek, Z.; Fukuzawa, H.; Motomura, K.; Nagaya, K.; Wada, S.; Johnsson, P.; Siano, M.; Mondal, S.; Ito, Y.; Kimura, M.; Sakai, T.; Matsunami, K.; Hayashita, H.; Kajikawa, J.; Liu, X.-J.; Robert, E.; Miron, C.; Feifel, R.; Marangos, J. P.; Tono, K.; Inubushi, Y.; Yabashi, M.; Son, S.-K.; Ziaja, B.; Yao, M.; Santra, R.; Ueda, K.

    2015-01-01

    Using electron spectroscopy, we have investigated nanoplasma formation from noble gas clusters exposed to high-intensity hard-x-ray pulses at ~5 keV. Our experiment was carried out at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility in Japan. Dedicated theoretical simulations were performed with the molecular dynamics tool XMDYN. We found that in this unprecedented wavelength regime nanoplasma formation is a highly indirect process. In the argon clusters investigated, nanoplasma is mainly formed through secondary electron cascading initiated by slow Auger electrons. Energy is distributed within the sample entirely through Auger processes and secondary electron cascading following photoabsorption, as in the hard x-ray regime there is no direct energy transfer from the field to the plasma. This plasma formation mechanism is specific to the hard-x-ray regime and may, thus, also be important for XFEL-based molecular imaging studies. In xenon clusters, photo- and Auger electrons contribute more significantly to the nanoplasma formation. Good agreement between experiment and simulations validates our modelling approach. This has wide-ranging implications for our ability to quantitatively predict the behavior of complex molecular systems irradiated by high-intensity hard x-rays. PMID:26077863

  10. Novel x-ray imaging diagnostics of high-energy nanosecond pulse accelerators

    NASA Astrophysics Data System (ADS)

    Smith, Graham W.; Beutler, David E.; Bell, John D.; Seymour, Calvin L. G.; Hohlfelder, Robert J.; Gallegos, Roque R.; Dudley, John

    2005-03-01

    Pioneering x-ray imaging has been undertaken on a number of AWE"s and Sandia National Laboratories" radiation effects x-ray simulators. These simulators typically yield a single very short (<50ns) pulse of high-energy (MeV endpoint energy bremsstrahlung) x-ray radiation with doses in the kilorad (krad(Si)) region. X-ray source targets vary in size from 2 to 25cm diameter, dependent upon the particular simulator. Electronic imaging of the source x-ray emission under dynamic conditions yields valuable information upon how the simulator is performing. The resultant images are of interest to the simulator designer who may configure new x-ray source converter targets and diode designs. The images can provide quantitative information about machine performance during radiation effects testing of components under active conditions. The effects testing program is a valuable interface for validation of high performance computer codes and models for the radiation effects community. A novel high-energy x-ray imaging spectrometer is described whereby the spectral energy (0.1 to 2.5MeV) profile may be discerned from the digitally recorded and viewable images via a pinhole/scintillator/CCD imaging system and knowledge of the filtration parameters. Unique images, analysis and a preliminary evaluation of the capability of the spectrometer are presented. Further, a novel time resolved imaging system is described that captures a sequence of high spatial resolution temporal images, with zero interframe time, in the nanosecond timeframe, of our source x-rays.

  11. Percent depth doses and X-ray beam characterizations of a fluoroscopic system incorporating copper filtration.

    PubMed

    Wunderle, Kevin A; Godley, Andrew R; Shen, Zhilei Liu; Rakowski, Joseph T; Dong, Frank F

    2017-04-01

    In this investigation, we sought to characterize X-ray beam qualities and quantitate percent depth dose (PDD) curves for fluoroscopic X-ray beams incorporating added copper (Cu) filtration, such as those commonly used in fluoroscopically guided interventions (FGI). The intended application of this research is for dosimetry in soft tissue from FGI procedures using these data. All measurements in this study were acquired on a Siemens (Erlangen, Germany) Artis zeego fluoroscope. X-ray beam characteristics of first half-value layer (HVL), second HVL, homogeneity coefficients (HCs), backscatter factors (BSFs) and kVp accuracy and precision were determined to characterize the X-ray beams used for the PDD measurements. A scanning water tank was used to measure PDD curves for 60, 80, 100, and 120 kVp X-ray beams with Cu filtration thicknesses of 0.0, 0.1, 0.3, 0.6, and 0.9 mm at 11 cm, 22 cm, and 42 cm nominal fields of view, in water depths of 0 to 150 mm. X-ray beam characteristics of first HVLs and HCs differed from previous published research of fluoroscopic X-ray beam qualities without Cu filtration. PDDs for 60, 80, 100, and 120 kVp with 0 mm of Cu filtration were comparable to previous published research, accounting for differences in fluoroscopes, geometric orientation, type of ionization chamber, X-ray beam quality, and the water tank used for data collection. PDDs and X-ray beam characteristics for beam qualities with Cu filtration are presented, which have not been previously reported. The data sets of X-ray beam characteristics and PDDs presented in this study can be used to estimate organ or soft tissue doses at depth involving similar beam qualities or to compare with mathematical models. © 2017 American Association of Physicists in Medicine.

  12. [Polymer gel dosimetry--the dose response for X-ray irradiation].

    PubMed

    Tominaga, Takahiro; Usui, Shuji; Hayashi, Shin-Ichiro; Yoshioka, Munenori; Haneda, Kiyofumi

    2012-01-01

    Polymer gel dosimetry has been considered a promising technique for clinical use, but this potential has not yet been fully realized in Japan. One reason may be because the commercialized gel detector, BANG gel, is expensive and it is only produced abroad. A second reason is the difficulty of controlling dose sensitivity of the gel so that it is stable under ordinary clinical conditions. In this work we introduce two types of gel detectors (MAG and PAG) which we produced in-house. First the method of fabrication of gel is presented in detail, then the dose responses of MAG and PAG for X-ray irradiation are evaluating for MRI and X-ray CT scanning. The MAG-type gel is useful in low contrast dosimetry because of the high sensitivity in its dose response (R2). The PAG-type gel is effective for dosimetry in multiple field irradiations because its dose response (CT value) has reproducibility independent of the different irradiation conditions. Finally, we summarize the potential for clinical use of polymer gel dosimetry with these gel detectors.

  13. Phase contrast imaging with coherent high energy X-rays

    SciTech Connect

    Snigireva, I.

    1997-02-01

    X-ray imaging concern high energy domain (>6 keV) like a contact radiography, projection microscopy and tomography is used for many years to discern the features of the internal structure non destructively in material science, medicine and biology. In so doing the main contrast formation is absorption that makes some limitations for imaging of the light density materials and what is more the resolution of these techniques is not better than 10-100 {mu}m. It was turned out that there is now way in which to overcome 1{mu}m or even sub-{mu}m resolution limit except phase contrast imaging. It is well known in optics that the phase contrast is realised when interference between reference wave front and transmitted through the sample take place. Examples of this imaging are: phase contrast microscopy suggested by Zernike and Gabor (in-line) holography. Both of this techniques: phase contrast x-ray microscopy and holography are successfully progressing now in soft x-ray region. For imaging in the hard X-rays to enhance the contrast and to be able to resolve phase variations across the beam the high degree of the time and more importantly spatial coherence is needed. Because of this it was reasonable that the perfect crystal optics was involved like Bonse-Hart interferometry, double-crystal and even triple-crystal set-up using Laue and Bragg geometry with asymmetrically cut crystals.

  14. The reduction methods of operator's radiation dose for portable dental X-ray machines.

    PubMed

    Cho, Jeong-Yeon; Han, Won-Jeong

    2012-08-01

    This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

  15. Critical review of high gain x-ray FEL experiments

    SciTech Connect

    Kim, Kwang-Je

    1996-08-01

    There is a renewed interest at the present time to develop x-ray free electron lasers (FELs). The interest is driven by the scientific opportunities with coherent x-rays glimpsed at the third generation light sources. With the recent development in linac technology in producing high-energy, high-brightness electron beams, it is now possible to design intense coherent x-ray source for wavelengths as short as one Angstrom based on the self- amplified spontaneous emission (SASE) principle. Major linac laboratories such as SLAC and DESY are therefore actively pursuing detailed design studies for the x-ray SASE facilities. The x-rays from these facilities will provide a peak brightness more than ten orders of magnitude higher than that of the current synchrotron radiation sources. Short wavelength coherent radiation could also be generated with harmonic generation techniques in linacs or storage rings. However, these schemes are not expected to be effective for 1 {Angstrom} wavelengths. This review will therefore concentrate on the linac based SASE scheme. The critical components of the SASE are: an electron source consisting of an RF photocathode gun with the emittance corrector producing high brightness electron beam; the beam bunching and acceleration; and a long undulator in which the radiation develops from initially incoherent radiation to intense, coherent radiation. We discuss the critical experimental issues in these components highlighting some relevant recent experiments. We also discuss issues related to the SASE experiment which are distinct from the usual free electron lasers. We give a brief survey of the world-wide SASE experiments. We conclude with a summary and outlook.

  16. Effect of X-ray energies on induced photo-neutron doses

    NASA Astrophysics Data System (ADS)

    Khaled, N. E.; Ghanim, E. H.; Shinashin, Kh.; El-Sersy, A. R.

    2014-03-01

    Photoneutrons induced by two high energies range from the Elekta medical linear accelerator (10 and 18 MV) were measured by nuclear track detectors (NTDs). CR-39 NTD in contact with converter screen slide films, natural boron of thickness 40 μm coated on the polyester film (BN1). Detectors were exposed at 100 cm SSD with field size 20×20 on the patient table, with chest phantom and with build-up Perspex used for high-energy exposure. CR-39 registers the thermal neutron by the (n-α) reaction with the thin layer of boron and the fast neutron was measured through the (n-p) elastic scattering with the H2 molecules in the CR-39 constituents.It was found that the total neutron dose (thermal and fast) from the 18 MV X-ray is higher than that of 10 MV. The measured thermal neutron dose is relatively smaller than the fast neutron dose in the case of direct exposure at the two X-ray energies. On the other hand, in the case of measurements on phantom and upon the use of build-up Perspex sheets, the ratio of fast to that of thermal is less than that of direct exposure.

  17. Equally sloped X-ray microtomography of living insects with low radiation dose and improved resolution capability

    NASA Astrophysics Data System (ADS)

    Yao, Shengkun; Fan, Jiadong; Zong, Yunbing; He, You; Zhou, Guangzhao; Sun, Zhibin; Zhang, Jianhua; Huang, Qingjie; Xiao, Tiqiao; Jiang, Huaidong

    2016-03-01

    Three-dimensional X-ray imaging of living specimens is challenging due to the limited resolution of conventional absorption contrast X-ray imaging and potential irradiation damage of biological specimens. In this letter, we present microtomography of a living specimen combining phase-contrast imaging and a Fourier-based iterative algorithm termed equally sloped tomography. Non-destructive 3D imaging of an anesthetized living yellow mealworm Tenebrio molitor was demonstrated with a relatively low dose using synchrotron generated X-rays. Based on the high-quality 3D images, branching tracheoles and different tissues of the insect in a natural state were identified and analyzed, demonstrating a significant advantage of the technique over conventional X-ray radiography or histotomy. Additionally, the insect survived without problem after a 1.92-s X-ray exposure and subsequent absorbed radiation dose of ˜1.2 Gy. No notable physiological effects were observed after reviving the insect from anesthesia. The improved static tomographic method demonstrated in this letter shows advantage in the non-destructive structural investigation of living insects in three dimensions due to the low radiation dose and high resolution capability, and offers many potential applications in biological science.

  18. Equally sloped X-ray microtomography of living insects with low radiation dose and improved resolution capability

    SciTech Connect

    Yao, Shengkun; Fan, Jiadong; Zong, Yunbing; Sun, Zhibin; Zhang, Jianhua; Jiang, Huaidong; He, You; Zhou, Guangzhao; Xiao, Tiqiao; Huang, Qingjie

    2016-03-21

    Three-dimensional X-ray imaging of living specimens is challenging due to the limited resolution of conventional absorption contrast X-ray imaging and potential irradiation damage of biological specimens. In this letter, we present microtomography of a living specimen combining phase-contrast imaging and a Fourier-based iterative algorithm termed equally sloped tomography. Non-destructive 3D imaging of an anesthetized living yellow mealworm Tenebrio molitor was demonstrated with a relatively low dose using synchrotron generated X-rays. Based on the high-quality 3D images, branching tracheoles and different tissues of the insect in a natural state were identified and analyzed, demonstrating a significant advantage of the technique over conventional X-ray radiography or histotomy. Additionally, the insect survived without problem after a 1.92-s X-ray exposure and subsequent absorbed radiation dose of ∼1.2 Gy. No notable physiological effects were observed after reviving the insect from anesthesia. The improved static tomographic method demonstrated in this letter shows advantage in the non-destructive structural investigation of living insects in three dimensions due to the low radiation dose and high resolution capability, and offers many potential applications in biological science.

  19. Megavoltage x-ray skin dose variation with an angle using grid carbon fibre couch tops.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2007-10-21

    It is well known that a skin dose from high-energy x-ray radiation varies with the angle of beam incidence or the presence of a radiotherapy linear accelerator couch top material. This note investigates changes produced to the skin dose from a Varian carbon fibre grid couch top at differing angles of incidence for 6 MV x-rays as is often the case clinically. Results have shown that the skin dose can easily be measured using an EBT Gafchromic film whereby the delivered skin dose can be quantified to a high level of spatial resolution, not easily achieved with other skin dose detectors. Results have shown a significant increase in the skin dose specifically at the point of a cross-sectional carbon fibre grid. Values in % of the skin dose increased from approximately 27% (an open area within a 10 cm x 10 cm field) up to 55% (same field size) at the centre of the carbon fibre mesh strip (0 degrees incidence). This is compared to 19% of the skin dose for an open field of a 10 cm x 10 cm beam without the couch material present. At larger angles similar effects occur with values changing from 52% to 75% (60 degrees , 10 cm x 10 cm) in the open area and under the grid, respectively. This produces a wave effect for the skin dose. The average skin dose magnitude increases with the angle of incidence of the beam, ranging from 37.5% to 66% from 0 degrees to 60 degrees (10 x 10 cm), respectively. The symmetric wave nature of the skin dose profile skews to deliver an increased dose on the posterior side of the carbon fibre grid as the angle of incidence increases. Simulated fractional dose delivery on a phantom has shown that over 30 fractions the wave nature of the delivered skin dose is minimized due to the random nature of most patient positioning on the treatment couch. However, some variations are still present as the ratio of the open to grid area is approximately 4:1 and the dose spread is not necessarily completely averaged during a typical fractionated radiotherapy

  20. Radiation dose and magnification in pelvic X-ray: EOS™imaging system versus plain radiographs.

    PubMed

    Chiron, P; Demoulin, L; Wytrykowski, K; Cavaignac, E; Reina, N; Murgier, J

    2017-09-20

    In plain pelvic X-ray, magnification makes measurement unreliable. The EOS™ (EOS Imaging, Paris France) imaging system is reputed to reproduce patient anatomy exactly, with a lower radiation dose. This, however, has not been assessed according to patient weight, although both magnification and irradiation are known to vary with weight. We therefore conducted a prospective comparative study, to compare: 1) image magnification and 2) radiation dose between the EOS imaging system and plain X-ray. The EOS imaging system reproduces patient anatomy exactly, regardless of weight, unlike plain X-ray. A single-center comparative study of plain pelvic X-ray and 2D EOS radiography was performed in 183 patients: 186 arthroplasties; 104 male, 81 female; mean age 61.3 ± 13.7 years (range, 24-87 years). Magnification and radiation dose (dose-area product: DAP) were compared between the two systems in 186 hips in patients with a mean body-mass index (BMI) of 27.1 ± 5.3kg/m(2) (range, 17.6-42.3kg/m(2)), including 7 with morbid obesity. Mean magnification was zero using the EOS system, regardless of patient weight, compared to 1.15 ± 0.05 (range, 1-1.32) on plain X-ray (p<10(-5)). In patients with BMI <25, mean magnification on plain X-ray was 1.15 ± 0.05 (range, 1-1.25) and, in patients with morbid obesity, 1.22 ± 0.06 (range, 1.18-1.32). The mean radiation dose was 8.19 ± 2.63 dGy/cm(2) (range, 1.77-14.24) with the EOS system, versus 19.38 ± .12.37 dGy/cm(2) (range, 4.77-81.75) with plain X-ray (p<10(-4)). For BMI >40, mean radiation dose was 9.36 ± 2.57 dGy/cm(2) (range, 7.4-14.2) with the EOS system, versus 44.76 ± 22.21 (range, 25.2-81.7) with plain X-ray. Radiation dose increased by 0.20 dGy with each extra BMI point for the EOS system, versus 0.74 dGy for plain X-ray. Magnification did not vary with patient weight using the EOS system, unlike plain X-ray, and radiation dose was 2.5-fold lower. 3, prospective case-control study. Copyright © 2017 Elsevier Masson SAS

  1. High duty cycle inverse Compton scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Ovodenko, A.; Agustsson, R.; Babzien, M.; Campese, T.; Fedurin, M.; Murokh, A.; Pogorelsky, I.; Polyanskiy, M.; Rosenzweig, J.; Sakai, Y.; Shaftan, T.; Swinson, C.

    2016-12-01

    Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this paper reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5- and 15- pulses per train and compared to a single pulse operation under the same operating conditions. With the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.

  2. A cross-sectional study of the radiation dose and image quality of X-ray equipment used in IVR.

    PubMed

    Inaba, Yohei; Chida, Koichi; Kobayashi, Ryota; Zuguchi, Masayuki

    2016-07-01

    There are case reports of injuries caused by the radiation from interventional radiology (IVR) X-ray systems. Therefore, the management of radiation doses in IVR is important. However, no detailed report has evaluated image quality for a large number of IVR X-ray systems. As a result, it is unclear whether the image quality of the X-ray equipment currently used in IVR procedures is optimal. We compared the entrance surface doses and image quality of multiple IVR X-ray systems. This study was conducted in 2014 at 13 medical facilities using 18 IVR X-ray systems. We evaluated image quality and simultaneously measured the radiation dose. Entrance surface doses for fluoroscopy (duration, 1 min) and cineradiography (duration, 10 s) are measured using a 20-cm-thick acrylic plate and skin dose monitor. The image quality (such as spatial resolution and low-contrast detectability) of both fluoroscopy and cineradiography was evaluated using a QC phantom. For fluoroscopy, the average entrance surface dose using the 20-cm-thick acrylic plate was 13.9 (range 2.1-28.2) mGy/min. For cineradiography, the average entrance surface dose was 24.6 (range 5.1-49.3) mGy/10 s. We found positive correlations between radiation doses and image quality scores, in general, especially for fluoroscopy. The differences in surface dose among the 18 IVR X-ray systems were high (max/min, 9.7-fold for cineradiography; 13.4-fold for fluoroscopy). The differences in image quality scores (spatial resolution, low-contrast detectability, and dynamic range) were also very large. In general, there tended to be a correlation between radiation dose and image quality. Periodical measurements of the radiation dose and image quality of the X-ray equipment used for cineradiography and fluoroscopy in IVR are necessary. The need to minimize patient exposure requires that the dose be reduced to the minimum level that will generate an image with an acceptable degree of noise. PACS number(s): 87.57.C, 87.57.uq, 87

  3. Changes in the electrical properties of pure and doped polymers under the influence of small doses of X-rays

    NASA Astrophysics Data System (ADS)

    Mahmoud, S. A.; Madi, N. K.; Kassem, M. E.; El-Khatib, A.

    A study has been made of the temperature dependence of the d.c. conductivity of pure and borated low density polyethylene LDPE (4% and 8% borax). The above calculations were carried out before and after X-ray irradiation. The irradiation dose was varied from 0 to 1000 rad. The d.c. electrical conductivity of Polyvinyl chloride (PVC) and perspex was measured as a function of temperature ranging from 20°C to 100°C. These samples were irradiated with X-rays of dose 200 rad. The variation of the d.c. conductivity of the treated samples versus temperature was investigated. The results reveal that the d.c. conductivity of LDPE is highly affected by radiation and/or dopant. In addition, the sensitivity of the explored polymers to X-ray irradiation is strongly dependent on its chemical nature.

  4. High-energy X-ray spectra of five sources.

    NASA Technical Reports Server (NTRS)

    Ricker, G. R.; Mcclintock, J. E.; Gerassimenko, M.; Lewin , W. H. G.

    1973-01-01

    On October 15-16, 1970, we carried out balloon X-ray observations from Australia at energies above 15 keV. We present the high-energy X-ray spectra of three sources discovered by us, GX 301-2, GX 304-1, and GX 1 + 4. The data suggest that these high-energy sources correspond to the sources 2U 1223-62, 2U 1258-61, and 2U 1728-24 respectively. We also present the spectra for two additional sources, GX 5-1 (2U 1757-25) and GX 3 + 1 (2U 1744-26). The average intensity of the highly variable source GX 301-2 was observed to be as great as Tau X-1 in the energy range 15-50 keV.

  5. A High Resolution X-Ray Imaging Devicm

    NASA Astrophysics Data System (ADS)

    Roehrig, Hans; Dallas, William J.; Ovitt, Theron W.; Lamoreaux, Richard D.; Vercillo, Richard; McNeill, Kevin M.

    1989-04-01

    This paper describes a high resolution x-ray imaging device, which is under development at the University of Arizona. It is sponsored by NIH for application in coronary angiography, but has also application in other x-ray imaging fields requi ing high spatial resolution, such as mammography and nondestructive tasting. It consists of a 6" diameter external modular sensor, coupled fiber optically to the input of a 6" proximity focussed image intensifier. The intensifier's output is coupled via 6 fiber optic tapers to 6 CCD's for readout. The tapers are joined at the large end to form a 6" by 6" coplanar fiber optic taper assembly. The electronics is designed to form a composite image out of the 6 individual images provided by the 6 CCD's and display the image in full resolution (1152 x 1152) on a high resolution physicians review console. The paper discusses the design considerations, the features, the major problems and some preliminary results.

  6. High Precision Assembly of Thin Mirror X-ray Telescopes

    NASA Astrophysics Data System (ADS)

    Schattenburg, Mark

    Lightweight high resolution x-ray telescope optics are one of the key technologies under development for next-generation x-ray telescopes. The ultimate goal of this effort is to realize optics with spatial resolution rivaling Chandra (<1 arc-sec) but with collecting areas that are larger by orders of magnitude. In the USA several institutions, including GSFC, MSFC, Harvard-SAO, MIT and Northwest University are working on a variety of approaches to this problem. An excellent example is the NuSTAR x-ray telescope, which teamed Cal Tech, GSFC, Columbia University and LLNL to produce a superb set of hard x-ray optics. The telescope was composed of thousands of 0.2 mm-thick glass mirrors which were epoxied into place around a spindle structure. While very light weight, this process resulted in ~1 arc min resolution. We want to achieve ~100 times better with similar mass. A group at NASA GSFC has recently demonstrated an alternative thin-glass assembly procedure that has achieved ~7 arc sec resolution with x-ray tests. Further progress towards 1 arc-sec will require mirrors with improved figure, lower stress coatings, improved alignment, better metrology, and low stress bonding. Many of the difficulties with current mirror assembly practice stem from the use of epoxy as a bonding agent. Epoxy has many disadvantages, including high shrinkage, large CTE and creep, resin aging effects, water absorption, outgassing, low tensile strength, exothermicity, and requiring large amounts of time and/or heat to cure. These effects can cause errors that become â€oefrozen in― to the bond with no possibility of correction. We propose to investigate replacing epoxy with low temperature, low shrinkage solder alloys. We use these solders in conjunction with high power, millisec-long pulses from a fiber IR laser to deliver controlled amounts of heat into the bond area. We have demonstrated that laser pulses can be used to actuate carefully designed bonds by permanently compressing

  7. Dose-volume histogram comparison between static 5-field IMRT with 18-MV X-rays and helical tomotherapy with 6-MV X-rays.

    PubMed

    Hayashi, Akihiro; Shibamoto, Yuta; Hattori, Yukiko; Tamura, Takeshi; Iwabuchi, Michio; Otsuka, Shinya; Sugie, Chikao; Yanagi, Takeshi

    2015-03-01

    We treated prostate cancer patients with static 5-field intensity-modulated radiation therapy (IMRT) using linac 18-MV X-rays or tomotherapy with 6-MV X-rays. As X-ray energies differ, we hypothesized that 18-MV photon IMRT may be better for large patients and tomotherapy may be more suitable for small patients. Thus, we compared dose-volume parameters for the planning target volume (PTV) and organs at risk (OARs) in 59 patients with T1-3 N0M0 prostate cancer who had been treated using 5-field IMRT. For these same patients, tomotherapy plans were also prepared for comparison. In addition, plans of 18 patients who were actually treated with tomotherapy were analyzed. The evaluated parameters were homogeneity indicies and a conformity index for the PTVs, and D2 (dose received by 2% of the PTV in Gy), D98, Dmean and V10-70 Gy (%) for OARs. To evaluate differences by body size, patients with a known body mass index were grouped by that index ( <21; 21-25; and >25 kg/m(2)). For the PTV, all parameters were higher in the tomotherapy plans compared with the 5-field IMRT plans. For the rectum, V10 Gy and V60 Gy were higher, whereas V20 Gy and V30 Gy were lower in the tomotherapy plans. For the bladder, all parameters were higher in the tomotherapy plans. However, both plans were considered clinically acceptable. Similar trends were observed in 18 patients treated with tomotherapy. Obvious trends were not observed for body size. Tomotherapy provides equivalent dose distributions for PTVs and OARs compared with 18-MV 5-field IMRT. Tomotherapy could be used as a substitute for high-energy photon IMRT for prostate cancer regardless of body size.

  8. High throughput x-ray optics: an overview.

    PubMed

    Gorenstein, P

    1988-04-15

    Several x-ray astronomy missions of the 1990s will contain focusing telescopes with significantly more collecting power than the Einstein Observatory. There is increasing emphasis on spectroscopy. ESA's XMM with 10(4) cm(2) of effective area will be the largest. A high throughput facility with over 10(5) cm(2) of effective area and 20-sec of arc angular resolution is needed ultimately for various scientific studies such as high resolution spectroscopic observations of QSOs. At least one of the following techniques currently being developed for fabricating x-ray telescopes including automated figuring of flats as parabolic reflectors, replication of cylindrical shells, and the alignment of thin lacquer-coated conical foils is likely to permit the construction of modular arrays of telescopes with the area and angular resolution required.

  9. Workshop on high heat load x-ray optics

    SciTech Connect

    Not Available

    1990-01-01

    A workshop on High Heat Load X-Ray Optics'' was held at Argonne National Laboratory on August 3--5, 1989. The object of this workshop was to discuss recent advances in the art of cooling x-ray optics subject to high heat loads from synchrotron beams. The cooling of the first optical element in the intense photon beams that will be produced in the next generation of synchrotron sources is recognized as one of the major challenges that must be faced before one will be able to use these very intense beams in future synchrotron experiments. Considerable advances have been made in this art during the last few years, but much work remains to be done before the heating problem can be said to be completely solved. Special emphasis was placed on recent cooling experiments and detailed finite element'' and finite difference'' calculations comparing experiment with theory and extending theory to optimize performance.

  10. High resolution X-ray CT for advanced electronics packaging

    NASA Astrophysics Data System (ADS)

    Oppermann, M.; Zerna, T.

    2017-02-01

    Advanced electronics packaging is a challenge for non-destructive Testing (NDT). More, smaller and mostly hidden interconnects dominate modern electronics components and systems. To solve the demands of customers to get products with a high functionality by low volume, weight and price (e.g. mobile phones, personal medical monitoring systems) often the designers use System-in-Package solutions (SiP). The non-destructive testing of such devices is a big challenge. So our paper will impart fundamentals and applications for non-destructive evaluation of inner structures of electronics packaging for quality assurance and reliability investigations with a focus on X-ray methods, especially on high resolution X-ray computed tomography (CT).

  11. Fabricating High Resolution Mirrors for Hand X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Speegle, Chet O.; Ramsey, Brian D.; Engelhaupt, Darell; Six, N. Frank (Technical Monitor)

    2001-01-01

    We describe the fabrication process for producing high-resolution conical mirrors for hard x-ray astronomy. When flown aboard stratospheric balloons, these high-resolution reflective mirrors focus hard x-rays (10-70 keV) emitted from cosmic sources such as supernovae, neutron stars, and quasars onto imaging focal plane detectors. Focused hard x-ray images allow scientists to determine the elemental compositions, temperatures, magnetic fields, velocities, and gravitational fields of these celestial bodies. The fabrication process involves generating super-polished mandrels, mandrel metrology, mirror shell nickel electroforming, and mirror testing. Each mandrel is a cylinder consisting of two conical segments; each segment is approximately 305-mm long. Through precision grinding these mandrels before super polishing, we have achieved 30 arc seconds, half power diameter replicated mirrors. During a May 2001 high atmosphere balloon flight, these mirrors focused high energy x-rays from three different celestial sources. However, we seek to improve the angular resolutions of future mirror shells by a factor of two. To achieve this goal, we have begun single point diamond turning the mandrels before super polishing. This has allowed greater precision tolerances on mandrel surface roughness and axial figure errors before super polishing. Surface roughnesses before polishing have been reduced from approximately 60 nm to approximately 15 nm. The peak to valley axial figure profile errors have been reduced from approximately 1.0 micrometers to approximately 0.4 micrometers. We are currently in Phase 2 of the HERO (high energy replicated optics) program which entails the production of sixteen 6-m-focal-length mirror modules, each containing a nested array of 15 mirror shells of diameters ranging from 50-mm to 94-mm. This flight is slated for the fall of 2003.

  12. Fabricating High Resolution Mirrors for Hand X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Speegle, Chet O.; Ramsey, Brian D.; Engelhaupt, Darell; Six, N. Frank (Technical Monitor)

    2001-01-01

    We describe the fabrication process for producing high-resolution conical mirrors for hard x-ray astronomy. When flown aboard stratospheric balloons, these high-resolution reflective mirrors focus hard x-rays (10-70 keV) emitted from cosmic sources such as supernovae, neutron stars, and quasars onto imaging focal plane detectors. Focused hard x-ray images allow scientists to determine the elemental compositions, temperatures, magnetic fields, velocities, and gravitational fields of these celestial bodies. The fabrication process involves generating super-polished mandrels, mandrel metrology, mirror shell nickel electroforming, and mirror testing. Each mandrel is a cylinder consisting of two conical segments; each segment is approximately 305-mm long. Through precision grinding these mandrels before super polishing, we have achieved 30 arc seconds, half power diameter replicated mirrors. During a May 2001 high atmosphere balloon flight, these mirrors focused high energy x-rays from three different celestial sources. However, we seek to improve the angular resolutions of future mirror shells by a factor of two. To achieve this goal, we have begun single point diamond turning the mandrels before super polishing. This has allowed greater precision tolerances on mandrel surface roughness and axial figure errors before super polishing. Surface roughnesses before polishing have been reduced from approximately 60 nm to approximately 15 nm. The peak to valley axial figure profile errors have been reduced from approximately 1.0 micrometers to approximately 0.4 micrometers. We are currently in Phase 2 of the HERO (high energy replicated optics) program which entails the production of sixteen 6-m-focal-length mirror modules, each containing a nested array of 15 mirror shells of diameters ranging from 50-mm to 94-mm. This flight is slated for the fall of 2003.

  13. High Resolution Energetic X-ray Imager (HREXI)

    NASA Astrophysics Data System (ADS)

    Grindlay, Jonathan

    We propose to design and build the first imaging hard X-ray detector system that incorporates 3D stacking of closely packed detector readouts in finely-spaced imaging arrays with their required data processing and control electronics. In virtually all imaging astronomical detectors, detector readout is done with flex connectors or connections that are not vertical but rather horizontal , requiring loss of focal plane area. For high resolution pixel detectors needed for high speed event-based X-ray imaging, from low energy applications (CMOS) with focusing X-ray telescopes, to hard X-ray applications with pixelated CZT for large area coded aperture telescopes, this new detector development offers great promise. We propose to extend our previous and current APRA supported ProtoEXIST program that has developed the first large area imaging CZT detectors and demonstrated their astrophysical capabilities on two successful balloon flight to a next generation High Resolution Energetic X-ray Imager (HREXI), which would incorporate microvia technology for the first time to connect the readout ASIC on each CZT crystal directly to its control and data processing system. This 3-dimensional stacking of detector and readout/control system means that large area (>2m2) imaging detector planes for a High Resolution Wide-field hard X-ray telescope can be built with initially greatly reduced detector gaps and ultimately with no gaps. This increases detector area, efficiency, and simplicity of detector integration. Thus higher sensitivity wide-field imagers will be possible at lower cost. HREXI will enable a post-Swift NASA mission such as the EREXS concept proposed to PCOS to be conducted as a future MIDEX mission. This mission would conduct a high resolution (<2 arcmin) , broad band (5 200 keV) hard X-ray survey of black holes on all scales with ~10X higher sensitivity than Swift. In the current era of Time Domain Astrophysics, such a survey capability, in conjunction with a n

  14. Advances toward high spectral resolution quantum X-ray calorimetry

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Kelley, R. L.; Schoelkopf, R. J.; Szymkowiak, A. E.; Mccammon, D.

    1988-01-01

    Thermal detectors for X-ray spectroscopy combining high spectral resolution and quantum efficiency have been developed. These microcalorimeters measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure. The ultimate energy resolution of such a device is limited by the thermodynamic power fluctuations in the thermal link between the calorimeter and isothermal bath and can in principle be made as low as 1 eV. The performance of a real device is degraded due to noise contributions such as excess 1/f noise in the thermistor and incomplete conversion of energy into phonons. The authors report some recent advances in thermometry, X-ray absorption and thermalization, fabrication techniques, and detector optimization in the presence of noise. These improvements have resulted in a device with a spectral resolution of 17 eV FWHM, measured at 6 keV.

  15. Bendable X-ray Optics for High Resolution Imaging

    NASA Technical Reports Server (NTRS)

    Gubarev, M.; Ramsey, B.; Kilaru, K.; Atkins, C.; Broadway, D.

    2014-01-01

    Current state-of the-art for x-ray optics fabrication calls for either the polishing of massive substrates into high-angular-resolution mirrors or the replication of thin, lower-resolution, mirrors from perfectly figured mandrels. Future X-ray Missions will require a change in this optics fabrication paradigm in order to achieve sub-arcsecond resolution in light-weight optics. One possible approach to this is to start with perfectly flat, light-weight surface, bend it into a perfect cone, form the desired mirror figure by material deposition, and insert the resulting mirror into a telescope structure. Such an approach is currently being investigated at MSFC, and a status report will be presented detailing the results of finite element analyses, bending tests and differential deposition experiments.

  16. High-Resolution X-ray Images of Dust Halos

    NASA Astrophysics Data System (ADS)

    Smith, Randall

    2005-09-01

    Measurements of X-ray halos will break the degeneracy that exists in dust models determined from infrared emission and UV/optical extinction measurements. This requires observations of bright halos within 1' of the source, as well as energy-resolved halos beyond 1'. The former can only be done with Chandra's HRC-I, while the ACIS-S is ideal for the latter. We have observed one source, GX13+1, with both detectors and proposed to extend our dataset with observations of GX5-1 and GX9+1. These are both bright, highly absorbed X-ray binaries. We present our AO6 data on GX13+1 which can reject at least one proposed model. Expending the dataset to three sources will substantially reduce the allowed range of dust parameters, shedding new light on the formation and dispersion of dust grains.

  17. Advances toward high spectral resolution quantum X-ray calorimetry

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Kelley, R. L.; Schoelkopf, R. J.; Szymkowiak, A. E.; Mccammon, D.

    1988-01-01

    Thermal detectors for X-ray spectroscopy combining high spectral resolution and quantum efficiency have been developed. These microcalorimeters measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure. The ultimate energy resolution of such a device is limited by the thermodynamic power fluctuations in the thermal link between the calorimeter and isothermal bath and can in principle be made as low as 1 eV. The performance of a real device is degraded due to noise contributions such as excess 1/f noise in the thermistor and incomplete conversion of energy into phonons. The authors report some recent advances in thermometry, X-ray absorption and thermalization, fabrication techniques, and detector optimization in the presence of noise. These improvements have resulted in a device with a spectral resolution of 17 eV FWHM, measured at 6 keV.

  18. X-Ray Dose in Microfocus Radiographic Inspections

    DTIC Science & Technology

    2007-03-15

    22 4.6 Thermoluminescent Dosimetry and Other Measurement Methods ................................ 23 4.7 M inim ization of...other materials of interest. One can, in principle, measure dose rates in a package directly if a small sensor such as a thermoluminescent dosimeter...relative dose in silicon with (blue triangles) and without (purple circles) an overlying 0.5-[rm- thick gold layer. 22 4.6 Thermoluminescent Dosimetry and

  19. Cryogenic, high-resolution x-ray detector with high count rate capability

    DOEpatents

    Frank, Matthias; Mears, Carl A.; Labov, Simon E.; Hiller, Larry J.; Barfknecht, Andrew T.

    2003-03-04

    A cryogenic, high-resolution X-ray detector with high count rate capability has been invented. The new X-ray detector is based on superconducting tunnel junctions (STJs), and operates without thermal stabilization at or below 500 mK. The X-ray detector exhibits good resolution (.about.5-20 eV FWHM) for soft X-rays in the keV region, and is capable of counting at count rates of more than 20,000 counts per second (cps). Simple, FET-based charge amplifiers, current amplifiers, or conventional spectroscopy shaping amplifiers can provide the electronic readout of this X-ray detector.

  20. New developments in high pressure x-ray spectroscopy beamline at High Pressure Collaborative Access Team

    SciTech Connect

    Xiao, Y. M. Chow, P.; Boman, G.; Bai, L. G.; Rod, E.; Bommannavar, A.; Kenney-Benson, C.; Sinogeikin, S.; Shen, G. Y.

    2015-07-15

    The 16 ID-D (Insertion Device - D station) beamline of the High Pressure Collaborative Access Team at the Advanced Photon Source is dedicated to high pressure research using X-ray spectroscopy techniques typically integrated with diamond anvil cells. The beamline provides X-rays of 4.5-37 keV, and current available techniques include X-ray emission spectroscopy, inelastic X-ray scattering, and nuclear resonant scattering. The recent developments include a canted undulator upgrade, 17-element analyzer array for inelastic X-ray scattering, and an emission spectrometer using a polycapillary half-lens. Recent development projects and future prospects are also discussed.

  1. Generation and dose distribution measurement of flash x-ray in KALI-5000 system

    SciTech Connect

    Menon, Rakhee; Roy, Amitava; Mitra, S.; Sharma, A.; Mondal, J.; Mittal, K. C.; Nagesh, K. V.; Chakravarthy, D. P.

    2008-10-15

    Flash x-ray generation studies have been carried out in KALI-5000 Pulse power system. The intense relativistic electron beam has been bombarded on a tantalum target at anode to produce flash x-ray via bremsstrahlung conversion. The typical electron beam parameter was 360 kV, 18 kA, and 100 ns, with a few hundreds of A/cm{sup 2} current density. The x-ray dose has been measured with calcium sulfate:dysposium (CaSO{sub 4}:Dy) thermoluminescent dosimeter and the axial dose distribution has been characterized. It has been observed that the on axis dose falls of with distance {approx}1/x{sup n}, where n varies from 1.8 to 1.85. A maximum on axis dose of 46 mrad has been measured at 1 m distance from the source. A plastic scintillator with optical fiber coupled to a photomultiplier tube has been developed to measure the x-ray pulse width. The typical x-ray pulse width varied from 50 to 80 ns.

  2. Generation and dose distribution measurement of flash x-ray in KALI-5000 system

    NASA Astrophysics Data System (ADS)

    Menon, Rakhee; Roy, Amitava; Mitra, S.; Sharma, A.; Mondal, J.; Mittal, K. C.; Nagesh, K. V.; Chakravarthy, D. P.

    2008-10-01

    Flash x-ray generation studies have been carried out in KALI-5000 Pulse power system. The intense relativistic electron beam has been bombarded on a tantalum target at anode to produce flash x-ray via bremsstrahlung conversion. The typical electron beam parameter was 360 kV, 18 kA, and 100 ns, with a few hundreds of A/cm2 current density. The x-ray dose has been measured with calcium sulfate:dysposium (CaSO4:Dy) thermoluminescent dosimeter and the axial dose distribution has been characterized. It has been observed that the on axis dose falls of with distance ˜1/xn, where n varies from 1.8 to 1.85. A maximum on axis dose of 46 mrad has been measured at 1 m distance from the source. A plastic scintillator with optical fiber coupled to a photomultiplier tube has been developed to measure the x-ray pulse width. The typical x-ray pulse width varied from 50 to 80 ns.

  3. Generation and dose distribution measurement of flash x-ray in KALI-5000 system.

    PubMed

    Menon, Rakhee; Roy, Amitava; Mitra, S; Sharma, A; Mondal, J; Mittal, K C; Nagesh, K V; Chakravarthy, D P

    2008-10-01

    Flash x-ray generation studies have been carried out in KALI-5000 Pulse power system. The intense relativistic electron beam has been bombarded on a tantalum target at anode to produce flash x-ray via bremsstrahlung conversion. The typical electron beam parameter was 360 kV, 18 kA, and 100 ns, with a few hundreds of A/cm(2) current density. The x-ray dose has been measured with calcium sulfate:dysposium (CaSO(4):Dy) thermoluminescent dosimeter and the axial dose distribution has been characterized. It has been observed that the on axis dose falls of with distance approximately 1/x(n), where n varies from 1.8 to 1.85. A maximum on axis dose of 46 mrad has been measured at 1 m distance from the source. A plastic scintillator with optical fiber coupled to a photomultiplier tube has been developed to measure the x-ray pulse width. The typical x-ray pulse width varied from 50 to 80 ns.

  4. High-energy x-ray imaging spectrometer (HEXIS)

    NASA Astrophysics Data System (ADS)

    Matteson, James L.; Gruber, Duane E.; Heindl, William A.; Pelling, Michael R.; Peterson, Laurence E.; Rothschild, Richard E.; Skelton, Robert E.; Hink, Paul L.; Slavis, Kimberly R.; Binns, W. Robert

    1998-11-01

    HEXIS is a MIDEX-class mission concept for x-ray astronomy. Its objectives are to improve our knowledge of the high energy x-ray sky by increasing the number of sources above 20 keV to > 2,000, discovering transient sources such as x-ray novae and gamma-ray bursts, and making spectral and temporal studies of the sources. With mission life > 3 years, a 1-year all-sky survey sensitivity of approximately 0.3 mCrab, and continuous monitoring of the entire visible sky, HEXIS will provide unprecedented capabilities. Source positions will be determined to accuracies of a few arcmin or better. Spectra will be determined with an energy resolution of a few keV and source variability will be studied on time scales from < 1 sec to years. In addition, 10 times more sensitive studies of limited fields will be performed at the same time. Gamma-ray bursts will be detected about 4 times/week at about the same sensitivity as BATSE and the sensitivity to nova-like x-ray transients will be approximately 6 mCrab in one day. HEXIS contains a set of coded mask imagers that use position-sensitive CZT detectors operating from approximately 5 keV to 200 keV. Detector planes are built with 41 cm(superscript 2) CZT detector modules which employ crossed-strip readout to obtain a pixel size of 0.5 mm. Nine modules are grouped in a 369 cm(superscript 2) array for each imager. In the past 2 years significant progress has been made on techniques requires for HEXIS: position-sensitive CZT detectors and ASIC readout, coded mask imaging, and background properties at balloon altitudes. Scientific and technical details of HEXIS are presented together with result form tests of detectors and a coded mask imager.

  5. High efficiency, multiterawatt x-ray free electron lasers

    NASA Astrophysics Data System (ADS)

    Emma, C.; Fang, K.; Wu, J.; Pellegrini, C.

    2016-02-01

    In this paper we present undulator magnet tapering methods for obtaining high efficiency and multiterawatt peak powers in x-ray free electron lasers (XFELs), a key requirement for enabling 3D atomic resolution single molecule imaging and nonlinear x-ray science. The peak power and efficiency of tapered XFELs is sensitive to time dependent effects, like synchrotron sideband growth. To analyze this dependence in detail we perform a comparative numerical optimization for the undulator magnetic field tapering profile including and intentionally disabling these effects. We show that the solution for the magnetic field taper profile obtained from time independent optimization does not yield the highest extraction efficiency when time dependent effects are included. Our comparative optimization is performed for a novel undulator designed specifically to obtain TW power x-ray pulses in the shortest distance: superconducting, helical, with short period and built-in strong focusing. This design reduces the length of the breaks between modules, decreasing diffraction effects, and allows using a stronger transverse electron focusing. Both effects reduce the gain length and the overall undulator length. We determine that after a fully time dependent optimization of a 100 m long Linac coherent light source-like XFEL we can obtain a maximum efficiency of 7%, corresponding to 3.7 TW peak radiation power. Possible methods to suppress the synchrotron sidebands, and further enhance the FEL peak power, up to about 6 TW by increasing the seed power and reducing the electron beam energy spread, are also discussed.

  6. High Resolution X-Ray Spectra of WR 6

    NASA Astrophysics Data System (ADS)

    Huenemoerder, D.; Gayley, K.; Hamann, W.-R.; Ignace, R.; Nichols, J.; Oskinova, L. M.; Pollock, A. M. T.; Schulz, N.

    As WR 6 is a putatively single WN4 star, and is relatively bright (V = 6.9), it is an ideal case for studying the wind mechanisms in these extremely luminous stars. To obtain higher resolution spectra at higher energy (above 1 keV) than previously obtained with the XMM/Newton RGS, we have observed WR 6 with the Chandra High Energy Transmission Grating Spectrometer for 450 ks. We have resolved emission lines of S, Si, Mg, Ne, and Fe, which all show a “fin"-shaped prole, characteristic of a self-absorbed uniformly expanding shell. Steep blue edges gives robust maximal expansion velocities of about 2000 km/s, somewhat larger than the 1700km/s derived from UV lines. The He-like lines all indicate that X-ray emitting plasmas are far from the photosphere - even at the higher energies where opacity is lowest { as was also the case for the longer wavelength lines observed with XMM-Newton/RGS. Abundances determined from X-ray spectral modeling indicate enhancements consistent with nucleosynthesis. The star was also variable in X-rays and in simultaneous optical photometry obtained with Chandra aspect camera, but not coherently with the optically known period of 3.765 days.

  7. X-ray emission from high temperature plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.

    1975-01-01

    The bremsstrahlung X-rays from a plasma focus device were investigated with emphasis on the emission versus position, time, energy, and angle of emission. It is shown that low energy X-rays come from the plasma focus region, but that the higher energy components come from the anode. The emission is anisotropic, the low energy polar diagram resembling a cardioid, while the high energy emission is a lobe into the anode. The plasma parameters were considered indicating that even in the dense focus, the plasma is collisionless near the axis. By considering the radiation patterns of relativistic electrons a qualitative picture is obtained, which explains the measured polar diagrams, assuming the electrons that produce the X-rays have velocity vectors lying roughly in a cone between the point of focus and the anode. The average electron energy is about 3keV at the focus and about 10 keV on the anode surface. Results are consistent with the converging beam model of neutron production.

  8. Physical characteristics of a low-dose gas microstrip detector for orthopedic x-ray imaging

    SciTech Connect

    Despres, Philippe; Beaudoin, Gilles; Gravel, Pierre; Guise, Jacques A. de

    2005-04-01

    A new scanning slit gas detector dedicated to orthopedic x-ray imaging is presented and evaluated in terms of its fundamental imaging characteristics. The system is based on the micromesh gaseous structure detector and achieves primary signal amplification through electronic avalanche in the gas. This feature, together with high quantum detection efficiency and fan-beam geometry, allows for imaging at low radiation levels. The system is composed of 1764 channels spanning a width of 44.8 cm and is capable of imaging an entire patient at speeds of up to 15 cm/s. The resolution was found to be anisotropic and significantly affected by the beam quality in the horizontal direction, but otherwise sufficient for orthopedic studies. As a consequence of line-by-line acquisition, the images contain some ripple components due to mechanical vibrations combined with variations in the x-ray tube output power. The reported detective quantum efficiency (DQE) values are relatively low (0.14 to 0.20 at 0.5 mm{sup -1}) as a consequence of a suboptimal collimation geometry. The DQE values were found to be unaffected by the exposure down to 7 {mu}Gy, suggesting that the system is quantum limited even for low radiation levels. A system composed of two orthogonal detectors is already in use and can produce dual-view full body scans at low doses. This device could contribute to reduce the risk of radiation induced cancer in sensitive clientele undergoing intensive x-ray procedures, like young scoliotic women.

  9. Physical characteristics of a low-dose gas microstrip detector for orthopedic x-ray imaging.

    PubMed

    Després, Philippe; Beaudoin, Gilles; Gravel, Pierre; de Guise, Jacques A

    2005-04-01

    A new scanning slit gas detector dedicated to orthopedic x-ray imaging is presented and evaluated in terms of its fundamental imaging characteristics. The system is based on the micromesh gaseous structure detector and achieves primary signal amplification through electronic avalanche in the gas. This feature, together with high quantum detection efficiency and fan-beam geometry, allows for imaging at low radiation levels. The system is composed of 1764 channels spanning a width of 44.8 cm and is capable of imaging an entire patient at speeds of up to 15 cm/s. The resolution was found to be anisotropic and significantly affected by the beam quality in the horizontal direction, but otherwise sufficient for orthopedic studies. As a consequence of line-by-line acquisition, the images contain some ripple components due to mechanical vibrations combined with variations in the x-ray tube output power. The reported detective quantum efficiency (DQE) values are relatively low (0.14 to 0.20 at 0.5 mm(-1)) as a consequence of a suboptimal collimation geometry. The DQE values were found to be unaffected by the exposure down to 7 microGy, suggesting that the system is quantum limited even for low radiation levels. A system composed of two orthogonal detectors is already in use and can produce dual-view full body scans at low doses. This device could contribute to reduce the risk of radiation induced cancer in sensitive clientele undergoing intensive x-ray procedures, like young scoliotic women.

  10. Patient dose and image quality in five standard x-ray examinations.

    PubMed

    Havukainen, R; Pirinen, M

    1993-01-01

    Patient doses and image quality in five standard x-ray examination projections (22-36 measurements per each projection) have been measured, using homogeneous phantoms. The means and range of variation for the entrance skin air kerma values were: abdomen AP 5.2 mGy (1.1-21 mGy), chest PA 0.27 mGy (0.035-0.84 mGy), lumbar spine AP 8.4 mGy (2.9-28 mGy), skull LAT 3.1 mGy (1.1-7.7 mGy), and thoracic spine AP 7.9 mGy (1.3-22 mGy). Considerable variation was found in image quality parameters: film optical densities, image contrasts, and resolutions as well as in exposure values, tube voltages, exposure times, and in half-value thicknesses. The study indicated the need to standardize medical x-ray examination techniques in different x-ray departments. The measuring method can be used for comparing the patient dose and image quality of an individual x-ray unit to the doses and image quality in general use. The results can be used as the reference values for quality control of x-ray equipment.

  11. Do flat detector cardiac X-ray systems convey advantages over image-intensifier-based systems? Study comparing X-ray dose and image quality.

    PubMed

    Davies, Andrew G; Cowen, Arnold R; Kengyelics, Stephen M; Moore, Janet; Sivananthan, Mohan U

    2007-07-01

    The recent introduction of "flat-panel detector" (FD)-based cardiac catheterisation laboratories should offer improvements in image quality and/or dose efficiency over X-ray systems of conventional design. We compared three X-ray systems, one image-intensifier (II)-based system (system A), and two FD-based designs (systems B and C), assessing their image quality and dose efficiency. Phantom measurements were performed to assess dose rates in fluoroscopy and cine acquisition. Phantom dose rates were broadly similar for all systems, with all systems classified as offering "low" dose rates in fluoroscopy on standard phantoms. Patient X-ray dose rate and subjective image quality was assessed for 90 patients. Dose area product (DAP) rates were similar for all systems, except system C, which had a lower DAP rate in fluoroscopy. In terms of subjective image quality, the order of preference was (best to worst): system C, system A, system B. This study indicates that the use of an FD detector does not infer an automatic improvement in image quality or dose efficiency over II based designs. Specification and configuration of all of the components in the X-ray system contribute to the dose levels used and image quality achieved.

  12. High Resolution X-Ray Spectroscopy with a Microcalorimeter

    SciTech Connect

    Norrell, J.; Anderson, I.

    2005-01-01

    of spectral artifacts. It was found that the detector is capable of distinguishing many Lα and Lβ spectral lines, with a resolution between 13 and 17 eV. It was also observed that the background has an unusual shape, and this is largely being attributed to the variable transmission coefficient of the X-ray optic. These preliminary results suggest that the microcalorimeter has a high potential for use in microanalysis, but more work to quantify its capabilities must still be done.

  13. Attenuation properties and percentage depth dose of tannin-based Rhizophora spp. particleboard phantoms using computed tomography (CT) and treatment planning system (TPS) at high energy x-ray beams

    NASA Astrophysics Data System (ADS)

    Yusof, M. F. Mohd; Abdullah, R.; Tajuddin, A. A.; Hashim, R.; Bauk, S.

    2016-01-01

    A set of tannin-based Rhizophora spp. particleboard phantoms with dimension of 30 cm x 30 cm was fabricated at target density of 1.0 g/cm3. The mass attenuation coefficient of the phantom was measured using 60Co gamma source. The phantoms were scanned using Computed Tomography (CT) scanner and the percentage depth dose (PDD) of the phantom was calculated using treatment planning system (TPS) at 6 MV and 10 MV x-ray and compared to that in solid water phantoms. The result showed that the mass attenuation coefficient of tannin-based Rhizohora spp. phantoms was near to the value of water with χ2 value of 1.2. The measured PDD also showed good agreement with solid water phantom at both 6 MV and 10 MV x-ray with percentage deviation below 8% at depth beyond the maximum dose, Zmax.

  14. Attenuation properties and percentage depth dose of tannin-based Rhizophora spp. particleboard phantoms using computed tomography (CT) and treatment planning system (TPS) at high energy x-ray beams

    SciTech Connect

    Yusof, M. F. Mohd; Abdullah, R.; Tajuddin, A. A.; Hashim, R.; Bauk, S.

    2016-01-22

    A set of tannin-based Rhizophora spp. particleboard phantoms with dimension of 30 cm x 30 cm was fabricated at target density of 1.0 g/cm{sup 3}. The mass attenuation coefficient of the phantom was measured using {sup 60}Co gamma source. The phantoms were scanned using Computed Tomography (CT) scanner and the percentage depth dose (PDD) of the phantom was calculated using treatment planning system (TPS) at 6 MV and 10 MV x-ray and compared to that in solid water phantoms. The result showed that the mass attenuation coefficient of tannin-based Rhizohora spp. phantoms was near to the value of water with χ{sup 2} value of 1.2. The measured PDD also showed good agreement with solid water phantom at both 6 MV and 10 MV x-ray with percentage deviation below 8% at depth beyond the maximum dose, Z{sub max}.

  15. Dose to persons assisting voluntarily during X-ray examinations of large animals.

    PubMed

    Hupe, O; Ankerhold, U

    2008-01-01

    Pet owners often assist voluntarily while their pets are being X-rayed during a medical examination. Medical staff members occupationally exposed to radiation are monitored regularly, as they wear personal dosemeters, whereas no dose measurements are carried out on voluntarily assisting persons, as measurements are both cost- and time-intensive. However, the dose limits prescribed in the German radiation protection regulations have to be observed for these volunteers as well. To assist the legislator in deciding whether the German regulation should be changed so that in future the dose of voluntarily assisting persons should also be determined-either by wearing a dosemeter or in another way-investigations with regard to the radiation dose exposure suffered by volunteers were performed within the scope of a research project. The personal dose equivalent Hp(10) for persons assisting knowingly and willingly in X-ray examinations in veterinary medicine was measured for different examination scenarios. Typical exposure situations have been identified and measurements performed in the field of scattered X-rays. The measurements were carried out on animals in veterinary practices and, to verify these measurements, also under laboratory conditions. This paper deals with X-ray examinations of large animals, with the focus especially on horses. The measured personal dose equivalent values of voluntary helpers in equine radiology are in the order of a few microsieverts.

  16. Measurement of a wide-range of X-ray doses using specialty doped silica fibres

    NASA Astrophysics Data System (ADS)

    Abdul Sani, S. F.; Hammond, R.; Jafari, S. M.; Wahab, Norfadira; Amouzad Mahdiraji, G.; Siti Shafiqah, A. S.; Abdul Rashid, H. A.; Maah, M. J.; Aldousari, H.; Alkhorayef, M.; Alzimami, M.; Bradley, D. A.

    2017-08-01

    Using six types of tailor-made doped optical fibres, we carry out thermoluminescent (TL) studies of X-rays, investigating the TL yield for doses from 20 mGy through to 50 Gy. Dosimetric parameters were investigated for nominal 8 wt% Ge doped fibres that in two cases were co-doped, using B in one case and Br in the other. A comparative measurement of surface analysis has also been made for non-annealed and annealed capillary fibres, use being made of X-ray Photoelectron Spectroscopy (XPS) analysis. Comparison was made with the conventional TL phosphor LiF in the form of the proprietary product TLD-100, including dose response and glow curves investigated for X-rays generated at 60 kVp over a dose range from 2 cGy to 50 Gy. The energy response of the fibres was also performed for X-rays generated at peak accelerating potentials of 80 kVp, 140 kVp, 250 kVp and 6 MV photons for an absorbed dose of 2 Gy. Present results show the samples to be suitable for use as TL dosimeters, with good linearity of response and a simple glow curve (simple trap) distribution. It has been established that the TL performance of an irradiated fibre is not only influenced by radiation parameters such as energy, dose-rate and total dose but also the type of fibre.

  17. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy

    PubMed Central

    Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

    2015-01-01

    The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (−50 to −6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

  18. Refractive optical elements and optical system for high energy x-ray microscopy

    SciTech Connect

    Simon, M.; Altapova, V.; Baumbach, T.; Kluge, M.; Last, A.; Marschall, F.; Mohr, J.; Nazmov, V.; Vogt, H.

    2012-05-17

    In material science, X-ray radiation with photon energies above 25 keV is used because of its penetration into high density materials. Research of the inner structure of novel materials, such as electrodes in high power batteries for engines, require X-ray microscopes operating in the hard X-ray energy range. A flexible X-ray microscope for hard X-rays with photon energies higher than 25 keV will be realized at the synchrotron source ANKA in Karlsruhe, Germany. The device will use refractive X-ray lenses as condenser as well as objective lenses.

  19. Masks for high aspect ratio x-ray lithography

    SciTech Connect

    Malek, C.K.; Jackson, K.H.; Bonivert, W.D.; Hruby, J.

    1997-04-01

    Fabrication of very high aspect ratio microstructures, as well as ultra-high precision manufacturing is of increasing interest in a multitude of applications. Fields as diverse as micromechanics, robotics, integrated optics, and sensors benefit from this technology. The scale-length of this spatial regime is between what can be achieved using classical machine tool operations and that which is used in microelectronics. This requires new manufacturing techniques, such as the LIGA process, which combines x-ray lithography, electroforming, and plastic molding.

  20. Effects of low-dose X-ray irradiation of eggshells on radical production.

    PubMed

    Nakagawa, K

    2014-06-01

    We investigated effects of low-dose X-ray irradiation on eggshells radical production. Eggshells irradiated by low-dose X-ray produced stable radicals. The stable radicals at the central region of the spectrum are the carbonates and CO2(•-) signals. The electron spin resonance (ESR) signals increase with increasing absorbed dose. The estimated radical concentration (spin number) was approximately 3.6 × 10(12) (spins/g) at 10-Gy dose using various known concentrations of TEMPOL (4-hydroxy-2, 2, 6, 6-tretramethylpiperidin-1-oxyl) aqueous solutions. The stable radicals in irradiated eggshells were recognized at the low-level dose (0.10 Gy). In addition, no significant dose rate (0.5-1.5 Gy/min) dependence was found for the radical production.

  1. High resolution x-ray scattering and diffraction

    SciTech Connect

    Moncton, D.

    1983-01-01

    In the general class of high resolution x-ray scattering studies experiments one analyzes the distribution of photon energies and wave vectors resulting from illumination of a sample with collimated monochromatic radiation. Applications abound in the field of structural physics, which may be described as the study of structures for their intrinsic physical interest. This includes studies of novel states of matter, phase transitions, and dynamics. As both the wave vector and the energy of scattered photons are of interest, one may conceptually divide high resolution experimental setups for this work into two classes: those with high Q-resolution (momemtum transfer analysis) and those with high E-resolution (energy transfer analysis). The former class is exemplified by the existing experimental station on SSRL wiggler experimental station VII-2 and the proposed high Q-resolution wiggler station for NSLS Phase II. The latter class is dependent on extremely high flux, as discussed more fully below, and the possibility of constructing a high E-resolution scattering station fed by an x-ray undulator is one of the exciting opportunities presented by the proposed construction of a 6 GeV storage ring.

  2. X-ray tube current modulation and patient doses in chest CT.

    PubMed

    He, Wenjun; Huda, Walter; Magill, Dennise; Tavrides, Emily; Yao, Hai

    2011-01-01

    The aim of the study was to investigate how patient effective doses vary as a function of X-ray tube projection angle, as well as the patient long axis, and quantify how X-ray tube current modulation affects patient doses in chest CT examinations. Chest examinations were simulated for a gantry CT scanner geometry with projections acquired for a beam width of 4 cm. PCXMC 2.0.1 was used to calculate patient effective doses at 15° intervals around the patient's isocentre, and at nine locations along the patient long axis. Idealised tube current modulation schemes were modelled as a function of the X-ray tube angle and the patient long axis. Tube current modulations were characterised by the modulation amplitude R, which was allowed to vary between 1.5 and 5. Effective dose maxima occur for anteroposterior projections at the location of the (radiosensitive) breasts. The maximum to minimum ratio of effective doses as a function of the patient long axis was 4.9, and as a function of the X-ray tube angle was 2.1. Doubling the value of R reduces effective doses from longitudinal modulation alone by ∼4% and from angular modulation alone by ∼2%. In chest CT, tube current modulation schemes currently have longitudinal R values of ∼2.2, and angular R values that range between 1.5 and 3.4. Current X-ray tube current modulation schemes are expected to reduce patient effective doses in chest CT examinations by ∼10%, with longitudinal modulation accounting for two-thirds and angular modulation for the remaining one-third.

  3. High resolution near edge x-ray spectroscopy

    SciTech Connect

    Haemaelaeinen, K.; Siddons, D.P.; Berman, L.E.; Kao, C.C.; Hastings, J.B.

    1992-12-01

    A technique to suppress the core-hole lifetime broadening in near- edge x-ray spectroscopy is presented. A simple theoretical explanation based on total energy conservation in the fluorescence process is given to explain the improved resolution. The experimental arrangement is shown together with an application to the L{sub III} edge of dysprosium. Furthermore, the application of high-resolution fluorescence spectroscopy in the study of magnetism is presented. The spin-resolved absorption spectra from MnF{sub 2} are shown as an example.

  4. High resolution near edge x-ray spectroscopy

    SciTech Connect

    Haemaelaeinen, K.; Siddons, D.P.; Berman, L.E.; Kao, C.C.; Hastings, J.B.

    1992-01-01

    A technique to suppress the core-hole lifetime broadening in near- edge x-ray spectroscopy is presented. A simple theoretical explanation based on total energy conservation in the fluorescence process is given to explain the improved resolution. The experimental arrangement is shown together with an application to the L[sub III] edge of dysprosium. Furthermore, the application of high-resolution fluorescence spectroscopy in the study of magnetism is presented. The spin-resolved absorption spectra from MnF[sub 2] are shown as an example.

  5. X-RAY OBSERVATIONS OF HIGH-B RADIO PULSARS

    SciTech Connect

    Olausen, S. A.; Kaspi, V. M.; Zhu, W. W.; Vogel, J. K.; Lyne, A. G.; Espinoza, C. M.; Stappers, B. W.; Manchester, R. N.; McLaughlin, M. A.

    2013-02-10

    The study of high-magnetic-field pulsars is important for examining the relationships between radio pulsars, magnetars, and X-ray-isolated neutron stars (XINSs). Here, we report on X-ray observations of three such high-magnetic-field radio pulsars. We first present the results of a deep XMM-Newton observation of PSR J1734-3333, taken to follow up on its initial detection in 2009. The pulsar's spectrum is well fit by a blackbody with a temperature of 300 {+-} 60 eV, with bolometric luminosity L{sub bb}=2.0{sub -0.7}{sup +2.2} Multiplication-Sign 10{sup 32} erg s{sup -1}{approx}0.0036 E-dot for a distance of 6.1 kpc. We detect no X-ray pulsations from the source, setting a 1{sigma} upper limit on the pulsed fraction of 60% in the 0.5-3 keV band. We compare PSR J1734-3333 to other rotation-powered pulsars of similar age and find that it is significantly hotter, supporting the hypothesis that the magnetic field affects the observed thermal properties of pulsars. We also report on XMM-Newton and Chandra observations of PSRs B1845-19 and J1001-5939. We do not detect either pulsar, setting 3{sigma} upper limits on their blackbody temperatures of 48 and 56 eV, respectively. Despite the similarities in rotational properties, these sources are significantly cooler than all but one of the XINSs, which we attribute to the two groups having been born with different magnetic fields and hence evolving differently.

  6. X-Ray Observations of High-B Radio Pulsars

    NASA Astrophysics Data System (ADS)

    Olausen, S. A.; Zhu, W. W.; Vogel, J. K.; Kaspi, V. M.; Lyne, A. G.; Espinoza, C. M.; Stappers, B. W.; Manchester, R. N.; McLaughlin, M. A.

    2013-02-01

    The study of high-magnetic-field pulsars is important for examining the relationships between radio pulsars, magnetars, and X-ray-isolated neutron stars (XINSs). Here, we report on X-ray observations of three such high-magnetic-field radio pulsars. We first present the results of a deep XMM-Newton observation of PSR J1734-3333, taken to follow up on its initial detection in 2009. The pulsar's spectrum is well fit by a blackbody with a temperature of 300 ± 60 eV, with bolometric luminosity L_{{bb}}=2.0_{-0.7}^{+2.2}× 10^{32} {erg s^{-1}}≈ 0.0036 \\dot{E} for a distance of 6.1 kpc. We detect no X-ray pulsations from the source, setting a 1σ upper limit on the pulsed fraction of 60% in the 0.5-3 keV band. We compare PSR J1734-3333 to other rotation-powered pulsars of similar age and find that it is significantly hotter, supporting the hypothesis that the magnetic field affects the observed thermal properties of pulsars. We also report on XMM-Newton and Chandra observations of PSRs B1845-19 and J1001-5939. We do not detect either pulsar, setting 3σ upper limits on their blackbody temperatures of 48 and 56 eV, respectively. Despite the similarities in rotational properties, these sources are significantly cooler than all but one of the XINSs, which we attribute to the two groups having been born with different magnetic fields and hence evolving differently.

  7. No threshold for the induction of chromosomal damage at clinically relevant low doses of X rays.

    PubMed

    Boei, Jan J W A; Vermeulen, Sylvia; Skubakova, Martina M; Meijers, Matty; Loenen, Wil A M; Wolterbeek, Ron; Mullenders, Leon H F; Vrieling, Harry; Giphart-Gassler, Micheline

    2012-05-01

    The recent steep increase in population dose from radiation-based medical diagnostics, such as computed tomography (CT) scans, requires insight into human health risks, especially in terms of cancer development. Since the induction of genetic damage is considered a prominent cause underlying the carcinogenic potential of ionizing radiation, we quantified the induction of micronuclei and loss of heterozygosity events in human cells after exposure to clinically relevant low doses of X rays. A linear dose-response relationship for induction of micronuclei was observed in human fibroblasts with significantly increased frequencies at doses as low as 20 mGy. Strikingly, cells exposed during S-phase displayed the highest induction, whereas non S-phase cells showed no significant induction below 100 mGy. Similarly, the induction of loss of heterozygosity in human lymphoblastoid cells quantified at HLA loci, was linear with dose and reached significance at 50 mGy. Together the findings favor a linear-no-threshold model for genetic damage induced by acute exposure to ionizing radiation. We speculate that the higher radiosensitivity of S-phase cells might relate to the excessive cancer risk observed in highly proliferative tissues in radiation exposed organisms.

  8. Soft x-ray transmission grating spectrometer for X-ray Surveyor and smaller missions with high resolving power

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alexander; Schattenburg, Mark; Kolodziejczak, jeffery; Gaskin, Jessica; O'Dell, Stephen L.

    2017-01-01

    A number of high priority subjects in astrophysics are addressed by a state-of-the-art soft x-ray grating spectrometer, e.g. the role of Active Galactic Nuclei in galaxy and star formation, characterization of the WHIM and the “missing baryon” problem, characterization of halos around the Milky Way and nearby galaxies, and stellar coronae and surrounding winds and disks. An Explorer-scale, large-area (A > 1,000 cm2), high resolving power (R > 3,000) soft x-ray grating spectrometer is highly feasible based on Critical-Angle Transmission (CAT) grating technology, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance could be provided by a CAT grating spectrometer on an X-ray-Surveyor-type mission (A > 4,000 cm2, R > 5,000). CAT gratings combine advantages of blazed reflection gratings (high efficiency, use of higher orders) with those of transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies) with minimal mission resource requirements. Blazing is achieved through grazing-incidence reflection off the smooth silicon grating bar sidewalls. Silicon is well matched to the soft x-ray band, and 30% absolute diffraction efficiency has been acheived with clear paths for further improvement. CAT gratings with sidewalls made of high-Z elements allow extension of blazing to higher energies and larger dispersion angles, enabling higher resolving power at shorter wavelengths. X-ray data from CAT gratings coated with a thin layer of platinum using atomic layer deposition demonstrate efficient blazing to higher energies and much larger blaze angles than possible with silicon alone. Measurements of the resolving power of a breadboard CAT grating spectrometer consisting of a Wolter-I slumped-glass focusing optic from GSFC and CAT gratings, taken at the MSFC Stray Light Facility, have demonstrated resolving power > 10,000. Thus currently fabricated CAT gratings are compatible

  9. Mutations induced in Tradescantia by small doses of X-rays and neutrons - Analysis of dose-response curves.

    NASA Technical Reports Server (NTRS)

    Sparrow, A. H.; Underbrink, A. G.; Rossi, H. H.

    1972-01-01

    Dose-response curves for pink somatic mutations in Tradescantia stamen hairs were analyzed after neutron and X-ray irradiation with doses ranging from a fraction of a rad to the region of saturation. The dose-effect relation for neutrons indicates a linear dependence from 0.01 to 8 rads; between 0.25 and 5 rads, a linear dependence is indicated for X-rays also. As a consequence the relative biological effectiveness reaches a constant value (about 50) at low doses. The observations are in good agreement with the predictions of the theory of dual radiation action and support its interpretation of the effects of radiation on higher organisms. The doubling dose of X-rays was found to be nearly 1 rad.

  10. Mutations induced in Tradescantia by small doses of X-rays and neutrons - Analysis of dose-response curves.

    NASA Technical Reports Server (NTRS)

    Sparrow, A. H.; Underbrink, A. G.; Rossi, H. H.

    1972-01-01

    Dose-response curves for pink somatic mutations in Tradescantia stamen hairs were analyzed after neutron and X-ray irradiation with doses ranging from a fraction of a rad to the region of saturation. The dose-effect relation for neutrons indicates a linear dependence from 0.01 to 8 rads; between 0.25 and 5 rads, a linear dependence is indicated for X-rays also. As a consequence the relative biological effectiveness reaches a constant value (about 50) at low doses. The observations are in good agreement with the predictions of the theory of dual radiation action and support its interpretation of the effects of radiation on higher organisms. The doubling dose of X-rays was found to be nearly 1 rad.

  11. High duty cycle inverse Compton scattering X-ray source

    DOE PAGES

    Ovodenko, A.; Agustsson, R.; Babzien, M.; ...

    2016-12-22

    Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this article reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5-more » and 15- pulses per train and compared to a single pulse operation under the same operating conditions. Lastly, with the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.« less

  12. X-Ray Diagnostics of CUEBIT Highly Charged Ion Plasma

    NASA Astrophysics Data System (ADS)

    Silwal, Roshani; Gall, Amy; Sosolik, Chad; Harriss, James; Takacs, Endre

    2015-05-01

    Clemson University Electron Beam Ion Trap (CUEBIT) is one of the few EBIT facilities around the globe that produces highly charged ions by successive electron impact ionization. Ions are confined in the machine by the space-charge of the electron beam, a 6 T magnetic field generated by a superconducting magnet, and the voltages applied to axial electrodes. The device is a small laboratory scale instrument for the study of the structure and emission of highly charged ions and the collisions of these ions with external targets. Along with the introduction of the facility including its structure and capabilities, we present an overview of various spectroscopic and imaging tools that allow the diagnosis of the high temperature ion cloud of the CUEBIT. Instruments include a crystal spectrometer, solid-state detectors, and pin-hole imaging setup equipped with an x-ray CCD camera. Measurements of x-ray radiation from CUEBIT are used to investigate the fundamental properties of the highly charged ions and their interaction with the energetic electron beam.

  13. High duty cycle inverse Compton scattering X-ray source

    SciTech Connect

    Ovodenko, A.; Agustsson, R.; Babzien, M.; Campese, T.; Fedurin, M.; Murokh, A.; Pogorelsky, I.; Polyanskiy, M.; Rosenzweig, J.; Sakai, Y.; Shaftan, T.; Swinson, C.

    2016-12-22

    Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this article reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5- and 15- pulses per train and compared to a single pulse operation under the same operating conditions. Lastly, with the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.

  14. Soft x-ray-controlled dose deposition in yeast cells: techniques, model, and biological assessment

    NASA Astrophysics Data System (ADS)

    Milani, Marziale; Batani, Dimitri; Conti, Aldo; Masini, Alessandra; Costato, Michele; Pozzi, Achille; Turcu, I. C. Edmond

    1996-12-01

    A procedure is presented to release soft x-rays onto yeast cell membrane allegedly damaging the resident enzymatic processes connected with fermentation. The damage is expected to be restricted to regulating fermentation processes without interference with respiration. By this technique fermentation is followed leading to CO2 production, and respiration resulting in global pressure measurements. A solid state pressure sensor system has been developed linked to a data acquisition system. Yeast cells cultures have been investigated at different concentrations and with different nutrients. A non-monotone response in CO2 production as a function of the delivered x-ray dose is observed.

  15. Active x-ray optics for Generation-X, the next high resolution x-ray observatory

    NASA Astrophysics Data System (ADS)

    Elvis, Martin; Brissenden, R. J.; Fabbiano, G.; Schwartz, D. A.; Reid, P.; Podgorski, W.; Eisenhower, M.; Juda, M.; Phillips, J.; Cohen, L.; Wolk, S.

    2006-06-01

    X-rays provide one of the few bands through which we can study the epoch of reionization, when the first galaxies, black holes and stars were born. To reach the sensitivity required to image these first discrete objects in the universe needs a major advance in X-ray optics. Generation-X (Gen-X) is currently the only X-ray astronomy mission concept that addresses this goal. Gen-X aims to improve substantially on the Chandra angular resolution and to do so with substantially larger effective area. These two goals can only be met if a mirror technology can be developed that yields high angular resolution at much lower mass/unit area than the Chandra optics, matching that of Constellation-X (Con-X). We describe an approach to this goal based on active X-ray optics that correct the mid-frequency departures from an ideal Wolter optic on-orbit. We concentrate on the problems of sensing figure errors, calculating the corrections required, and applying those corrections. The time needed to make this in-flight calibration is reasonable. A laboratory version of these optics has already been developed by others and is successfully operating at synchrotron light sources. With only a moderate investment in these optics the goals of Gen-X resolution can be realized.

  16. X-ray emission from star-forming galaxies - I. High-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Mineo, S.; Gilfanov, M.; Sunyaev, R.

    2012-01-01

    Based on a homogeneous set of X-ray, infrared and ultraviolet observations from Chandra, Spitzer, GALEX and 2MASS archives, we study populations of high-mass X-ray binaries (HMXBs) in a sample of 29 nearby star-forming galaxies and their relation to the star-formation rate (SFR). In agreement with previous results, we find that HMXBs are a good tracer of the recent star-formation activity in the host galaxy and their collective luminosity and number scale with the SFR: in particular, ?. However, the scaling relations still bear a rather large dispersion of rms ˜ 0.4 dex, which we believe is of a physical origin. We present the catalogue of 1055 X-ray sources detected within the D25 ellipse for galaxies of our sample and construct the average X-ray luminosity function (XLF) of HMXBs with substantially improved statistical accuracy and better control of systematic effects than achieved in previous studies. The XLF follows a power law with a slope of 1.6 in the log (LX) ˜ 35-40 luminosity range with moderately significant evidence for a break or cut-off at LX˜ 1040 erg s-1. As before, we did not find any features at the Eddington limit for a neutron star or a stellar-mass black hole. We discuss the implications of our results for the theory of binary evolution. In particular we estimate the fraction of compact objects that once in their lifetime experienced an X-ray active phase powered by accretion from a high-mass companion and obtain a rather large number, fX˜ 0.2 × (0.1 Myr/τX), where τX is the lifetime of the X-ray active phase. This is ˜4 orders of magnitude more frequent than in low-mass X-ray binaries (LMXBs). We also derive constraints on the mass distribution of the secondary star in HMXBs.

  17. High Resolution X-Ray Phase Contrast Imaging With Acoustic Tissue-Selective Contrast Enhancement

    DTIC Science & Technology

    2006-06-01

    microfocus x - ray source. Rev. Sci. Instr. 68, 2774 (1997). 8. Krol, A. et al. Laser-based microfocused x - ray source for mammography: Feasibility study...W81XWH-04-1-0481 TITLE: High Resolution X - ray Phase Contrast Imaging With Acoustic Tissue-Selective Contrast Enhancement PRINCIPAL...REPORT TYPE Annual 3. DATES COVERED (From - To) 1 Jun 2005 – 31 May 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER High Resolution X - ray

  18. Absorbed Dose Determination Using Experimental and Analytical Predictions of X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Edwards, D. L.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the U.S. Space Shuttle. This series of experiments was named the international space welding experiment (ISWE). The hardware associated with the ISWE was leased to NASA by the Paton Welding Institute (PWI) in Ukraine for ground-based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used thermoluminescence dosimeters (TLD's) shielded with material currently used by astronauts during extravehicular activities to measure the radiation dose. The TLD's were exposed to x-ray radiation generated by operation of the ISWE in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure, then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the ISWE in-vacuum electron beam welding tool. The calculated absorbed dose

  19. X-ray dose from pediatric cardiac catheterization: a comparison of materials and methods for measurement or calculation.

    PubMed

    Herron, Brent; Strain, John; Fagan, Thomas; Wright, Linda; Shockley, Heather

    2010-11-01

    Pediatric cardiac catheterization procedures have the potential to transmit high X-ray doses, which may lead to acute effects or latent skin reactions. Direct measurement of radiation dose was facilitated using nanodot dosimeters and radiochromic film. Direct measurement results were compared with vendor-listed dosimetry and calculation using phantom data. Vendor-listed data demonstrated a wide discrepancy with measured data, whereas the calculation reproducibly overestimated the actual dose. A simple formula was derived to calculate the dose using fluoroscopy time, cine frame quantity and average cine mA in a biplane environment.

  20. Dose, exposure time, and resolution in Serial X-ray Crystallography

    SciTech Connect

    Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N; Fromme, P; Schmidt, K; Weierstall, U; Doak, R B; Spence, J C

    2007-03-22

    Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.

  1. Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy

    SciTech Connect

    Kojima, Sadaoki E-mail: sfujioka@ile.osaka-u.ac.jp; Ikenouchi, Takahito; Arikawa, Yasunobu; Sakata, Shohei; Zhang, Zhe; Abe, Yuki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke E-mail: sfujioka@ile.osaka-u.ac.jp; Azechi, Hiroshi; Ozaki, Tetsuo; Miyamoto, Shuji; Yamaguchi, Masashi; Takemoto, Akinori

    2016-04-15

    Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10{sup 13} photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO{sub 2} converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.

  2. Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy.

    PubMed

    Kojima, Sadaoki; Ikenouchi, Takahito; Arikawa, Yasunobu; Sakata, Shohei; Zhang, Zhe; Abe, Yuki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Ozaki, Tetsuo; Miyamoto, Shuji; Yamaguchi, Masashi; Takemoto, Akinori; Fujioka, Shinsuke; Azechi, Hiroshi

    2016-04-01

    Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10(13) photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO2 converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.

  3. High-Resolution Detector For X-Ray Diffraction

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Withrow, William K.; Pusey, Marc L.; Yost, Vaughn H.

    1988-01-01

    Proposed x-ray-sensitive imaging detector offers superior spatial resolution, counting-rate capacity, and dynamic range. Instrument based on laser-stimulated luminescence and reusable x-ray-sensitive film. Detector scans x-ray film line by line. Extracts latent image in film and simultaneously erases film for reuse. Used primarily for protein crystallography. Principle adapted to imaging detectors for electron microscopy and fluorescence spectroscopy and general use in astronomy, engineering, and medicine.

  4. The integral dose in panoramic intraoral x-ray tube radiography

    SciTech Connect

    Hayami, A.; Fujishita, M.; Sumida, A.; Kanke, M.; Fujiki, T.; Uemura, S.; Fuchihata, H.

    1983-07-01

    A Monte Carlo computer program was developed to estimate the integral dose to the head and thyroid for panoramic intraoral x-ray tube radiography. The advantage of this computer simulation is that it is able to avoid many of the difficulties associated with low-energy and low-dose x-ray dosimetry. The calculations were made for maxillary and mandibular projections separately, using 10 kv. increments between 40 and 60 kv. The results obtained were presented in terms of the integral dose per milliampere second. Typical integral doses for a routine examination of the head are 2.1 mJ. and 8.5 microJ for the thyroid during mandibular radiography and 1.7 microJ for the thyroid during radiography of the maxilla using 55 kv. and 0.5 mAs.

  5. High resolution millimeter & X-ray view of NGC6240

    NASA Astrophysics Data System (ADS)

    Feruglio, Chiara

    2012-09-01

    In the last two years, finally AGN-driven massive outflows have been seen in molecular gas in several local QSOs/ULIRGs and mergers, and they start to be found in a few high redshift galaxies. These observational results show that outflows can invest the bulk of the gas in galaxies, supporting models of AGN and galaxy co-evolution. Molecular outflows are therefore regarded as the long sought mechanism leading to the formation of red passive galaxies, deprived of gas. We present new sensitive interferometric observations of CO(1-0) in NGC 6240, plus a spatially resolved re-analysis of Chandra X-ray data, showing a molecular outflow associated with X-ray emitting, shocked gas. NGC6240 is the prototypical example of a major galaxy merger in progress, caught at an early stage, with an extended, strongly- disturbed butterfly-like morphology and the presence of a heavily obscured active nucleus in the core of each progenitor galaxy. We discuss the powering mechanism of such outflow in relation with the transformations ongoing in this system.

  6. X-ray Diffraction Study of Arsenopyrite at High Pressure

    SciTech Connect

    D Fan; M Ma; W Zhou; S Wei; Z Chen; H Xie

    2011-12-31

    The high-pressure X-ray diffraction study of a natural arsenopyrite was investigated up to 28.2 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at National Synchrotron Light Source, Brookhaven National Laboratory. The 16:3:1 methanol-ethanol-water mixture was used as a pressure-transmitting medium. Pressures were measured using the ruby-fluorescence method. No phase change has been observed up to 28.2 GPa. The isothermal equation of state (EOS) was determined. The values of K{sub 0}, and K'{sub 0} refined with a third-order Birch-Murnaghan EOS are K{sub 0} = 123(9) GPa, and K'{sub 0} = 5.2(8). Furthermore, we confirm that the linear compressibilities ({beta}) along a, b and c directions of arsenopyrite is elastically isotropic ({beta}{sub a} = 6.82 x 10{sup -4}, {beta}{sub b} = 6.17 x 10{sup -4} and {beta}{sub c} = 6.57 x 10{sup -4} GPa{sup -1}).

  7. X-ray diffraction study of arsenopyrite at high pressure

    NASA Astrophysics Data System (ADS)

    Fan, D. W.; Ma, M. N.; Zhou, W. G.; Wei, S. Y.; Chen, Z. Q.; Xie, H. S.

    2011-02-01

    The high-pressure X-ray diffraction study of a natural arsenopyrite was investigated up to 28.2 GPa using in situ angle-dispersive X-ray diffraction and a diamond anvil cell at National Synchrotron Light Source, Brookhaven National Laboratory. The 16:3:1 methanol-ethanol-water mixture was used as a pressure-transmitting medium. Pressures were measured using the ruby-fluorescence method. No phase change has been observed up to 28.2 GPa. The isothermal equation of state (EOS) was determined. The values of K 0, and K' 0 refined with a third-order Birch-Murnaghan EOS are K 0 = 123(9) GPa, and K' 0 = 5.2(8). Furthermore, we confirm that the linear compressibilities (β) along a, b and c directions of arsenopyrite is elastically isotropic (β a = 6.82 × 10-4, β b = 6.17 × 10-4 and β c = 6.57 × 10-4 GPa-1).

  8. The X-ray properties of high redshift, optically selected QSOs. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Anderson, S. F.

    1985-01-01

    In order to study the X-ray properties of high redshift QSOs, grism/grens plates covering 17 deg. of sky previously imaged to very sensitive X-ray flux levels with the Einstein Observatory were taken. Following optical selection of the QSO, the archived X-ray image is examined to extract an X-ray flux detection or a sensitive upper limit.

  9. The ultrafast high-peak power lasers in future biomedical and medical x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kieffer, J. C.; Fourmaux, S.; Krol, A.

    2016-01-01

    This paper reviews recent progresses in ultrafast laser-based X-ray sources and their potential applications to high throughput X-ray imaging. Prospects for the utilization of X-rays sources related to the Laser Wakefield electron Acceleration (LWFA) are more specifically discussed with emphasis on application in diagnostic radiology.

  10. Dose properties of x-ray beams produced by laser-wakefield-accelerated electrons.

    PubMed

    Kainz, K K; Hogstrom, K R; Antolak, J A; Almond, P R; Bloch, C D

    2005-01-07

    Given that laser wakefield acceleration (LWFA) has been demonstrated experimentally to accelerate electron beams to energies beyond 25 MeV, it is reasonable to assess the ability of existing LWFA technology to compete with conventional radiofrequency linear accelerators in producing electron and x-ray beams for external-beam radiotherapy. We present calculations of the dose distributions (off-axis dose profiles and central-axis depth dose) and dose rates of x-ray beams that can be produced from electron beams that are generated using state-of-the-art LWFA. Subsets of an LWFA electron energy distribution were propagated through the treatment head elements (presuming an existing design for an x-ray production target and flattening filter) implemented within the EGSnrc Monte Carlo code. Three x-ray energy configurations (6 MV, 10 MV and 18 MV) were studied, and the energy width deltaE of the electron-beam subsets varied from 0.5 MeV to 12.5 MeV. As deltaE increased from 0.5 MeV to 4.5 MeV, we found that the off-axis and central-axis dose profiles for x-rays were minimally affected (to within about 3%), a result slightly different from prior calculations of electron beams broadened by scattering foils. For deltaE of the order of 12 MeV, the effect on the off-axis profile was of the order of 10%, but the central-axis depth dose was affected by less than 2% for depths in excess of about 5 cm beyond d(max). Although increasing deltaE beyond 6.5 MeV increased the dose rate at d(max) by more than 10 times, the absolute dose rates were about 3 orders of magnitude below those observed for LWFA-based electron beams at comparable energies. For a practical LWFA-based x-ray device, the beam current must be increased by about 4-5 orders of magnitude.

  11. The effects of x-ray beam hardening on detective quantum efficiency and radiation dose.

    PubMed

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

    2011-01-01

    The goal of this preliminary study was to investigate the effects of x-ray beam hardening on the detective quantum efficiency (DQE) and the radiation dose of an inline x-ray imaging system. The ability to decrease the risk of harmful radiation to the patient without compromising the detection capability would more effectively balance the tradeoff between image quality and radiation dose, and therefore benefit the fields of diagnostic x-ray imaging, especially mammography. The DQE and the average glandular dose were both calculated under the same experimental conditions for a range of beam hardening levels, corresponding to no added beam hardening and two thicknesses each of Rhodium (Rh) and Molybdenum (Mo) filters. The dose calculation results demonstrate a reduction of 15% to 24% for the range of beam hardening levels. The comparison of all quantities comprising the DQE exhibit very close correlation between the results obtained without added beam hardening to the results corresponding to the range of beam hardening levels. For the specific experimental conditions utilized in this preliminary study, the results are an indication that the use of beam hardening holds the potential to reduce the radiation dose without decreasing the performance of the system. Future studies will seek to apply this method in a clinical environment and perform a comprehensive image quality evaluation, in an effort to further evaluate the potential of beam hardening to balance the tradeoff between dose and image quality.

  12. X-RAY ABSORPTION OF HIGH-REDSHIFT QUASARS

    SciTech Connect

    Eitan, Assaf; Behar, Ehud E-mail: behar@physics.technion.ac.il

    2013-09-01

    The soft X-ray photoelectric absorption of high-z quasars has been known for two decades, but has no unambiguous astrophysical context. We construct the largest sample to date of 58 high-redshift quasars (z > 0.45) selected from the XMM-Newton archive based on a high photon count criterion (>1800). We measure the optical depth {tau} at 0.5 keV and find that 43% of the quasars show significant absorption. We aim to find which physical parameters of the quasars, e.g., redshift, radio luminosity, radio loudness, or X-ray luminosity, drive their observed absorption. We compare the absorption behavior with redshift with the pattern expected if the diffuse intergalactic medium (IGM) is responsible for the observed absorption. We also compare the absorption with a comparison sample of gamma-ray burst (GRB) X-ray afterglows. Although the z > 2 quasar opacity is consistent with diffuse IGM absorption, many intermediate-z (0.45 < z < 2) quasars are not sufficiently absorbed for this scenario, and are appreciably less absorbed than GRBs. Only 10/37 quasars at z < 2 are absorbed, and only 5/30 radio-quiet quasars are absorbed. We find a weak correlation between {tau} and z, and an even weaker correlation between {tau} and radio luminosity. These findings lead to the conclusion that although a diffuse IGM origin for the quasar absorption is unlikely, the optical depth does seem to increase with redshift, roughly as (1 + z){sup 2.2{+-}0.6}, tending to {tau} Almost-Equal-To 0.4 at high redshifts, similar to the high-z GRBs. This result can be explained by an ionized and clumpy IGM at z < 2, and a cold, diffuse IGM at higher redshift. If, conversely, the absorption occurs at the quasar, and owing to the steep L{sub x} {proportional_to}(1 + z){sup 7.1{+-}0.5} correlation in the present sample, the host column density scales as N{sub H}{proportional_to}L{sub x}{sup 0.7{+-}0.1}.

  13. Exposure to Low-Dose X-Ray Radiation Alters Bone Progenitor Cells and Bone Microarchitecture.

    PubMed

    Lima, Florence; Swift, Joshua M; Greene, Elisabeth S; Allen, Matthew R; Cunningham, David A; Braby, Leslie A; Bloomfield, Susan A

    2017-10-01

    Exposure to high-dose ionizing radiation during medical treatment exerts well-documented deleterious effects on bone health, reducing bone density and contributing to bone growth retardation in young patients and spontaneous fracture in postmenopausal women. However, the majority of human radiation exposures occur in a much lower dose range than that used in the radiation oncology clinic. Furthermore, very few studies have examined the effects of low-dose ionizing radiation on bone integrity and results have been inconsistent. In this study, mice were irradiated with a total-body dose of 0.17, 0.5 or 1 Gy to quantify the early (day 3 postirradiation) and delayed (day 21 postirradiation) effects of radiation on bone microarchitecture and bone marrow stromal cells (BMSCs). Female BALBc mice (4 months old) were divided into four groups: irradiated (0.17, 0.5 and 1 Gy) and sham-irradiated controls (0 Gy). Micro-computed tomography analysis of distal femur trabecular bone from animals at day 21 after exposure to 1 Gy of X-ray radiation revealed a 21% smaller bone volume (BV/TV), 22% decrease in trabecular numbers (Tb.N) and 9% greater trabecular separation (Tb.Sp) compared to sham-irradiated controls (P < 0.05). We evaluated the differentiation capacity of bone marrow stromal cells harvested at days 3 and 21 postirradiation into osteoblast and adipocyte cells. Osteoblast and adipocyte differentiation was decreased when cells were harvested at day 3 postirradiation but enhanced in cells isolated at day 21 postirradiation, suggesting a compensatory recovery process. Osteoclast differentiation was increased in 1 Gy irradiated BMSCs harvested at day 3 postirradiation, but not in those harvested at day 21 postirradiation, compared to controls. This study provides evidence of an early, radiation-induced decrease in osteoblast activity and numbers, as well as a later recovery effect after exposure to 1 Gy of X-rays, whereas osteoclastogenesis was enhanced. A better

  14. Modeling a superficial radiotherapy X-ray source for relative dose calculations.

    PubMed

    Johnstone, Christopher D; LaFontaine, Richard; Poirier, Yannick; Tambasco, Mauro

    2015-05-08

    The purpose of this study was to empirically characterize and validate a kilovoltage (kV) X-ray beam source model of a superficial X-ray unit for relative dose calculations in water and assess the accuracy of the British Journal of Radiology Supplement 25 (BJR 25) percentage depth dose (PDD) data. We measured central axis PDDs and dose profiles using an Xstrahl 150 X-ray system. We also compared the measured and calculated PDDs to those in the BJR 25. The Xstrahl source was modeled as an effective point source with varying spatial fluence and spectra. In-air ionization chamber measurements were made along the x- and y-axes of the X-ray beam to derive the spatial fluence and half-value layer (HVL) measurements were made to derive the spatially varying spectra. This beam characterization and resulting source model was used as input for our in-house dose calculation software (kVDoseCalc) to compute radiation dose at points of interest (POIs). The PDDs and dose profiles were measured using 2, 5, and 15 cm cone sizes at 80, 120, 140, and 150 kVp energies in a scanning water phantom using IBA Farmer-type ionization chambers of volumes 0.65 and 0.13 cc, respectively. The percent difference in the computed PDDs compared with our measurements range from -4.8% to 4.8%, with an overall mean percent difference and standard deviation of 1.5% and 0.7%, respectively. The percent difference between our PDD measurements and those from BJR 25 range from -14.0% to 15.7%, with an overall mean percent difference and standard deviation of 4.9% and 2.1%, respectively - showing that the measurements are in much better agreement with kVDoseCalc than BJR 25. The range in percent difference between kVDoseCalc and measurement for profiles was -5.9% to 5.9%, with an overall mean percent difference and standard deviation of 1.4% and 1.4%, respectively. The results demonstrate that our empirically based X-ray source modeling approach for superficial X-ray therapy can be used to accurately

  15. High-speed X-ray phase imaging and X-ray phase tomography with Talbot interferometer and white synchrotron radiation.

    PubMed

    Momose, Atsushi; Yashiro, Wataru; Maikusa, Hirohide; Takeda, Yoshihiro

    2009-07-20

    X-ray Talbot interferometry, which uses two transmission gratings, has the advantage that broad energy bandwidth x-rays can be used. We demonstrate the use of white synchrotron radiation for high-speed X-ray phase imaging and tomography in combination with an X-ray Talbot interferometer. The moiré fringe visibility over 20% was attained, enabling quantitative phase measurement. X-ray phase images with a frame rate of 500 f/s and an X-ray phase tomogram with a scan time of 0.5 s were obtained successfully. This result suggests a breakthrough for time-resolved three-dimensional observation of objects that weakly absorb X-rays, such as soft material and biological objects.

  16. Note: Studies on target placement in TE(111) cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose.

    PubMed

    Selvakumaran, T S; Baskaran, R; Singh, A K; Sista, V L S Rao

    2010-03-01

    X-ray source based on electron cyclotron resonance principle has been constructed using TE(111) cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE(111) cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W.

  17. Note: Studies on target placement in TE{sub 111} cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose

    SciTech Connect

    Selvakumaran, T. S.; Baskaran, R.; Singh, A. K.; Sista, V. L. S. Rao

    2010-03-15

    X-ray source based on electron cyclotron resonance principle has been constructed using TE{sub 111} cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE{sub 111} cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W.

  18. Novel Hybrid CMOS X-ray Detector Developments for Future Large Area and High Resolution X-ray Astronomy Missions

    NASA Astrophysics Data System (ADS)

    Falcone, Abe

    In the coming years, X-ray astronomy will require new soft X-ray detectors that can be read very quickly with low noise and can achieve small pixel sizes over a moderately large focal plane area. These requirements will be present for a variety of X-ray missions that will attempt to address science that was highly ranked by the 2010 Decadal Survey, including missions with science that overlaps with that of IXO and Athena, as well as other missions addressing science topics beyond those of IXO and Athena. An X-ray Surveyor mission was recently chosen by NASA for study by a Science & Technology Definition Team (STDT) so it can be considered as an option for an upcom-ing flagship mission. A mission such as this was endorsed by the NASA long term planning document entitled "Enduring Quests, Daring Visions," and a detailed description of one possible reali-zation of such a mission has been referred to as SMART-X, which was described in a recent NASA RFI response. This provides an example of a future mission concept with these requirements since it has high X-ray throughput and excellent spatial resolution. We propose to continue to modify current active pixel sensor designs, in particular the hybrid CMOS detectors that we have been working with for several years, and implement new in-pixel technologies that will allow us to achieve these ambitious and realistic requirements on a timeline that will make them available to upcoming X-ray missions. This proposal is a continuation of our program that has been work-ing on these developments for the past several years. The first 3 years of the program led to the development of a new circuit design for each pixel, which has now been shown to be suitable for a larger detector array. The proposed activity for the next four years will be to incorporate this pixel design into a new design of a full detector array (2k×2k pixels with digital output) and to fabricate this full-sized device so it can be thoroughly tested and

  19. High-sensitive computed tomography system using a silicon-PIN x-ray diode

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Sato, Yuich; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2012-10-01

    A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT system with a tube current of 1.91 mA was developed using a silicon-PIN X-ray diode (Si-PIN-XD). The Si-PIN-XD is a selected high-sensitive Si-PIN photodiode (PD) for detecting X-ray photons. X-ray photons are detected directly using the Si-PIN-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to differentiator with a time constant of 1 μs to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 1.91 mA and 100 kV, respectively, and gadolinium K-edge CT was carried out using filtered X-ray spectra with a peak energy of 52 keV.

  20. High resolution energy-sensitive digital X-ray

    DOEpatents

    Nygren, David R.

    1995-01-01

    An apparatus and method for detecting an x-ray and for determining the depth of penetration of an x-ray into a semiconductor strip detector. In one embodiment, a semiconductor strip detector formed of semiconductor material is disposed in an edge-on orientation towards an x-ray source such that x-rays From the x-ray source are incident upon and substantially perpendicular to the front edge of the semiconductor strip detector. The semiconductor strip detector is formed of a plurality of segments. The segments are coupled together in a collinear arrangement such that the semiconductor strip detector has a length great enough such that substantially all of the x-rays incident on the front edge of the semiconductor strip detector interact with the semiconductor material which forms the semiconductor strip detector. A plurality of electrodes are connected to the semiconductor strip detect or such that each one of the of semiconductor strip detector segments has at least one of the of electrodes coupled thereto. A signal processor is also coupled to each one of the electrodes. The present detector detects an interaction within the semiconductor strip detector, between an x-ray and the semiconductor material, and also indicates the depth of penetration of the x-ray into the semiconductor strip detector at the time of the interaction.

  1. High resolution energy-sensitive digital X-ray

    DOEpatents

    Nygren, D.R.

    1995-07-18

    An apparatus and method for detecting an x-ray and for determining the depth of penetration of an x-ray into a semiconductor strip detector. In one embodiment, a semiconductor strip detector formed of semiconductor material is disposed in an edge-on orientation towards an x-ray source such that x-rays from the x-ray source are incident upon and substantially perpendicular to the front edge of the semiconductor strip detector. The semiconductor strip detector is formed of a plurality of segments. The segments are coupled together in a collinear arrangement such that the semiconductor strip detector has a length great enough such that substantially all of the x-rays incident on the front edge of the semiconductor strip detector interact with the semiconductor material which forms the semiconductor strip detector. A plurality of electrodes are connected to the semiconductor strip detector such that each one of the semiconductor strip detector segments has at least one of the of electrodes coupled thereto. A signal processor is also coupled to each one of the electrodes. The present detector detects an interaction within the semiconductor strip detector, between an x-ray and the semiconductor material, and also indicates the depth of penetration of the x-ray into the semiconductor strip detector at the time of the interaction. 5 figs.

  2. Calibration of a High Resolution Soft X-ray Spectrometer

    SciTech Connect

    Dunn, J; Beiersdorfer, P; Brown, G V; Magee, E W

    2010-01-26

    A high resolution grating spectrometer (HRGS) with 2400 line/mm variable line spacing grating for the 10-50 {angstrom} wavelength range has been designed for laser-produced plasma experiments at the Lawrence Livermore National Laboratory (LLNL). The spectrometer has a large radius of curvature, R=44.3 m, is operated at a 2{sup o} grazing angle and can record high signal-to-noise spectra when used with a low-noise, cooled, charge-coupled device detector. The instrument can be operated with a 10-25 {micro}m wide slit to achieve the best spectral resolving power on laser plasma sources, approaching 2000, or in slitless mode with a small symmetrical emission source. Results will be presented for the spectral response of the spectrometer cross-calibrated at the LLNL Electron Beam Ion Trap facility using the broadband x-ray energy EBIT Calorimeter Spectrometer (ECS).

  3. High-resolution compact X-ray microscopy.

    PubMed

    Takman, P A C; Stollberg, H; Johansson, G A; Holmberg, A; Lindblom, M; Hertz, H M

    2007-05-01

    We demonstrate compact full-field soft X-ray transmission microscopy with sub 60-nm resolution operating at lambda= 2.48 nm. The microscope is based on a 100-Hz regenerative liquid-nitrogen-jet laser-plasma source in combination with a condenser zone plate and a micro-zone plate objective for high-resolution imaging onto a 2048 x 2048 pixel CCD detector. The sample holder is mounted in a helium atmosphere and allows imaging of both dry and wet specimens. The microscope design enables fast sample switching and the sample can be pre-aligned using a visible-light microscope. High-quality images can be acquired with exposure times of less than 5 min. We demonstrate the performance of the microscope using both dry and wet samples.

  4. Calibration of a High Resolution Soft X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Dunn, J.; Beiersdorfer, P.; Brown, G. V.; Magee, E. W.

    A high resolution grating spectrometer (HRGS) with 2400 line/mm variable line spacing grating for the 10 - 50 Å wavelength range has been designed for laser—produced plasma experiments at the Lawrence Livermore National Laboratory (LLNL). The spectrometer has a large radius of curvature, R=44.3 m, is operated at a 2° grazing angle and can record high signal-to-noise spectra when used with a low-noise, cooled, charge-coupled device detector. The instrument can be operated with a 10 - 25 μm wide slit to achieve the best spectral resolving power on laser plasma sources, approaching 2000, or in slitless mode with a small symmetrical emission source. Results will be presented for the spectral response of the spectrometer cross-calibrated at the LLNL Electron Beam Ion Trap facility using the broadband x-ray energy EBIT Calorimeter Spectrometer (ECS).

  5. 30-lens interferometer for high energy x-rays

    SciTech Connect

    Lyubomirskiy, M. Snigireva, I. Vaughan, G.; Kohn, V.; Kuznetsov, S.; Yunkin, V.; Snigirev, A.

    2016-07-27

    We report a hard X-ray multilens interferometer consisting of 30 parallel compound refractive lenses. Under coherent illumination each CRL creates a diffraction limited focal spot - secondary source. An overlapping of coherent beams from these sources resulting in the interference pattern which has a rich longitudinal structure in accordance with the Talbot imaging formalism. The proposed interferometer was experimentally tested at ID11 ESRF beamline for the photon energies 32 keV and 65 keV. The fundamental and fractional Talbot images were recorded with the high resolution CCD camera. An effective source size in the order of 15 µm was determined from the first Talbot image proving that the multilens interferometer can be used as a high resolution beam diagnostic tool.

  6. Fabricating High-Resolution X-Ray Collimators

    NASA Technical Reports Server (NTRS)

    Appleby, Michael; Atkinson, James E.; Fraser, Iain; Klinger, Jill

    2008-01-01

    A process and method for fabricating multi-grid, high-resolution rotating modulation collimators for arcsecond and sub-arcsecond x-ray and gamma-ray imaging involves photochemical machining and precision stack lamination. The special fixturing and etching techniques that have been developed are used for the fabrication of multiple high-resolution grids on a single array substrate. This technology has application in solar and astrophysics and in a number of medical imaging applications including mammography, computed tomography (CT), single photon emission computed tomography (SPECT), and gamma cameras used in nuclear medicine. This collimator improvement can also be used in non-destructive testing, hydrodynamic weapons testing, and microbeam radiation therapy.

  7. 30-Lens interferometer for high-energy X-rays.

    PubMed

    Lyubomirskiy, Mikhail; Snigireva, Irina; Kohn, Victor; Kuznetsov, Sergey; Yunkin, Vyacheslav; Vaughan, Gavin; Snigirev, Anatoly

    2016-09-01

    A novel high-energy multi-lens interferometer consisting of 30 arrays of planar compound refractive lenses is reported. Under coherent illumination each lens array creates a diffraction-limited secondary source. Overlapping such coherent beams produces an interference pattern demonstrating strong longitudinal functional dependence. The proposed multi-lens interferometer was tested experimentally at the 100 m-long ID11 ESRF beamline in the X-ray energy range from 30 to 65 keV. The interference pattern generated by the interferometer was recorded at fundamental and fractional Talbot distances. An effective source size (FWHM) of the order of 15 µm was determined from the first Talbot image, proving the concept that the multi-lens interferometer can be used as a high-resolution tool for beam diagnostics.

  8. X-ray emission from high temperature plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.

    1974-01-01

    X-rays from a 25-hJ plasma focus apparatus were observed with pinhole cameras. The cameras consist of 0.4 mm diameter pinholes in 2 cm thick lead housing enclosing an X-ray intensifying screen at the image plane. Pictures recorded through thin aluminum foils or plastic sheets for X-ray energies sub gamma smaller than 15 keV show distributed X-ray emissions from the focussed plasma and from the anode surface. However, when thick absorbers are used, radial filamentary structure in the X-ray emission from the anode surface is revealed. Occasionally larger structures are observed in addition to the filaments. Possible mechanisms for the filamentary structure are discussed.

  9. Theoretical Calculations and Simulations of Interaction of X-Rays with High-Z Nanomoities for Use in Cancer Radiotherapy

    NASA Astrophysics Data System (ADS)

    Lim, Sara N.; Pradhan, Anil K.; Nahar, Sultana N.

    2013-06-01

    When used with X-ray radiotherapy, heavy elements (high atomic number Z or HZ) such as gold(Au) and platinum(Pt) have the potential to greatly sensitize and enhance the damage to tumor tissues. While HZ radiosensitization has been shown to be higly effective in reducing tumor sizes, much work still needs to be done to determine the ideal X-ray energy/energy spectrum. The likelihood of photoelectric absorption of X-rays that result in the production of cell-killing Auger electrons relative to the photon scatter in an HZ sensitized tumor has to be determined for treatments using X-rays from various sources and energies to assess their efficacy. In this report, we present computations that outline the dependence of photoelectric absorption on X-ray energy. The relative X-ray absorption by a radiosensitized tumor was calculated to contrast the efficacy of different X-ray sources in Auger electron production at different tumor depths. Enhanced photoabsorption of low-energy X-rays from broadband sources in the keV range is shown to be much higher than from those in the MeV range. In addition, with the use of the Monte Carlo code package Geant4, we present the total X-ray energy deposited into a radiosensitized tumor located at different depths in a phantom. The enhancement in radiation dose deposition will also be analysed at the microscopic cellular level to determine the HZ radiosensitizer concentration required. Potential use of monochromatic X-rays for more precise HZ radiosensitization will also be described.

  10. Adjustment function among antioxidant substances in acatalasemic mouse brain and its enhancement by low-dose X-ray irradiation.

    PubMed

    Yamaoka, Kiyonori; Nomura, Takaharu; Wang, Da-Hong; Mori, Shuji; Taguchi, Takehito; Ishikawa, Tetsuya; Hanamoto, Katsumi; Kira, Shohei

    2002-01-01

    The catalase activities in blood and organs of the acatalasemic (C3H/AnLCsbCsb) mouse of the C3H strain are lower than those of the normal (C3H/AnLCsaCsa) mouse. We conducted a study to examine changes in the activities of antioxidant enzymes, such as catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPX), the total gluathione content, and the lipid peroxide level in the brain, which is more sensitive to oxidative stress than other organs, at 3, 6, or 24 hr following X-ray irradiation at doses of 0.25, 0.5, or 5.0 Gy to the acatalasemic and the normal mice. No significant change in the lipid peroxide level in the acatalasemic mouse brain was seen under non-irradiation conditions. However, the acatalasemic mouse brain was more damaged than the normal mouse brain by excessive oxygen stress, such as a high-dose (5.0 Gy) X-ray. On the other hand, we found that, unlike 5.0 Gy X-ray, a relatively low-dose (0.5 Gy) irradiation specifically increased the activities of both catalase and GPX in the acatalasemic mouse brain making the activities closer to those in the normal mouse brain. These findings may indicate that the free radical reaction induced by the lack of catalase is more properly neutralized by low dose irradiation.

  11. Nonlinear Sinogram Smoothing for Low-Dose X-Ray CT

    NASA Astrophysics Data System (ADS)

    Li, Tianfang; Li, Xiang; Wang, Jing; Wen, Junhai; Lu, Hongbing; Hsieh, Jiang; Liang, Zhengrong

    2004-10-01

    When excessive quantum noise is present in extremely low dose X-ray CT imaging, statistical properties of the data has to be considered to achieve a satisfactory image reconstruction. Statistical iterative reconstruction with accurate modeling of the noise, rather than a filtered back-projection (FBP) with low-pass filtering, is one way to deal with the problem. Estimating a noise-free sinogram to satisfy the FBP reconstruction for the Radon transform is another way. The benefits of the latter include a higher computation efficiency, more uniform spatial resolution in the reconstructed image, and less modification of the current machine configurations. In a clinic X-ray CT system, the acquired raw data must be calibrated, in addition to the logarithmic transform, to achieve the high diagnostic image quality. The calibrated projection data or sinogram no longer follow a compound Poisson distribution in general, but are close to a Gaussian distribution with signal-dependent variance. In this paper, we first investigated a relatively accurate statistical model for the sinogram data, based on several phantom experiments. Then we developed a penalized likelihood method to smooth the sinogram, which led to a set of nonlinear equations that can be solved by iterated conditional mode (ICM) algorithm within a reasonable computing time. The method was applied to several experimental datasets acquired at 120 kVp, 10 mA/20 mA/50 mA protocols with a GE HiSpeed multi-slice detector CT scanner and demonstrated a significant noise suppression without noticeable sacrifice of the spatial resolution.

  12. Patient size and x-ray technique factors in head computed tomography examinations. I. Radiation doses.

    PubMed

    Huda, Walter; Lieberman, Kristin A; Chang, Jack; Roskopf, Marsha L

    2004-03-01

    We investigated how patient age, size and composition, together with the choice of x-ray technique factors, affect radiation doses in head computed tomography (CT) examinations. Head size dimensions, cross-sectional areas, and mean Hounsfield unit (HU) values were obtained from head CT images of 127 patients. For radiation dosimetry purposes patients were modeled as uniform cylinders of water. Dose computations were performed for 18 x 7 mm sections, scanned at a constant 340 mAs, for x-ray tube voltages ranging from 80 to 140 kV. Values of mean section dose, energy imparted, and effective dose were computed for patients ranging from the newborn to adults. There was a rapid growth of head size over the first two years, followed by a more modest increase of head size until the age of 18 or so. Newborns have a mean HU value of about 50 that monotonically increases with age over the first two decades of life. Average adult A-P and lateral dimensions were 186+/-8 mm and 147+/-8 mm, respectively, with an average HU value of 209+/-40. An infant head was found to be equivalent to a water cylinder with a radius of approximately 60 mm, whereas an adult head had an equivalent radius 50% greater. Adult males head dimensions are about 5% larger than for females, and their average x-ray attenuation is approximately 20 HU greater. For adult examinations performed at 120 kV, typical values were 32 mGy for the mean section dose, 105 mJ for the total energy imparted, and 0.64 mSv for the effective dose. Increasing the x-ray tube voltage from 80 to 140 kV increases patient doses by about a factor of 5. For the same technique factors, mean section doses in infants are 35% higher than in adults. Energy imparted for adults is 50% higher than for infants, but infant effective doses are four times higher than for adults. CT doses need to take into account patient age, head size, and composition as well as the selected x-ray technique factors.

  13. Low-Dose CT of the Paranasal Sinuses: Minimizing X-Ray Exposure with Spectral Shaping.

    PubMed

    Wuest, Wolfgang; May, Matthias; Saake, Marc; Brand, Michael; Uder, Michael; Lell, Michael

    2016-11-01

    Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study's aim was to investigate dose and image quality of tin filtration at 100 kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100 kV with additional tin filtration, 150mAs, 192x0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100 kV, 50mAs, 128 × 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDIvol 1.2 mGy vs. 4.4 mGy, p < 0.001). Spectral optimization (tin filtration at 100 kV) allows for visualization of the paranasal sinus with sufficient image quality at a very low radiation exposure. • Spectral optimization (tin filtration) is beneficial to low-dose parasinus CT • Tin filtration at 100 kV yields sufficient image quality for pre-operative planning • Diagnostic parasinus CT can be performed with an effective dose <0.05 mSv.

  14. High energy X-ray phase and dark-field imaging using a random absorption mask.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-28

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  15. Multiplexed high resolution soft x-ray RIXS

    SciTech Connect

    Chuang, Y.-D.; Voronov, D.; Warwick, T.; Yashchuk, V.; Padmore, H. A.; Anderson, C.; Benk, M.; Goldberg, K.

    2016-07-27

    High-resolution Resonance Inelastic X-ray Scattering (RIXS) is a technique that allows us to probe the electronic excitations of complex materials with unprecedented precision. However, the RIXS process has a low cross section, compounded by the fact that the optical spectrometers used to analyze the scattered photons can only collect a small solid angle and overall have a small efficiency. Here we present a method to significantly increase the throughput of RIXS systems, by energy multiplexing, so that a complete RIXS map of scattered intensity versus photon energy in and photon energy out can be recorded simultaneously{sup 1}. This parallel acquisition scheme should provide a gain in throughput of over 100.. A system based on this principle, QERLIN, is under construction at the Advanced Light Source (ALS).

  16. High temperature x-ray micro-tomography

    NASA Astrophysics Data System (ADS)

    MacDowell, Alastair A.; Barnard, Harold; Parkinson, Dilworth Y.; Haboub, Abdel; Larson, Natalie; Zok, Frank; Panerai, Francesco; Mansour, Nagi N.; Bale, Hrishikesh; Gludovatz, Bernd; Acevedo, Claire; Liu, Dong; Ritchie, Robert O.

    2016-07-01

    There is increasing demand for 3D micro-scale time-resolved imaging of samples in realistic - and in many cases extreme environments. The data is used to understand material response, validate and refine computational models which, in turn, can be used to reduce development time for new materials and processes. Here we present the results of high temperature experiments carried out at the x-ray micro-tomography beamline 8.3.2 at the Advanced Light Source. The themes involve material failure and processing at temperatures up to 1750°C. The experimental configurations required to achieve the requisite conditions for imaging are described, with examples of ceramic matrix composites, spacecraft ablative heat shields and nuclear reactor core Gilsocarbon graphite.

  17. High-Energy X-Ray Diffraction Analysis Tool

    SciTech Connect

    2011-11-29

    The functionality of heRXD includes the following: distance and angular calibration and viewing flat-panel detector images used for X-ray diffraction; image (polar) rebinning or "caking"; line position fitting in powder diffraction images; image segmentation or "blob finding"; crystal orentation indesing; and lattice vector refinement. These functionalities encompass a critical set analyzing teh data for high-energy diffraction measurements that are currently performed at synchrotron sources such as the Advanced Photon Source (APS). The software design modular and open source under LGPL. The intent is to provide a common framework and graphical user interface that has the ability to utillize internal as well as external subroutines to provide various optins for performing the fuctionalities listed above. The software will initially be deployed at several national user facilities--including APS, ALS, and CHESS--and then made available for download using a hosting service such as sourceforge.

  18. High temperature x-ray micro-tomography

    SciTech Connect

    MacDowell, Alastair A. Barnard, Harold; Parkinson, Dilworth Y.; Gludovatz, Bernd; Haboub, Abdel; Larson, Natalie; Zok, Frank; Panerai, Francesco; Mansour, Nagi N.; Bale, Hrishikesh; Acevedo, Claire; Liu, Dong; Ritchie, Robert O.

    2016-07-27

    There is increasing demand for 3D micro-scale time-resolved imaging of samples in realistic - and in many cases extreme environments. The data is used to understand material response, validate and refine computational models which, in turn, can be used to reduce development time for new materials and processes. Here we present the results of high temperature experiments carried out at the x-ray micro-tomography beamline 8.3.2 at the Advanced Light Source. The themes involve material failure and processing at temperatures up to 1750°C. The experimental configurations required to achieve the requisite conditions for imaging are described, with examples of ceramic matrix composites, spacecraft ablative heat shields and nuclear reactor core Gilsocarbon graphite.

  19. Focusing high-energy x rays by compound refractive lenses.

    PubMed

    Snigirev, A; Kohn, V; Snigireva, I; Souvorov, A; Lengeler, B

    1998-02-01

    Compound lenses made from low-Z materials (e.g., Be, B, C, and Al) set up as a linear array of refractive lenses are proposed for submicrometer focusing of high-energy x rays (>5 keV) in one or two dimensions. A theory of focusing based on Maxwell's equation and the Fresnel-Kirchhoff approach is presented. Compound refractive lenses were manufactured by drilling into an Al block a linear array of 200 closely spaced holes 0.5 mm in diameter for linear focusing and two crossed arrays of 100 holes each for point focusing. Focal spots of 3.7 mum and 8 mum x 18 mum were obtained at 30 keV for linear and two-dimensional lenses, respectively. Different technologies of manufacturing and possible applications of the proposed lenses are discussed.

  20. Potential enhancement of warm X-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.

    1995-08-01

    The potential for generating intense bursts of warm x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions, for a Jupiter (60-MA, 5-MV, 100-ns) class accelerator. The calculations are compared with data from Gamble-II experiments and applied to two suggested Jupiter diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung, which accompanies the warm x rays, is a concern then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately}400 {mu}m for low-Z targets like aluminum and thinner than {approximately}5 {mu}m for high-Z targets like gold.

  1. Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.; Weber, B.V.

    1995-07-01

    The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.

  2. Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

    PubMed Central

    Sakurai, T; Kawamata, R; Kozai, Y; Kaku, Y; Nakamura, K; Saito, M; Wakao, H; Kashima, I

    2010-01-01

    Objectives The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction. Methods Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose. Results The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC. Conclusions The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction. PMID:20395461

  3. Differential Effects of X-Rays and High-Energy {sup 56}Fe Ions on Human Mesenchymal Stem Cells

    SciTech Connect

    Kurpinski, Kyle; Jang, Deok-Jin; Bhattacharya, Sanchita; Rydberg, Bjorn; Chu, Julia; So, Joanna; Wyrobek, Andy; Li Song; Wang Daojing

    2009-03-01

    Purpose: Stem cells hold great potential for regenerative medicine, but they have also been implicated in cancer and aging. How different kinds of ionizing radiation affect stem cell biology remains unexplored. This study was designed to compare the biological effects of X-rays and of high-linear energy transfer (LET) {sup 56}Fe ions on human mesenchymal stem cells (hMSC). Methods and Materials: A multi-functional comparison was carried out to investigate the differential effects of X-rays and {sup 56}Fe ions on hMSC. The end points included modulation of key markers such as p53, cell cycle progression, osteogenic differentiation, and pathway and networks through transcriptomic profiling and bioinformatics analysis. Results: X-rays and {sup 56}Fe ions differentially inhibited the cell cycle progression of hMSC in a p53-dependent manner without impairing their in vitro osteogenic differentiation process. Pathway and network analyses revealed that cytoskeleton and receptor signaling were uniquely enriched for low-dose (0.1 Gy) X-rays. In contrast, DNA/RNA metabolism and cell cycle regulation were enriched for high-dose (1 Gy) X-rays and {sup 56}Fe ions, with more significant effects from {sup 56}Fe ions. Specifically, DNA replication, DNA strand elongation, and DNA binding/transferase activity were perturbed more severely by 1 Gy {sup 56}Fe ions than by 1 Gy X-rays, consistent with the significant G2/M arrest for the former while not for the latter. Conclusions: {sup 56}Fe ions exert more significant effects on hMSC than X-rays. Since hMSC are the progenitors of osteoblasts in vivo, this study provides new mechanistic understandings of the relative health risks associated with low- and high-dose X-rays and high-LET space radiation.

  4. Differential effects of x-rays and high-energy 56Fe ions on human mesenchymal stem cells.

    PubMed

    Kurpinski, Kyle; Jang, Deok-Jin; Bhattacharya, Sanchita; Rydberg, Bjorn; Chu, Julia; So, Joanna; Wyrobek, Andy; Li, Song; Wang, Daojing

    2009-03-01

    Stem cells hold great potential for regenerative medicine, but they have also been implicated in cancer and aging. How different kinds of ionizing radiation affect stem cell biology remains unexplored. This study was designed to compare the biological effects of X-rays and of high-linear energy transfer (LET) (56)Fe ions on human mesenchymal stem cells (hMSC). A multi-functional comparison was carried out to investigate the differential effects of X-rays and (56)Fe ions on hMSC. The end points included modulation of key markers such as p53, cell cycle progression, osteogenic differentiation, and pathway and networks through transcriptomic profiling and bioinformatics analysis. X-rays and (56)Fe ions differentially inhibited the cell cycle progression of hMSC in a p53-dependent manner without impairing their in vitro osteogenic differentiation process. Pathway and network analyses revealed that cytoskeleton and receptor signaling were uniquely enriched for low-dose (0.1 Gy) X-rays. In contrast, DNA/RNA metabolism and cell cycle regulation were enriched for high-dose (1 Gy) X-rays and (56)Fe ions, with more significant effects from (56)Fe ions. Specifically, DNA replication, DNA strand elongation, and DNA binding/transferase activity were perturbed more severely by 1 Gy (56)Fe ions than by 1 Gy X-rays, consistent with the significant G2/M arrest for the former while not for the latter. (56)Fe ions exert more significant effects on hMSC than X-rays. Since hMSC are the progenitors of osteoblasts in vivo, this study provides new mechanistic understandings of the relative health risks associated with low- and high-dose X-rays and high-LET space radiation.

  5. A combination of high dose rate (10X FFF/2400 MU/min/10 MV X-rays) and total low dose (0.5 Gy) induces a higher rate of apoptosis in melanoma cells in vitro and superior preservation of normal melanocytes.

    PubMed

    Sarojini, Sreeja; Pecora, Andrew; Milinovikj, Natasha; Barbiere, Joseph; Gupta, Saakshi; Hussain, Zeenathual M; Tuna, Mehmet; Jiang, Jennifer; Adrianzen, Laura; Jun, Jaewook; Catello, Laurice; Sanchez, Diana; Agarwal, Neha; Jeong, Stephanie; Jin, Youngjin; Remache, Yvonne; Goy, Andre; Ndlovu, Alois; Ingenito, Anthony; Suh, K Stephen

    2015-10-01

    The aim of this study was to determine the apoptotic effects, toxicity, and radiosensitization of total low dose irradiation delivered at a high dose rate in vitro to melanoma cells, normal human epidermal melanocytes (HEM), or normal human dermal fibroblasts (HDF) and to study the effect of mitochondrial inhibition in combination with radiation to enhance apoptosis in melanoma cells. Cells irradiated using 10X flattening filter-free (FFF) 10 MV X-rays at a dose rate of 400 or 2400 MU/min and a total dose of 0.25-8 Gy were analyzed by cell/colony counting, MitoTracker, MTT, and DNA-damage assays, as well as by quantitative real-time reverse transcriptase PCR in the presence or absence of mitochondrial respiration inhibitors. A dose rate of 2400 MU/min killed on average five-fold more melanoma cells than a dose rate 400 MU/min at a total dose of 0.5 Gy and preserved 80% survival of HEM and 90% survival of HDF. Increased apoptosis at the 2400 MU/min dose rate is mediated by greater DNA damage, reduced cell proliferation, upregulation of apoptotic genes, and downregulation of cell cycle genes. HEM and HDF were relatively unharmed at 2400 MU/min. Radiation induced upregulation of mitochondrial respiration in both normal and cancer cells, and blocking the respiration with inhibitors enhanced apoptosis only in melanoma cells. A high dose rate with a low total dose (2400 MU/min, 0.5 Gy/10X FFF 10 MV X-rays) enhances radiosensitivity of melanoma cells while reducing radiotoxicity toward HEM and HDF. Selective cytotoxicity of melanoma cells is increased by blocking mitochondrial respiration.

  6. Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

    NASA Astrophysics Data System (ADS)

    Cha, B. K.; Kim, J. Y.; Kim, Y. J.; Yun, S.; Cho, G.; Kim, H. K.; Seo, C.-W.; Jeon, S.; Huh, Y.

    2012-04-01

    In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 μm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

  7. Low-dose phase contrast tomography with conventional x-ray sources

    SciTech Connect

    Hagen, C. K. Endrizzi, M.; Diemoz, P. C.; Olivo, A.; Munro, P. R. T.

    2014-07-15

    Purpose: The edge illumination (EI) x-ray phase contrast imaging (XPCi) method has been recently further developed to perform tomographic and, thus, volumetric imaging. In this paper, the first tomographic EI XPCi images acquired with a conventional x-ray source at dose levels below that used for preclinical small animal imaging are presented. Methods: Two test objects, a biological sample and a custom-built phantom, were imaged with a laboratory-based EI XPCi setup in tomography mode. Tomographic maps that show the phase shift and attenuating properties of the object were reconstructed, and analyzed in terms of signal-to-noise ratio and quantitative accuracy. Dose measurements using thermoluminescence devices were performed. Results: The obtained images demonstrate that phase based imaging methods can provide superior results compared to attenuation based modalities for weakly attenuating samples also in 3D. Moreover, and, most importantly, they demonstrate the feasibility of low-dose imaging. In addition, the experimental results can be considered quantitative within the constraints imposed by polychromaticity. Conclusions: The results, together with the method's dose efficiency and compatibility with conventional x-ray sources, indicate that tomographic EI XPCi can become an important tool for the routine imaging of biomedical samples.

  8. Fluorescence imaging of reactive oxygen species by confocal laser scanning microscopy for track analysis of synchrotron X-ray photoelectric nanoradiator dose: X-ray pump-optical probe.

    PubMed

    Jeon, Jae Kun; Han, Sung Mi; Kim, Jong Ki

    2016-09-01

    Bursts of emissions of low-energy electrons, including interatomic Coulomb decay electrons and Auger electrons (0-1000 eV), as well as X-ray fluorescence produced by irradiation of large-Z element nanoparticles by either X-ray photons or high-energy ion beams, is referred to as the nanoradiator effect. In therapeutic applications, this effect can damage pathological tissues that selectively take up the nanoparticles. Herein, a new nanoradiator dosimetry method is presented that uses probes for reactive oxygen species (ROS) incorporated into three-dimensional gels, on which macrophages containing iron oxide nanoparticles (IONs) are attached. This method, together with site-specific irradiation of the intracellular nanoparticles from a microbeam of polychromatic synchrotron X-rays (5-14 keV), measures the range and distribution of OH radicals produced by X-ray emission or superoxide anions ({\\rm{O}}_2^-) produced by low-energy electrons. The measurements are based on confocal laser scanning of the fluorescence of the hydroxyl radical probe 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl] benzoic acid (APF) or the superoxide probe hydroethidine-dihydroethidium (DHE) that was oxidized by each ROS, enabling tracking of the radiation dose emitted by the nanoradiator. In the range 70 µm below the irradiated cell, ^\\bullet{\\rm{OH}} radicals derived mostly from either incident X-ray or X-ray fluorescence of ION nanoradiators are distributed along the line of depth direction in ROS gel. In contrast, {\\rm{O}}_2^- derived from secondary electron or low-energy electron emission by ION nanoradiators are scattered over the ROS gel. ROS fluorescence due to the ION nanoradiators was observed continuously to a depth of 1.5 mm for both oxidized APF and oxidized DHE with relatively large intensity compared with the fluorescence caused by the ROS produced solely by incident primary X-rays, which was limited to a depth of 600 µm, suggesting dose enhancement as well as more

  9. A waveguide electron cyclotron resonance source of X-ray emission for low-dose introscopy

    NASA Astrophysics Data System (ADS)

    Sergeichev, K. F.; Ionidi, V. Yu.; Karfidov, D. M.; Lukina, N. A.

    2013-12-01

    It is shown that a "point" target in a conventional evacuated waveguide in the magnetic field of a mirror trap formed by two disk magnets axially magnetized in the direction perpendicular to the electric field vector represents a source of X-ray bremsstrahlung of electrons accelerated in an ECR discharge with a broad range of photon energies up to 0.8 MeV. The dosage rate of the source is ˜1 R/h. The source fed from a conventional microwave oven has small dimensions and a low weight. It is easy-to-use and is suitable as a laboratory tool, in particular, in radiobiology and introscopy. After passing through the object, X-ray emission is recorded by a digital camera with the help of a highly sensitive X-ray fluorescent screen, which converts it into an optical image.

  10. Biphasic and triphasic dose responses in zebrafish embryos to low-dose 150 kV X-rays with different levels of hardness.

    PubMed

    Kong, Eva Yi; Cheng, Shuk Han; Yu, Kwan Ngok

    2016-07-01

    The in vivo low-dose responses of zebrafish (Danio rerio) embryos to 150 kV X-rays with different levels of hardness were examined through the number of apoptotic events revealed at 24 h post fertilization by vital dye acridine orange staining. Our results suggested that a triphasic dose response was likely a common phenomenon in living organisms irradiated by X-rays, which comprised an ultra-low-dose inhibition, low-dose stimulation and high-dose inhibition. Our results also suggested that the hormetic zone (or the stimulation zone) was shifted towards lower doses with application of filters. The non-detection of a triphasic dose response in previous experiments could likely be attributed to the use of hard X-rays, which shifted the hormetic zone into an unmonitored ultra-low-dose region. In such cases where the subhormetic zone was missed, a biphasic dose response would be reported instead. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  11. Physical dose distribution due to multi-sliced kV X-ray beam in labeled tissue-like media: an experimental approach.

    PubMed

    Ghasemi, M; Kakuee, O R; Fathollahi, V; Shahvar, A; Mohati, M; Ghafoori, M

    2011-02-01

    Radiotherapy remains a major modality of cancer therapy. Thanks to high flux and high brilliance of synchrotron-generated X-ray, laboratory research with planar microscopically thin X-ray beam promise exciting new opportunities for treatment of cancer. High tolerance of normal tissues at doses up to several hundred Gy in a single dose fraction and preferential damage of tumors at very high doses have been uniquely observed in animal models exposed to microbeams. The fact that beams as thick as 0.68 mm could retain a part of these effects, opens the possibility that the required beam can be produced by high power X-ray tubes besides a dedicated synchrotron. Fortunately, dose distribution due to kilovolt X-rays could be enhanced by the introduction of high-Z contrast agents to tissue-like media. In this work, dose deposition in a phantom--partially loaded with Au and I as contrast agents--irradiated by multi-sliced kV X-ray beam was experimentally investigated in the peak and valley regions both on the surface and in the depth of phantom. The results of experimental dosimetry using Gaf-chromic films were compared with corresponding Monte-Carlo simulation. Relative reduction in the deposited dose in the peak regions downstream the area containing contrast agents in comparison with the adjacent areas was experimentally observed.

  12. Collective effective dose in Europe from X-ray and nuclear medicine procedures.

    PubMed

    Bly, R; Jahnen, A; Järvinen, H; Olerud, H; Vassileva, J; Vogiatzi, S

    2015-07-01

    Population doses from radiodiagnostic (X-ray and nuclear medicine) procedures in Europe were estimated based on data collected from 36 European countries. For X-ray procedures in EU and EFTA countries (except Liechtenstein) the collective effective dose is 547,500 man Sv, resulting in a mean effective dose of 1.06 mSv per caput. For all European countries included in the survey the collective effective dose is 605,000 man Sv, resulting in a mean effective dose of 1.05 mSv per caput. For nuclear medicine procedures in EU countries and EFTA (except Liechtenstein) countries the collective effective dose is 30,700 man Sv, resulting in a mean effective dose of 0.06 mSv per caput. For all European countries included in the survey the collective effective dose is 31,100 man Sv, resulting in a mean effective dose of 0.05 mSv per caput. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. X-ray induced Sm{sup 3+} to Sm{sup 2+} conversion in fluorophosphate and fluoroaluminate glasses for the monitoring of high-doses in microbeam radiation therapy

    SciTech Connect

    Vahedi, Shahrzad; Okada, Go; Morrell, Brian; Muzar, Edward; Koughia, Cyril; Kasap, Safa; Edgar, Andy; Varoy, Chris; Belev, George; Wysokinski, Tomasz; Chapman, Dean

    2012-10-01

    Fluorophosphate and fluoroaluminate glasses doped with trivalent samarium were evaluated as sensors of x-ray radiation for microbeam radiation therapy at the Canadian Light Source using the conversion of trivalent Sm{sup 3+} to the divalent form Sm{sup 2+}. Both types of glasses show similar conversion rates and may be used as a linear sensor up to {approx}150 Gy and as a nonlinear sensor up to {approx}2400 Gy, where saturation is reached. Experiments with a multi-slit collimator show high spatial resolution of the conversion pattern; the pattern was acquired by a confocal fluorescence microscopy technique. The effects of previous x-ray exposure may be erased by annealing at temperatures exceeding the glass transition temperature T{sub g} while annealing at T{sub A} < T{sub g} enhances the Sm conversion. This enhancement is explained by a thermally stimulated relaxation of host glass ionic matrix surrounding x-ray induced Sm{sup 2+} ions. In addition, some of the Sm{sup 3+}-doped glasses were codoped with Eu{sup 2+}-ions but the results show that there is no marked improvement in the conversion efficiency by the introduction of Eu{sup 2+}.

  14. Flash imaging of fine structures of cellular organelles by contact x-ray microscopy with a high intensity laser plasma x-ray source

    NASA Astrophysics Data System (ADS)

    Kado, Masataka; Ishino, Masahiko; Kishimoto, Maki; Tamotsu, Satoshi; Yasuda, Keiko; Kinjo, Yasuhito; Shinohara, Kunio

    2011-09-01

    X-ray flash imaging by contact microscopy with a highly intense laser-plasma x-ray source was achieved for the observation of wet biological cells. The exposure time to obtain a single x-ray image was about 600 ps as determined by the pulse duration of the driving laser pulse. The x-ray flash imaging makes it possible to capture an x-ray image of living biological cells without any artificial treatment such as staining, fixation, freezing, and so on. The biological cells were cultivated directly on the surface of the silicon nitride membranes, which are used for the x-ray microscope. Before exposing the cells to x-rays they were observed by a conventional fluorescent microscope as reference, since the fluorescent microscopes can visualize specific organelles stained with fluorescent dye. Comparing the x-ray images with the fluorescent images of the exact same cells, each cellular organelle observed in the x-ray images was identified one by one and actin filaments and mitochondria were clearly identified in the x-ray images.

  15. Entrance surface doses to patients undergoing selected diagnostic X-ray examinations in Sudan.

    PubMed

    Suliman, I I; Abbas, N; Habbani, F I

    2007-01-01

    The aim of the study was to evaluate the entrance surface doses (ESDs) to patients undergoing selected diagnostic X-ray examinations in major Sudanese hospitals. ESD per examination was estimated from X-ray tube output parameters in four hospitals comprising eight X-ray units and a sample of 346 radiographs. Hospital mean ESDs estimated range from 0.17 to 0.27 mGy for chest AP, 1.04-2.26 mGy for Skull AP/PA, 0.83-1.32 mGy for Skull LAT, 1.31-1.89 mGy for Pelvis AP, 1.46-3.33 mGy for Lumbar Spine AP and 2.9-9.9 mGy for Lumbar Spine LAT. With exception of chest PA examination at two hospitals, mean ESDs were found to be within the established international reference doses. The results are useful to national and professional organisations and can be used as a baseline upon which future dose measurements may be compared.

  16. Comprehensive x-ray spectral code for high energy astrophysics

    SciTech Connect

    Liedahl, D A; Fournier, K B; Mauche, C W

    2000-08-18

    The aim of this project has been to develop a spectral analysis tool with a level of quality and completeness commensurate to that expected in data from the current generation of X-ray observatories. The code is called LXSS (Livermore X-Ray Spectral Synthesizer). X-ray-emitting astrophysical plasmas are rarely, if ever, in LTE, so they have adopted the detailed level accounting approach, in which rates for processes that populate or depopulate atomic energy levels are treated explicitly. This entails the generation of a large quantity of atomic data, most of which is calculated using ''in-house'' computer codes. Calculations are benchmarked against laboratory data, and spectral models have been used to provide first-time interpretations of astrophysical X-ray spectra. The design of a versatile graphical user interface that allows access to and manipulation of the atomic database comprises the second major part of the project.

  17. Impact of latest generation cardiac interventional X-ray equipment on patient image quality and radiation dose for trans-catheter aortic valve implantations.

    PubMed

    Gislason-Lee, Amber J; Keeble, Claire; Malkin, Christoper J; Egleston, Daniel; Bexon, Josephine; Kengyelics, Stephen M; Blackman, Daniel; Davies, Andrew G

    2016-11-01

    This study aimed to determine the impact on radiation dose and image quality of a new cardiac interventional X-ray system for trans-catheter aortic valve implantation (TAVI) patients compared to the previously-used cardiac X-ray system. Patient dose and image data were retrospectively collected from a Philips AlluraClarity (new) and Siemens Axion Artis (reference) X-ray system. Patient dose area product (DAP) and fluoroscopy duration of 41 patient cases from each X-ray system were compared using a Wilcoxon test. Ten patient aortograms from each X-ray system were scored by 32 observers on a continuous scale to assess the clinical image quality at the given phase of the TAVI procedure. Scores were dichotomised by acceptability and analysed using a Chi-squared test. Significant reductions in patient dose (p < 0.001) were found for the new system with no significant change in fluoroscopy duration (p = 0.052); procedure DAP reduced by 55%, fluoroscopy DAP by 48% and "cine" acquisition DAP by 61%. There was no significant difference between image quality scores of the two X-ray systems (p = 0.06). The new cardiac X-ray system demonstrated a very significant reduction in patient dose with no loss of clinical image quality. Advances in Knowledge: The huge growth of TAVI may impact on the radiation exposure of cardiac patients and particularly on operators including anaesthetists; cumulative exposure of interventional cardiologists performing high volume TAVI over 30-40 years may be harmful. The Phillips Clarity upgrade including improved image enhancement and optimised X-ray settings significantly reduced radiation without reducing clinically acceptable image quality.

  18. Radiation doses to paediatric patients and comforters undergoing chest X rays.

    PubMed

    Sulieman, A; Vlychou, M; Tsougos, I; Theodorou, K

    2011-09-01

    Pneumonia is an important cause of hospital admission among children in the developed world and it is estimated to be responsible for 3-18 % of all paediatric admissions. Chest X ray is an important examination for pneumonia diagnosis and for evaluation of complications. This study aims to determine the entrance surface dose (ESD), organ, effective doses and propose a local diagnostic reference level. The study was carried out at the university hospital of Larissa, Greece. Patients were divided into three groups: organ and effective doses were estimated using National Radiological Protection Board software. The ESD was determined by thermoluminescent dosemeters for 132 children and 76 comforters. The average ESD value was 55 ± 8 µGy. The effective dose for patients was 11.2 ± 5 µSv. The mean radiation dose for comforter is 22 ± 3 µGy. The radiation dose to the patients is well within dose constraint, in the light of the current practice.

  19. Normalized organ doses and effective doses to a reference Indian adult male in conventional medical diagnostic x-ray examinations.

    PubMed

    Biju, K; Nagarajan, P S

    2006-03-01

    This work discusses the dose computations of 80 kV diagnostic x-rays made on a mathematical phantom representing an average Indian adult, since it is felt that results based on MIRD adult phantom calculations are not strictly appropriate for the population in India. Normalized organ equivalent doses and effective doses for an Indian adult male have been estimated. Normalization is done with respect to the entrance skin dose of the patient. Twenty common diagnostic x-ray examinations have been considered in this study and the doses are presented. This study would enable estimation of radiation induced detriment to the patient subpopulation in India. Since the external dimensions of the phantom are nearly the same as that of 15-y-old NRPB pediatric phantom, our results are also compared with those of latter and the agreement was found to be satisfactory.

  20. Establishment of a Dose-response Curve for X-ray-Induced Micronuclei in Human Lymphocytes

    PubMed Central

    Lusiyanti, Yanti; Alatas, Zubaidah; Syaifudin, Mukh; Purnami, Sofiati

    2016-01-01

    The cytokinesis-block micronucleus assay in peripheral blood lymphocytes is an established technique for biodosimetry. The aim of this project was to generate a X-ray induced micronuclei (MN) curve for peripheral blood lymphocytes taken from five healthy donors. The blood samples were irradiated with X-rays of 122 KeV at a dose rate of 0.652 Gy/min to doses of 0.5, 1, 2, 3, and 4 Gy. The blood samples were then cultured for 72 h at 37°C and processed following the International Atomic Energy Agency standard procedure with slight modifications. The result showed that the yields of MN frequencies were increased with the increase of radiation dose. Reconstruction of the relationship of MN with dose was fitted to a linear-quadratic model using Chromosome Aberration Calculation Software version 2.0. Due to their advantages, mainly, the dependence on radiation dose and dose rate, despite their limitation, these curves will be useful as alternative method for in vitro dose reconstruction and can support the preparedness for public or occupational radiation overexposure and protection. The results reported here also give us confidence to apply the obtained calibration curve of MN for future biological dosimetry requirements in Indonesia. PMID:28217283

  1. Establishment of a Dose-response Curve for X-ray-Induced Micronuclei in Human Lymphocytes.

    PubMed

    Lusiyanti, Yanti; Alatas, Zubaidah; Syaifudin, Mukh; Purnami, Sofiati

    2016-01-01

    The cytokinesis-block micronucleus assay in peripheral blood lymphocytes is an established technique for biodosimetry. The aim of this project was to generate a X-ray induced micronuclei (MN) curve for peripheral blood lymphocytes taken from five healthy donors. The blood samples were irradiated with X-rays of 122 KeV at a dose rate of 0.652 Gy/min to doses of 0.5, 1, 2, 3, and 4 Gy. The blood samples were then cultured for 72 h at 37°C and processed following the International Atomic Energy Agency standard procedure with slight modifications. The result showed that the yields of MN frequencies were increased with the increase of radiation dose. Reconstruction of the relationship of MN with dose was fitted to a linear-quadratic model using Chromosome Aberration Calculation Software version 2.0. Due to their advantages, mainly, the dependence on radiation dose and dose rate, despite their limitation, these curves will be useful as alternative method for in vitro dose reconstruction and can support the preparedness for public or occupational radiation overexposure and protection. The results reported here also give us confidence to apply the obtained calibration curve of MN for future biological dosimetry requirements in Indonesia.

  2. Gas scintillation glass GEM detector for high-resolution X-ray imaging and CT

    NASA Astrophysics Data System (ADS)

    Fujiwara, T.; Mitsuya, Y.; Fushie, T.; Murata, K.; Kawamura, A.; Koishikawa, A.; Toyokawa, H.; Takahashi, H.

    2017-04-01

    A high-spatial-resolution X-ray-imaging gaseous detector has been developed with a single high-gas-gain glass gas electron multiplier (G-GEM), scintillation gas, and optical camera. High-resolution X-ray imaging of soft elements is performed with a spatial resolution of 281 μm rms and an effective area of 100×100 mm. In addition, high-resolution X-ray 3D computed tomography (CT) is successfully demonstrated with the gaseous detector. It shows high sensitivity to low-energy X-rays, which results in high-contrast radiographs of objects containing elements with low atomic numbers. In addition, the high yield of scintillation light enables fast X-ray imaging, which is an advantage for constructing CT images with low-energy X-rays.

  3. Compact high current generator for x-ray radiography

    NASA Astrophysics Data System (ADS)

    Kharlov, A. V.; Kovalchuk, B. M.; Zorin, V. B.

    2006-12-01

    We report here a design of the portable high current generator, which can be used for a row of experiments and applications, including, but not limited to, X pinch, plasma focus, vacuum spark, etc. The X generator consists of the capacitor bank, multigap spark switch, load chamber, and built-in high voltage triggering generator. The capacitor bank consists of 12 General Atomics 35404 type capacitors (20nF, 25nH, 0.2Ω, 100kV). It stores ˜0.8kJ at 80kV charging voltage. Each three capacitors are commuted to a load by the multigap spark switch, which is able to commute by eight parallel channels. Switches operate in ambient air at atmospheric pressure. At 76kV charging voltage the generator provides ˜260kA with 120ns rise time and 5nH inductive load and ˜220kA with 145ns rise time and 10nH. Delay of output pulse relative to high voltage triggering pulse is ˜65ns with 5ns jitter. The dimensions of the generator are 1240×1240×225mm3 and the weight is ˜250kg, and only one high voltage power supply is required as additional equipment for the generator. The generator with a pumping system is placed on area about 0.5m2. Operation and handling are very simple, because no oil nor purified gases are required for the generator. The X generator has been successfully employed for experiments on the Ni X pinch load. X-ray pulse duration (full width at half maximum above 1keV) was about 5ns. Radiation yield Wr⩾500mJ was observed in the 1.2-1.5KeV range and Wr⩾20mJ in the 3-5keV energy range, which is comparable to results, obtained on the nanosecond accelerators. Clearly resolved images of 6μm wire indicate micron level size of hot spot. These results demonstrate possibility of this generator for application for x-ray backlighting.

  4. Prunus armeniaca L (apricot) protects rat testes from detrimental effects of low-dose x-rays.

    PubMed

    Ugras, Murat Y; Kurus, Meltem; Ates, Burhan; Soylemez, Haluk; Otlu, Ali; Yilmaz, Ismet

    2010-03-01

    Exposure to low x-ray doses damages the spermatozoa, mainly by late-onset (ie, after 3 months) oxidative stress. Antioxidants ameliorate oxidation and prevent tissue damage. Prunus armeniaca L (apricot), rich in carotenoids and vitamins, is a potent natural antioxidant. We hypothesized that an apricot-rich diet might ameliorate the detrimental effects of low-dose x-rays on testis tissue. A 20% apricot diet was composed isoenergetically to the regular rodent diet. The total phenolic content, reducing power, and antioxidant capacity of both diets were determined. Sprague-Dawley rats received apricot-rich diets before and after x-ray exposure. Regular diets were given to controls. Rats were exposed to 0.2 Gy x-rays at the eighth week and were euthanized at the 20th postexposure week. Testicular oxidative status was determined by tissue thiobarbituric acid-reactive substances, reduced glutathione, superoxide dismutase, and catalase activities. For histologic evaluation, qualitative and quantitative microscopic determinations were performed, and Leydig and Sertoli cell counts and Johnsen scores were measured. The control diet group had significant testicular oxidative stress and mild tissue deterioration. Leydig and Sertoli cell counts, tubule diameters, and Johnsen scores were significantly decreased in the exposure groups. Apricot-rich diet significantly ameliorated the oxidative status and prevented the damage in tubular histology. The protective effects were prominent when the diet was maintained throughout the time course and were partially protected when the diet was initiated after exposure. The natural antioxidant activity of apricot ameliorates the delayed detrimental effects of low-dose irradiation on testis tissue. The high total antioxidant capacity of the apricot deserves further investigation. 2010 Elsevier Inc. All rights reserved.

  5. Effect of X-ray High-voltage Variations on the Conversion Coefficients.

    PubMed

    Behnke, B; Hupe, O; Behrens, R

    2016-10-20

    Conversion coefficients (CCs) are an essential vehicle in radiation protection for the determination of the dose (rate) of a given radiation field. According to the current draft of the revision of international standard ISO 4037, an X-ray field is a reference field if the CCs of the field match the tabulated ISO values within 2%. Deviations of the high-voltage (HV) tube-potential from its nominal value influence the resulting spectra and change the corresponding CCs. This work investigates the maximum allowable deviation of the HV from its nominal value such that the requirements of ISO 4037 remain fulfilled. This is achieved using both synthetic spectra created by a software simulation program and spectra measured at one of the X-ray facilities of the Physikalisch-Technische Bundesanstalt. The results are summarised in form of a new proposal for upper limit values which are suggested to be used in the next version of ISO 4037.

  6. Optimization Strategy of Distortion Rate Control for High Power Transfer Supplying an X-Ray Tube

    NASA Astrophysics Data System (ADS)

    Mohamed, Rachedi; Mohamed, Bourahla

    2012-03-01

    This paper mainly concerns a contribution in the art development of high power generator supplying an X-ray tube for medical use. A generic method is proposed to reduce thermal stresses induced in X-ray tube during successive doses. For such application resonant DC-DC converter should be required, which generate output voltage and load current strictly identical to reference signal accompanied with normalized power factor quality. Primordially an adequate structure active filter connected in parallel at load lover is used to adjust the input and out put current distortion rate. With fuzzy logic control strategy, out put characteristics in transient and steady state are integrally mastery. This robust control type permits successive and repetitive taken measurement of radiology.

  7. High-resolution 3D X-ray imaging of intracranial nitinol stents.

    PubMed

    Snoeren, Rudolph M; Söderman, Michael; Kroon, Johannes N; Roijers, Ruben B; de With, Peter H N; Babic, Drazenko

    2012-02-01

    To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out. Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations. We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom. We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.1 lp/mm allows struts to be visualized. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. Measured absorbed doses are shown to be lower than 50 mGy Computed Tomography Dose Index (CTDI). By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values. Experimental results compare well with imaging simulations.

  8. X-ray diffraction measurements in high magnetic fields and at high temperatures

    PubMed Central

    Mitsui, Yoshifuru; Koyama, Keiichi; Watanabe, Kazuo

    2009-01-01

    A system was developed measuring x-ray powder diffraction in high magnetic fields up to 5 T and at temperatures from 283 to 473 K. The stability of the temperature is within 1 K over 6 h. In order to examine the ability of the system, the high-field x-ray diffraction measurements were carried out for Si and a Ni-based ferromagnetic shape-memory alloy. The results show that the x-ray powder diffraction measurements in high magnetic fields and at high temperatures are useful for materials research. PMID:27877263

  9. Real-time, ray casting-based scatter dose estimation for c-arm x-ray system.

    PubMed

    Alnewaini, Zaid; Langer, Eric; Schaber, Philipp; David, Matthias; Kretz, Dominik; Steil, Volker; Hesser, Jürgen

    2017-03-01

    Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. The x-ray source of a Siemens Axiom Artix C-arm is modeled by a virtual source model using single Gaussian-shaped source. A Geant4-based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor. A phase space around these scatterers stores all photon information. Only those photons are traced that hit a surface of phantom that represents medical staff in the treatment room, no indirect scattering is considered; and a complete dose deposition on the surface is calculated. To evaluate the accuracy of the approximation, both experimental measurements using Thermoluminescent dosimeters (TLDs) and a Geant4-based Monte Carlo simulation of dose depositing for different tube angulations of the C-arm from cranial-caudal angle 0° and from LAO (Left Anterior Oblique) 0°-90° are realized. Since the measurements were performed on both sides of the table, using the symmetry of the setup, RAO (Right Anterior Oblique) measurements were not necessary. The Geant4-Monte Carlo simulation agreed within 3% with the measured data, which is within the accuracy of measurement and simulation. The ray casting approximation has been compared to TLD measurements and the achieved percentage difference was -7% for data from tube angulations 45°-90° and -29% from tube angulations 0°-45° on the side of the x-ray source, whereas on the opposite side of the x-ray source, the difference was -83.8% and -75%, respectively. Ray casting approximation for only LAO 90° was compared to a Monte Carlo simulation, where the percentage differences were between 0.5-3% on the side of the x-ray source where the highest dose

  10. High Intensity X-Ray Coupling to Meteorite Targets

    NASA Astrophysics Data System (ADS)

    Remo, J. L.; Furnish, M. D.; Hammerling, P.

    2001-06-01

    The responses of iron-nickel and stony meteorite samples to high-intensity X-ray pulses (70 - 215 GW/cm^2) pulses generated by exploding wire array hohlraums from the Sandia Z machine are reported. Induced shock waves created particle velocities of 25 - 75 m/s after rarefaction overtake, as measured by VISAR. From these values both momentum and energy coupling coefficients were obtained. These results are compared to recent high-powered-pulsed ( 1 GW/cm2 for 20 ns) 1054 nm laser induced shock pressures and momentum transfer, and energy coupling to iron-rich and stony meteorite targets (J. L. Remo et al, Laser and Particle Beams, 17, 25-44, 1999). These comparisons provide data on the scaling of shock induced effects on inhomogeneous materials in general and meteoritic materials in particular. The combination of both of these experiments extends the regime of high intensity pulsed energy deposition on non-homogeneous materials from the GW/cm^2 to 100's of GW/cm^2, providing valuable empirical insights into the shock critical equations of state and coupling responses. Application to astrophysical and geophysical modeling will be discussed.

  11. Measurement of percentage depth dose and lateral beam profile for kilovoltage x-ray therapy beams.

    PubMed

    Li, X A; Ma, C M; Salhani, D

    1997-12-01

    In this work, nine commonly used dosimetry detectors have been investigated to determine suitable relative dosimeters for kilovoltage x-ray beams. By comparison with the Monte Carlo calculated data, it was determined that for the detectors studied the PTW N23342, Markus and NACP parallel-plate chambers are more suitable for the measurement of percentage depth dose (PDD) data for this beam quality range with an uncertainty of about 3%. A diode detector may be used to measure the PDD for the 100 kVp beam, but it is not suitable for higher energies (300 kVp). The Capintec parallel-plate chamber may be adequate for medium-energy photons, but it has a slightly higher uncertainty for low-energy x-rays (100 kVp). For the measurement of beam profiles, diode and film yield incorrect profile tails, which can be corrected using the RK ionization chamber.

  12. Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice modulates oxidative damage induced by low dose X-ray in mice.

    PubMed

    Mohammad, Mohd Khairul Amran; Mohamed, Muhamad Idham; Zakaria, Ainul Mardhiyah; Abdul Razak, Hairil Rashmizal; Saad, Wan Mazlina Md

    2014-01-01

    Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice against oxidative damage induced by low dose X-ray exposure in mice. Twelve adult male ICR mice were randomly divided into two groups consisting of radiation (Rx) and supplementation (Tx) groups. Rx received filtered tap water, while Tx was supplemented with 50% (v/v) watermelon juice for 28 days ad libitum prior to total body irradiation by 100 μGy X-ray on day 29. Brain, lung, and liver tissues were assessed for the levels of malondialdehyde (MDA), apurinic/apyrimidinic (AP) sites, glutathione (GSH), and superoxide dismutase (SOD) inhibition activities. Results showed significant reduction of MDA levels and AP sites formation of Tx compared to Rx (P < 0.05). Mice supplemented with 50% watermelon juice restore the intracellular antioxidant activities by significantly increased SOD inhibition activities and GSH levels compared to Rx. These findings may postulate that supplementation of 50% watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice could modulate oxidative damage induced by low dose X-ray exposure.

  13. Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) Juice Modulates Oxidative Damage Induced by Low Dose X-Ray in Mice

    PubMed Central

    Mohammad, Mohd Khairul Amran; Mohamed, Muhamad Idham; Abdul Razak, Hairil Rashmizal; Saad, Wan Mazlina Md.

    2014-01-01

    Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice against oxidative damage induced by low dose X-ray exposure in mice. Twelve adult male ICR mice were randomly divided into two groups consisting of radiation (Rx) and supplementation (Tx) groups. Rx received filtered tap water, while Tx was supplemented with 50% (v/v) watermelon juice for 28 days ad libitum prior to total body irradiation by 100 μGy X-ray on day 29. Brain, lung, and liver tissues were assessed for the levels of malondialdehyde (MDA), apurinic/apyrimidinic (AP) sites, glutathione (GSH), and superoxide dismutase (SOD) inhibition activities. Results showed significant reduction of MDA levels and AP sites formation of Tx compared to Rx (P < 0.05). Mice supplemented with 50% watermelon juice restore the intracellular antioxidant activities by significantly increased SOD inhibition activities and GSH levels compared to Rx. These findings may postulate that supplementation of 50% watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice could modulate oxidative damage induced by low dose X-ray exposure. PMID:24877107

  14. X-ray spectral evolution of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    At z approx. equals 3, the x-ray spectra of radio-loud and radio-quiet quasars are different. High-redshift radio-quiet quasars either have large absorbing columns, N(sub H), and steeper power law spectral indices, alpha(sub epsilon), than low redshift quasars, or no absorption and similar alpha(sub epsilon)'s. In contrast, the radio-loud quasars at high redshift have substantial absorption and similar alpha(sub epsilon)'s to low redshift quasars. Implications for the interpretation of the evolution of the luminosity function of quasars are discussed. If the absorption arises outside the central engine for both radio-loud and radio-quiet quasars, then radio-quiet quasars differ from the radio-loud quasars in that their emitted power law spectrum has evolved with redshift. We argue that this favors models where quasars are numerous and short-lived, rather than rare and long-lived.

  15. X-ray spectral evolution of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    At z approx. equals 3, the x-ray spectra of radio-loud and radio-quiet quasars are different. High-redshift radio-quiet quasars either have large absorbing columns, N(sub H), and steeper power law spectral indices, alpha(sub epsilon), than low redshift quasars, or no absorption and similar alpha(sub epsilon)'s. In contrast, the radio-loud quasars at high redshift have substantial absorption and similar alpha(sub epsilon)'s to low redshift quasars. Implications for the interpretation of the evolution of the luminosity function of quasars are discussed. If the absorption arises outside the central engine for both radio-loud and radio-quiet quasars, then radio-quiet quasars differ from the radio-loud quasars in that their emitted power law spectrum has evolved with redshift. We argue that this favors models where quasars are numerous and short-lived, rather than rare and long-lived.

  16. High-throughput screening with micro-x-ray fluorescence

    SciTech Connect

    Havrilla, George J.; Miller, Thomasin C.

    2005-06-15

    Micro-x-ray fluorescence (MXRF) is a useful characterization tool for high-throughput screening of combinatorial libraries. Due to the increasing threat of use of chemical warfare (CW) agents both in military actions and against civilians by terrorist extremists, there is a strong push to improve existing methods and develop means for the detection of a broad spectrum of CW agents in a minimal amount of time to increase national security. This paper describes a combinatorial high-throughput screening technique for CW receptor discovery to aid in sensor development. MXRF can screen materials for elemental composition at the mesoscale level (tens to hundreds of micrometers). The key aspect of this work is the use of commercial MXRF instrumentation coupled with the inherent heteroatom elements within the target molecules of the combinatorial reaction to provide rapid and specific identification of lead species. The method is demonstrated by screening an 11-mer oligopeptide library for selective binding of the degradation products of the nerve agent VX. The identified oligopeptides can be used as selective molecular receptors for sensor development. The MXRF screening method is nondestructive, requires minimal sample preparation or special tags for analysis, and the screening time depends on the desired sensitivity.

  17. High-throughput screening with micro-x-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Havrilla, George J.; Miller, Thomasin C.

    2005-06-01

    Micro-x-ray fluorescence (MXRF) is a useful characterization tool for high-throughput screening of combinatorial libraries. Due to the increasing threat of use of chemical warfare (CW) agents both in military actions and against civilians by terrorist extremists, there is a strong push to improve existing methods and develop means for the detection of a broad spectrum of CW agents in a minimal amount of time to increase national security. This paper describes a combinatorial high-throughput screening technique for CW receptor discovery to aid in sensor development. MXRF can screen materials for elemental composition at the mesoscale level (tens to hundreds of micrometers). The key aspect of this work is the use of commercial MXRF instrumentation coupled with the inherent heteroatom elements within the target molecules of the combinatorial reaction to provide rapid and specific identification of lead species. The method is demonstrated by screening an 11-mer oligopeptide library for selective binding of the degradation products of the nerve agent VX. The identified oligopeptides can be used as selective molecular receptors for sensor development. The MXRF screening method is nondestructive, requires minimal sample preparation or special tags for analysis, and the screening time depends on the desired sensitivity.

  18. High pressure x-ray diffraction techniques with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Jing, Liu

    2016-07-01

    This article summarizes the developments of experimental techniques for high pressure x-ray diffraction (XRD) in diamond anvil cells (DACs) using synchrotron radiation. Basic principles and experimental methods for various diffraction geometry are described, including powder diffraction, single crystal diffraction, radial diffraction, as well as coupling with laser heating system. Resolution in d-spacing of different diffraction modes is discussed. More recent progress, such as extended application of single crystal diffraction for measurements of multigrain and electron density distribution, time-resolved diffraction with dynamic DAC and development of modulated heating techniques are briefly introduced. The current status of the high pressure beamline at BSRF (Beijing Synchrotron Radiation Facility) and some results are also presented. Project supported by the National Natural Science Foundation of China (Grant Nos. 10875142, 11079040, and 11075175). The 4W2 beamline of BSRF was supported by the Chinese Academy of Sciences (Grant Nos. KJCX2-SW-N20, KJCX2-SW-N03, and SYGNS04).

  19. Novel X-ray image noise reduction technology reduces patient radiation dose while maintaining image quality in coronary angiography.

    PubMed

    Ten Cate, T; van Wely, M; Gehlmann, H; Mauti, M; Camaro, C; Reifart, N; Suryapranata, H; de Boer, M J

    2015-11-01

    The consequences of high radiation dose for patient and staff demand constant improvements in X-ray dose reduction technology. This study assessed non-inferiority of image quality and quantified patient dose reduction in interventional cardiology for an anatomy-specific optimised cine acquisition chain combined with advanced real-time image noise reduction algorithms referred to as 'study cine', compared with conventional angiography. Fifty patients underwent two coronary angiographic acquisitions: one with advanced image processing and optimised exposure system settings to enable dose reduction (study cine) and one with standard image processing and exposure settings (reference cine). The image sets of 39 patients (18 females, 21 males) were rated by six experienced independent reviewers, blinded to the patient and image characteristics. The image pairs were randomly presented. Overall 85 % of the study cine images were rated as better or equal quality compared with the reference cine (95 % CI 0.81-0.90). The median dose area product per frame decreased from 55 to 26 mGy.cm(2)/frame (53 % reduction, p < 0.001). This study demonstrates that the novel X-ray imaging technology provides non-inferior image quality compared with conventional angiographic systems for interventional cardiology with a 53 % patient dose reduction.

  20. Low-dose 4D myocardial perfusion with x-ray micro-CT

    NASA Astrophysics Data System (ADS)

    Clark, D. P.; Badea, C. T.

    2017-03-01

    X-ray CT is widely used, both clinically and pre-clinically, for fast, high-resolution, anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, temporally-resolved CT data can detail cardiac motion and blood flow dynamics for one-stop cardiovascular CT imaging procedures. In previous work, we demonstrated efficient, low-dose projection acquisition and reconstruction strategies for cardiac micro-CT imaging and for multiple-injection micro-CT perfusion imaging. Here, we extend this previous work with regularization based on rank-sparse kernel regression and on filtration with the Karhunen-Loeve transform. Using a dual source, prospectively gated sampling strategy which produces an approximately uniform distribution of projections, we apply this revised algorithm to the assessment of both myocardial perfusion and cardiac functional metrics from the same set of projection data. We test the algorithm in simulations using a modified version of the MOBY mouse phantom which contains realistic perfusion and cardiac dynamics. The proposed algorithm reduces the reconstruction error by 81% relative to unregularized, algebraic reconstruction. The results confirm our ability to simultaneously solve for cardiac temporal motion and perfusion dynamics. In future work, we will apply the algorithm and sampling protocol to small animal cardiac studies.

  1. High-resolution multi-MeV x-ray radiography using relativistic laser-solid interaction

    SciTech Connect

    Courtois, C.; Compant La Fontaine, A.; Barbotin, M.; Bazzoli, S.; Brebion, D.; Bourgade, J. L.; Gazave, J.; Lagrange, J. M.; Landoas, O.; Le Dain, L.; Lefebvre, E.; Pichoff, N.; Edwards, R.; Aedy, C.; Biddle, L.; Drew, D.; Gardner, M.; Ramsay, M.; Simons, A.; Sircombe, N.

    2011-02-15

    When high intensity ({>=}10{sup 19} W cm{sup -2}) laser light interacts with matter, multi-MeV electrons are produced. These electrons can be utilized to generate a MeV bremsstrahlung x-ray emission spectrum as they propagate into a high-Z solid target positioned behind the interaction area. The short duration (<10 ps) and the small diameter (<500 {mu}m) of the x-ray pulse combined with the MeV x-ray spectrum offers an interesting alternative to conventional bremsstrahlung x-ray sources based on an electron accelerator used to radiograph dense, rapidly moving objects. In experiments at the Omega EP laser, a multi-MeV x-ray source is characterized consistently with number of independent diagnostics. An unfiltered x-ray dose of approximately 2 rad in air at 1 m and a source diameter of less than 350 {mu}m are inferred. Radiography of a complex and high area density (up to 61 g/cm{sup 2}) object is then performed with few hundred microns spatial resolution.

  2. High Resolution Temporal and Spectral Monitoring of Eta Carinae's X-Ray Emission the June Eclipse

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.; Hamaguchi, K.; Henley, D.; Pittard, J. M.; Gull, T. R.; Davidson, K.; Swank, J. H.; Petre, R.; Ishibashi, K.

    2004-01-01

    The supermassive and luminous star Eta Carinae undergoes strong X-ray variations every 5.5 years when its 2-10 keV X-ray emission brightens rapidly with wild fluctuations before dropping by a factor of 100 to a minimum lasting 3 months. The most recent X-ray "eclipse" began in June 2003 and during this time Eta Carinae was intensely observed throughout the electromagnetic spectrum. Here we report the first results of frequent monitoring of the 2-10 keV band X-ray emission by the Rossi X-ray Timing Explorer along wit high resolution X-ray spectra obtained with the transmission gratings on the Chandra X-ray Observatory. We compare these observations to those results obtained during the previous X-ray eclipse in 1998, and interpret the variations in the X-ray brightness, in the amount of absorption, in the X-ray emission measure and in the K-shell emission lines in terms of a colliding wind binary model.

  3. High Resolution Temporal and Spectral Monitoring of Eta Carinae's X-Ray Emission the June Eclipse

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.; Hamaguchi, K.; Henley, D.; Pittard, J. M.; Gull, T. R.; Davidson, K.; Swank, J. H.; Petre, R.; Ishibashi, K.

    2004-01-01

    The supermassive and luminous star Eta Carinae undergoes strong X-ray variations every 5.5 years when its 2-10 keV X-ray emission brightens rapidly with wild fluctuations before dropping by a factor of 100 to a minimum lasting 3 months. The most recent X-ray "eclipse" began in June 2003 and during this time Eta Carinae was intensely observed throughout the electromagnetic spectrum. Here we report the first results of frequent monitoring of the 2-10 keV band X-ray emission by the Rossi X-ray Timing Explorer along wit high resolution X-ray spectra obtained with the transmission gratings on the Chandra X-ray Observatory. We compare these observations to those results obtained during the previous X-ray eclipse in 1998, and interpret the variations in the X-ray brightness, in the amount of absorption, in the X-ray emission measure and in the K-shell emission lines in terms of a colliding wind binary model.

  4. Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems.

    PubMed

    Bowden, Louise; Faulkner, Ronan; Clancy, Conor; Gallagher, Aoife; Devine, Mark; Gorman, Dermot; O'Reilly, Geraldine; Dowling, Anita

    2011-09-01

    Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.

  5. The effects of x-ray beam hardening on detective quantum efficiency and radiation dose

    PubMed Central

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

    2011-01-01

    The goal of this preliminary study was to investigate the effects of x-ray beam hardening on the detective quantum efficiency (DQE) and the radiation dose of an inline x-ray imaging system. The DQE and the average glandular dose were both calculated under the same experimental conditions for a range of beam hardening levels, corresponding to no added beam hardening and two thicknesses each of Rhodium (Rh) and Molybdenum (Mo) filters. The dose calculation results demonstrate a reduction of 15% to 24% for the range of beam hardening levels. The comparison of all quantities comprising the DQE exhibit very close correlation between the results obtained without added beam hardening to the results corresponding to the range of beam hardening levels. For the specific experimental conditions utilized in this preliminary study, the results are an indication that the use of beam hardening holds the potential to reduce the radiation dose without decreasing the performance of the system. Future studies will seek to apply this method in a clinical environment and perform a comprehensive image quality evaluation, in an effort to further evaluate the potential of beam hardening to balance the tradeoff between dose and image quality. PMID:25214383

  6. Low dose X -ray effects on catalase activity in animal tissue

    NASA Astrophysics Data System (ADS)

    Focea, R.; Nadejde, C.; Creanga, D.; Luchian, T.

    2012-12-01

    This study was intended to investigate the effect of low-dose X ray-irradiation upon the activity of catalase (CAT) in freshly excised chicken tissues (liver, kidney, brain, muscle). The tissue samples were irradiated with 0.5Gy and 2Gy respectively, in a 6 MV photon beam produced by a clinical linear accelerator (VARIAN CLINAC 2100SC). The dose rate was of 260.88cGy/min. at 100 cm source to sample distance. The catalase level was assayed spectrophotometrically, based on reaction kinetics, using a catalase UV assay kit (SIGMA). Catalase increased activity in various tissue samples exposed to the studied X ray doses (for example with 24 % in the liver cells, p<0.05) suggested the stimulation of the antioxidant enzyme biosynthesis within several hours after exposure at doses of 0.5 Gy and 2 Gy; the putative enzyme inactivation could also occur (due to the injuries on the hydrogen bonds that ensure the specificity of CAT active site) but the resulted balance of the two concurrent processes indicates the cell ability of decomposing the hydrogen peroxide-with benefits for the cell physiology restoration for the chosen low dose radiation.

  7. High resolution, high rate X-ray spectrometer

    DOEpatents

    Goulding, Frederick S.; Landis, Donald A.

    1987-01-01

    A pulse processing system (10) for use in an X-ray spectrometer in which a ain channel pulse shaper (12) and a fast channel pulse shaper (13) each produce a substantially symmetrical triangular pulse (f, p) for each event detected by the spectrometer, with the pulse width of the pulses being substantially independent of the magnitude of the detected event and with the pulse width of the fast pulses (p) being substantially shorter than the pulse width of the main channel pulses (f). A pile-up rejector circuit (19) allows output pulses to be generated, with amplitudes linearly related to the magnitude of the detected events, whenever the peak of a main channel pulse (f) is not affected by a preceding or succeeding main channel pulse, while inhibiting output pulses wherein peak magnitudes of main channel pulses are affected by adjacent pulses. The substantially symmetrical triangular main channel pulses (f) are generated by the weighted addition (27-31) of successive RC integrations (24, 25, 26) of an RC differentiated step wave (23). The substantially symmetrical triangular fast channel pulses (p) are generated by the RC integration ( 43) of a bipolar pulse (o) in which the amplitude of the second half is 1/e that of the first half, with the RC time constant of integration being equal to one-half the width of the bipolar pulse.

  8. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  9. High resolution, low energy avalanche photodiode X-ray detectors

    NASA Technical Reports Server (NTRS)

    Farrell, R.; Vanderpuye, K.; Entine, G.; Squillante, M. R.

    1991-01-01

    Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

  10. Figure Measurements of High-Energy-X-Ray Replicated Optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Kester, Thomas; Engelhaupt, Darell; Speegle, Chet; Martin, Greg

    2003-01-01

    We are developing grazing incidence x-ray optics for a balloon-borne hard-x-ray telescope (HERO). The HERO mirror shells are fabricated using electroform-nickel replication off super-polished cylindrical mandrels. One of the sources for mirror resolution error is departure of the shell figure from prescription. We have modified a Vertical-scan Long Trace Profilometer (VLTP) in order to measure the figure of the inner surface of the HERO mirror shells for diameters as small as 76 mm. Mirror alignment method and sources for systematic errors will be discussed. Comparison of figure metrology of the mandrel and the shells will be presented together with results from x-ray tests.

  11. High ionisation absorption in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Bianchi, S.; Muñoz-Darias, T.; De, K.; Fender, R.; Merloni, A.

    2016-05-01

    The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and narrow absorption features, sporadically present in the X-ray spectra of some systems, are actually the signature of equatorial outflows, which might carry away more matter than that being accreted. Therefore, they play a major role in the accretion phenomenon. These outflows (or ionised atmospheres) are ubiquitous during the softer states but absent during the power-law dominated, hard states, suggesting a strong link with the state of the inner accretion disc, presence of the radio-jet and the properties of the central source. Here, we discuss the current understanding of this field.

  12. Absorbed XFEL Dose in the Components of the LCLS X-Ray Optics

    SciTech Connect

    Hau-Riege, Stefan

    2010-12-03

    There is great concern that the short, intense XFEL pulse of the LCLS will damage the optics that will be placed into the beam. We have analyzed the extent of the problem by considering the anticipated materials and position of the optical components in the beam path, calculated the absorbed dose as a function of photon energy, and compared these doses with the expected doses required (i) to observe rapid degradation due to thermal fatigue, (ii) to reach the melting temperature, or (iii) to actually melt the material. We list the materials that are anticipated to be placed into the Linac Coherent Light Source (LCLS) x-ray free electron laser (XFEL) beam line, their positions, and the absorbed dose, and compare this dose with anticipated damage thresholds.

  13. A dual-energy medical instrument for measurement of x-ray source voltage and dose rate

    NASA Astrophysics Data System (ADS)

    Ryzhikov, V. D.; Naydenov, S. V.; Volkov, V. G.; Opolonin, O. D.; Makhota, S.; Pochet, T.; Smith, C. F.

    2016-03-01

    An original dual-energy detector and medical instrument have been developed to measure the output voltages and dose rates of X-ray sources. Theoretical and experimental studies were carried out to characterize the parameters of a new scintillator-photodiode sandwich-detector based on specially-prepared zinc selenide crystals in which the low-energy detector (LED) works both as the detector of the low-energy radiation and as an absorption filter allowing the highenergy fraction of the radiation to pass through to the high-energy detector (HED). The use of the LED as a low-energy filter in combination with a separate HED opens broad possibilities for such sandwich structures. In particular, it becomes possible to analyze and process the sum, difference and ratio of signals coming from these detectors, ensuring a broad (up to 106) measurement range of X-ray intensity from the source and a leveling of the energy dependence. We have chosen an optimum design of the detector and the geometry of the component LED and HED parts that allow energy-dependence leveling to within specified limits. The deviation in energy dependence of the detector does not exceed about 5% in the energy range from 30 to 120 keV. The developed detector and instrument allow contactless measurement of the anode voltage of an X-ray emitter from 40 to 140 kV with an error no greater than 3%. The dose rate measurement range is from 1 to 200 R/min. An original medical instrument has passed clinical testing and was recommended for use in medical institutions for X-ray diagnostics.

  14. Note: High-pressure in situ x-ray laminography using diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Nomura, Ryuichi; Uesugi, Kentaro

    2016-04-01

    A high-pressure in situ X-ray laminography technique was developed using a newly designed, laterally open diamond anvil cell. A low X-ray beam of 8 keV energy was used, aiming at future application to dual energy X-ray chemical imaging techniques. The effects of the inclination angle and the imaging angle range were evaluated at ambient pressure using the apparatus. Sectional images of ruby ball samples were successfully reconstructed at high pressures, up to approximately 50 GPa. The high-pressure in situ X-ray laminography technique is expected to provide new insights into the deep Earth sciences.

  15. Note: High-pressure in situ x-ray laminography using diamond anvil cell

    SciTech Connect

    Nomura, Ryuichi; Uesugi, Kentaro

    2016-04-15

    A high-pressure in situ X-ray laminography technique was developed using a newly designed, laterally open diamond anvil cell. A low X-ray beam of 8 keV energy was used, aiming at future application to dual energy X-ray chemical imaging techniques. The effects of the inclination angle and the imaging angle range were evaluated at ambient pressure using the apparatus. Sectional images of ruby ball samples were successfully reconstructed at high pressures, up to approximately 50 GPa. The high-pressure in situ X-ray laminography technique is expected to provide new insights into the deep Earth sciences.

  16. High energy x-ray phase contrast CT using glancing-angle grating interferometers

    SciTech Connect

    Sarapata, A.; Stayman, J. W.; Siewerdsen, J. H.; Finkenthal, M.; Stutman, D.; Pfeiffer, F.

    2014-02-15

    Purpose: The authors present initial progress toward a clinically compatible x-ray phase contrast CT system, using glancing-angle x-ray grating interferometry to provide high contrast soft tissue images at estimated by computer simulation dose levels comparable to conventional absorption based CT. Methods: DPC-CT scans of a joint phantom and of soft tissues were performed in order to answer several important questions from a clinical setup point of view. A comparison between high and low fringe visibility systems is presented. The standard phase stepping method was compared with sliding window interlaced scanning. Using estimated dose values obtained with a Monte-Carlo code the authors studied the dependence of the phase image contrast on exposure time and dose. Results: Using a glancing angle interferometer at high x-ray energy (∼45 keV mean value) in combination with a conventional x-ray tube the authors achieved fringe visibility values of nearly 50%, never reported before. High fringe visibility is shown to be an indispensable parameter for a potential clinical scanner. Sliding window interlaced scanning proved to have higher SNRs and CNRs in a region of interest and to also be a crucial part of a low dose CT system. DPC-CT images of a soft tissue phantom at exposures in the range typical for absorption based CT of musculoskeletal extremities were obtained. Assuming a human knee as the CT target, good soft tissue phase contrast could be obtained at an estimated absorbed dose level around 8 mGy, similar to conventional CT. Conclusions: DPC-CT with glancing-angle interferometers provides improved soft tissue contrast over absorption CT even at clinically compatible dose levels (estimated by a Monte-Carlo computer simulation). Further steps in image processing, data reconstruction, and spectral matching could make the technique fully clinically compatible. Nevertheless, due to its increased scan time and complexity the technique should be thought of not as

  17. High energy x-ray phase contrast CT using glancing-angle grating interferometers.

    PubMed

    Sarapata, A; Stayman, J W; Finkenthal, M; Siewerdsen, J H; Pfeiffer, F; Stutman, D

    2014-02-01

    The authors present initial progress toward a clinically compatible x-ray phase contrast CT system, using glancing-angle x-ray grating interferometry to provide high contrast soft tissue images at estimated by computer simulation dose levels comparable to conventional absorption based CT. DPC-CT scans of a joint phantom and of soft tissues were performed in order to answer several important questions from a clinical setup point of view. A comparison between high and low fringe visibility systems is presented. The standard phase stepping method was compared with sliding window interlaced scanning. Using estimated dose values obtained with a Monte-Carlo code the authors studied the dependence of the phase image contrast on exposure time and dose. Using a glancing angle interferometer at high x-ray energy (∼ 45 keV mean value) in combination with a conventional x-ray tube the authors achieved fringe visibility values of nearly 50%, never reported before. High fringe visibility is shown to be an indispensable parameter for a potential clinical scanner. Sliding window interlaced scanning proved to have higher SNRs and CNRs in a region of interest and to also be a crucial part of a low dose CT system. DPC-CT images of a soft tissue phantom at exposures in the range typical for absorption based CT of musculoskeletal extremities were obtained. Assuming a human knee as the CT target, good soft tissue phase contrast could be obtained at an estimated absorbed dose level around 8 mGy, similar to conventional CT. DPC-CT with glancing-angle interferometers provides improved soft tissue contrast over absorption CT even at clinically compatible dose levels (estimated by a Monte-Carlo computer simulation). Further steps in image processing, data reconstruction, and spectral matching could make the technique fully clinically compatible. Nevertheless, due to its increased scan time and complexity the technique should be thought of not as replacing, but as complimentary to

  18. Laser Produced X-Ray for High Resolution Lithography.

    DTIC Science & Technology

    2014-09-26

    Neodymium Laser Pulse ....... ....................... ... 24 Figure 11. Densitometer Trace of Al X-Ray Spectrum ........... ... 26...typical x-ray lithography experiments, 100 joule light pulses with a nanosecond pulse width (full-width-half-maximum) were produced with a neodymium -doped...34."..’’’.. ’ ’.’/ .. ".-".’ ’ ’ . > . . ’ ’ ’ ’ ’ , ’ : . r "" ’ "" " " ". . . .;" 23 The Laser -, The laser used in prior research is a neodymium

  19. Next Generation Astronomical X-ray Optics: High Angular Resolution, Light Weight, and Low Production Cost

    NASA Technical Reports Server (NTRS)

    Zhang. W. W.; Biskach, M. P.; Blake, P. N.; Chan, K. W.; Gaskin, J. A.; Hong, M. L.; Jones, W. D.; Kolos, L. D.; Mazzarella, J. R.; McClelland, R. S.; O'Dell, S. L.; Saha, T. T.; Sharpe, M. V.

    2012-01-01

    X-ray astronomy depends on the availability of telescopes with high resolution and large photon collecting areas. Since x-ray observation can only be carried out above the atmosphere, these telescopes must be necessarily lightweight. Compounding the lightweight requirement is that an x-ray telescope consists of many nested concentric shells, which further require that x-ray mirrors must also be geometrically thin to achieve high packing efficiency. This double lightweight and geometrically thin requirement poses significant technical challenges in fabricating the mirrors and in integrating them into mirror assemblies. This paper reports on the approach, strategy and status of our x-ray optics development program whose objective is to meet these technical challenges at modest cost to enable future x-ray missions, including small Explorer missions in the near term, probe class missions in the medium term, and large flagship missions in the long term.

  20. High-speed x-ray radiographic measurement of laser-driven hydrodynamic instability

    NASA Astrophysics Data System (ADS)

    Shiraga, Hiroyuki; Azechi, Hiroshi; Nakai, Mitsuo; Shigemori, Keisuke; Nishikino, Masaharu; Sakaiya, Tatsuhiro; Fujioka, Shinsuke; Tamari, Yohei; Yamanaka, Tatsuhiko

    2003-07-01

    Hydrodynamic instability in laser-irradiated targets have been investigated in detail by using ultra high-speed x-ray radiographic technique. Recently developed high-resolution x-ray imaging for laser-driven Rayleigh-Taylor (RT) instability experiments as well as data including RT growth rate, ablation density and plasma density profile are desribed. Results are of great importance for comprehensive understanding of the dispersion relation of the laser-driven RT instability. Especially, direct observation of the ablation density was first achieved with temporal and spatial resolutions of 100 ps and 3 μm, respectively. Imaging techniques includes x-ray Moire imaging, x-ray penumbral imaging and Fresnel phase zone plate imaging coupled with x-ray streak cameras or x-ray CCD cameras. Experiments were performed by using Gekko-XII/HIPER laser system at the Institute of Laser Engineering, Osaka University.

  1. Comparison of enhanced device response and predicted x-ray dose enhancement effects on MOS oxides

    SciTech Connect

    Fleetwood, D.M.; Beutler, D.E.; Lorence, L.J. Jr.; Draper, B.L.; Brown, D.B.; Riewe, L.C.; Rosenstock, H.B.; Knott, D.P.

    1988-12-01

    The response of MOS capacitors to low- and medium-energy x-ray irradiation is investigated as a function of gate material (TaSi or Al), oxide thickness, and electric field. Measured device response is compared with predictions based on discrete ordinates and Monte Carlo code simulations of dose enhancement effects, coupled with recent estimates of electron-hole recombination in MOS oxides. In comparisons of 10-keV x-ray and Co-60 irradiations of Al-gate MOS capacitors at an oxide electric field of 1 MV/cm, it is found that predictions and experiments agree to within better than 20 percent for oxide thicknesses ranging from 35 to 1060 nm. For capacitors having TaSi/Al gates, predictions and experiments agree to within better than 30 percent at 1 MV/cm, with the largest differences occurring for 35-nm gate oxides. At other electric fields, the disagreement between experiment and prediction increases significantly for both Al- and TaSi/Al-gate capacitors, and can be greater than a factor of 2 at applied electric fields below 0.1 MV/cm. For medium energy (-- 100 keV average photon energy) x-ray irradiations, the enhanced device response exhibits a much stronger dependence on endpoint bremsstrahlung energy than expected from TIGERP or CEPXS/ONETRAN simulations. Implications for hardness assurance testing are discussed.

  2. A novel position-sensitive mega-size dosimeter for photoneutrons in high-energy X-ray medical accelerators.

    PubMed

    Sohrabi, Mehdi; Hakimi, Amir; Mahdavi, Seyed Rabi

    2016-06-01

    A novel position-sensitive mega-size polycarbonate (MSPC) dosimeter is introduced. It provides photoneutron (PN) dose equivalent matrix of positions in and out of a beam of a high energy X-ray medical accelerator under a single exposure. A novel position-sensitive MSPC dosimeter was developed and applied. It has an effective etched area of 50×50cm(2), as used in this study, processed in a mega-size electrochemical etching chamber to amplify PN-induced-recoil tracks to a point viewed by the unaided eyes. Using such dosimeters, PN dose equivalents, dose equivalent profiles and isodose equivalent distribution of positions in and out of beams for different X-ray doses and field sizes were determined in a Siemens ONCOR Linac. The PN dose equivalent at each position versus X-ray dose was linear up to 20Gy studied. As the field size increased, the PN dose equivalent in the beam was also increased but it remained constant at positions out of the beam up to 20cm away from the beam edge. The jaws and MLCs due to material differences and locations relative to the target produce different PN contributions. The MSPC dosimeter introduced in this study is a perfect candidate for PN dosimetry with unique characteristics such as simplicity, efficiency, dose equivalent response, large size, flexibility to be bent, resembling the patient's skin, highly position-sensitive with high spatial resolution, highly insensitive to X-rays, continuity in measurements and need to a single dosimeter to obtain PN dose equivalent matrix data under a single X-ray exposure. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. X-Ray Resonant Irradiation and High-Z Radiosensitization in Cancer Therapy Using Platinum Nano-Reagents

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.; Lim, S.; Montenegro, M.; Pradhan, A. K.; Barth, R.; Bell, E.; Turro, C.; Pitzer, R.

    2012-06-01

    %TEXT OF YOUR ABSTRACT We describe the atomic-molecular-bio physics of X-ray irradiation of High-Z heavy-element nanomaterials as radiosensitizing agents in cancer therapy. Our reports in past few ISMSs showed that compounds of High-Z elements, Pt and Au, embedded in tumors could provide the most efficient therapy and diagnostics (theranostics) when X-rays are targeted at their resonant energies. Harmful damages due to unnecessary broadband radiation from conventional X-ray sources can be reduced considerably by using a monochromatic X-ray source at resonant energy. We will present our recent findings from Monte Carlo simulations, using Geant4 code, for X-ray energy absorption and dose deposition in tissues where the broadband X-ray sources have three different peak voltages, 100 keV, 170 keV and 6 MeV. We use platinum as an agent for killing cancerous cells via increased linear-energy-transfer (LET) and dose enhancement. We find that X-ray energies in the range below 100 keV are most efficient in achieving both the required tissue penetrative depths and deposition of energy. This confirms the previous results for Au that it is only the low-energy component around 100 keV from the 6 MV linear accelerator (LINAC) that is most effective in dose-enhanced cell killing. Preliminary experimental results cancer cells with Pt and results on Kα radiation of Al will also be presented. Acknowledgement: Partially supported by DOE, NSF; Computational work was carried out at the Ohio Supercomputer Center

  4. MOSFET dosimeter depth-dose measurements in heterogeneous tissue-equivalent phantoms at diagnostic x-ray energies

    SciTech Connect

    Jones, A.K.; Pazik, F.D.; Hintenlang, D.E.; Bolch, W.E.

    2005-10-15

    The objective of the present study was to explore the use of the TN-1002RD metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter for measuring tissue depth dose at diagnostic photon energies in both homogeneous and heterogeneous tissue-equivalent materials. Three cylindrical phantoms were constructed and utilized as a prelude to more complex measurements within tomographic physical phantoms of pediatric patients. Each cylindrical phantom was constructed as a stack of seven 5-cm-diameter and 1-cm-thick discs of materials radiographically representative of either soft tissue (S), bone (B), or lung tissue (L) at diagnostic photon energies. In addition to a homogeneous phantom of soft tissue (SSSSSSS), two heterogeneous phantoms were constructed: SSBBSSS and SBLLBSS. MOSFET dosimeters were then positioned at the interface of each disc, and the phantoms were then irradiated at 66 kVp and 200 mAs. Measured values of absorbed dose at depth were then compared to predicated values of point tissue dose as determined via Monte Carlo radiation transport modeling. At depths exceeding 2 cm, experimental results matched the computed values of dose with high accuracy regardless of the dosimeter orientation (epoxy bubble facing toward or away from the x-ray beam). Discrepancies were noted, however, between measured and calculated point doses near the surface of the phantom (surface to 2 cm depth) when the dosimeters were oriented with the epoxy bubble facing the x-ray beam. These discrepancies were largely eliminated when the dosimeters were placed with the flat side facing the x-ray beam. It is therefore recommended that the MOSFET dosimeters be oriented with their flat sides facing the beam when they are used at shallow depths or on the surface of either phantoms or patients.

  5. Ultrahigh-resolution soft-x-ray microscopy with zone plates in high orders of diffraction.

    PubMed

    Rehbein, S; Heim, S; Guttmann, P; Werner, S; Schneider, G

    2009-09-11

    We present an x-ray optical approach to overcome the current limitations in spatial resolution of x-ray microscopes. Our new BESSY full-field x-ray microscope operates with an energy resolution up to E/DeltaE=10(4). We demonstrate that under these conditions it is possible to employ high orders of diffraction for imaging. Using the third order of diffraction of a zone plate objective with 25 nm outermost zone width, 14 nm lines and spaces of a multilayer test structure were clearly resolved. We believe that high-order imaging paves the way towards sub-10-nm real space x-ray imaging.

  6. Common envelope mechanisms: constraints from the X-ray luminosity function of high-mass X-ray binaries

    SciTech Connect

    Zuo, Zhao-Yu; Li, Xiang-Dong E-mail: lixd@nju.edu.cn

    2014-12-10

    We use the measured X-ray luminosity function (XLF) of high-mass X-ray binaries (HMXBs) in nearby star-forming galaxies to constrain the common envelope (CE) mechanisms, which play a key role in governing the binary evolution. We find that the XLF can be reproduced quite closely under both CE mechanisms usually adopted, i.e., the α{sub CE} formalism and the γ algorithm, with a reasonable range of parameters considered. Provided that the parameter combination is the same, the γ algorithm is likely to produce more HMXBs than the α{sub CE} formalism, by a factor of up to ∼10. In the framework of the α{sub CE} formalism, a high value of α{sub CE} is required to fit the observed XLF, though it does not significantly affect the global number of the HMXB populations. We present the detailed components of the HMXB populations under the γ algorithm and compare them with those in Zuo et al. and observations. We suggest the distinct observational properties, as well as period distributions of HMXBs, may provide further clues to discriminate between these two types of CE mechanisms.

  7. Paediatric x-ray radiation dose reduction and image quality analysis.

    PubMed

    Martin, L; Ruddlesden, R; Makepeace, C; Robinson, L; Mistry, T; Starritt, H

    2013-09-01

    Collaboration of multiple staff groups has resulted in significant reduction in the risk of radiation-induced cancer from radiographic x-ray exposure during childhood. In this study at an acute NHS hospital trust, a preliminary audit identified initial exposure factors. These were compared with European and UK guidance, leading to the introduction of new factors that were in compliance with European guidance on x-ray tube potentials. Image quality was assessed using standard anatomical criteria scoring, and visual grading characteristics analysis assessed the impact on image quality of changes in exposure factors. This analysis determined the acceptability of gradual radiation dose reduction below the European and UK guidance levels. Chest and pelvis exposures were optimised, achieving dose reduction for each age group, with 7%-55% decrease in critical organ dose. Clinicians confirmed diagnostic image quality throughout the iterative process. Analysis of images acquired with preliminary and final exposure factors indicated an average visual grading analysis result of 0.5, demonstrating equivalent image quality. The optimisation process and final radiation doses are reported for Carestream computed radiography to aid other hospitals in minimising radiation risks to children.

  8. Fetal radiation doses and subsequent risks from X-ray examinations: Should we be concerned?

    PubMed Central

    Chaparian, Ali; Aghabagheri, Mahdi

    2013-01-01

    Background: Pregnant women are sometimes exposed to ionizing radiation in radiology examinations for various reasons. In such cases, the radiation dose to the conceptus and subsequent risks should be estimated. Objective: The purpose of this study was the calculation and presentation of fetal dose and subsequent risks resulted from different X-ray examinations. Materials and Methods: An analytical simulation study was conducted and six common radiographies in different views and three types of special examinations were evaluated. The entrance skin exposure (ESE) was measured using a solid-state dosimeter. A Monte Carlo program was used in order to simulate different views of X-ray examinations and calculate the radiation doses received by the conceptus for every view of each examination. Then the risk of childhood cancer and small head size were calculated for different radiographies. Results: The fetal doses and consequence risks of the small head size and childhood cancer for the radiographs of chest, skull, and sinuses were negligible but the risks of childhood cancer and small head size due to radiographies of abdomen, lumbar spine, and pelvis areas were ponderable. Conclusion: Results of this study can be used for the pregnant women radiographies management. PMID:24639714

  9. Sun Shines in High-Energy X-rays

    NASA Image and Video Library

    2014-12-22

    X-rays stream off the sun in this first picture of the sun, overlaid on a picture taken by NASA Solar Dynamics Observatory SDO, taken by NASA NuSTAR. The field of view covers the west limb of the sun.

  10. A real-time regional adaptive exposure method for saving dose-area product in x-ray fluoroscopy

    SciTech Connect

    Burion, Steve; Funk, Tobias; Speidel, Michael A.

    2013-05-15

    Purpose: Reduction of radiation dose in x-ray imaging has been recognized as a high priority in the medical community. Here the authors show that a regional adaptive exposure method can reduce dose-area product (DAP) in x-ray fluoroscopy. The authors' method is particularly geared toward providing dose savings for the pediatric population. Methods: The scanning beam digital x-ray system uses a large-area x-ray source with 8000 focal spots in combination with a small photon-counting detector. An imaging frame is obtained by acquiring and reconstructing up to 8000 detector images, each viewing only a small portion of the patient. Regional adaptive exposure was implemented by varying the exposure of the detector images depending on the local opacity of the object. A family of phantoms ranging in size from infant to obese adult was imaged in anteroposterior view with and without adaptive exposure. The DAP delivered to each phantom was measured in each case, and noise performance was compared by generating noise arrays to represent regional noise in the images. These noise arrays were generated by dividing the image into regions of about 6 mm{sup 2}, calculating the relative noise in each region, and placing the relative noise value of each region in a one-dimensional array (noise array) sorted from highest to lowest. Dose-area product savings were calculated as the difference between the ratio of DAP with adaptive exposure to DAP without adaptive exposure. The authors modified this value by a correction factor that matches the noise arrays where relative noise is the highest to report a final dose-area product savings. Results: The average dose-area product saving across the phantom family was (42 {+-} 8)% with the highest dose-area product saving in the child-sized phantom (50%) and the lowest in the phantom mimicking an obese adult (23%). Conclusions: Phantom measurements indicate that a regional adaptive exposure method can produce large DAP savings without

  11. Entrance surface dose and image quality: comparison of adult chest and abdominal X-ray examinations in general practitioner clinics, public and private hospitals in Malaysia.

    PubMed

    Hambali, Ahmad Shariff; Ng, Kwan-Hoong; Abdullah, Basri Johan Jeet; Wang, Hwee-Beng; Jamal, Noriah; Spelic, David C; Suleiman, Orhan H

    2009-01-01

    This study was undertaken to compare the entrance surface dose (ESD) and image quality of adult chest and abdominal X-ray examinations conducted at general practitioner (GP) clinics, and public and private hospitals in Malaysia. The surveyed facilities were randomly selected within a given category (28 GP clinics, 20 public hospitals and 15 private hospitals). Only departmental X-ray units were involved in the survey. Chest examinations were done at all facilities, while only hospitals performed abdominal examinations. This study used the x-ray attenuation phantoms and protocols developed for the Nationwide Evaluation of X-ray Trends (NEXT) survey program in the United States. The ESD was calculated from measurements of exposure and clinical geometry. An image quality test tool was used to evaluate the low-contrast detectability and high-contrast detail performance under typical clinical conditions. The median ESD value for the adult chest X-ray examination was the highest (0.25 mGy) at GP clinics, followed by private hospitals (0.22 mGy) and public hospitals (0.17 mGy). The median ESD for the adult abdominal X-ray examination at public hospitals (3.35 mGy) was higher than that for private hospitals (2.81 mGy). Results of image quality assessment for the chest X-ray examination show that all facility types have a similar median spatial resolution and low-contrast detectability. For the abdominal X-ray examination, public hospitals have a similar median spatial resolution but larger low-contrast detectability compared with private hospitals. The results of this survey clearly show that there is room for further improvement in performing chest and abdominal X-ray examinations in Malaysia.

  12. Radiation Dose to the Skin and to the Gonads from Diagnostic X-Ray Procedures

    PubMed Central

    Duggan, H. E.; Olde, G. L.

    1963-01-01

    The design of a study to assess the hazard to patients from radiation received during diagnostic radiological procedures is described. The long-term accumulation of data relating to the skin and gonadal doses received by patients in a large x-ray department has been initiated. This will serve as a model for any situation involving small recurrent radiation doses to a significant proportion of the population. A description is given of the basic dose measurements made and the method used in calculating and recording the skin and gonadal doses for each patient. Although no definite conclusions concerning the presence or absence of a radiation hazard have yet been made, the proposed future course of this study is discussed. ImagesFig. 3Fig. 4 PMID:14079142

  13. Formation of high mass X-ray black hole binaries

    NASA Astrophysics Data System (ADS)

    Brown, G. E.; Heger, A.; Langer, N.; Lee, C.-H.; Wellstein, S.; Bethe, H. A.

    2001-10-01

    The discrepancy in the past years of many more black-hole soft X-ray transients (SXTs), of which a dozen have now been identified, had challenged accepted wisdom in black hole evolution. Reconstruction in the literature of high-mass X-ray binaries has required stars of up to ˜40 M ⊙ to evolve into low-mass compact objects, setting this mass as the limit often used for black hole formation in population syntheses. On the other hand, the sheer number of inferred SXTs requires that many, if not most, stars of ZAMS masses 20-35 M ⊙ end up as black holes ( Portegies Zwart et al., 1997; Ergma and van den Heuvel, 1998). In this paper we show that this can be understood by challenging the accepted wisdom that the result of helium core burning in a massive star is independent of whether the core is covered by a hydrogen envelope, or 'naked' while it burns. The latter case occurs in binaries when the envelope of the more massive star is transferred to the companion by Roche Lobe overflow while in either main sequence or red giant stage. For solar metallicity, whereas the helium cores which burn while naked essentially never go into high-mass black holes, those that burn while clothed do so, beginning at ZAMS mass ˜20 M ⊙, the precise mass depending on the 12C( α, γ) 16O rate as we outline. In this way the SXTs can be evolved, provided that the H envelope of the massive star is removed only following the He core burning. Whereas this scenario was already outlined in 1998 by Brown et al. [NewA 4 (1999) 313], their work was based on evolutionary calculations of Woosley et al. [ApJ 448 (1995) 315] which employed wind loss rates which were too high. In this article we collect results for lower, more correct wind loss rates, finding that these change the results only little. We go into the details of carbon burning in order to reconstruct why the low Fe core masses from naked He stars are relatively insensitive to wind loss rate. The main reason is that without the

  14. The superconducting high-resolution soft X-ray spectrometer at the advanced biological and environmental X-ray facility

    NASA Astrophysics Data System (ADS)

    Friedrich, S.; Drury, O. B.; George, S. J.; Cramer, S. P.

    2007-11-01

    We have built a 36-pixel superconducting tunnel junction X-ray spectrometer for chemical analysis of dilute samples in the soft X-ray band. It offers an energy resolution of ˜10-20 eV FWHM below 1 keV, a solid angle coverage of ˜10 -3, and can be operated at total rates of up to ˜10 6 counts/s. Here, we describe the spectrometer performance in speciation measurements by fluorescence-detected X-ray absorption spectroscopy at the Advanced Biological and Environmental X-ray facility at the ALS synchrotron.

  15. Patient dose simulations for scanning-beam digital x-ray tomosynthesis of the lungs

    SciTech Connect

    Nelson, Geoff; Fahrig, Rebecca; Yoon, Sungwon; Krishna, Ganesh; Wilfley, Brian

    2013-11-15

    location. When tumor SNR is held constant (i.e., x-ray fluence is scaled appropriately), SBDX gives 2–10 times less dose than fluoroscopy for the same conditions within the typical range of patient locations. The relative position of the patient (as a percent of SDD) has a much more significant impact on dose than either SDD or patient position. The patient position providing the minimum dose for a given tumor SNR and SDD is approximately the same as the position of maximum tomographic angle.Conclusions: SBDX offers a significant dose advantage over currently used C-arm fluoroscopy. The patient location with lowest dose coincides with the location of maximum tomographic angle. In order to provide adequate space for the patient and for the pulmonologists’ equipment, a SDD of 100 cm is recommended.

  16. Patient dose simulations for scanning-beam digital x-ray tomosynthesis of the lungs

    PubMed Central

    Nelson, Geoff; Yoon, Sungwon; Krishna, Ganesh; Wilfley, Brian; Fahrig, Rebecca

    2013-01-01

    location. When tumor SNR is held constant (i.e., x-ray fluence is scaled appropriately), SBDX gives 2–10 times less dose than fluoroscopy for the same conditions within the typical range of patient locations. The relative position of the patient (as a percent of SDD) has a much more significant impact on dose than either SDD or patient position. The patient position providing the minimum dose for a given tumor SNR and SDD is approximately the same as the position of maximum tomographic angle. Conclusions: SBDX offers a significant dose advantage over currently used C-arm fluoroscopy. The patient location with lowest dose coincides with the location of maximum tomographic angle. In order to provide adequate space for the patient and for the pulmonologists’ equipment, a SDD of 100 cm is recommended. PMID:24320450

  17. Estimating head and neck tissue dose from x-ray scatter to physicians performing x-ray guided cardiovascular procedures: a phantom study.

    PubMed

    Fetterly, Kenneth A; Schueler, Beth A; Grams, Michael P; Sturchio, Glenn M

    2017-03-20

    Physicians performing x-ray guided interventional procedures have a keen interest in radiation safety. Radiation dose to tissues and organs of the head and neck are of particular interest because they are not routinely protected by wearable radiation safety devices. This study was conducted to facilitate estimation of radiation dose to tissues of the head and neck of interventional physicians based on the dose recorded by a personal dosimeter worn on the left collar. Scatter beam qualities maximum energy and HVL were measured for 40 scatter beams emitting from an anthropomorphic patient phantom. Variables of the scatter beams included scatter angle (35° and 90°), primary beam peak tube potential (60, 80, 100, and 120 kVp), and 5 Cu spectral filter thicknesses (0-0.9 mm). Four reference scatter beam qualities were selected to represent the range of scatter beams realized in a typical practice. A general radiographic x-ray tube was tuned to produce scatter-equivalent radiographic beams and used to simultaneously expose the head and neck of an anthropomorphic operator phantom and radiochromic film. The geometric relationship between the x-ray source of the scatter-equivalent beams and the operator phantom was set to mimic that between a patient and physician performing an invasive cardiovascular procedure. Dose to the exterior surface of the operator phantom was measured with both 3 × 3 cm(2) pieces of film and personal dosimeters positioned at the location of the left collar. All films were scanned with a calibrated flatbed scanner, which converted the film's reflective density to dose. Films from the transverse planes of the operator phantom provided 2D maps of the dose distribution within the phantom. These dose maps were normalized by the dose at the left collar, providing 2D percent of left collar dose (LCD) maps. The percent LCD maps were overlain with bony anatomy CT images of the operator phantom and estimates of percent LCD to the left, right and whole

  18. The effects of device position on the operator's radiation dose when using a handheld portable X-ray device.

    PubMed

    Makdissi, Jimmy; Pawar, Ravikiran R; Johnson, Ben; Chong, Bun S

    2016-01-01

    Handheld X-ray devices are now offered in dental practice. Handheld X-ray units challenge the concept of a restricted access to the "controlled area" as they are held by the operator. Although an integral lead shield is provided, the distance from the body is variable, dependent on how the device is held. The aim of this article was to investigate the level of operator dose when using a handheld X-ray device in various positions. A NOMAD Pro™ Handheld X-ray system (Aribex Inc., Charlotte, NC) fitted with a remote control and mounted on a tripod was used in this study. A maxillofacial phantom ATOM(®) Max Dental and Diagnostic Phantom, model 711 HN (CIRS Inc., Norfolk, VA) was used to simulate the patient's head position. A mannequin was used to represent the operator. Pre-calibrated thermoluminescent dosemeters (TLDs) (Qados, Agar Scientific, Stansted, UK) were placed on the mannequin close to the eyes and at the level of thyroid, trunk, waist, hand (right finger + left palm) and feet, and three TLDs were used for background radiation. Three test scenarios were investigated; Position 1, close to operators' body and parallel to the ground; Position 2, away from the body with the arms fully extended (approximately 40 cm distance) and parallel to the ground; Position 3, perpendicular to the ground while the arms are partially extended. 30 exposures each of 1 s were performed in each test. Background radiation was measured at 0.0110 mGy. The highest exposure after subtracting background radiation was recorded on the palm of the left hand (0.0310 mGy) at Position 3. The estimated dose to the operator was calculated based on an average workload of 100 intraoral radiographs weekly for a dental practitioner working 46 weeks a year. There is a negligible increase in operator exposure levels using handheld X-ray devices which remain well below the recommended levels of the Ionizing Radiation Regulations 1999. They could however represent an increase from what

  19. The effects of device position on the operator's radiation dose when using a handheld portable X-ray device

    PubMed Central

    Pawar, Ravikiran R; Johnson, Ben; Chong, Bun S

    2016-01-01

    Introduction: Handheld X-ray devices are now offered in dental practice. Handheld X-ray units challenge the concept of a restricted access to the “controlled area” as they are held by the operator. Although an integral lead shield is provided, the distance from the body is variable, dependent on how the device is held. The aim of this article was to investigate the level of operator dose when using a handheld X-ray device in various positions. Material and Methods: A NOMAD Pro™ Handheld X-ray system (Aribex Inc., Charlotte, NC) fitted with a remote control and mounted on a tripod was used in this study. A maxillofacial phantom ATOM® Max Dental and Diagnostic Phantom, model 711 HN (CIRS Inc., Norfolk, VA) was used to simulate the patient's head position. A mannequin was used to represent the operator. Pre-calibrated thermoluminescent dosemeters (TLDs) (Qados, Agar Scientific, Stansted, UK) were placed on the mannequin close to the eyes and at the level of thyroid, trunk, waist, hand (right finger + left palm) and feet, and three TLDs were used for background radiation. Three test scenarios were investigated; Position 1, close to operators' body and parallel to the ground; Position 2, away from the body with the arms fully extended (approximately 40 cm distance) and parallel to the ground; Position 3, perpendicular to the ground while the arms are partially extended. 30 exposures each of 1 s were performed in each test. Results: Background radiation was measured at 0.0110 mGy. The highest exposure after subtracting background radiation was recorded on the palm of the left hand (0.0310 mGy) at Position 3. The estimated dose to the operator was calculated based on an average workload of 100 intraoral radiographs weekly for a dental practitioner working 46 weeks a year. Conclusions: There is a negligible increase in operator exposure levels using handheld X-ray devices which remain well below the recommended levels of the Ionizing Radiation

  20. Ultraprecision motion control technique for high-resolution x-ray instrumentation

    SciTech Connect

    Shu, D.; Toellner, T. S.; Alp, E. E.

    2000-07-17

    With the availability of third-generation hard x-ray synchrotron radiation sources, such as the Advanced Photon Source (APS) at Argonne National Laboratory, x-ray inelastic scattering and x-ray nuclear resonant scattering provide powerful means for investigating the vibrational dynamics of a variety of materials and condensed matter systems. Novel high-resolution hard x-ray optics with meV energy resolution requires a compact positioning mechanism with 20--50-nrad angular resolution and stability. In this paper, the authors technical approach to this design challenge is presented. Sensitivity and stability test results are also discussed.

  1. Estimated collective effective dose to the population from X-ray and nuclear medicine examinations in Finland.

    PubMed

    Bly, R; Järvinen, H; Korpela, M H; Tenkanen-Rautakoski, P; Mäkinen, A

    2011-09-01

    The collective effective doses to the population from X-ray and nuclear medicine (NM) examinations in Finland in 2008 and 2009, respectively, were estimated. The estimated collective effective dose per inhabitant was 0.45 mSv from X-ray examinations and 0.03 mSv from NM examinations. The collective effective doses per inhabitant have not changed substantially during the last 10 y. However, proportional dose due to CT examinations has increased from 50 % in 2005 to 58 % in 2009 of the total collective effective dose from all X-ray examinations and proportional dose of PET examinations from 7 to 13 % of the total collective effective dose from NM examinations. The collective effective dose from conventional plain radiography was over 20 % higher when estimated using the new (ICRP 103) tissue weighting factors than that obtained using the old (ICRP 60) tissue weighting factors.

  2. A Review of X-ray Diagnostic Calibrations in the 2 to 100 keV Region Using the High Energy X-ray Calibration Facility (HEX)

    SciTech Connect

    Ali, Zaheer; Pond, T; Buckles, R A; Maddox, B R; Chen, C D; DeWald, E L; Izumi, N; Stewart, R

    2010-05-19

    The precise and accurate measurement of X-rays in the 2 keV to 100 keV region is crucial to the understanding of HED plasmas and warm dense matter in general. With the emergence of inertially confined plasma facilities as the premier platforms for ICF, laboratory astrophysics, and national security related plasma experiments, the need to calibrate diagnostics in the high energy X-ray regime has grown. At National Security Technologies High Energy X-ray Calibration Facility (HEX) in Livermore, California, X-ray imagers, filter-fluorescer spectrometers, crystal spectrometers, image plates, and nuclear diagnostics are calibrated. The HEX can provide measurements of atomic line radiation, X-ray flux (accuracy within 10%), and X-ray energy (accuracy within 1%). The HEX source is comprised of a commercial 160 kV X-ray tube, a fluorescer wheel, a filter wheel, and a lead encasement. The X-ray tube produces a Tungsten bremsstrahlung spectrum which causes a foil to fluoresce line radiation. To minimize bremsstrahlung in the radiation for calibration we also provide various foils as filters. For experimental purposes, a vacuum box capable of 10{sup -7} Torr, as well as HPGe and CdTe radiation detectors, are provided on an optical table. Most geometries and arrangements can be changed to meet experimental needs.

  3. Spatial resolution of synchrotron x-ray microtomography in high energy range: Effect of x-ray energy and sample-to-detector distance

    NASA Astrophysics Data System (ADS)

    Seo, D.; Tomizato, F.; Toda, H.; Uesugi, K.; Takeuchi, A.; Suzuki, Y.; Kobayashi, M.

    2012-12-01

    Spatial resolution of three-dimensional images obtained by synchrotron X-ray microtomography technique is evaluated using cyclic bar patterns machined on a steel wire. Influences of X-ray energy and the sample-to-detector distance on spatial resolution were investigated. High X-ray energies of 33-78 keV are applied due to the high X-ray absorption of transition metals. Best spatial resolution of about 1.2 μm pitch was observed at the sample-to-detector distance range of 20-110 mm and at the energy range of 68-78 keV. Several factors such as X-ray scattering and diffraction phenomena affecting the degradation of spatial resolution are also discussed.

  4. Optomechanical design of a high-precision detector robot arm system for x-ray nano-diffraction with x-ray nanoprobe

    NASA Astrophysics Data System (ADS)

    Shu, D.; Kalbfleisch, S.; Kearney, S.; Anton, J.; Chu, Y. S.

    2014-03-01

    Collaboration between Argonne National Laboratory and Brookhaven National Laboratory has created a design for the high-precision detector robot arm system that will be used in the x-ray nano-diffraction experimental station at the Hard X-ray Nanoprobe (HXN) beamline for the NSLS-II project. The robot arm system is designed for positioning and manipulating an x-ray detector in three-dimensional space for nano-diffraction data acquisition with the HXN x-ray microscope. It consists of the following major component groups: a granite base with air-bearing support, a 2-D horizontal base stage, a vertical axis goniometer, a 2-D vertical plane robot arm, a 3-D fast scanning stages group, and a 2-D x-ray pixel detector. The design specifications and unique optomechanical structure of this novel high-precision detector robot arm system will be presented in this paper.

  5. Johann Spectrometer for High Resolution X-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Machek, Pavel; Welter, Edmund; Caliebe, Wolfgang; Brüggmann, Ulf; Dräger, Günter; Fröba, Michael

    2007-01-01

    A newly designed vacuum Johann spectrometer with a large focusing analyzer crystal for inelastic x-ray scattering and high resolution fluorescence spectroscopy has been installed at the DORIS III storage ring. Spherically bent crystals with a maximum diameter of 125 mm, and cylindrically bent crystals are employed as dispersive optical elements. Standard radius of curvature of the crystals is 1000 mm, however, the design of the mechanical components also facilitates measurements with smaller and larger bending radii. Up to four crystals are mounted on a revolving crystal changer which enables crystal changes without breaking the vacuum. The spectrometer works at fixed Bragg angle. It is preferably designed for the measurements in non-scanning mode with a broad beam spot, and offers a large flexibility to set the sample to the optimum position inside the Rowland circle. A deep depletion CCD camera is employed as a position sensitive detector to collect the energy-analyzed photons on the circumference of the Rowland circle. The vacuum in the spectrometer tank is typically 10-6 mbar. The sample chamber is separated from the tank either by 25 μm thick Kapton windows, which allows samples to be measured under ambient conditions, or by two gate valves. The spectrometer is currently installed at wiggler beamline W1 whose working range is 4-10.5 keV with typical flux at the sample of 5×1010photons/s/mm2. The capabilities of the spectrometer are illustrated by resonant inelastic experiments on 3d transition metals and rare earth compounds, and by chemical shift measurements on chromium compounds.

  6. X-ray radiation and the risk of multiple sclerosis: Do the site and dose of exposure matter?

    PubMed Central

    Motamed, Mohammad Reza; Fereshtehnejad, Seyed-Mohammad; Abbasi, Maryam; Sanei, Mastaneh; Abbaslou, Mina; Meysami, Somayeh

    2014-01-01

    Background: The sporadic cases of radiation-activated multiple sclerosis (MS) has been previously described, with a few studies focused on the relationship between radiation and the risk of MS. The aim of our study was to evaluate the association between history of X-ray radiation and MS. Methods: This case-control study was conducted on 150 individuals including 65 MS patients and 85 age- and sex-matched healthy controls enrolled using non-probability convenient sampling. Any history of previous Xray radiation consisted of job-related X-ray exposure, radiotherapy, radiographic evaluations including chest Xray, lumbosacral X-ray, skull X-ray, paranasal sinuses (PNS) X-ray, gastrointestinal (GI) series, foot X-ray and brain CT scanning were recorded and compared between two groups. Statistical analysis was performed using independent t test, Chi square and receiver operating characteristics (ROC) curve methods through SPSS software. Results: History of both diagnostic [OR=3.06 (95% CI: 1.32-7.06)] and therapeutic [OR=7.54 (95% CI: 1.5935.76) X-ray radiations were significantly higher among MS group. Mean number of skull X-rays [0.4 (SD=0.6) vs. 0.1 (SD=0.3), p=0.004] and brain CT scanning [0.9 (SD=0.8) vs. 0.5 (SD=0.7), p=0.005] was higher in MS group as well as mean of the cumulative X-ray radiation dosage [1.84 (SD=1.70) mSv vs. 1.11 (SD=1.54) mSv; p=0.008]. Conclusion: Our study was one of the first to show higher history of X-ray radiation in patients with MS compared to healthy controls. A possible association was also found between the dose and the site exposed to X-ray radiation and risk of developing MS PMID:25695003

  7. A High-Resolution X-Ray Image of the Jet in M87

    NASA Astrophysics Data System (ADS)

    Marshall, H. L.; Miller, B. P.; Davis, D. S.; Perlman, E. S.; Wise, M.; Canizares, C. R.; Harris, D. E.

    2002-01-01

    We present the first high-resolution X-ray image of the jet in M87 using the Chandra X-Ray Observatory. There is clear structure in the jet and almost all of the optically bright knots are detected individually. The unresolved core is the brightest X-ray feature but is only 2-3 times brighter than knot A (12.3" from the core) and the inner knot HST-1 (1.0" from the core). The X-ray and optical positions of the knots are consistent at the 0.1" level, but the X-ray emission from the brightest knot (A) is marginally upstream of the optical emission peak. Detailed Gaussian fits to the X-ray jet one-dimensional profile show distinct X-ray emission that is not associated with specific optical features. The X-ray/optical flux ratio decreases systematically from the core, and X-ray emission is not clearly detected beyond 20" from the core. The X-ray spectra of the core and the two brightest knots, HST-1 and A, are consistent with a simple power law (Sν~ν-α) with α=1.46+/-0.05, practically ruling out inverse Compton models as the dominant X-ray emission mechanism. The core flux is significantly larger than expected from an advective accretion flow, and the spectrum is much steeper, indicating that the core emission may be due to synchrotron emission from a small-scale jet. The spectral energy distributions of the knots are well fitted by synchrotron models. The spectral indices in the X-ray band, however, are comparable to that expected in the Kardashev-Pacholczyk synchrotron model but are much flatter than expected in the pitch-angle isotropization model of Jaffe and Perola. The break frequencies derived from both models drop by factors of 10-100 with distance from the core.

  8. A High Resolution X-ray Image of the Jet in M 87

    NASA Astrophysics Data System (ADS)

    Miller, B. P.; Marshall, H. L.; Davis, D. S.; Perlman, E. S.; Wise, M.; Canizares, C. R.; Harris, D. E.

    2001-12-01

    We present the first high resolution X-ray image of the jet in M 87 using the Chandra X-ray Observatory. There is clear structure in the jet and almost all of the optically bright knots are detected individually. The unresolved core is the brightest X-ray feature but is only 2-3 times brighter than knot A (12.3" from the core) and the inner knot HST-1 (1.0" from the core). The X-ray and optical positions of the knots are consistent at the 0.1" level but the X-ray emission from the brightest knot (A) is marginally upstream of the optical emission peak. Detailed Gaussian fits to the X-ray jet one-dimensional profile show distinct X-ray emission that is not associated with specific optical features. The X-ray/optical flux ratio decreases systematically from the core and X-ray emission is not clearly detected beyond 20" from the core. The X-ray spectra of the core and the two brightest knots, HST-1 and A1, are consistent with a simple power law with alpha = 1.46 +/- 0.05, practically ruling out inverse Compton models as the dominant X-ray emission mechanism. The core flux is significantly larger than expected from an advective accretion flow and the spectrum is much steeper, indicating that the core emission may be due to synchrotron emission from a small scale jet. The spectral energy distributions (SEDs) of the knots are well fit by synchrotron models. The spectral indices in the X-ray band, however are comparable to that expected in the Kardashev-Pacholczyk synchrotron model but are much flatter than expected in the pitch angle isotropization model of Jaffe and Perola. The break frequencies derived from both models drop by factors of 10-100 with distance from the core.

  9. K-edge digital subtraction imaging with dichromatic x-ray sources: SNR and dose studies

    NASA Astrophysics Data System (ADS)

    Sarnelli, A.; Elleaume, H.; Taibi, A.; Gambaccini, M.; Bravin, A.

    2006-09-01

    The aim of the present work is to analytically evaluate the signal to noise ratio (SNR) and the delivered dose in K-edge digital subtraction imaging (KES) using two types of x-ray sources: a monochromatic x-ray source (available at synchrotron radiation facilities and considered as gold standard) and a quasi-monochromatic compact source. The energy separation ΔE between the two monochromatic beams is 1 keV and 4 keV for the two sources, respectively. The evaluation has been performed for both radiography and computed tomography. Different geometries have been studied to mimic clinical situations. In mammography, a pathology perfused by a contrast agent has been modelled; in angiography, a vessel superimposed to a ventricle or a stand-alone artery stenosis has been studied. The SNR and the skin dose have been calculated as a function of the detail diameter, the contrast agent (iodine and gadolinium), and its concentration in the tissues. Results show that for ΔE = 4 keV a slightly higher delivered dose is required to obtain the same SNR with respect to ΔE < 1 keV. A similar study has been performed for KES-CT. Computer simulations of CT images performed with Snark software are shown to validate the analytical calculations.

  10. Experimental validation of a kilovoltage x-ray source model for computing imaging dose

    SciTech Connect

    Poirier, Yannick; Kouznetsov, Alexei; Koger, Brandon; Tambasco, Mauro

    2014-04-15

    Purpose: To introduce and validate a kilovoltage (kV) x-ray source model and characterization method to compute absorbed dose accrued from kV x-rays. Methods: The authors propose a simplified virtual point source model and characterization method for a kV x-ray source. The source is modeled by: (1) characterizing the spatial spectral and fluence distributions of the photons at a plane at the isocenter, and (2) creating a virtual point source from which photons are generated to yield the derived spatial spectral and fluence distribution at isocenter of an imaging system. The spatial photon distribution is determined by in-air relative dose measurements along the transverse (x) and radial (y) directions. The spectrum is characterized using transverse axis half-value layer measurements and the nominal peak potential (kVp). This source modeling approach is used to characterize a Varian{sup ®} on-board-imager (OBI{sup ®}) for four default cone-beam CT beam qualities: beams using a half bowtie filter (HBT) with 110 and 125 kVp, and a full bowtie filter (FBT) with 100 and 125 kVp. The source model and characterization method was validated by comparing dose computed by the authors’ inhouse software (kVDoseCalc) to relative dose measurements in a homogeneous and a heterogeneous block phantom comprised of tissue, bone, and lung-equivalent materials. Results: The characterized beam qualities and spatial photon distributions are comparable to reported values in the literature. Agreement between computed and measured percent depth-dose curves is ⩽2% in the homogeneous block phantom and ⩽2.5% in the heterogeneous block phantom. Transverse axis profiles taken at depths of 2 and 6 cm in the homogeneous block phantom show an agreement within 4%. All transverse axis dose profiles in water, in bone, and lung-equivalent materials for beams using a HBT, have an agreement within 5%. Measured profiles of FBT beams in bone and lung-equivalent materials were higher than their

  11. A versatile, highly-efficient, high-resolution von Hamos Bragg crystal x-ray spectrometer

    SciTech Connect

    Vane, C.R.; Smith, M.S.; Raman, S.

    1988-01-01

    An efficient, high-resolution, vertical-focusing, Bragg crystal x-ray spectrometer has been specifically designed and constructed for use in measurements of x rays produced in collisions of energetic heavy ions. In this report the design and resulting operational characteristics of the final instrument are fully described. A wide variety of sample data is also included to illustrate the utility of this device in several areas of research. 14 refs., 38 figs.

  12. Image quality and dose optimization using novel x-ray source filters tailored to patient size

    NASA Astrophysics Data System (ADS)

    Toth, Thomas L.; Cesmeli, Erdogan; Ikhlef, Aziz; Horiuchi, Tetsuya

    2005-04-01

    The expanding set of CT clinical applications demands increased attention to obtaining the maximum image quality at the lowest possible dose. Pre-patient beam shaping filters provide an effective means to improve dose utilization. In this paper we develop and apply characterization methods that lead to a set of filters appropriately matched to the patient. We developed computer models to estimate image noise and a patient size adjusted CTDI dose. The noise model is based on polychromatic X-ray calculations. The dose model is empirically derived by fitting CTDI style dose measurements for a demographically representative set of phantom sizes and shapes with various beam shaping filters. The models were validated and used to determine the optimum IQ vs dose for a range of patient sizes. The models clearly show that an optimum beam shaping filter exists as a function of object diameter. Based on noise and dose alone, overall dose efficiency advantages of 50% were obtained by matching the filter shape to the size of the object. A set of patient matching filters are used in the GE LightSpeed VCT and Pro32 to provide a practical solution for optimum image quality at the lowest possible dose over the range of patient sizes and clinical applications. Moreover, these filters mark the beginning of personalized medicine where CT scanner image quality and radiation dose utilization is truly individualized and optimized to the patient being scanned.

  13. High-energy x-ray Talbot-Lau radiography of a human knee

    NASA Astrophysics Data System (ADS)

    Horn, F.; Gelse, K.; Jabari, S.; Hauke, C.; Kaeppler, S.; Ludwig, V.; Meyer, P.; Michel, T.; Mohr, J.; Pelzer, G.; Rieger, J.; Riess, C.; Seifert, M.; Anton, G.

    2017-08-01

    We report on a radiographic measurement of an ex vivo human knee using a grating-based phase-contrast imaging setup and a medical x-ray tube at a tube voltage of 70 kV. The measurement has been carried out using a Talbot-Lau setup that is suitable to achieve a high visibility in the energy regime of medical imaging. In a medical reading by an experienced trauma surgeon signatures of chondrocalcinosis in the medial meniscus have been identified more evidently using the dark-field image in comparison to the conventional attenuation image. The analysis has been carried out at various dose levels down to 0.14 mGy measured as air kerma, which is a dose comparable to clinically used radiographic devices. The diagnosis has been confirmed by a histological analysis of the meniscus tissue. In the introduced high-frequency filtered phase-contrast image the anterior and posterior horn of the medial meniscus and the posterior cruciate ligament have also been visible. Furthermore, atherosclerotic plaque is visible in both imaging modalities, attenuation and dark-field, despite the presence of overlaying bone. This measurement, for the first time, proves the feasibility of Talbot-Lau x-ray imaging at high-energy spectra above 40 kVp and reasonable dose levels with regard to spacious and dense objects.

  14. 21 CFR 892.1700 - Diagnostic x-ray high voltage generator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Diagnostic x-ray high voltage generator. 892.1700 Section 892.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... generator. (a) Identification. A diagnostic x-ray high voltage generator is a device that is intended to...

  15. 21 CFR 892.1700 - Diagnostic x-ray high voltage generator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Diagnostic x-ray high voltage generator. 892.1700 Section 892.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... generator. (a) Identification. A diagnostic x-ray high voltage generator is a device that is intended to...

  16. 21 CFR 892.1700 - Diagnostic x-ray high voltage generator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Diagnostic x-ray high voltage generator. 892.1700 Section 892.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... generator. (a) Identification. A diagnostic x-ray high voltage generator is a device that is intended to...

  17. 21 CFR 892.1700 - Diagnostic x-ray high voltage generator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Diagnostic x-ray high voltage generator. 892.1700 Section 892.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... generator. (a) Identification. A diagnostic x-ray high voltage generator is a device that is intended to...

  18. 21 CFR 892.1700 - Diagnostic x-ray high voltage generator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Diagnostic x-ray high voltage generator. 892.1700 Section 892.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... generator. (a) Identification. A diagnostic x-ray high voltage generator is a device that is intended to...

  19. Early effects of low dose 12C6+ ion or X-ray irradiation on human peripheral blood lymphocytes

    NASA Astrophysics Data System (ADS)

    Chen, Yingtai; Li, Yumin; Zhang, Hong; Xie, Yi; Chen, Xuezhong; Ren, Jinyu; Zhang, Xiaowei; Zhu, Zijiang; Liu, Hongliang; Zhang, Yawei

    2010-04-01

    The aim of this study was to estimate the acute effects of low dose 12C6+ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy 12C6+ ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy 12C6+ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) 12C6+ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI.

  20. Toward an organ based dose prescription method for the improved accuracy of murine dose in orthovoltage x-ray irradiators

    PubMed Central

    Belley, Matthew D.; Wang, Chu; Nguyen, Giao; Gunasingha, Rathnayaka; Chao, Nelson J.; Chen, Benny J.; Dewhirst, Mark W.; Yoshizumi, Terry T.

    2014-01-01

    Purpose: Accurate dosimetry is essential when irradiating mice to ensure that functional and molecular endpoints are well understood for the radiation dose delivered. Conventional methods of prescribing dose in mice involve the use of a single dose rate measurement and assume a uniform average dose throughout all organs of the entire mouse. Here, the authors report the individual average organ dose values for the irradiation of a 12, 23, and 33 g mouse on a 320 kVp x-ray irradiator and calculate the resulting error from using conventional dose prescription methods. Methods: Organ doses were simulated in the Geant4 application for tomographic emission toolkit using the MOBY mouse whole-body phantom. Dosimetry was performed for three beams utilizing filters A (1.65 mm Al), B (2.0 mm Al), and C (0.1 mm Cu + 2.5 mm Al), respectively. In addition, simulated x-ray spectra were validated with physical half-value layer measurements. Results: Average doses in soft-tissue organs were found to vary by as much as 23%–32% depending on the filter. Compared to filters A and B, filter C provided the hardest beam and had the lowest variation in soft-tissue average organ doses across all mouse sizes, with a difference of 23% for the median mouse size of 23 g. Conclusions: This work suggests a new dose prescription method in small animal dosimetry: it presents a departure from the conventional approach of assigning a single dose value for irradiation of mice to a more comprehensive approach of characterizing individual organ doses to minimize the error and uncertainty. In human radiation therapy, clinical treatment planning establishes the target dose as well as the dose distribution, however, this has generally not been done in small animal research. These results suggest that organ dose errors will be minimized by calibrating the dose rates for all filters, and using different dose rates for different organs. PMID:24593746

  1. Toward an organ based dose prescription method for the improved accuracy of murine dose in orthovoltage x-ray irradiators

    SciTech Connect

    Belley, Matthew D.; Wang, Chu; Nguyen, Giao; Gunasingha, Rathnayaka; Chao, Nelson J.; Chen, Benny J.; Dewhirst, Mark W.; Yoshizumi, Terry T.

    2014-03-15

    Purpose: Accurate dosimetry is essential when irradiating mice to ensure that functional and molecular endpoints are well understood for the radiation dose delivered. Conventional methods of prescribing dose in mice involve the use of a single dose rate measurement and assume a uniform average dose throughout all organs of the entire mouse. Here, the authors report the individual average organ dose values for the irradiation of a 12, 23, and 33 g mouse on a 320 kVp x-ray irradiator and calculate the resulting error from using conventional dose prescription methods. Methods: Organ doses were simulated in the Geant4 application for tomographic emission toolkit using the MOBY mouse whole-body phantom. Dosimetry was performed for three beams utilizing filters A (1.65 mm Al), B (2.0 mm Al), and C (0.1 mm Cu + 2.5 mm Al), respectively. In addition, simulated x-ray spectra were validated with physical half-value layer measurements. Results: Average doses in soft-tissue organs were found to vary by as much as 23%–32% depending on the filter. Compared to filters A and B, filter C provided the hardest beam and had the lowest variation in soft-tissue average organ doses across all mouse sizes, with a difference of 23% for the median mouse size of 23 g. Conclusions: This work suggests a new dose prescription method in small animal dosimetry: it presents a departure from the conventional approach of assigninga single dose value for irradiation of mice to a more comprehensive approach of characterizing individual organ doses to minimize the error and uncertainty. In human radiation therapy, clinical treatment planning establishes the target dose as well as the dose distribution, however, this has generally not been done in small animal research. These results suggest that organ dose errors will be minimized by calibrating the dose rates for all filters, and using different dose rates for different organs.

  2. Towards phasing using high X-ray intensity

    SciTech Connect

    Galli, Lorenzo; Son, Sang -Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; Nass, Karol; Shoeman, Robert L.; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N.

    2015-09-30

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. In conclusion, a pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.

  3. Towards phasing using high X-ray intensity

    DOE PAGES

    Galli, Lorenzo; Son, Sang -Kil; Barends, Thomas R. M.; ...

    2015-09-30

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential `bleaching' of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. In conclusion, a pattern sorting schememore » is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed.« less

  4. High energy X-ray observations of extragalactic objects

    NASA Technical Reports Server (NTRS)

    Baity, W. A.; Gruber, D. E.; Matteson, J. L.; Knight, F. K.; Nolan, P. L.; Scheepmaker, A.; Wheaton, W. A.; Hofman, J. A.; Primini, F. A.; Lewin, W. H. G.

    1979-01-01

    Preliminary results are reported for scanning observations of the active galaxy NGC 5128 (Cen A) and the Type 1 Seyfert galaxy NGC 4151 with the low-energy detectors of the HEAO-1 A-4 hard X-ray instrument. The X-ray spectra in the energy range from 15 to 100 keV are shown to be consistent with previous observations of these galaxies. It is noted that NGC 5128 rose in intensity from 1972 to 1975, that spectral softening occurred after early 1973, and that the source has since decreased in intensity while maintaining an E to the -1.7 photon power law. The results for NGC 4151 indicate variable absorption below 10 keV and a power-law slope of about E to the -1.4 in the range from 10 keV to 10 MeV.

  5. Towards phasing using high X-ray intensity

    PubMed Central

    Galli, Lorenzo; Son, Sang-Kil; Barends, Thomas R. M.; White, Thomas A.; Barty, Anton; Botha, Sabine; Boutet, Sébastien; Caleman, Carl; Doak, R. Bruce; Nanao, Max H.; Nass, Karol; Shoeman, Robert L.; Timneanu, Nicusor; Santra, Robin; Schlichting, Ilme; Chapman, Henry N.

    2015-01-01

    X-ray free-electron lasers (XFELs) show great promise for macromolecular structure determination from sub-micrometre-sized crystals, using the emerging method of serial femtosecond crystallography. The extreme brightness of the XFEL radiation can multiply ionize most, if not all, atoms in a protein, causing their scattering factors to change during the pulse, with a preferential ‘bleaching’ of heavy atoms. This paper investigates the effects of electronic damage on experimental data collected from a Gd derivative of lysozyme microcrystals at different X-ray intensities, and the degree of ionization of Gd atoms is quantified from phased difference Fourier maps. A pattern sorting scheme is proposed to maximize the ionization contrast and the way in which the local electronic damage can be used for a new experimental phasing method is discussed. PMID:26594370

  6. Highly sensitive resist material for deep x-ray lithography

    NASA Astrophysics Data System (ADS)

    Ehrfeld, Wolfgang; Hessel, Volker; Lehr, Heinz; Loewe, Holger; Schmidt, Martin; Schenk, Rainer

    1997-07-01

    The present paper describes the first chemically amplified negative-tone resist for deep x-ray lithography (DXRL). The choice of the resist material for this new resist has been oriented on the experience of the photo, electron beam and x- ray lithography (XRL) for microelectronic applications. In this work a negative tone resist containing a novolak, a crosslinker and an acid generator was developed by varying the different components. It was found that only few components, which proved to be good in thin films, were suitable for DXRL. The new resist fulfills all technological requirements and shows an increased sensitivity by a factor 15 as compared to the standard resist material, poly(methyl methacrylate). This tremendous increase in sensitivity leads to a huge cost reduction of the DXRL process. Furthermore, an excellent adhesion of this new resist to metallic substrates has been achieved which allows us to fabricate free standing columns with an aspect ratio of 80.

  7. Organ Doses to Airline Passengers Screened by X-Ray Backscatter Imaging Systems.

    PubMed

    Stepusin, Elliott J; Maynard, Matthew R; O'Reilly, Shannon E; Redzovic, Sadije; Bolch, Wesley E; Hintenlang, David E; Borak, Thomas B

    2017-02-01

    Advanced imaging technologies (AIT) are being developed for passenger airline transportation. They are designed to provide enhanced security benefits by identifying objects on passengers that would not be detected by methodologies now used for routine surveillance. X-ray backscatter imaging is one AIT system being considered. Since this technology is based on scanning passengers with ionizing radiation, concern has been raised relating to the health risks associated with these exposures. Recommendations for standards of radiation safety have been proposed by the American National Standards Institute published in ANSI/HPS N43.17-2009. A Monte Carlo based methodology for estimating organ doses received from an X-ray backscatter AIT system is presented. Radiological properties of a reference scanner including beam intensity, geometry and energy spectra were modeled based on previous studies and physical measurements. These parameters were incorporated into a Monte Carlo source subroutine and validated with comparison of simulated versus measured data. One extension of this study was to calculate organ and effective dose on a wide range of potential passengers. Computational phantoms with realistic morphologies were used including adults of 5th, 25th, 50th, 75th and 95th percentile weight, children of 5th, 50th and 95th percentile weight, and the developing fetus of 15, 25, and 38 weeks after conception. Additional sensitivity studies were performed to evaluate effects of passenger positioning within the scanner, energy spectrum and beam geometry, as well as failure mode analyses. Results for routine operations yielded a maximum effective dose to the adult and pediatric passengers of 15 and 25 nSv per screen, respectively. The developing fetus received a maximum organ dose and whole body dose of 16 nGy and 8.5 nGy per screen, respectively. The sensitivity analyses indicated that variations in positioning, energy spectra, and beam geometry yielded a range of effective

  8. High Resolution Adjustable Mirror Control for X-ray Astronomy

    NASA Astrophysics Data System (ADS)

    Trolier-McKinstry, Susan

    We propose to build and test thin film transistor control circuitry for a new highresolution adjustable X-ray mirror technology. This control circuitry will greatly simplify the wiring scheme to address individual actuator cells. The result will be a transformative improvement for the X-ray Surveyor mission concept: mathematical models, which fit the experimental data quite well, indicate that 0.5 arcsecond imaging is feasible through this technique utilizing thin slumped glass substrates with uncorrected angular resolution of order 5-10 arcseconds. In order to correct for figures errors in a telescope with several square meters of collecting area, millions of actuator cells must be set and held at specific voltages. It is clearly not feasible to do this via millions of wires, each one connected to an actuator. Instead, we propose to develop and test thin-film technology that operates on the same principle as megapixel computer screens. We will develop the technologies needed to build thin film piezoelectric actuators, controlled by thin film ZnO transistors, on flexible polyimide films, and to connect those films to the back surfaces of X-ray mirrors on thin glass substrates without deforming the surface. These technologies represent a promising avenue of the development of mirrors for the X-Ray Surveyor mission concept. Such a telescope will make possible detailed studies of a wide variety of astrophysical sources. One example is the Warm-Hot Intergalactic Medium (WHIM), which is thought to account for a large fraction of the normal matter in the universe but which has not been detected unambiguously to date. Another is the growth of supermassive black holes in the early universe. This proposal supports NASA's goals of technical advancement of technologies suitable for future missions, and training of graduate students.

  9. A high resolution small animal radiation research platform (SARRP) with x-ray tomographic guidance capabilities

    PubMed Central

    Wong, John; Armour, Elwood; Kazanzides, Peter; Iordachita, Iulian; Tryggestad, Erik; Deng, Hua; Matinfar, Mohammad; Kennedy, Christopher; Liu, Zejian; Chan, Timothy; Gray, Owen; Verhaegen, Frank; McNutt, Todd; Ford, Eric; DeWeese, Theodore L.

    2008-01-01

    Purpose To demonstrate the CT imaging, conformal irradiation and treatment planning capabilities of a small animal radiation research platform (SARRP). Methods The SARRP employs a dual-focal spot, constant voltage x-ray source mounted on a gantry with a source-to-isocenter distance of 35 cm. Gantry rotation is limited to 120° from vertical. Eighty to 100 kVp x-rays from the smaller 0.4 mm focal spot are used for imaging. Both 0.4 mm and 3.0 mm focal spots operate at 225 kVp for irradiation. Robotic translate/rotate stages are used to position the animal. Cone-beam (CB) CT imaging is achieved by rotating the horizontal animal between the stationary x-ray source and a flat-panel detector. Radiation beams range from 0.5 mm in diameter to (60 × 60) mm2. Dosimetry is measured with radio-chromic films. Monte Carlo dose calculations are employed for treatment planning. The combination of gantry and robotic stage motions facilitate conformal irradiation. Results The SARRP spans 3 ft × 4 ft × 6 ft (WxLxH). Depending on filtration, the isocenter dose outputs at 1 cm depth in water range from 22 to 375 cGy/min from the smallest to the largest radiation fields. The 20% to 80% dose fall-off spans 0.16 mm. CBCT with (0.6 × 0.6 × 0.6) mm3 voxel resolution is acquired with less than 1 cGy. Treatment planning is performed at sub-mm resolution. Conclusions The capability of the SARRP to deliver highly focal beams to multiple animal model systems provides new research opportunities that more realistically bridge laboratory research and clinical translation. PMID:18640502

  10. A synthetic diamond probe for low-energy X-ray dose measurements.

    PubMed

    Assiamah, M; Nam, T L; Keddy, R J

    2007-05-01

    The desirable physical properties of diamond have made the mineral a choice material in radiation measurements. Diamond detectors are currently used extensively in high-energy physics. Their use for low-energy beams such as, for example, in mammography X-ray beams however, has not been fully investigated. This paper describes a diamond probe which has been constructed for the evaluation, as the radiation sensing material, of polycrystalline synthetic diamonds produced by chemical vapour deposition (CVD). The specimens were fabricated in wafer form and so the exposure orientation geometry of the diamond wafers, to give optimum absorption of the incident X-ray beam, was also investigated both experimentally and theoretically. The samples were characterized to obtain information regarding the elemental impurity levels, especially nitrogen, and consequently to establish the material quality. Nitrogen impurities and concentration levels in the diamond lattice have been shown to have a profound effect on the radiation detection properties of diamond. The probe described has the diamond surfaces metallized with titanium, platinum and gold to provide ohmic contacts. The probe was connected independently to both Wellhöfer Dosimetrie (model CU 500) and PTW Unidos E commercial electrometers. In all of the measurements, the incident radiation beam was normal to the edge of the diamond wafer to optimize absorption of the X-ray beam after establishing that this orientation was the optimum geometry. The results of the study are presented in both tabular and graphical forms.

  11. Grazing Incidence Pumping for High Efficiency X-ray Lasers

    SciTech Connect

    Dunn, J; Keenan, R; Shlyaptsev, V N

    2005-10-03

    Over the last decade, most laser-driven collisional excitation x-ray lasers have relied on the absorption of the pump energy incident at normal incidence to a pre-formed plasma. The main advantage is that the inversion can be created at various plasma regions in space and time where the amplification and ray propagation processes are best served. The main disadvantage is that different plasma regions regardless of the contribution to the inversion have to be pumped simultaneously in order to make the laser work. This leads to a loss of efficiency. The new scheme of grazing incidence pumping (GRIP) addresses this issue. In essence, a chosen electron density region of a pre-formed plasma column, produced by a longer pulse at normal incidence onto a slab target, is selectively pumped by focusing a short pulse of 100 fs-10 ps duration laser at a determined grazing incidence angle to the target surface. The exact angle is dependent on the pump wavelength and relates to refraction of the drive beam in the plasma. The controlled use of refraction of the pumping laser in the plasma results in several benefits: The pump laser path length is longer and there is an increase in the laser absorption in the gain region for creating a collisional Ni-like ion x-ray laser. There is also an inherent traveling wave, close to c, that increases the overall pumping efficiency. This can lead to a 3-30 times reduction in the pump energy for mid-Z, sub-20 nm lasers. We report several examples of this new x-ray laser on two different laser systems. The first demonstrates a 10 Hz x-ray laser operating at 18.9 nm pumped with a total of 150 mJ of 800 nm wavelength from a Ti:Sapphire laser. The second case is shown where the COMET laser is used both at 527 nm and 1054 nm wavelength to pump higher Z materials with the goal of extending the wavelength regime of tabletop x-ray lasers below 10 nm.

  12. Filtration to reduce paediatric dose for a linear slot-scanning digital X-ray machine.

    PubMed

    Perks, T D; Dendere, R; Irving, B; Hartley, T; Scholtz, P; Lawson, A; Trauernicht, C; Steiner, S; Douglas, T S

    2015-12-01

    This paper describes modelling, application and validation of a filtration technique for a linear slot-scanning digital X-ray system to reduce radiation dose to paediatric patients while preserving diagnostic image quality. A dose prediction model was implemented, which calculates patient entrance doses using variable input parameters. Effective dose is calculated using a Monte Carlo simulation. An added filter of 1.8-mm aluminium was predicted to lower the radiation dose significantly. An objective image quality study was conducted using detective quantum efficiency (DQE). The PTW Normi 4FLU test phantom was used for quantitative assessment, showing that image contrast and spatial resolution were maintained with the proposed filter. A paediatric cadaver full-body imaging trial assessed the diagnostic quality of the images and measured the dose reduction using a 1.8-mm aluminium filter. Assessment by radiologists indicated that diagnostic quality was maintained with the added filtration, despite a reduction in DQE. A new filtration technique for full-body paediatric scanning on the Lodox Statscan has been validated, reducing entrance dose for paediatric patients by 36 % on average and effective dose by 27 % on average, while maintaining image quality.

  13. The dose response of normoxic polymer gel dosimeters measured using X-ray CT.

    PubMed

    Hill, B; Venning, A; Baldock, C

    2005-07-01

    X-ray CT was used to determine the dose response of normoxic polymer gel dosimeters. Normoxic polymer gel dosimeters were manufactured and irradiated up to 150 Gy. Up to 50 CT images were acquired on a Toshiba Aquilion Multislice CT scanner using protocols for 80 kV and 135 kV to determine dose response. HU-dose sensitivity, the linear regression of data for the HU versus dose for the linear part of the curve up to 60 Gy was 0.38+/-0.07 HU Gy(-1) for 135 kV and 0.37+/-0.01 HU Gy(-1) for 80 kV. Dose resolution was found to be < 1.3 Gy for an absorbed dose range up to 70 Gy for 135 kV, similar to that measured previously for polyacrylamide gel (PAG). Although the HU-dose sensitivity was lower than that previously measured for PAG gel dosimeters it had a greater range of absorbed dose indicating that normoxic polymer gel dosimeters have potential in CT gel dosimetry.

  14. The dose received by patients during dental X-ray examination and the technical condition of radiological equipment.

    PubMed

    Bekas, Marcin; Pachocki, Krzysztof A

    2013-01-01

    Implementation of X-ray dental examination is associated with the patients exposure to ionizing radation. The size of the exposure depends on the type of medical procedure, the technical condition of the X-ray unit and selected exposure conditions. The aim of this study was to determine the dose received by patients during dental X-ray examination and the assessment of the technical condition of medical equipment, The study included a total number of 79 dental X-ray units located in the region of Mazovia. The test methods for the assessment of the technical condition of dental X-ray units and measurement of radiation dose received by patients were based on the procedures elaborated in the Department of Radiation Hygiene and Radiobiology in the National Institute of Public Health - National Institute of Hygiene (Warszawa, Poland) accredited for the certification of compliance with PN-EN 17025. The research found that 69.6% fully meets the criteria set out in the Polish legislation regarding the safe use of ionizing radiation in medicine, while 30.4% did not meet some of them. A tenfold difference in the size of the dose received by patients during dental X-ray examinations was discovered. For example, during a radiography of the canine teeth of a child, the recorded entrance surface dose (ESD) ranged from 72.8 to 2430 microGy with the average value of 689.1 microGy. Cases where the dose reference level defined in Polish legislation of 5 mGy was exceeded were also found. CONCKUSIONS: It is essential to constantly monitor the situation regarding the technical condition of X-ray units which affects the size of the population's exposure to ionizing radiation as well as raising dentists' awareness about the effects of X-rays on the human body.

  15. Low-Dose X-ray CT Reconstruction via Dictionary Learning

    PubMed Central

    Xu, Qiong; Zhang, Lei; Hsieh, Jiang; Wang, Ge

    2013-01-01

    Although diagnostic medical imaging provides enormous benefits in the early detection and accuracy diagnosis of various diseases, there are growing concerns on the potential side effect of radiation induced genetic, cancerous and other diseases. How to reduce radiation dose while maintaining the diagnostic performance is a major challenge in the computed tomography (CT) field. Inspired by the compressive sensing theory, the sparse constraint in terms of total variation (TV) minimization has already led to promising results for low-dose CT reconstruction. Compared to the discrete gradient transform used in the TV method, dictionary learning is proven to be an effective way for sparse representation. On the other hand, it is important to consider the statistical property of projection data in the low-dose CT case. Recently, we have developed a dictionary learning based approach for low-dose X-ray CT. In this paper, we present this method in detail and evaluate it in experiments. In our method, the sparse constraint in terms of a redundant dictionary is incorporated into an objective function in a statistical iterative reconstruction framework. The dictionary can be either predetermined before an image reconstruction task or adaptively defined during the reconstruction process. An alternating minimization scheme is developed to minimize the objective function. Our approach is evaluated with low-dose X-ray projections collected in animal and human CT studies, and the improvement associated with dictionary learning is quantified relative to filtered backprojection and TV-based reconstructions. The results show that the proposed approach might produce better images with lower noise and more detailed structural features in our selected cases. However, there is no proof that this is true for all kinds of structures. PMID:22542666

  16. Low-dose X-ray CT reconstruction via dictionary learning.

    PubMed

    Xu, Qiong; Yu, Hengyong; Mou, Xuanqin; Zhang, Lei; Hsieh, Jiang; Wang, Ge

    2012-09-01

    Although diagnostic medical imaging provides enormous benefits in the early detection and accuracy diagnosis of various diseases, there are growing concerns on the potential side effect of radiation induced genetic, cancerous and other diseases. How to reduce radiation dose while maintaining the diagnostic performance is a major challenge in the computed tomography (CT) field. Inspired by the compressive sensing theory, the sparse constraint in terms of total variation (TV) minimization has already led to promising results for low-dose CT reconstruction. Compared to the discrete gradient transform used in the TV method, dictionary learning is proven to be an effective way for sparse representation. On the other hand, it is important to consider the statistical property of projection data in the low-dose CT case. Recently, we have developed a dictionary learning based approach for low-dose X-ray CT. In this paper, we present this method in detail and evaluate it in experiments. In our method, the sparse constraint in terms of a redundant dictionary is incorporated into an objective function in a statistical iterative reconstruction framework. The dictionary can be either predetermined before an image reconstruction task or adaptively defined during the reconstruction process. An alternating minimization scheme is developed to minimize the objective function. Our approach is evaluated with low-dose X-ray projections collected in animal and human CT studies, and the improvement associated with dictionary learning is quantified relative to filtered backprojection and TV-based reconstructions. The results show that the proposed approach might produce better images with lower noise and more detailed structural features in our selected cases. However, there is no proof that this is true for all kinds of structures.

  17. Ultra-high vacuum compatible optical chopper system for synchrotron x-ray scanning tunneling microscopy

    SciTech Connect

    Chang, Hao; Cummings, Marvin; Shirato, Nozomi; Stripe, Benjamin; Preissner, Curt; Freeland, John W.; Rosenmann, Daniel; Kersell, Heath; Hla, Saw-Wai; Rose, Volker

    2016-01-28

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM.

  18. High power x-ray welding of metal-matrix composites

    DOEpatents

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1999-01-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10.sup.4 watts/cm.sup.2 and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  19. High power X-ray welding of metal-matrix composites

    SciTech Connect

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1997-12-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10{sup 4} watts/cm{sup 2} and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  20. Diamond x-ray optics: Transparent, resilient, high-resolution, and wavefront preserving

    DOE PAGES

    Shvyd’ko, Yuri; Blank, Vladimir; Terentyev, Sergey

    2017-06-09

    Diamond features a unique combination of outstanding physical properties perfect for numerous x-ray optics applications, where traditional materials such as silicon fail to perform. In the last two decades, impressive progress has been achieved in synthesizing diamond with high crystalline perfection, in manufacturing efficient, resilient, high-resolution, wavefront-preserving diamond optical components, and in implementing them in cutting-edge x-ray instruments. Diamond optics are essential for tailoring x-rays to the most challenging needs of x-ray research. Furthermore, they are becoming vital for the generation of fully coherent hard x-rays by seeded x-ray free-electron lasers. In this article, we review progress in manufacturing flawlessmore » diamond crystal components and their applications in diverse x-ray optical devices, such as x-ray monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, bent-crystal spectrographs, and windows.« less

  1. Importance of dose settings in the x-ray systems used for interventional radiology: a national survey.

    PubMed

    Vano, E; Sanchez, R; Fernandez, J M; Rosales, F; Garcia, M A; Sotil, J; Hernandez, J; Carrera, F; Ciudad, J; Soler, M M; Ballester, T

    2009-01-01

    The purpose of this work was to investigate the differences in dose settings among the X-ray units involved in a national survey of patient doses in interventional radiology (IR). The survey was promoted by the National Society of IR and involved 10 centers. As part of the agreed quality control for the survey, entrance doses were measured in a 20-cm-thick acrylic phantom simulating a medium-sized patient. A standard digital subtraction angiography (DSA) imaging protocol for the abdomen was used at the different centers. The center of the phantom was placed at the isocenter of the C-arm system during the measurements to simulate clinical conditions. Units with image intensifiers and flat detectors were involved in the survey. Entrance doses for low, medium, and high fluoroscopy modes and DSA acquisitions were measured for a field of view of 20 cm (or closest). A widespread range of entrance dose values was obtained: 4.5-18.6, 9.2-28.4, and 15.4-51.5 mGy/min in low, medium, and high fluoroscopy mode, respectively, and 0.7-5.0 mGy/DSA image. The ratios between the maximum and the minimum values measured (3-4 for fluoroscopy and 7 for DSA) suggest an important margin for optimization. The calibration factor for the dose-area product meter was also included in the survey and resulted in a mean value of 0.73, with a standard deviation of 0.07. It seems clear that the dose setting for the X-ray systems used in IR requires better criteria and approaches.

  2. Importance of Dose Settings in the X-Ray Systems Used for Interventional Radiology: A National Survey

    SciTech Connect

    Vano, E. Sanchez, R.; Fernandez, J. M.; Rosales, F.; Garcia, M. A.; Sotil, J.; Hernandez, J.; Carrera, F.; Ciudad, J.; Soler, M. M.; Ballester, T.

    2009-01-15

    The purpose of this work was to investigate the differences in dose settings among the X-ray units involved in a national survey of patient doses in interventional radiology (IR). The survey was promoted by the National Society of IR and involved 10 centers. As part of the agreed quality control for the survey, entrance doses were measured in a 20-cm-thick acrylic phantom simulating a medium-sized patient. A standard digital subtraction angiography (DSA) imaging protocol for the abdomen was used at the different centers. The center of the phantom was placed at the isocenter of the C-arm system during the measurements to simulate clinical conditions. Units with image intensifiers and flat detectors were involved in the survey. Entrance doses for low, medium, and high fluoroscopy modes and DSA acquisitions were measured for a field of view of 20 cm (or closest). A widespread range of entrance dose values was obtained: 4.5-18.6, 9.2-28.4, and 15.4-51.5 mGy/min in low, medium, and high fluoroscopy mode, respectively, and 0.7-5.0 mGy/DSA image. The ratios between the maximum and the minimum values measured (3-4 for fluoroscopy and 7 for DSA) suggest an important margin for optimization. The calibration factor for the dose-area product meter was also included in the survey and resulted in a mean value of 0.73, with a standard deviation of 0.07. It seems clear that the dose setting for the X-ray systems used in IR requires better criteria and approaches.

  3. MiR-34a is up-regulated in response to low dose, low energy X-ray induced DNA damage in breast cells.

    PubMed

    Stankevicins, Luiza; Almeida da Silva, Ana Paula; Ventura Dos Passos, Flavia; Dos Santos Ferreira, Evelin; Menks Ribeiro, Maria Cecilia; G David, Mariano; J Pires, Evandro; Ferreira-Machado, Samara Cristina; Vassetzky, Yegor; de Almeida, Carlos Eduardo; de Moura Gallo, Claudia Vitoria

    2013-10-05

    MicroRNAs are non-coding RNAs involved in the regulation of gene expression including DNA damage responses. Low doses of low energy X-ray radiation, similar to those used in mammographic exams, has been described to be genotoxic. In the present work we investigated the expression of miR-34a; a well described p53-regulated miRNA implicated in cell responses to X-ray irradiation at low doses. Non-cancerous breast cell line MCF-10A and cancerous T-47D and MCF-7 cell lines were submitted to a low-energy X-ray irradiation (ranging from 28-30 Kv) using a dose of 5 Gy. The expression level of miR-34a, let-7a and miR-21 was assessed by qRT-PCR at 4 and 24 hours post-irradiation. DNA damage was then measured by comet assay and micronuclei estimation in MCF-10A and MCF-7 cell lines, where an increase of miR-34a levels could be observed after irradiation. The rate of apoptotic cells was estimated by nuclear staining and fluorescence microscopy. These experiments were also performed at low doses (3; 12 and 48 mGy) in MCF-10A and MCF-7 cell lines. We have observed an increase in miR-34a expression 4 hours post-irradiation at 5 Gy in MCF-10A and MCF-7 cell lines while its level did not change in T-47D, a breast cancer cell line bearing non-functional p53. At low doses, miR-34a was up-regulated in non-tumoral MCF-10A to a higher extent as compared to MCF-7. MiR-34a levels decreased 24 hours post-irradiation. We have also observed DNA damage and apoptosis at low-energy X-ray irradiation at low doses and the high dose in MCF-10A and MCF-7 4 and 24 hours post-irradiation relative to the mock control. Low energy X-ray is able to promote DNA strand breaks and miR-34a might be involved in cell responses to low energy X-ray DNA damage. MiR-34a expression correlates with X-ray dose, time after irradiation and cell type. The present study reinforces the need of investigating consequences of low dose X-ray irradiation of breast cells.

  4. MiR-34a is up-regulated in response to low dose, low energy X-ray induced DNA damage in breast cells

    PubMed Central

    2013-01-01

    Background MicroRNAs are non-coding RNAs involved in the regulation of gene expression including DNA damage responses. Low doses of low energy X-ray radiation, similar to those used in mammographic exams, has been described to be genotoxic. In the present work we investigated the expression of miR-34a; a well described p53-regulated miRNA implicated in cell responses to X-ray irradiation at low doses. Methods Non-cancerous breast cell line MCF-10A and cancerous T-47D and MCF-7 cell lines were submitted to a low-energy X-ray irradiation (ranging from 28–30 Kv) using a dose of 5 Gy. The expression level of miR-34a, let-7a and miR-21 was assessed by qRT-PCR at 4 and 24 hours post-irradiation. DNA damage was then measured by comet assay and micronuclei estimation in MCF-10A and MCF-7 cell lines, where an increase of miR-34a levels could be observed after irradiation. The rate of apoptotic cells was estimated by nuclear staining and fluorescence microscopy. These experiments were also performed at low doses (3; 12 and 48 mGy) in MCF-10A and MCF-7 cell lines. Results We have observed an increase in miR-34a expression 4 hours post-irradiation at 5 Gy in MCF-10A and MCF-7 cell lines while its level did not change in T-47D, a breast cancer cell line bearing non-functional p53. At low doses, miR-34a was up-regulated in non-tumoral MCF-10A to a higher extent as compared to MCF-7. MiR-34a levels decreased 24 hours post-irradiation. We have also observed DNA damage and apoptosis at low-energy X-ray irradiation at low doses and the high dose in MCF-10A and MCF-7 4 and 24 hours post-irradiation relative to the mock control. Conclusion Low energy X-ray is able to promote DNA strand breaks and miR-34a might be involved in cell responses to low energy X-ray DNA damage. MiR-34a expression correlates with X-ray dose, time after irradiation and cell type. The present study reinforces the need of investigating consequences of low dose X-ray irradiation of breast cells. PMID

  5. Patient dosimetry activities in the United States: the nationwide evaluation of X-ray trends (NEXT) and tissue dose handbooks.

    PubMed

    Suleiman, O H; Stern, S H; Spelic, D C

    1999-01-01

    In the United States the Food and Drug Administration (FDA) in collaboration with the Conference of Radiation Control Program Directors (CRCPD) and state and local government agencies surveys clinical facilities about X-ray system air kerma and ancillary data related to patient dosimetry for a variety of diagnostic X-ray examinations. The survey program is known as the Nationwide Evaluation of X-ray Trends (NEXT). The survey utilizes reference patient-equivalent phantoms in the collection of comprehensive technical information. With knowledge of the skin-entrance air kerma, specific tissue doses can be calculated. An overview of NEXT and previously published FDA tissue dose handbooks for diagnostic X-ray examinations is presented.

  6. Applications of nonlocal means algorithm in low-dose X-ray CT image processing and reconstruction: A review.

    PubMed

    Zhang, Hao; Zeng, Dong; Zhang, Hua; Wang, Jing; Liang, Zhengrong; Ma, Jianhua

    2017-03-01

    Low-dose X-ray computed tomography (LDCT) imaging is highly recommended for use in the clinic because of growing concerns over excessive radiation exposure. However, the CT images reconstructed by the conventional filtered back-projection (FBP) method from low-dose acquisitions may be severely degraded with noise and streak artifacts due to excessive X-ray quantum noise, or with view-aliasing artifacts due to insufficient angular sampling. In 2005, the nonlocal means (NLM) algorithm was introduced as a non-iterative edge-preserving filter to denoise natural images corrupted by additive Gaussian noise, and showed superior performance. It has since been adapted and applied to many other image types and various inverse problems. This paper specifically reviews the applications of the NLM algorithm in LDCT image processing and reconstruction, and explicitly demonstrates its improving effects on the reconstructed CT image quality from low-dose acquisitions. The effectiveness of these applications on LDCT and their relative performance are described in detail.

  7. A Compact X-Ray System for Support of High Throughput Crystallography

    NASA Technical Reports Server (NTRS)

    Ciszak, Ewa; Gubarev, Mikhail; Gibson, Walter M.; Joy, Marshall K.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Standard x-ray systems for crystallography rely on massive generators coupled with optics that guide X-ray beams onto the crystal sample. Optics for single-crystal diffractometry include total reflection mirrors, polycapillary optics or graded multilayer monochromators. The benefit of using polycapillary optic is that it can collect x-rays over tile greatest solid angle, and thus most efficiently, utilize the greatest portion of X-rays emitted from the Source, The x-ray generator has to have a small anode spot, and thus its size and power requirements can be substantially reduced We present the design and results from the first high flux x-ray system for crystallography that combine's a microfocus X-ray generator (40microns FWHM Spot size at a power of 45 W) and a collimating, polycapillary optic. Diffraction data collected from small test crystals with cell dimensions up to 160A (lysozyme and thaumatin) are of high quality. For example, diffraction data collected from a lysozyme crystal at RT yielded R=5.0% for data extending to 1.70A. We compare these results with measurements taken from standard crystallographic systems. Our current microfocus X-ray diffraction system is attractive for supporting crystal growth research in the standard crystallography laboratory as well as in remote, automated crystal growth laboratory. Its small volume, light-weight, and low power requirements are sufficient to have it installed in unique environments, i.e.. on-board International Space Station.

  8. Phase-contrast microscopy at high x-ray energy with a laboratory setup.

    PubMed

    Endrizzi, Marco; Vittoria, Fabio A; Diemoz, Paul C; Lorenzo, Rodolfo; Speller, Robert D; Wagner, Ulrich H; Rau, Christoph; Robinson, Ian K; Olivo, Alessandro

    2014-06-01

    We report on the design and realization of an x-ray imaging system for quantitative phase-contrast microscopy at high x-ray energy with laboratory-scale instrumentation. Phase and amplitude were separated quantitatively at x-ray energies up to 80 keV with micrometric spatial resolution. The accuracy of the results was tested against numerical simulations, and the spatial resolution was experimentally quantified by measuring a Siemens star phase object. This simple setup should find broad application in those areas of x-ray imaging where high energy and spatial resolution are simultaneously required and in those difficult cases where the sample contains materials with similar x-ray absorption.

  9. Optimized Fluoroscopy Setting and Appropriate Project Position Can Reduce X-ray Radiation Doses Rates during Electrophysiology Procedures.

    PubMed

    Hou, Bing-Bo; Yao, Yan; Wu, Ling-Min; Qiao, Yu; Zheng, Li-Hui; Ding, Li-Gang; Chen, Gang; Zhang, Shu

    2015-05-05

    Nonfluoroscopic three-dimensional electroanatomical system is widely used nowadays, but X-ray remains indispensable for complex electrophysiology procedures. This study aimed to evaluate the value of optimized parameter setting and different projection position to reduce X-ray radiation dose rates. From June 2013 to October 2013, 105 consecutive patients who underwent complex ablation were enrolled in the study. After the ablation, the radiation dose rates were measured by two different settings (default setting and optimized setting) with three projection positions (posteroanterior [PA] projection; left anterior oblique [LAO] 30° projection; and LAO 45° projection). The parameter of preset voltage, pulse width, critical voltage, peak voltage, noise reduction, edge enhancement, pulse rate, and dose per frame was modified in the optimized setting. The optimized setting reduced radiation dose rates by 87.5% (1.7 Gy/min vs. 13.6 Gy/min, P < 0.001) in PA, 87.3% (2.5 Gy/min vs. 19.7 Gy/min, P < 0.001) in LAO 30°, 85.9% (3.1 Gy/min vs. 22.1 Gy/min, P < 0.001) in LAO 45°. Increase the angle of projection position will increase the radiation dose rate. We can reduce X-ray radiation dose rates by adjusting the parameter setting of X-ray system. Avoiding oblique projection of large angle is another way to reduce X-ray radiation dose rates.

  10. Determination of the implantation dose in silicon wafers by X-ray fluorescence analysis

    SciTech Connect

    Klockenkaemper, R.; Becker, M.; Bubert, H.; Burba, P. ); Palmetshofer, L. )

    1990-08-01

    The ion dose implanted in silicon wafers was determined by X-ray fluorescence analysis after the implantation process. As only near-surface layers below 1-{mu}m thickness were considered, the calibration could be carried out with external standards consisting of thin films of doped gelatine spread on pure wafers. Dose values for Cr and Co were determined between 4 {times} 10{sup 15} and 2 {times} 10{sup 17} atoms/cm{sup 2}, the detection limits being about 3 {times} 10{sup 14} atoms/cm{sup 2}. The results are precise and accurate apart from a residual scatter of less than 7%. This was confirmed by flame atomic absorption spectrometry after volatilization of the silicon matrix as SiF{sub 4}. It was found that ion-current measurements carried out during the implantation process can have considerable systematic errors.

  11. Absorbed dose measurements in dual energy X-ray absorptiometry (DXA).

    PubMed

    Bezakova, E; Collins, P J; Beddoe, A H

    1997-02-01

    In this study a predominantly film dosimetric method was used to measure the effective dose from posteroanterior (PA) lumbar spine and proximal femur scans performed on a Lunar DPX-L machine. Because of the very low dose rate in scanning mode, the depth dose data were determined using a stationary detector configuration. The characteristic curve for the film (Kodak TMAT-H) was obtained and depth dose measurements were made using slabs of "solid water". The film was calibrated using a superficial X-ray unit (calibrated against a standard traceable to a national standard). To assess the change in film response with beam hardening at depth, the film was exposed to calibration beams of different half value layer (HVL). The HVL of the DXA beam was determined for surface and depth doses using aluminium filters and a diamond detector (an energy independent device). All measurements were performed three times. Beam size was measured using film, and the scan areas and times were determined by scanning phantoms. The dose from a scan was calculated using Dsc = DTscAb/Asc, where D = dose rate (stationary), Tsc = scan time, Ab = beam area, and Asc = scan area. Organ doses were determined using an anatomical atlas and ICRP 23 female reference. All film measurements had good precision (coefficient of variation < 4%). There was little variation in film sensitivity with change in HVL (< 1% change for the first three HVLs) and consequently no corrections were applied to the depth dose data. Skin entrance dose was 11.5 microGy. Effective dose in females was 0.19 microSv for the PA lumbar spine. For the proximal femur scan, the effective dose was 0.14 microSv (ovaries included) and 0.023 microSv (ovaries excluded) for pre-menopausal and pos-menopausal women, respectively.

  12. Patient radiation dose reduction using an X-ray imaging noise reduction technology for cardiac angiography and intervention.

    PubMed

    Nakamura, Shigeru; Kobayashi, Tomoko; Funatsu, Atsushi; Okada, Tadahisa; Mauti, Maria; Waizumi, Yuki; Yamada, Shinichi

    2016-05-01

    Coronary angiography and intervention can expose patients to high radiation dose. This retrospective study quantifies the patient dose reduction due to the introduction of a novel X-ray imaging noise reduction technology using advanced real-time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in interventional cardiology. Patient, procedure and radiation dose data were retrospectively collected in the period August 2012-August 2013 for 883 patients treated with the image noise reduction technology (referred as "new system"). The same data were collected for 1083 patients in the period April 2011-July 2012 with a system using state-of-the-art image processing and reference acquisition chain (referred as "reference system"). Procedures were divided into diagnostic (CAG) and intervention (PCI). Acquisition parameters such as fluoroscopy time, volume of contrast medium, number of exposure images and number of stored fluoroscopy images were collected to classify procedure complexity. The procedural dose reduction was investigated separately for three main cardiologists. The new system provides significant dose reduction compared to the reference system. Median DAP values decreased for all procedures (p < 0.0001) from 172.7 to 59.4 Gy cm(2), for CAG from 155.1 to 52.0 Gy cm(2) and for PCI from 229.0 to 85.8 Gy cm(2) with reduction quantified at 66, 66 and 63 %, respectively. Based on median values, the dose reduction for all procedures was 68, 60 and 67 % for cardiologists 1, 2 and 3, respectively. The X-ray imaging technology combining advanced real-time image noise reduction algorithms and anatomy-specific optimized fluoroscopy and cine acquisition chain provides 66 % patient dose reduction in interventional cardiology.

  13. Stereoscopic observations of a solar flare hard X-ray source in the high corona

    SciTech Connect

    Kane, S.R.; Mctiernan, J.; Loran, J.; Fenimore, E.E.; Klebesadel, R.W.; Laros, J.G. Los Alamos National Laboratory, NM )

    1992-05-01

    The vertical structure of the impulsive and gradual hard X-ray sources in high coronae and the characteristics of the impulsive soft X-ray emission are investigated on the basis of PVE, ICE, and GOES observations of the energetic flare on February 16, 1984. The average photon spectra observed by these instruments during the impulsive and gradual hard X-ray bursts are summarized. A comparison of these unocculted and partially occulted spectra shows that the sources of the impulsive hard X-ray (greater than about 25 keV) and impulsive soft X-ray (2-5 keV) emissions in this flare extended to coronal altitudes greater than about 200,000 km above the photosphere. At about 100 keV, the ratio of the coronal source brightness to the total source brightness was 0.001 during the impulsive phase and less than about 0.01 during the gradual hard X-ray burst. The sources of the gradual hard X-ray burst and gradual soft X-ray burst were almost completely occulted, indicating that these sources were located at heights less than 200,000 km above the photosphere. 47 refs.

  14. High Energy Astronomy Observatory (HEAO)-2 in the X-Ray Calibration Facility

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being evaluated by engineers in the clean room of the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

  15. High Energy Astronomy Observatory (HEAO)-2 in the X-Ray Calibration Facility

    NASA Technical Reports Server (NTRS)

    1977-01-01

    This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being evaluated by engineers in the clean room of the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

  16. High Pressure X-ray Diffraction Study of Potassium Azide

    SciTech Connect

    C Ji; F Zhang; D Hong; H Zhu; J Wu; M Chyu; V Levitas; Y Ma

    2011-12-31

    Crystal structure and compressibility of potassium azide was investigated by in-situ synchrotron powder X-ray diffraction in a diamond anvil cell at room temperature up to 37.7 GPa. In the body-centered tetragonal (bct) phase, an anisotropic compressibility was observed with greater compressibility in the direction perpendicular to the plane containing N{sub 3}{sup -} ions than directions within that plane. The bulk modulus of the bct phase was determined to be 18.6(7) GPa. A pressure-induced phase transition may occur at 15.5 GPa.

  17. Scintillator Evaluation for High-Energy X-Ray Diagnostics

    SciTech Connect

    S. S. Lutz; S. A. Baker

    2001-09-01

    This report presents results derived from a digital radiography study performed using x-rays from a 2.3 MeV, rod-pinch diode. Detailed is a parameter study of cerium-doped lutetium ortho-silicate (LSO) scintillator thickness, as it relates to system resolution and detection quantum efficiency (DQE). Additionally, the detection statistics of LSO were compared with that of CsI(Tl). As a result of this study we found the LSO scintillator with a thickness of 3 mm to yield the highest system DQE over the range of spatial frequencies from 0.75 to 2.5 mm{sup -1}.

  18. The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: the high energy x-ray source and some applications.

    PubMed

    Hubert, S; Dubois, J L; Gontier, D; Lidove, G; Reverdin, C; Soullié, G; Stemmler, P; Villette, B

    2010-05-01

    The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented.

  19. High sensitivity all sky X-ray monitor and survey with MAXI

    NASA Astrophysics Data System (ADS)

    Isobe, N.; Mihara, T.; Kohama, M.; Suzuki, M.; Matsuoka, M.; Ueno, S.; Tomida, H.; Kawai, N.; Kataoka, J.; Yoshida, A.; Yamaoka, K.; Tsunemi, H.; Miyata, E.; Negoro, H.; Nakajima, M.; Morii, M.

    2007-07-01

    MAXI is an all sky X-ray monitor to be mounted on the Japanese Experimental Module in the International Space Station (ISS). It scans almost all over the sky every 96 minutes, in the course of the orbital motion of the ISS. MAXI is designed to have a sensitivity, significantly higher than the previous X-ray monitors, and then, to detect X-ray sources as faint as 1 mCrab in a week observation. Therefore, MAXI is expected to create a novel catalogue of not only the stable X-ray sources but also the highly variable ones in the sky, especially active galactic nuclei for the first time. If MAXI detects X-ray phenomena, alerts will be quickly made through the Internet.

  20. Some new schemes for producing high-accuracy elliptical X-ray mirrors by elastic bending

    SciTech Connect

    Padmore, H.A.; Howells, M.R.; Irick, S.; Renner, T.; Sandler, R.; Koo, Y.-M.

    1996-08-01

    Although x-ray micro-foci can be produced by a variety of diffractive methods, grazing incidence mirrors are the only route to an achromatic focus. In this paper we describe our efforts to produce elliptically shaped mirrors with the very high figure accuracy necessary for producing a micro-focus. The motivation for this work is provided by the need to produce achromatic foci for a range of applications ranging from tunable micro-focus x-ray photoelectron spectroscopy ({mu}-XPS) at soft x-ray energies to micro-focus white beam x-ray diffraction ({mu}-XRD) at hard x-ray energies. We describe the methodology of beam bending, a practical example of a system we have produced for {mu}-XRD, and results demonstrating the production of a surface with micro-radian figure accuracy.

  1. Hollow Atom Production Due to High Intensity X-ray Sources Irradiating Clusters And Its Applications

    SciTech Connect

    Moribayashi, Kengo

    2009-07-25

    This paper shows the production of hollow atoms and the proposal of the measurement by using x-ray flux irradiating clusters by continuing work from our previous papers left braceK. Moribayashi, J.Phys.B, 41 085602 (2008)right brace. The x-ray emissions from hollow atoms produced by high intensity x-ray sources are employed for this measurement. This measurement is useful for the application of laser-driven x-ray sources and x-ray free electron lasers to the measurement of diffraction patterns of bio-molecules, which is indispensable for the study of their three-dimensional structure. This paper develops the methods and discussions of our previous paper. Namely, the electron impact ionization processes are added to our calculation model. Further, the size effects of the targets are shown.

  2. High sensitivity all sky X-ray monitor and survey with MAXI

    SciTech Connect

    Isobe, N.; Mihara, T.; Kohama, M.; Suzuki, M.; Matsuoka, M.; Ueno, S.; Tomida, H.; Yoshida, A.; Yamaoka, K.; Tsunemi, H.; Miyata, E.; Negoro, H.; Nakajima, M.; Morii, M.

    2007-07-12

    MAXI is an all sky X-ray monitor to be mounted on the Japanese Experimental Module in the International Space Station (ISS). It scans almost all over the sky every 96 minutes, in the course of the orbital motion of the ISS. MAXI is designed to have a sensitivity, significantly higher than the previous X-ray monitors, and then, to detect X-ray sources as faint as 1 mCrab in a week observation. Therefore, MAXI is expected to create a novel catalogue of not only the stable X-ray sources but also the highly variable ones in the sky, especially active galactic nuclei for the first time. If MAXI detects X-ray phenomena, alerts will be quickly made through the Internet.

  3. The relative biological effectiveness of low-dose mammography quality X rays in the human breast MCF-10A cell line.

    PubMed

    Mills, Caitlin E; Thome, Christopher; Koff, David; Andrews, David W; Boreham, Douglas R

    2015-01-01

    Mammography is used to screen a large fraction of the population for breast cancer, and mammography quality X rays are speculated to be more damaging than the higher energy X rays used for other diagnostic procedures. The radiation dose delivered to breast cells as a result of these screening exposures may be a concern. The purpose of this current study was to determine the relative biological effectiveness (RBE) of low-energy mammography X rays for radiation-induced DNA double-strand breaks evaluated using a highly sensitive automated 53BP1 assay. Automation of the 53BP1 assay enabled the quantification and analysis of meaningful image-based features, including foci counting, within the cell nuclei. Nontumorigenic, human breast epithelial MCF-10A cells were irradiated in the low-dose range with approximately 3-30 mGy of 29 kVp mammography X rays or (137)Cs (662 keV) gamma rays. The induction and resolution of the 53BP1 foci did not differ significantly between exposures to (137)Cs gamma rays and 29 kVp X rays. The RBE was calculated to be 1.1 with a standard deviation of 0.2 for the initial number of radiation-induced double-strand breaks. The radiation dose from a single mammogram did not yield a significant change in the number of detectable foci. However, analysis of additional features revealed subtle differences in the distribution of 53BP1 throughout the nuclei after exposure to the different radiation qualities. A single mammogram was sufficient to alter the distribution of 53BP1 within the nuclear area, but not into discrete foci, while a dose-matched gamma exposure was not sufficient to alter the distribution of 53BP1. Our results indicate that exposure to clinically relevant doses of low-energy mammography quality X rays does not induce more DNA double-strand breaks than exposure to higher energy photons.

  4. A laser-driven undulator x-ray source: simulation of image formation and dose deposition in mammography

    NASA Astrophysics Data System (ADS)

    Müller, Bernhard; Schlattl, Helmut; Grüner, Florian; Hoeschen, Christoph

    2011-03-01

    Since overcoming some of the inherent limitations of x-ray tubes becomes increasingly harder, it is important to consider new ways of x-ray generation and to study their applications in the field of medical imaging. In the present work we investigate a novel table-top-sized x-ray source, developed in a joint project within the Cluster of Excellence "Munich Center for Advanced Photonics". It uses laser-accelerated electrons emitting x-ray radiation in a short period undulator. This source has the potential to deliver tunable x-rays with a very narrow spectral bandwidth. The main purpose of this contribution is to investigate the performance of this source in the field of mammography and to compare it to that of conventional x-ray tubes. We simulated the whole imaging process from the electron beam dynamics through the generation of the synchrotron radiation in the undulator up to the x-ray-matter interaction and detection in the mammographic setting. A Monte Carlo simulation of the absorption and scattering processes based on the Geant4 software toolkit has been developed that uses a high-resolution voxel phantom of the female breast for the accurate simulation of mammography. We present simulated mammograms generated by using quasi-monochromatic undulator radiation and by using the polychromatic spectrum of a conventional x-ray tube.

  5. On filtration for high-energy phase-contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Riess, Christian; Mohamed, Ashraf; Hinshaw, Waldo; Fahrig, Rebecca

    2015-03-01

    Phase-sensitive x-ray imaging promises unprecedented soft-tissue contrast and resolution. However, several practical challenges have to be overcome when using the setup in a clinical environment. The system design that is currently closest to clinical use is the grating-based Talbot-Lau interferometer (GBI).1-3 The requirements for patient imaging are low patient dose, fast imaging time, and high image quality. For GBI, these requirements can be met most successfully with a narrow energy width, high- ux spectrum. Additionally, to penetrate a human-sized object, the design energy of the system has to be well above 40 keV. To our knowledge, little research has been done so far to investigate optimal GBI filtration at such high x-ray energies. In this paper, we study different filtration strategies and their impact on high-energy GBI. Specifically, we compare copper filtration at low peak voltage with equal-absorption, equal-imaging time K-edge filtration of spectra with higher peak voltage under clinically realistic boundary conditions. We specifically focus on a design energy of 59 keV and investigate combinations of tube current, peak voltage, and filtration that lead to equal patient absorption. Theoretical considerations suggest that the K edge of tantalum might provide a transmission pocket at around 59 keV, yielding a well-shaped spectrum. Although one can observe a slight visibility benefit when using tungsten or tantalum filtration, experimental results indicate that visibility benefits most from a low x-ray tube peak voltage.

  6. High Intensity e-beam Diode Development for Flash X-ray Radiography

    NASA Astrophysics Data System (ADS)

    Oliver, Bryan

    2007-11-01

    A variety of electron beam diodes are being used and developed for the purpose of creating high-brightness, flash x-ray radiography sources. In these diodes, high energy (multi MeV), high current (multi kA), small spot (multi mm) electron beams are generated and stopped in high atomic number anode-targets (typically Ta or W). Beam stopping in the target creates copious amounts of bremsstrahlung radiation. In addition, beam heating of the target liberates material, either in the form of low density (˜10^12-10^14 cm-3) ion emission or higher density (> 10^15 cm-3) plasma. In all cases, beam/target collective effects dominate the diode and beam characteristics, affecting the radiation properties (dose and spot-size). Recent experiments at Sandia National Laboratories have demonstrated diodes capable of producing > 350 rad@m with 1.7mm FWHM x-ray source distributions. A review of our present theoretical understanding of the diode (s) operation and our experimental and simulation methods to investigate them will be presented. Emphasis will be given to e- beam sources used on state-of-the-art Inductive Voltage Adder (IVA) pulsed-power accelerators. In particular, the physics of magnetically pinched diodes (e.g. the rod-pinch [1,2]), gas-cell focusing diodes [3] and the magnetically immersed [4] diode will be discussed. Various proposed methods to optimize the x-ray intensity and the direction of future diode research will be discussed. [1] G. Cooperstein, et al., Phys. Plasmas 8, 4618 (2001).[2] B.V. Oliver et al., Phys. Plasmas 11, 3976 (2004)[3] B.V. Oliver, et al., IEEE Trans. on Plasma Science 33, 704 (2005).[4] M.G. Mazarakis, et al., Appl. Phys. Lett. 70, 832 (1997)

  7. INTEGRAL/IBIS observations of a hard X-ray outburst in high-mass X-ray binary 4U 2206+54

    NASA Astrophysics Data System (ADS)

    Wang, W.

    2010-09-01

    Aims: 4U 2206+54 is a wind-fed high-mass X-ray binary with a main-sequence donor star. The nature of its compact object has been recently identified as a slow-pulsation magnetized neutron star. Methods: INTEGRAL/IBIS observations have a long-term hard X-ray monitoring of 4U 2206+54 and detected a hard X-ray outburst around 15 December 2005 combined with the RXTE/ASM data. Results: The hard X-ray outburst had a double-flare feature with a duration of ~2 days. The first flare showed a fast rise and long-term decaying light curve about 15 h with a peak luminosity of ~4 × 1036 erg s-1 from 1.5-12 keV and a hard spectrum (only significantly seen above 5 keV). The second one had the mean hard X-ray luminosity of 1.3 × 1036 erg s-1 from 20-150 keV with a modulation period at ~5550 s which is the pulse period of the neutron star in 4U 2206+54. Its hard X-ray spectrum from 20-300 keV can be fitted by a broken power-law model with the photon indexes Γ1 ~ 2.3, and Γ2 ~ 3.3, and the break energy is Eb ~ 31 keV or by a bremsstrahlung model of kT ~ 23 keV. Conclusions: We suggest that the hard X-ray flare could be induced by suddenly enhanced accreting dense materials from stellar winds hitting the polar cap region of the neutron star. This hard X-ray outburst may be a link to supergiant fast X-ray transients though 4U 2206+54 has a different type of companion.

  8. Compact pnCCD-based X-ray camera with high spatial and energy resolution: a color X-ray camera.

    PubMed

    Scharf, O; Ihle, S; Ordavo, I; Arkadiev, V; Bjeoumikhov, A; Bjeoumikhova, S; Buzanich, G; Gubzhokov, R; Günther, A; Hartmann, R; Kühbacher, M; Lang, M; Langhoff, N; Liebel, A; Radtke, M; Reinholz, U; Riesemeier, H; Soltau, H; Strüder, L; Thünemann, A F; Wedell, R

    2011-04-01

    For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 μm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69,696 spectra with an energy resolution of 152 eV for manganese K(α) with a spatial resolution of 50 μm over an imaging area of 12.7 × 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 μm beryllium window, and the sensitive thickness of 450 μm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.

  9. High-pressure studies with x-rays using diamond anvil cells

    SciTech Connect

    Shen, Guoyin; Mao, Ho Kwang

    2016-11-22

    Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and

  10. High-pressure studies with x-rays using diamond anvil cells

    NASA Astrophysics Data System (ADS)

    Shen, Guoyin; Mao, Ho Kwang

    2017-01-01

    Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials’ properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and

  11. High-pressure studies with x-rays using diamond anvil cells.

    PubMed

    Shen, Guoyin; Mao, Ho Kwang

    2017-01-01

    Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and

  12. Minority additive distributions in a ceramic metal-halide arc lamp using high-energy x-ray induced fluorescence

    NASA Astrophysics Data System (ADS)

    Curry, J. J.; Adler, H. G.; Shastri, S. D.; Lawler, J. E.

    2001-09-01

    X-ray induced fluorescence is used to measure the elemental densities of minority additives in a metal-halide arc contained inside a translucent ceramic envelope. A monochromatic x-ray beam from the Sector 1 Insertion Device beamline at the Advanced Photon Source is used to excite K-shell x-ray fluorescence in the constituents of a ceramic metal-halide arc lamp dosed with DyI3 and CsI. Fluorescence and scattered photons are collected by a cryogenic energy-resolving Ge detector. The high signal-to-noise spectra show strong fluorescence from Dy, Cs, and I, as well as elastic scattering from Hg. Radial distributions of the absolute elemental densities of Dy, Cs, and I are obtained.

  13. Minority additive distributions in a ceramic metal-halide arc lamp using high-energy x-ray induced fluorescence

    SciTech Connect

    Curry, J. J.; Adler, H. G.; Shastri, S. D.; Lawler, J. E.

    2001-09-24

    X-ray induced fluorescence is used to measure the elemental densities of minority additives in a metal-halide arc contained inside a translucent ceramic envelope. A monochromatic x-ray beam from the Sector 1 Insertion Device beamline at the Advanced Photon Source is used to excite K-shell x-ray fluorescence in the constituents of a ceramic metal-halide arc lamp dosed with DyI{sub 3} and CsI. Fluorescence and scattered photons are collected by a cryogenic energy-resolving Ge detector. The high signal-to-noise spectra show strong fluorescence from Dy, Cs, and I, as well as elastic scattering from Hg. Radial distributions of the absolute elemental densities of Dy, Cs, and I are obtained.

  14. Monochromatization of high-current nanosecond pulse source of x-ray bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Adischev, Y. N.; Afanasiev, K. V.; Vukolov, A. V.; Potylitsyn, Alexander P.

    2007-05-01

    The bremsstrahlung spectrum of the nanosecond electron accelerator on the basis of the vacuum diode supplied by the high-voltage nanosecond generator SINUS - 150 with the coaxial forming line combined with the transformer has been monochromatized by the tungsten crystal under the Bragg - geometry (θ B = 45 0). The dose field map has been taken by the dosimeter on the basis of the diamond detector in the median acceleration plane. The bremsstrahlung radiation beam divergence has left 62°. It has been shown that the maximum dose is 16 cGrey/s at the distance of 10 cm from the collector, then it falls down proportionally to the square of distance to the level less than 0.1 cGrey/s at the distance of 1 m. The X-Ray spectrum has been measured by the silicon semi-conductor X-ray spectrometer with energy resolution 280 eV for 5.9 keV. It has been shown that the two maximum at the spectrum corresponds the second and third orders of diffraction on (111) planes of a tungsten crystal.

  15. High resolution, high rate x-ray spectrometer

    DOEpatents

    Goulding, F.S.; Landis, D.A.

    1983-07-14

    It is an object of the invention to provide a pulse processing system for use with detected signals of a wide dynamic range which is capable of very high counting rates, with high throughput, with excellent energy resolution and a high signal-to-noise ratio. It is a further object to provide a pulse processing system wherein the fast channel resolving time is quite short and substantially independent of the energy of the detected signals. Another object is to provide a pulse processing system having a pile-up rejector circuit which will allow the maximum number of non-interfering pulses to be passed to the output. It is also an object of the invention to provide new methods for generating substantially symmetrically triangular pulses for use in both the main and fast channels of a pulse processing system.

  16. The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32

    PubMed Central

    Kummer, K.; Fondacaro, A.; Jimenez, E.; Velez-Fort, E.; Amorese, A.; Aspbury, M.; Yakhou-Harris, F.; van der Linden, P.; Brookes, N. B.

    2016-01-01

    A new high-field magnet endstation for X-ray magnetic dichroism experiments has been installed and commissioned at the ESRF soft X-ray beamline ID32. The magnet consists of two split-pairs of superconducting coils which can generate up to 9 T along the beam and up to 4 T orthogonal to the beam. It is connected to a cluster of ultra-high-vacuum chambers that offer a comprehensive set of surface preparation and characterization techniques. The endstation and the beam properties have been designed to provide optimum experimental conditions for X-ray magnetic linear and circular dichroism experiments in the soft X-ray range between 400 and 1600 eV photon energy. User operation started in November 2014. PMID:26917134

  17. Evaluation of paediatric X-ray doses in Moroccan university hospitals.

    PubMed

    Nfaoui, Khadija; Bentayeb, Farida; El Basraoui, O; de Azevedo, Ana Cecilia Pedrosa

    2010-12-01

    This work evaluates the entrance skin dose (ESD), the body organ dose (BOD) and the effective dose (E) for chest X-ray exposures of paediatric patients. Two Moroccan university hospitals in Rabat, composed of two departments, and one in Casablanca with one paediatric compartment has been considered. For reasons of confidentiality, the departments are named A, B and C. Patients were divided into four age groups: 0-1, 1-5, 5-10 and 10-15 y, so that the results could be compared with previous published data found in the literature. The results have been calculated with the use of the Dose Cal software. Results of mean ESD for the age interval 1-5 y and antero-posterior (AP) projection are: 162 µGy for hospital A, 91 µGy for hospital B and 105 µGy for hospital C. The diagnostic reference levels (DRLs) of 100 µGy for this age range is exceeded in hospital A, while in the other two hospitals results were within the DRL and comparable with the results found in Brazil, Soudan, Nigeria and other radiological centres inpean Countries. The results of BOD and E showed that for the three departments, the BOD varies in the same proportion as the ESD. The highest values are those of hospital A. For the PA examination, the dose is reduced compared with the AP projection, especially for sensitive organs.

  18. High energy X-ray phase and dark-field imaging using a random absorption mask

    PubMed Central

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-01-01

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science. PMID:27466217

  19. Absorbed dose distributions for X-ray beams and beams of electrons from the Therac 20 Saturne linear accelerator.

    PubMed

    Tronc, D; Noël, A

    1978-11-01

    After a brief description of the Therac 20 Saturne linear accelerator a complete set of absorbed-dose distribution values is given. These values define the depths on the axis as a function of the depth dose and define the penumbra (as characterized by the positions of the intersections of the isodose curves with planes parallel to the phantom surface) for beams of X-rays and for beams of electrons. Tissue-maximum ratios are given for beams of X-rays. Analytical values for the electron depth dose curve are compared with the values obtained on the Sagittaire linear accelerator.

  20. Ultrafast ionization and fragmentation dynamics of molecules at high x-ray intensity

    NASA Astrophysics Data System (ADS)

    Son, Sang-Kil

    2016-05-01

    X-ray free-electron lasers (XFEL) open a new era in science and technology, offering many unique opportunities that have not been conceivable with conventional light sources. Because of their very high x-ray photon fluence within very short pulse duration, materials interacting with XFEL undergo significant radiation damage -- they possibly become highly ionized and then explode. To comprehend underlying physics, it is crucial to understand detailed ionization and fragmentation dynamics of atoms and molecules during intense XFEL pulses. We have developed the XMOLECULE toolkit to describe molecular x-ray-induced processes and to simulate radiation damage dynamics of molecules. In this talk, I will present a theoretical framework of XFEL-matter interaction, namely x-ray multiphoton absorption. Then I will discuss recent results of ultrafast x-ray-induced explosion of methyl iodide (CH3 I) molecules. Charge state distribution and kinetic energy releases of fragments are calculated to probe ionization and fragmentation dynamics, and compared with recent experimental results. It will be demonstrated that ionization of heavy-atom-containing molecules at high x-ray intensity is much enhanced in comparison with the isolated atomic case, due to ultrafast charge rearrangement during x-ray multiphoton absorption.

  1. Therapy Imaging: Limitations Of Imaging With High Energy X-Ray Beams

    NASA Astrophysics Data System (ADS)

    Munro, P.; Rawlinson, J. A.; Fenster, A.

    1987-01-01

    One of the major problems in radiation therapy is ensuring that the correct region of the patient receives the prescribed x-ray treatment and that the surrounding tissues are spared. One way to identify patient positioning errors is to make an image using the radiotherapy treatment beam. We have examined two of the factors that can influence the quality of images made with high energy x-ray beams: (i) the size of the x-ray source, and; (ii) the signal-to-noise characteristics of the detectors used to form images with high energy x-ray beams. We have developed a novel method of measuring the source distributions for 60Co machines and linear accelerators and from the measurements have been able to obtain the modulation transfer functions of their x-ray sources. We have also measured the modulation transfer functions (MTFs) and the noise power spectra (NPS) of the x-ray detectors. Based on these measurements, we conclude that images made with high energy x-ray beams are limited by film granularity and that improved images can be obtained by alternative detector systems.

  2. High Energy X-Ray Source Generation by Short Pulse High Intensity Lasers

    SciTech Connect

    Park, H-S; Koch, J A; Landen, O L; Phillips, T W; Goldsack, T; Clark, E; Eagleton, R; Edwards, R

    2003-09-02

    We are studying the feasibility of utilizing K{alpha} x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K{alpha} sources are created by relativistic electron plasma interactions in the target material after a radiation by short pulse high intensity lasers. In order to understand K{alpha} source characteristics such as production efficiency and brightness as a function of laser parameters, we have performed experiments using the 10 J, 100 fs JanUSP laser. We utilized single-photon counting spectroscopy and x-ray imaging diagnostics to characterize the K{alpha} source. We find that the K{alpha} conversion efficiency from the laser energy at 22 keV is {approx} 3 x 10{sup -4}.

  3. High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

    NASA Technical Reports Server (NTRS)

    Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

  4. Very high resolution UV and X-ray spectroscopy and imagery of solar active regions

    NASA Technical Reports Server (NTRS)

    Bruner, M.; Brown, W. A.; Haisch, B. M.

    1987-01-01

    A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft X-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the X-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical X-ray observations using this new technique.

  5. High-average-power water window soft X-rays from an Ar laser plasma

    NASA Astrophysics Data System (ADS)

    Amano, Sho

    2016-07-01

    A high average power of 140 mW and high conversion efficiency of 14% were demonstrated in “water window” soft X-rays generated using a laser plasma source developed in-house, when a solid Ar target was irradiated by a commercial Nd:YAG Q-switched laser with an energy of 1 J at a repetition rate of 1 Hz. This soft X-ray power compared favorably with that produced using a synchrotron radiation source, and the developed laser plasma source can be used in various applications, such as soft X-ray microscopy, in place of synchrotron facilities.

  6. Calibration of a high resolution grating soft x-ray spectrometer.

    PubMed

    Magee, E W; Dunn, J; Brown, G V; Cone, K V; Park, J; Porter, F S; Kilbourne, C A; Kelley, R L; Beiersdorfer, P

    2010-10-01

    The calibration of the soft x-ray spectral response of a large radius of curvature, high resolution grating spectrometer (HRGS) with a back-illuminated charge-coupled device detector is reported. The instrument is cross-calibrated for the 10-50 Å waveband at the Lawrence Livermore National Laboratory electron beam ion trap (EBIT) x-ray source with the EBIT calorimeter spectrometer. The HRGS instrument is designed for laser-produced plasma experiments and is important for making high dynamic range measurements of line intensities, line shapes, and x-ray sources.

  7. Calibration of a high resolution grating soft x-ray spectrometer

    SciTech Connect

    Magee, E. W.; Dunn, J.; Brown, G. V.; Cone, K. V.; Park, J.; Porter, F. S.; Kilbourne, C. A.; Kelley, R. L.; Beiersdorfer, P.

    2010-10-01

    The calibration of the soft x-ray spectral response of a large radius of curvature, high resolution grating spectrometer (HRGS) with a back-illuminated charge-coupled device detector is reported. The instrument is cross-calibrated for the 10–50 Å waveband at the Lawrence Livermore National Laboratory electron beam ion trap (EBIT) x-ray source with the EBIT calorimeter spectrometer. The HRGS instrument is designed for laser-produced plasma experiments and is important for making high dynamic range measurements of line intensities, line shapes, and x-ray sources.

  8. Lensless diffractive imaging using tabletop coherent high-harmonic soft-X-ray beams.

    PubMed

    Sandberg, Richard L; Paul, Ariel; Raymondson, Daisy A; Hädrich, Steffen; Gaudiosi, David M; Holtsnider, Jim; Tobey, Ra'anan I; Cohen, Oren; Murnane, Margaret M; Kapteyn, Henry C; Song, Changyong; Miao, Jianwei; Liu, Yanwei; Salmassi, Farhad

    2007-08-31

    We present the first experimental demonstration of lensless diffractive imaging using coherent soft x rays generated by a tabletop soft-x-ray source. A 29 nm high harmonic beam illuminates an object, and the subsequent diffraction is collected on an x-ray CCD camera. High dynamic range diffraction patterns are obtained by taking multiple exposures while blocking small-angle diffraction using beam blocks of varying size. These patterns reconstruct to images with 214 nm resolution. This work demonstrates a practical tabletop lensless microscope that promises to find applications in materials science, nanoscience, and biology.

  9. X-ray resonant photoexcitation: linewidths and energies of Kα transitions in highly charged Fe ions.

    PubMed

    Rudolph, J K; Bernitt, S; Epp, S W; Steinbrügge, R; Beilmann, C; Brown, G V; Eberle, S; Graf, A; Harman, Z; Hell, N; Leutenegger, M; Müller, A; Schlage, K; Wille, H-C; Yavaş, H; Ullrich, J; Crespo López-Urrutia, J R

    2013-09-06

    Photoabsorption by and fluorescence of the Kα transitions in highly charged iron ions are essential mechanisms for x-ray radiation transfer in astrophysical environments. We study photoabsorption due to the main Kα transitions in highly charged iron ions from heliumlike to fluorinelike (Fe24+ to Fe17+) using monochromatic x rays around 6.6 keV at the PETRA III synchrotron photon source. Natural linewidths were determined with hitherto unattained accuracy. The observed transitions are of particular interest for the understanding of photoexcited plasmas found in x-ray binary stars and active galactic nuclei.

  10. High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

    NASA Technical Reports Server (NTRS)

    Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

  11. High efficiency replicated x-ray optics and fabrication method

    DOEpatents

    Barbee, Jr., Troy W.; Lane, Stephen M.; Hoffman, Donald E.

    2001-01-01

    Replicated x-ray optics are fabricated by sputter deposition of reflecting layers on a super-polished reusable mandrel. The reflecting layers are strengthened by a supporting multilayer that results in stronger stress-relieved reflecting surfaces that do not deform during separation from the mandrel. The supporting multilayer enhances the ability to part the replica from the mandrel without degradation in surface roughness. The reflecting surfaces are comparable in smoothness to the mandrel surface. An outer layer is electrodeposited on the supporting multilayer. A parting layer may be deposited directly on the mandrel before the reflecting surface to facilitate removal of the layered, tubular optic device from the mandrel without deformation. The inner reflecting surface of the shell can be a single layer grazing reflection mirror or a resonant multilayer mirror. The resulting optics can be used in a wide variety of applications, including lithography, microscopy, radiography, tomography, and crystallography.

  12. High resolution, monochromatic x-ray topography capability at CHESS

    SciTech Connect

    Finkelstein, K. D. Pauling, A.; Brown, Z.; Jones, R.; Tarun, A.; Misra, D. S.; Jupitz, S.; Sagan, D. C.

    2016-07-27

    CHESS has a monochromatic x-ray topography capability serving continually expanding user interest. The setup consists of a beam expanding monochromator, 6-circle diffactometer, and CHESS designed CMOS camera with real time sample-alignment capability. This provides rocking curve mapping with angle resolution as small as 2 µradians, spatial resolution to 3 microns, and field of view up to 7mm. Thus far the capability has been applied for: improving CVD-diamond growth, evaluating perfection of ultra-thin diamond membranes, correlating performance of diamond-based electronics with crystal defect structure, and defect analysis of single crystal silicon carbide. This paper describes our topography system, explains its capabilities, and presents experimental results from several applications.

  13. Design and Development of Thin Plastic Foil, Conical Approximation, High Through-out X-Ray Telescope: Light Weight, Thin Plastic Foil, X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    Schnopper, Herbert W.; Barbera, Marco; Silver, Eric; Ingram, Russell; Christensen, Finn E.; Romaine, Suzanne; Cohen, Lester; Collura, Alfonso; Murray, Stephen S.; Brinton, John C. (Technical Monitor)

    2002-01-01

    We present results from a program to develop an X-ray telescope made from thin plastic shells. Our initial results have been obtained from multi-shell cylindrical lenses that are used in a point-to-point configuration to image the small focal spot of a an X-ray tube on a microchannel plate detector. We describe the steps that led up to the present design and present data from the tests that have been used to identify the properties of the plastic material that make it a suitable X-ray reflector. We discuss two applications of our technology to X-ray missions that are designed to address some of the scientific priorities set forth in NASA's long term plans for high energy astrophysics. One mission will observe in the 1 - 10 keV band, the other will extend up to ca. 100 keV.

  14. Exploratory X-ray monitoring of luminous radio-quiet quasars at high redshift: Initial results

    SciTech Connect

    Shemmer, Ohad; Stein, Matthew S.; Brandt, W. N.; Schneider, Donald P.; Paolillo, Maurizio; Kaspi, Shai; Vignali, Cristian; Lira, Paulina; Gibson, Robert R.

    2014-03-10

    We present initial results from an exploratory X-ray monitoring project of two groups of comparably luminous radio-quiet quasars (RQQs). The first consists of four sources at 4.10 ≤ z ≤ 4.35, monitored by Chandra, and the second is a comparison sample of three sources at 1.33 ≤ z ≤ 2.74, monitored by Swift. Together with archival X-ray data, the total rest-frame temporal baseline spans ∼2-4 yr and ∼5-13 yr for the first and second group, respectively. Six of these sources show significant X-ray variability over rest-frame timescales of ∼10{sup 2}-10{sup 3} days; three of these also show significant X-ray variability on rest-frame timescales of ∼1-10 days. The X-ray variability properties of our variable sources are similar to those exhibited by nearby and far less luminous active galactic nuclei (AGNs). While we do not directly detect a trend of increasing X-ray variability with redshift, we do confirm previous reports of luminous AGNs exhibiting X-ray variability above that expected from their luminosities, based on simplistic extrapolation from lower luminosity sources. This result may be attributed to luminous sources at the highest redshifts having relatively high accretion rates. Complementary UV-optical monitoring of our sources shows that variations in their optical-X-ray spectral energy distribution are dominated by the X-ray variations. We confirm previous reports of X-ray spectral variations in one of our sources, HS 1700+6416, but do not detect such variations in any of our other sources in spite of X-ray flux variations of up to a factor of ∼4. This project is designed to provide a basic assessment of the X-ray variability properties of RQQs at the highest accessible redshifts that will serve as a benchmark for more systematic monitoring of such sources with future X-ray missions.

  15. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    SciTech Connect

    Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Seguin, F. H.; Petrasso, R. D.; Filkins, T.; Steidle, Jeffrey A.; Steidle, Jessica A.; Traynor, N.; Freeman, C.

    2015-12-23

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Lastly, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

  16. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    SciTech Connect

    Rinderknecht, H. G. Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Filkins, T.; Steidle, Jessica A.; Traynor, N.; Freeman, C.; Steidle, Jeffrey A.

    2015-12-15

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

  17. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    DOE PAGES

    Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; ...

    2015-12-23

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protonsmore » with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Furthermore, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.« less

  18. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays.

    PubMed

    Zygmanski, Piotr; Sajo, Erno

    2016-01-01

    We review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics.

  19. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays

    PubMed Central

    Sajo, Erno

    2016-01-01

    We review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics. PMID:26642305

  20. Copper filtration in pediatric digital X-ray imaging: its impact on image quality and dose.

    PubMed

    Brosi, Philippe; Stuessi, Anja; Verdun, Francis R; Vock, Peter; Wolf, Rainer

    2011-07-01

    The effect of copper (Cu) filtration on image quality and dose in different digital X-ray systems was investigated. Two computed radiography systems and one digital radiography detector were used. Three different polymethylmethacrylate blocks simulated the pediatric body. The effect of Cu filters of 0.1, 0.2, and 0.3 mm thickness on the entrance surface dose (ESD) and the corresponding effective doses (EDs) were measured at tube voltages of 60, 66, and 73 kV. Image quality was evaluated in a contrast-detail phantom with an automated analyzer software. Cu filters of 0.1, 0.2, and 0.3 mm thickness decreased the ESD by 25-32%, 32-39%, and 40-44%, respectively, the ranges depending on the respective tube voltages. There was no consistent decline in image quality due to increasing Cu filtration. The estimated ED of anterior-posterior (AP) chest projections was reduced by up to 23%. No relevant reduction in the ED was noted in AP radiographs of the abdomen and pelvis or in posterior-anterior radiographs of the chest. Cu filtration reduces the ESD, but generally does not reduce the effective dose. Cu filters can help protect radiosensitive superficial organs, such as the mammary glands in AP chest projections.

  1. High-order multilayer coated blazed gratings for high resolution soft x-ray spectroscopy

    DOE PAGES

    Voronov, Dmitriy L.; Goray, Leonid I.; Warwick, Tony; ...

    2015-02-17

    A grand challenge in soft x-ray spectroscopy is to drive the resolving power of monochromators and spectrometers from the 104 achieved routinely today to well above 105. This need is driven mainly by the requirements of a new technique that is set to have enormous impact in condensed matter physics, Resonant Inelastic X-ray Scattering (RIXS). Unlike x-ray absorption spectroscopy, RIXS is not limited by an energy resolution dictated by the core-hole lifetime in the excitation process. Using much higher resolving power than used for normal x-ray absorption spectroscopy enables access to the energy scale of soft excitations in matter. Thesemore » excitations such as magnons and phonons drive the collective phenomena seen in correlated electronic materials such as high temperature superconductors. RIXS opens a new path to study these excitations at a level of detail not formerly possible. However, as the process involves resonant excitation at an energy of around 1 keV, and the energy scale of the excitations one would like to see are at the meV level, to fully utilize the technique requires the development of monochromators and spectrometers with one to two orders of magnitude higher energy resolution than has been conventionally possible. Here we investigate the detailed diffraction characteristics of multilayer blazed gratings. These elements offer potentially revolutionary performance as the dispersive element in ultra-high resolution x-ray spectroscopy. In doing so, we have established a roadmap for the complete optimization of the grating design. Traditionally 1st order gratings are used in the soft x-ray region, but we show that as in the optical domain, one can work in very high spectral orders and thus dramatically improve resolution without significant loss in efficiency.« less

  2. High-order multilayer coated blazed gratings for high resolution soft x-ray spectroscopy

    SciTech Connect

    Voronov, Dmitriy L.; Goray, Leonid I.; Warwick, Tony; Yashchuk, Valeriy V.; Padmore, Howard A.

    2015-02-17

    A grand challenge in soft x-ray spectroscopy is to drive the resolving power of monochromators and spectrometers from the 104 achieved routinely today to well above 105. This need is driven mainly by the requirements of a new technique that is set to have enormous impact in condensed matter physics, Resonant Inelastic X-ray Scattering (RIXS). Unlike x-ray absorption spectroscopy, RIXS is not limited by an energy resolution dictated by the core-hole lifetime in the excitation process. Using much higher resolving power than used for normal x-ray absorption spectroscopy enables access to the energy scale of soft excitations in matter. These excitations such as magnons and phonons drive the collective phenomena seen in correlated electronic materials such as high temperature superconductors. RIXS opens a new path to study these excitations at a level of detail not formerly possible. However, as the process involves resonant excitation at an energy of around 1 keV, and the energy scale of the excitations one would like to see are at the meV level, to fully utilize the technique requires the development of monochromators and spectrometers with one to two orders of magnitude higher energy resolution than has been conventionally possible. Here we investigate the detailed diffraction characteristics of multilayer blazed gratings. These elements offer potentially revolutionary performance as the dispersive element in ultra-high resolution x-ray spectroscopy. In doing so, we have established a roadmap for the complete optimization of the grating design. Traditionally 1st order gratings are used in the soft x-ray region, but we show that as in the optical domain, one can work in very high spectral orders and thus dramatically improve resolution without significant loss in efficiency.

  3. High-order multilayer coated blazed gratings for high resolution soft x-ray spectroscopy.

    PubMed

    Voronov, Dmitriy L; Goray, Leonid I; Warwick, Tony; Yashchuk, Valeriy V; Padmore, Howard A

    2015-02-23

    A grand challenge in soft x-ray spectroscopy is to drive the resolving power of monochromators and spectrometers from the 10(4) achieved routinely today to well above 10(5). This need is driven mainly by the requirements of a new technique that is set to have enormous impact in condensed matter physics, Resonant Inelastic X-ray Scattering (RIXS). Unlike x-ray absorption spectroscopy, RIXS is not limited by an energy resolution dictated by the core-hole lifetime in the excitation process. Using much higher resolving power than used for normal x-ray absorption spectroscopy enables access to the energy scale of soft excitations in matter. These excitations such as magnons and phonons drive the collective phenomena seen in correlated electronic materials such as high temperature superconductors. RIXS opens a new path to study these excitations at a level of detail not formerly possible. However, as the process involves resonant excitation at an energy of around 1 keV, and the energy scale of the excitations one would like to see are at the meV level, to fully utilize the technique requires the development of monochromators and spectrometers with one to two orders of magnitude higher energy resolution than has been conventionally possible. Here we investigate the detailed diffraction characteristics of multilayer blazed gratings. These elements offer potentially revolutionary performance as the dispersive element in ultra-high resolution x-ray spectroscopy. In doing so, we have established a roadmap for the complete optimization of the grating design. Traditionally 1st order gratings are used in the soft x-ray region, but we show that as in the optical domain, one can work in very high spectral orders and thus dramatically improve resolution without significant loss in efficiency.

  4. Ultra-high aspect ratio high-resolution nanofabrication for hard X-ray diffractive optics.

    PubMed

    Chang, Chieh; Sakdinawat, Anne

    2014-06-27

    Although diffractive optics have played a major role in nanoscale soft X-ray imaging, high-resolution and high-efficiency diffractive optics have largely been unavailable for hard X-rays where many scientific, technological and biomedical applications exist. This is owing to the long-standing challenge of fabricating ultra-high aspect ratio high-resolution dense nanostructures. Here we report significant progress in ultra-high aspect ratio nanofabrication of high-resolution, dense silicon nanostructures using vertical directionality controlled metal-assisted chemical etching. The resulting structures have very smooth sidewalls and can be used to pattern arbitrary features, not limited to linear or circular. We focus on the application of X-ray zone plate fabrication for high-efficiency, high-resolution diffractive optics, and demonstrate the process with linear, circular, and spiral zone plates. X-ray measurements demonstrate high efficiency in the critical outer layers. This method has broad applications including patterning for thermoelectric materials, battery anodes and sensors among others.

  5. Impact of hollow-atom formation on coherent x-ray scattering at high intensity

    SciTech Connect

    Son, Sang-Kil; Young, Linda; Santra, Robin

    2011-03-15

    X-ray free-electron lasers (FELs) are promising tools for structural determination of macromolecules via coherent x-ray scattering. During ultrashort and ultraintense x-ray pulses with an atomic-scale wavelength, samples are subject to radiation damage and possibly become highly ionized, which may influence the quality of x-ray scattering patterns. We develop a toolkit to treat detailed ionization, relaxation, and scattering dynamics for an atom within a consistent theoretical framework. The coherent x-ray scattering problem including radiation damage is investigated as a function of x-ray FEL parameters such as pulse length, fluence, and photon energy. We find that the x-ray scattering intensity saturates at a fluence of {approx}10{sup 7} photon/A{sup 2} per pulse but can be maximized by using a pulse duration much shorter than the time scales involved in the relaxation of the inner-shell vacancy states created. Under these conditions, both inner-shell electrons in a carbon atom are removed, and the resulting hollow atom gives rise to a scattering pattern with little loss of quality for a spatial resolution >1 A. Our numerical results predict that in order to scatter from a carbon atom 0.1 photon per x-ray pulse, within a spatial resolution of 1.7 A, a fluence of 1x10{sup 7} photons/A{sup 2} per pulse is required at a pulse length of 1 fs and a photon energy of 12 keV. By using a pulse length of a few hundred attoseconds, one can suppress even secondary ionization processes in extended systems. The present results suggest that high-brightness attosecond x-ray FELs would be ideal for single-shot imaging of individual macromolecules.

  6. First results from the high-brightness x-ray spectroscopy beamline at ALS

    SciTech Connect

    Perera, R.C.C.; Ng, W.; Jones, G.

    1997-04-01

    Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range, designed to achieve the goal of high brightness at the sample for use in the X-ray Atomic and Molecular Spectroscopy (XAMS) science, surface and interface science, biology and x-ray optical development programs at ALS. X-ray absorption and time of flight photo emission measurements in 2 - 5 keV photon energy in argon along with the flux, resolution, spot size and stability of the beamline will be discussed. Prospects for future XAMS measurements will also be presented.

  7. X-ray two-photon absorption with high fluence XFEL pulses

    DOE PAGES

    Hoszowska, Joanna; Szlachetko, J.; Dousse, J. -Cl.; ...

    2015-09-07

    Here, we report on nonlinear interaction of solid Fe with intense femtosecond hard x-ray free-electron laser (XFEL) pulses. The experiment was performed at the CXI end-station of the Linac Coherent Light Source (LCLS) by means of high- resolution x-ray emission spectroscopy. The focused x-ray beam provided extreme fluence of ~105 photons/Å2. Two-photon absorption leading to K-shell hollow atom formation and to single K-shell ionization of solid Fe was investigated.

  8. X-ray two-photon absorption with high fluence XFEL pulses

    SciTech Connect

    Hoszowska, Joanna; Szlachetko, J.; Dousse, J. -Cl.; Błachucki, W.; Kayser, Y.; Milne, Ch.; Pajek, M.; Boutet, S.; Messerschmidt, M.; Williams, G.; Chantler, C. T.

    2015-09-07

    Here, we report on nonlinear interaction of solid Fe with intense femtosecond hard x-ray free-electron laser (XFEL) pulses. The experiment was performed at the CXI end-station of the Linac Coherent Light Source (LCLS) by means of high- resolution x-ray emission spectroscopy. The focused x-ray beam provided extreme fluence of ~105 photons/Å2. Two-photon absorption leading to K-shell hollow atom formation and to single K-shell ionization of solid Fe was investigated.

  9. Monte Carlo Simulator to Study High Mass X-Ray Binary System

    SciTech Connect

    Watanabe, Shin; Nagase, Fumiaki; Takahashi, Tadayuki; Sako, Masao; Kahn, Steve M.; Ishida, Manabu; Ishisaki, Yoshitaka; Paerels, Frederik; /Columbia U.

    2005-07-08

    We have developed a Monte Carlo simulator for astrophysical objects, which incorporate the transportation of X-ray photons in photoionized plasma. We applied the code to X-ray spectra of high mass X-ray binaries, Vela X-1 and GX 301-2, obtained with Chandra HETGS. By utilizing the simulator, we have successfully reproduced many emission lines observed from Vela X-1. The ionization structure and the matter distribution in the Vela X-1 system are deduced. For GX 301-2, we have derived the physical parameters of material surrounding the neutron star from fully resolved shape of the Compton shoulder in the iron K{alpha} line.

  10. High-speed videography combined with an x-ray image intensifier for dynamic radiography

    SciTech Connect

    Bryant, L.E. Jr.

    1983-01-01

    The Spin Physics SP-2000 high-speed video system can be combined with an x-ray source, a dynamic event having internal (not directly visible) movement and an x-ray image intensifier to perform dynamic radiography. The cesium iodide input fluor and P-20 output fluor of the image intensifier have rapid decay to allow x-ray imaging up to 12,000 pictures per second. Applications of this technique include internal functioning of a compressor, turbulent-water action, and other mechanical actions.

  11. Efficient electronic structure calculation for molecular ionization dynamics at high x-ray intensity

    PubMed Central

    Hao, Yajiang; Inhester, Ludger; Hanasaki, Kota; Son, Sang-Kil; Santra, Robin

    2015-01-01

    We present the implementation of an electronic-structure approach dedicated to ionization dynamics of molecules interacting with x-ray free-electron laser (XFEL) pulses. In our scheme, molecular orbitals for molecular core-hole states are represented by linear combination of numerical atomic orbitals that are solutions of corresponding atomic core-hole states. We demonstrate that our scheme efficiently calculates all possible multiple-hole configurations of molecules formed during XFEL pulses. The present method is suitable to investigate x-ray multiphoton multiple ionization dynamics and accompanying nuclear dynamics, providing essential information on the chemical dynamics relevant for high-intensity x-ray imaging. PMID:26798806

  12. Radiation dose fractionation studies with hypoxic cell radiosensitizers using a murine tumor. [X-ray; mice

    SciTech Connect

    Hill, R.P.

    1982-03-01

    The ability of five nitroimidazoles, metronidazole (MET), misonidazole (MISO), desmethymisonidazole (DMM), SR 2508 and SR 2555, to sensitize the KHT sarcoma to radiation treatment has been compared for drug doses in the range 0-1.5 g/Kg. Single radiation doses or two different daily fractionation schedules (4 fractions of 5 Gy each or 7 fraction of 3 Gy each) were used; the tumor cell survival was determined using either an in vivo or in vitro colony assay. Each radiation (100 kVp X rays at 11 Gy/min) treatment was given locally, 60-70 min (MET) or 30-40 min (other drugs) after either intraperitoneal (MET, MISO, DMM) or intraveous (SR 2508, SR 2555) injection of the drugs; these times have been shown to be optimum for this tumor. For the single doses and both fractionation schedules the tumor cell survival, following the irradiation treatment, declined as the drug dose increased in the range 0 to 0.75 g/Kg for all the drugs, but above this dose level a plateau was reached and the amount of sensitization remained essentially constant. In this plateau region the reduction in survival achieved was similar for single doses and 5 Gy fraction but was less for 3 Gy fractions, indicating that sensitization was smaller for the smaller dose fractions. For the 4 x 5 Gy fractionation schedule the plateau level of survival was lowest for MISO, DMM and SR 2508, slightly higher for SR 2555 and much higher for MET. For the 3 Gy fractions SR 2508 appeared slightly less effective than MISO and DMM.

  13. Event-Driven X-Ray CCD Detectors for High Energy Astrophysics

    NASA Technical Reports Server (NTRS)

    Ricker, George R.

    2004-01-01

    A viewgraph presentation describing the Event-Driven X- Ray CCD (EDCCD) detector system for high energy astrophysics is presented. The topics include: 1) EDCCD: Description and Advantages; 2) Summary of Grant Activity Carried Out; and 3) EDCCD Test System.

  14. Bright High Average Power Table-top Soft X-Ray Lasers

    SciTech Connect

    Rocca, Jorge; Reagan, Brendon; Wernsing, Keith; Luther, Brad; Curtis, Alden; Nichols,, Anthony; Wang, Yong; Alessi, David; Martz, Dale; Yin, Liang; Wang, Shoujun; Berrill, Mark A; Furch, Federico; Woolston, Mark; Patel, Dinesh; Marconi, Mario; Menoni, Carmen

    2012-01-01

    We have demonstrated the generation of bright soft x-ray laser pulses with record-high average power from compact plasma amplifiers excited by ultrafast solid state lasers. These lasers have numerous applications in nanoscience and nanotechnology.

  15. First Look at Milky Way Monster in High-Energy X-ray Light

    NASA Image and Video Library

    2012-10-23

    These images, taken by NASA black-hole hunter, NuSTAR, are the first, focused high-energy X-ray views of the area surrounding the supermassive black hole, called Sagittarius A*, at the center of our galaxy.

  16. Insights into spray development from metered-dose inhalers through quantitative X-ray radiography

    SciTech Connect

    Mason-Smith, Nicholas; Duke, Daniel J.; Kastengren, Alan L.; Stewart, Peter J; Traini, Daniela; Young, Paul M; Chen, Yang; Lewis, David; Soria, Julio; Edgington-Mitchell, Daniel M; Honnery, Damon R

    2016-05-01

    Typical methods to study pMDI sprays employ particle sizing or visible light diagnostics, which suffer in regions of high spray density. X-ray techniques can be applied to pharmaceutical sprays to obtain information unattainable by conventional particle sizing and light-based techniques. We present a technique for obtaining quantitative measurements of spray density in pMDI sprays. A monochromatic focused X-ray beam was used to perform quantitative radiography measurements in the near-nozzle region and plume of HFA-propelled sprays. Measurements were obtained with a temporal resolution of 0.184 ms and spatial resolution of 5 mu m. Steady flow conditions were reached after around 30 ms for the formulations examined with the spray device used. Spray evolution was affected by the inclusion of ethanol in the formulation and unaffected by the inclusion of 0.1% drug by weight. Estimation of the nozzle exit density showed that vapour is likely to dominate the flow leaving the inhaler nozzle during steady flow. Quantitative measurements in pMDI sprays allow the determination of nozzle exit conditions that are difficult to obtain experimentally by other means. Measurements of these nozzle exit conditions can improve understanding of the atomization mechanisms responsible for pMDI spray droplet and particle formation.

  17. High-speed X-ray phase tomography with Talbot interferometer and fringe scanning method

    SciTech Connect

    Kibayashi, Shunsuke; Harasse, Sebastien; Yashiro, Wataru; Momose, Atsushi

    2012-07-31

    High-speed X-ray phase tomography based on the Fourier-transform method has been demonstrated with an X-ray Talbot interferometer using white synchrotron radiation. We report the experimental results of high-speed X-ray phase tomography with fringe-scanning method instead of Fourier-transform method to improve spatial resolution without a considerable increase of scan time. To apply fringe-scanning method to high speed tomography, we tested a scan that is a synchronous combination of one-way continuous movements of the sample rotation and the grating displacement. When this scanning method was combined with X-ray phase tomography, we were able to obtain a scan time of 5 s. A comparison of the image quality derived with the conventional approach and with the proposed approach using the fringe-scanning method showed that the latter had better spatial resolution.

  18. Wire array z-pinch insights for high x-ray power generation

    SciTech Connect

    Sanford, T.W.L.; Mock, R.C.; Marder, B.M.

    1997-12-31

    The discovery that the use of very large numbers of wires enables high x-ray power to be generated from wire-array z-pinches represents a breakthrough in load design for large pulsed power generators, and has permitted high temperatures to be generated in radiation cavities on Saturn and Z. In this paper, changes in x-ray emission characteristics as a function of wire number, array mass, and load radius, for 20-mm-long aluminum arrays on Saturn that led to these breakthrough hohlraum results, are discussed and compared with a few related emission characteristics of high-wire-number aluminum and tungsten arrays on Z. X-ray measurement comparisons with analytic models and 2-D radiation-magnetohydrodynamic (RMHC) code simulations in the x-y and r-z planes provide confidence in the ability of the models and codes to predict future x-ray performance with very-large-number wire arrays.

  19. Wire array z-pinch insights for high X-ray power generation

    SciTech Connect

    Sanford, T.W.L.; Marder, B.M.; Desjarlais, M.P.

    1998-12-31

    The discovery that the use of very large numbers of wires enables high x-ray power to be generated from wire-array z-pinches represents a breakthrough in load design for large pulsed power generators, and has permitted high temperatures to be generated in radiation cavities on Saturn and Z. In this paper, changes in x-ray emission characteristics as a function of wire number, array mass, and load radius, for 20-mm-long aluminum arrays on Saturn that led to these breakthrough hohlraum results, are discussed and compared with a few related emission characteristics of high-wire-number aluminum and tungsten arrays on Z. X-ray measurement comparisons with analytic models and 2-D radiation-magnetohydrodynamic (RMHC) code simulations in the x-y and r-z planes provide confidence in the ability of the models and codes to predict future x-ray performance with very-large-number wire arrays.

  20. Wire array z-pinch insights for high x-ray power generation

    SciTech Connect

    Sanford, T.W.L.; Mock, R.C.; Nash, T.J.

    1998-08-01

    The discovery that the use of very large numbers of wires enables high x-ray power to be generated from wire-array z-pinches represents a breakthrough in load design for large pulsed power generators, and has permitted high temperatures to be generated in radiation cavities on Saturn. In this paper, changes in x-ray emission characteristics as a function of wire number, array mass, and load radius, for 20-mm-long aluminum arrays on Saturn that led to these breakthrough hohlraum results, are discussed and compared with a few related emission characteristics of high-wire-number aluminum and tungsten arrays on Z. X=ray measurement comparisons with analytic models and 2-D radiation-magnetohydrodynamic (RMHC) code simulations in the x-y and r-z planes provide confidence in the ability of the models and codes to predict future x-ray performance with very-large-number wire arrays.

  1. Prospects for using high power x-rays as a volumetric heat source

    SciTech Connect

    Rosenberg, R.A.; Farrell, W.; Ma, Q.

    1997-09-01

    Third-generation, high-intensity, x-ray synchrotron radiation sources are capable of producing high heat-flux x-ray beams. In many applications finding ways to handle these powers is viewed as a burden. However, there are some technological applications where the deep penetration length of the x-rays may find beneficial uses as a volumetric heat source. In this paper the authors discuss the prospects for using high power x-rays for volumetric heating and report some recent experimental results. The particular applications they focus on are welding and surface heat treatment. The radiation source is an undulator at the Advanced Photon Source (APS). Results of preliminary tests on aluminum, aluminum metal matrix composites, and steel will be presented.

  2. Experimental setup for high resolution x-ray spectroscopy of solids and liquid samples

    NASA Astrophysics Data System (ADS)

    Yin, Zhong; Rajković, Ivan; Raiser, Dirk; Scholz, Mirko; Techert, Simone

    2013-09-01

    Here we present a next-generation experimental setup for high-resolution X-ray spectroscopy of solid and liquid samples in the soft X-ray reg