High Miller-index germanium crystals for high-energy x-ray imaging applications.

Near-normal-incidence bent crystals are widely used for x-ray imaging applications. Advantages include high collection solid angle and potentially high efficiency for narrow-band sources, while disadvantages include relatively large (several Å) interatomic spacings and a limited number of suitable matches between a crystal 2d value and an integral multiple of useful emission line wavelengths. The disadvantages become more significant at x-ray energies >10 keV. The former disadvantage can be mitigated by using high-order reflections from crystal planes having low Miller indices, but both disadvantages can be mitigated by using low-order reflections from crystal planes having high Miller indices. We report here on integrated reflectivity measurements we performed of Ge (15,7,7) (2d=0.6296 Å), a candidate for imaging Ru He-α (θ(B)=87°). We find good agreement with calculations, and the data show a multitude of closely spaced reflections with slightly different Bragg angles including a fifth-order reflection of Ge (3,1,1) that has comparable reflectivity. This demonstrates that arbitrary choices of Miller indices in Ge crystals can be used to fine-tune Bragg angles for near-normal-incidence x-ray imaging at tens of kiloelectron volt x-ray energies with minimal lower-energy contamination from lower-order reflections, and that existing calculational tools can be used to reliably estimate integrated reflectivity.

Diagnostic value and clinical impact of complementary CT scan prior to surgery for non-localized primary hyperparathyroidism.

INTRODUCTION: Successful localization is mandatory for focused parathyroidectomy. If ultrasound and sestamibi scan are negative, bilateral neck exploration is necessary. We examined the contribution of complementary computed tomography (CT) scan to identify the affected parathyroid gland. METHODS: Between November 1999 and April 2014, 25 patients (20 females and 5 males; mean age 67 ± 11 years) with negative or dubious standard imaging (ultrasound and sestamibi scan) underwent CT scan prior to parathyroidectomy and were included in this study. Fifteen patients had had previous neck surgery for parathyroidectomy (n = 11) or thyroidectomy (n = 4). Thin-slice CT (n = 9) or four-dimensional (4D) CT imaging (n = 16) was used. Cure was defined as >50 % post-excision fall of intraoperatively measured parathyroid hormone or fall into the normal range, confirmed by normocalcaemia at least 6 months after surgery. RESULTS: Preoperative CT scan provided correct localization in 13 out of 25 patients (52 %) and was false positive once. Parathyroidectomy was performed by a focused approach in 11 of these 13 patients as well as in 1 patient guided by intraoperatively measured parathyroid hormone (ioPTH). Thirteen patients required bilateral neck exploration. The cure rate was 96 % (24/25 patients). One patient has persistent primary hyperparathyroidism (pHPT) and one a recurrent disease. Six patients presented a multiglandular disease. CONCLUSION: A CT scan identifies about half of abnormal parathyroid glands missed by conventional imaging and allows focused surgery in selected cases.

Simple solution to the Fresnel-Kirchoff diffraction integral for application to refraction-enhanced radiography.

We present a simple solution to the Fresnel-Kirchoff diffraction integral that is appropriate for x-ray radiography of strongly absorbing and phase-shifting objects in the geometrical optics regime, where phase contrast enhancements can be considered to be caused by refraction by a semi-opaque object. We demonstrate its accuracy by comparison to brute-force numerical ray trace and diffraction calculations of a representative simulated object, and show excellent agreement for spatial scales corresponding to Fresnel numbers greater than unity. The result represents a significant improvement over approximate formulas typically used in analysis of refraction-enhanced radiographs, particularly for radiography of transient phenomena in objects that strongly refract and show significant absorption.

X-ray streaked refraction enhanced radiography for inferring inflight density gradients in ICF capsule implosions.

In the quest for reaching ignition of deuterium-tritium (DT) fuel capsule implosions, experiments on the National Ignition Facility (NIF) have shown lower final fuel areal densities than simulated. Possible explanations for reduced compression are higher preheat that can increase the ablator-DT ice density jump and induce mix at that interface or reverberating shocks. We are hence developing x-ray Refraction Enhanced Radiography (RER) to infer the inflight density profiles in layered fuel capsule implosions. We use a 5 µm slit backlit by a Ni 7.8 keV He-α NIF laser driven x-ray source positioned at 20 mm from the capsule to cast refracted images of the inflight capsule onto a streak camera in a high magnification (M ∼ 60×) setup. Our first experiments have validated our setup that recorded a streaked x-ray fringe pattern from an undriven high density carbon (HDC) capsule consistent with ray tracing calculations at the required ∼6 µm and 25 ps resolution. Streaked RER was then applied to inflight layered HDC capsule implosions using a hydrogen-tritium fuel mix rather than DT to reduce neutron yields and associated backgrounds. The first RER of an imploding capsule revealed strong features associated with the ablation front and ice-ablator interface that are not visible in standard absorption radiographs.

Spectroscopic determination of temperature and density spatial profiles and mix in indirect-drive implosion cores.

In the field of inertial confinement fusion (ICF), work has been consistently progressing in the past decade toward a more fundamental understanding of the plasma conditions in ICF implosion cores. The research presented here represents a substantial evolution in the ability to diagnose plasma temperatures and densities, along with characteristics of mixing between fuel and shell materials. Mixing is a vital property to study and quantify, since it can significantly affect implosion quality. We employ a number of new spectroscopic techniques that allow us to probe these important quantities. The first technique developed is an emissivity analysis, which uses the emissivity ratio of the optically thin Lybeta and Hebeta lines to spectroscopically extract temperature profiles, followed by the solution of emissivity equations to infer density profiles. The second technique, an intensity analysis, models the radiation transport through the implosion core. The nature of the intensity analysis allows us to use an optically thick line, the Lyalpha, to extract information on mixing near the core edge. With this work, it is now possible to extract directly from experimental data not only detailed temperature and density maps of the core, but also spatial mixing profiles.

Measuring the diffraction properties of an imaging quartz(211) crystal.

A dual goniometer X-ray system was used to measure the reflectivity curve for a spherically bent quartz(211) crystal. An analysis of the dual goniometer instrument response function for the rocking curve width measurement was developed and tested against the actual measurements. The rocking curve was measured at 4510.8 eV using the Ti Kα1 characteristic spectral line. The crystal is the dispersion element for a high resolution spectrometer used for plasma studies. It was expected to have a very narrow rocking curve width. The analysis showed that we could measure the upper bound for the rocking curve width of the Qz(211) crystal. The upper bound was 58 µrad giving a lower bound for the instrument resolving power E/ΔE = 34 000. Greatly improved insight into the dual goniometer operation and its limitations was achieved.

Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas.

Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

Structured photocathodes for improved high-energy x-ray efficiency in streak cameras.

We have designed and fabricated a structured streak camera photocathode to provide enhanced efficiency for high energy X-rays (1-12 keV). This gold coated photocathode was tested in a streak camera and compared side by side against a conventional flat thin film photocathode. Results show that the measured electron yield enhancement at energies ranging from 1 to 10 keV scales well with predictions, and that the total enhancement can be more than 3×. The spatial resolution of the streak camera does not show degradation in the structured region. We predict that the temporal resolution of the detector will also not be affected as it is currently dominated by the slit width. This demonstration with Au motivates exploration of comparable enhancements with CsI and may revolutionize X-ray streak camera photocathode design.

A multi-wavelength, high-contrast contact radiography system for the study of low-density aerogel foams.

A multi-wavelength, high contrast contact radiography system has been developed to characterize density variations in ultra-low density aerogel foams. These foams are used to generate a ramped pressure drive in materials strength experiments at the National Ignition Facility and require precision characterization in order to reduce errors in measurements. The system was used to characterize density variations in carbon and silicon based aerogels to ∼10.3% accuracy with ∼30 µm spatial resolution. The system description, performance, and measurement results collected using a 17.8 mg/cc carbon based JX-6 (C20H30) aerogel are discussed in this manuscript.

Dopant radiative cooling effects in indirect-drive Ar-doped capsule implosion experiments.

We present results from simulations performed to investigate the effects of dopant radiative cooling in inertial confinement fusion indirect-drive capsule implosion experiments. Using a one-dimensional radiation-hydrodynamics code that includes inline collisional-radiative modeling, we compute in detail the non-local thermodynamic equilibrium atomic kinetics and spectral characteristics for Ar-doped DD fuel. Specifically, we present results from a series of calculations in which the concentration of the Ar is varied, and examine the sensitivity of the fuel conditions (e.g., electron temperature) and neutron yield to the Ar dopant concentration. Simulation results are compared with data obtained in OMEGA indirect-drive experiments in which monochromatic imaging and spectral measurements of Ar Hebeta and Lybeta line emission were recorded. The incident radiation drive on the capsule is computed with a three-dimensional view factor code using the laser beam pointings and powers from the OMEGA experiments. We also examine the sensitivity of the calculated compressed core electron temperatures and neutron yields to the radiation drive on the capsule and to the radiation and atomic modeling in the simulations.

[Differential diagnosis of focal liver lesions using contrast-enhanced MRI with SHU 555 A in comparison with unenhanced MRI and multidetector spiral-CT]. / Dignitätsbeurteilung fokaler Leberläsionen mit der kontrastverstärkten MRT mit SHU 555 A im Vergleich zur nativen MRT und zur Mehrzeilen-Detektor-Spiral-CT.

PURPOSE: To evaluate the ability of contrast-enhanced MRI with SHU 555 A to provide additional information for characterization of focal liver tumors compared with non-enhanced MRI and multislice spiral CT. MATERIALS AND METHODS: In a prospective manner the images of 45 patients who underwent multislice spiral CT, unenhanced MRI alone and unenhanced and SHU 555 A-enhanced MRI including dynamic imaging at a field strength of 1.0 T were analyzed in a blinded reading. The readers had to determine on a scale from 1 to 5 whether a tumor was benign or malignant. Furthermore, the readers had to give a definitive diagnosis for each lesion. A true cut needle biopsy served as gold standard against which all imaging procedures were compared. RESULTS: The sensitivity for differentiation malignant vs. benign lesion was 77 % with spiral CT, 72 % with unenhanced MRI and 94 % with SHU 555 A-enhanced MRI, respectively (p < 0.05). The specificity for spiral CT was 73 %, for unenhanced MRI 83 % and for contrast-enhanced MRI 83 %, respectively (n. s.). Compared with the histopathologic results, the correct diagnosis was made with spiral CT in 25/45 (56 %), unenhanced MRI in 16/45 (36 %) and contrast-enhanced MRI in 32/45 (71 %) of the patients (p < 0.05). For the subgroup of patients with liver cirrhosis, the correct diagnosis was established with spiral CT in 16/23 (70 %), unenhanced MRI in 9/23 (39 %) and contrast-enhanced MRI in 19/23 (83 %) of the patients (p < 0.05). CONCLUSION: Contrast-enhanced MRI with SHU 555 A has the ability to improve the differential diagnosis of focal liver tumors compared with unenhanced MRI and multislice spiral CT.

Development of antiviral treatment strategies in murine models.

Murine models with type C murine leukemia viruses have been used to develop major new prophylactic and therapeutic strategies in vaccination, drug therapy of acute virus exposure and chronic viremia, combination therapy, prevention of maternal transmission, and therapy targeted to the central nervous system. Transgenic mice expressing either the whole human immunodeficiency virus type 1 (HIV-1) provirus or subgenomic sequences allow the in vivo analysis of selected HIV-1 functions. The full replicative cycle of HIV-1 can be studied in human/mouse chimerae which were created by transplanting human hematolymphoid cells into SCID mice. The chimeric SCID mouse models have been used successfully to evaluate anti-HIV-1 drugs. The role of the various murine retrovirus systems in the development of anti-HIV-1 and anti-AIDS therapies is summarized.

Animal models for anti-AIDS therapy.

Primate and non-primate species have been used to study the pathobiology of the simian immunodeficiency virus (SIV) and of the human immunodeficiency virus type 1 (HIV-1), respectively, and to develop new therapeutic regimes. Transgenic mice which express either the entire HIV-1 provirus or subgenomic fragments have been used to analyze viral gene products in vivo and may serve as models for the development of agents targeted to select viral functions. Chimeric mice which were created by transplanting human hematolymphoid cells into mice suffering from congenital severe combined immunodeficiency (scid/scid or so called SCID mice), can be infected with HIV-1 and allow one to study the entire HIV-1 replicative cycle. Type C murine leukemia virus models have been used to develop new prophylactic and therapeutic strategies but their use is restricted to the evaluation of select antiviral drug inhibition, targeted to retroviral genes common to both Lentivirinae and Oncovirinae. The role of various animal model systems in the development of anti-HIV-1 and anti-AIDS therapies is summarized.

Synergistic antitumor activity of vitamins C and K3 on human urologic tumor cell lines.

A micro-tetrazolium assay was employed to evaluate vitamin C (VC), vitamin K3 (VK3) and vitamin C/vitamin K3 combinations (VC/VK3) for their antitumor activity against eight human urologic tumor cell lines. While the individual vitamins exhibited antitumor activity at high concentrations, co-administration of the vitamins in a VC : VK3 ratio of 100 : 1 potentiated antitumor activity 4- to 61-fold even when exposure times were as short as 1 hour. Administration of exogenous catalase destroyed the antitumor activity of the vitamins and suggested that hydrogen peroxide and perhaps other reactive oxygen species were involved in the antitumor mechanism of these vitamins. Electron micrographs taken in a previous study demonstrated that vitamin treatment damaged mitochondria and may have impaired ATP synthesis. Analysis of cellular ATP and thiol levels as well as DNA and protein synthesis during the first five hours following a one hour VC/VK3 treatment, revealed: a transient increase in ATP production, a substantial decrease in DNA synthesis, an increase in protein synthesis and a decrease in thiol levels. These results suggested that redox cycling of the vitamin combination increased oxidative stress until it surpassed the reducing ability of the cellular thiols and cellular or genetic damage ensued.

New peripherally inserted midline catheter: a better alternative for intravenous antibiotic therapy in patients with cystic fibrosis.

A study was performed on outpatients with cystic fibrosis (CF) to evaluate the performance of an over-the-needle peripherally inserted midline catheter for the delivery of 2-week courses of antibiotic therapy. The midline is a 7-inch catheter inserted in the antecubital region with the tip located in the axillary region. It is made of a newly developed biomaterial that softens and expands upon contact with body fluids. The hypotheses for the study were that the midline catheter: 1) is useful for intermediate-length therapies; 2) can prevent multiple 3-day conventional peripheral catheter restarts; 3) can prevent or delay the use of more invasive central devices; 4) is comfortable for patients; and 5) is economical. A total of 41 midlines were inserted in 27 patients with an average age and weight of 22 years and 109 pounds, respectively. Prior to this study implanted ports and primarily conventional short peripheral catheters were used to administer I.V. therapy to these patients; fifty percent of these short peripheral catheters failed within 2.6 days. At 2 weeks of dwell, 80% of the midline catheters placed in these patients were still indwelling. Also, 80% of all midline catheter removals were for non-catheter-related reasons. There were no cases of midline catheter phlebitis. In contrast, the phlebitis rates published for peripherally inserted central catheters (PICCs) and conventional short peripheral catheters at 7 days of dwell are 20% and greater than 51% respectively. The midline catheters were comfortable and well liked by most patients and became more economical than conventional peripheral catheters for therapies lasting approximately 6 days through 1 to 2 months.(ABSTRACT TRUNCATED AT 250 WORDS)

HRCT findings of amiodarone pulmonary toxicity: clinical and radiologic regression.

Amiodarone is an antiarrhythmic drug that can cause interstitial pneumonitis leading to pulmonary fibrosis. A 62-year-old man suffering from atrial fibrillation and recurrent dyspnea was treated with amiodarone. After 15 months of treatment, HRCT revealed bilateral interstitial and alveolar opacifications with high-attenuating pleural-parenchymal consolidations, suggesting amiodarone induced pneumonitis. Three months after cessation of amiodarone treatment, HRCT shows complete regression of pneumonitis. Amiodarone pneumonitis can be misinterpreted and mistreated in patients with further underlying diseases. The present case report demonstrates the diagnostic value of HRCT in the diagnosis of interstitial pneumonitis.

Experimental measurements of deep directional columnar heating by laser-generated relativistic electrons at near-solid density.

In our experiments, we irradiated solid CH targets with a 400 J, 5 ps, 3 x 10(19) W/cm(2) laser, and we used x-ray imaging and spectroscopic diagnostics to monitor the keV x-ray emission from thin Al or Au tracer layers buried within the targets. The experiments were designed to quantify the spatial distribution of the thermal electron temperature and density as a function of buried layer depth; these data provide insights into the behavior of relativistic electron currents which flow within the solid target and are directly and indirectly responsible for the heating. We measured approximately 200-350 eV temperatures and near-solid densities at depths ranging from 5 to 100 microm beneath the target surface. Time-resolved x-ray spectra from Al tracers indicate that the tracers emit thermal x rays and cool slowly compared to the time scale of the laser pulse. Most intriguingly, we consistently observe annular x-ray images in all buried tracer-layer experiments, and these data show that the temperature distribution is columnar, with enhanced heating along the edges of the column. The ring diameters are much greater than the laser focal spot diameter and do not vary significantly with the depth of the tracer layer for depths greater than 30 microm. The local temperatures are 200-350 eV for all tracer depths. We discuss recent simulations of the evolution of electron currents deep within solid targets irradiated by ultra-high-intensity lasers, and we discuss how modeling and analytical results suggest that the annular patterns we observe may be related to locally strong growth of the Weibel instability. We also suggest avenues for future research in order to further illuminate the complex physics of relativistic electron transport and energy deposition inside ultra-high-intensity laser-irradiated solid targets.

K(alpha) fluorescence measurement of relativistic electron transport in the context of fast ignition.

Electron transport within solid targets, irradiated by a high-intensity short-pulse laser, has been measured by imaging K(alpha) radiation from high- Z layers (Cu, Ti) buried in low- Z (CH, Al) foils. Although the laser spot is approximately 10 microm [full width at half maximum (FWHM)], the electron beam spreads to > or =70 microm FWHM within <20 microm of penetration into an Al target then, at depths >100 microm, diverges with a 40 degree spreading angle. Monte Carlo and analytic models are compared to our data. We find that a Monte Carlo model with a heuristic model for the electron injection gives a reasonable fit with our data.

[Gadodiamide and gadolinium-DTPA as intravenous media in computed tomography]. / Gadodiamid und Gadolinium-DTPA als intravenöse Kontrastmittel in der Computertomographie.

PURPOSE: To evaluate the effect of intravenously applied gadolinium-based contrast medium in computed tomographic (CT) studies. MATERIAL AND METHODS: Serial dilutions of iohexol 300, Gd-DTPA and gadodiamide were scanned with CT in a phantom study using water filled tubes. For quantification of x-ray attenuation, the mean Hounsfield units (HU) were calculated from the CT scans. Five patients with contraindications against iodine contrast agents were examined with abdominal or thoracic CT before and after application of 0.2 mmol/kg body weight of a gadolinium-based contrast agent. In these patients attenuation values were obtained in ROI from unenhanced and enhanced CT scans. RESULTS: The phantom study revealed a 38.4% enhancement for Gd-DTPA and a 35.7% enhancement for gadodiamide scaled on the reference measurements with iohexol 300. Thus, 130.2 ml Gd-DTPA or 140.1 ml gadodiamide are needed to achieve the same attenuation as an i.v. injection of 50 ml iohexol 300. Consequently the corresponding dose of 1 mmol/kg body weight would exceed the manufacturer's recommended dose. In four patients with complete thoracic or abdominal CT, i.v. applied gadolinium-based contrast medium (0.2 mmol/kg) yielded no visible advantage. In these patients parenchymal enhancement did not exceed 25%. Dynamic CT of a patient with focal liver lesion revealed an arterial enhancement peak of 75%. CONCLUSION: Sufficient parenchymal enhancement in CT studies cannot be achieved with the available gadolinium-based contrast mediums. They might be helpful if only short time vascular enhancement is required.

[Prostaglandin E1 for prevention of contrast medium-induced kidney dysfunction]. / Prostaglandin E1 zur Prophylaxe kontrastmittelinduzierter Nierenfunktionsstörungen.

PURPOSE: Acute renal failure is a known complication of contrast media (CM) application in risk patients. Therefore an efficient prevention is highly desirable. The purpose of this pilot study was a) to demonstrate the efficacy and safety of prostaglandin E1 (PGE1 = alprostadil) in the prophylaxis against CM associated renal dysfunction in patients with renal disease, and b) to identify the adequate dose. METHODS: A total of 130 patients with renal dysfunction who were scheduled for intravascular CM administration were enrolled. They received PGE1 (10, 20, or 40 ng/kg/min) or placebo intravenously over a period of six hours (beginning one hour prior to exposure). Efficacy was determined by measuring serum creatinine and creatinine clearance. Safety was assessed by recording adverse experiences throughout the study and close monitoring of vital parameters especially during study drug administration. RESULTS: PGE1 proved to be superior to placebo in all doses. The dose of 20 ng/kg/min was most promising due to the lowest increase of serum creatinine 48 hours after CM administration. With respect to creatinine clearance, no relevant differences between study and control groups were observed. CONCLUSION: Our results suggest that intravenously administered PGE1 may be efficient in preventing CM-induced renal dysfunction in patients with renal impairment.