High repetition-rate foam targetry for laser-plasma interaction experiments: Concept and preliminary results.

Foam targets have gained considerable importance over the last decade in laser-matter interaction. They find widespread applications such as in inertial confinement fusion and secondary sources for particles and radiation. At the same time, the advent of high repetition-rate laser systems, be they short-pulse in the tens of femtosecond regime or in the kilo-Joule nanosecond regime, calls for equally high repetition rate targetry systems. A well-established repetition-rate targetry system is the tape target. In this article, we present the successful marriage of a tape target delivery system with 3D-printed foam targets produced by two photon polymerization.

High-repetition rate solid target delivery system for PW-class laser-matter interaction at ELI Beamlines.

L3-HAPLS (High-repetition-rate Advanced Petawatt Laser System) at ELI (Extreme Light Infrastructure) Beamlines currently delivers 0.45 PW pulses (12 J in 27 fs) at 3.3 Hz repetition rate. A fresh target surface for every shot was placed at the laser focus using an in-house tape target system designed to withstand large laser intensities and energies. It has been tested for different material thicknesses (25 and 7.6 µm), while L3-HAPLS delivered laser shots for energies ranging from 1 to 12 J. A technical description of the tape target system is given. The device can be used in diverse geometries needed for laser-matter interaction studies by providing an ≈300° free angle of view on the target in the equatorial plane. We show experimental data demonstrating the shot-to-shot stability of the device. An x-ray crystal spherical spectrometer was set up to measure the Kα yield stability, while a GHz H-field probe was used to check the shot-to-shot electromagnetic pulse generation. Finally, we discuss short and mid-term future improvements of the tape target system for efficient user operation.

Validation of histogram-based virtual source models for different IGRT kV-imaging systems.

PURPOSE: Image-guided radiotherapy (IGRT) improves tumor control but its intensive use may entrain late side effects caused by the additional imaging doses. There is a need to better quantify the additional imaging doses, so they can be integrated in the therapeutic workflow. Currently, no dedicated software enables to compute patient-specific imaging doses on a wide range of systems and protocols. As a first step toward this objective, we propose a common methodology to model four different kV-imaging systems used in radiotherapy (Varian's OBI, Elekta's XVI, Brainlab's ExacTrac, and Accuray's Cyberknife) using a new type of virtual source model based on Monte Carlo calculations. METHODS: We first describe our method to build a simplified description of the photon output, or virtual source models (VSMs), of each imaging system. Instead of being constructed using measurement data, as it is most commonly the case, our VSM is used as the summary of the phase-space files (PSFs) resulting from a first Monte Carlo simulation of the considered x-ray tube. Second, the VSM is used as a photon generator for a second MC simulation in which we compute the dose. Then, the proposed VSM is thoroughly validated against standard MC simulation using PSFs on the XVI system. Last, each modeled system is compared to profiles and depth-dose-curve measurements performed in homogeneous phantom. RESULTS: Comparisons between PSF-based and VSM-based calculations highlight that VSMs could provide equivalent dose results (within 1% of difference) than PSFs inside the imaging field-of-view (FOV). In contrast, VSMs tend to underestimate (for up to 20%) calculated doses outside of the imaging FOV due to the assumptions underlying the VSM construction. In addition, we showed that the use of VSMs allows reducing calculation time by at least a factor of 2.8. Indeed, for identical simulation times, statistical uncertainties on dose distributions computed using VSMs were much lower than those obtained from PSF-based calculations. CONCLUSIONS: For each of the four imaging systems, VSMs were successfully validated against measurements in homogeneous phantoms, and are therefore ready to be used for future preclinical studies in heterogeneous or anthropomorphic phantoms. The cross system modeling methodology developed here should enable, later on, to estimate precisely and accurately patient-specific 3D dose maps delivered during a large range of kV-imaging procedures.

Solid mesenchymal hamartoma in an adult: a case report

Mesenchymal hamartoma of the liver (MHL) is an uncommon tumour composed of architecturally abnormal bile ducts in an uncommitted myxoid stroma. Most MHL are diagnosed in childhood and few cases have been reported in adults. This report describes a case of a well defined solid mass in the right lobe of the liver in a 51 year old man. Preoperative radiological examination revealed a large completely solid mass. Biopsy showed a dense fibrous stroma with hyalinisation and some bile ducts. A provisional diagnosis of MHL was made. Surgical excision was impossible and liver transplantation was undertaken. Definitive pathology confirmed the diagnosis. Review of published reports shows this to be the fourth case of MHL treated by liver transplantation(AU)

Hamartoma mesenquimal del hígado (MHL) es un tumor poco frecuente, compuesto de arquitectura anormal de los conductos biliares no comprometidos en un estroma mixoide. MHL mayoría se diagnostican en la infancia y pocos casos han sido reportados en adultos. Este informe describe un caso de una masa sólida bien definida en el lóbulo derecho del hígado en un 51 años de edad. Preoperatorio examen radiológico reveló una gran masa sólida completamente. La biopsia mostró un estroma fibroso denso con hyalinisation y algunos conductos biliares. Se establece un diagnóstico de MHL se hizo. Extirpación quirúrgica fue imposible y se llevó a cabo el trasplante de hígado. Definitivo de patología confirmó el diagnóstico. Examen de los informes publicados muestran que este es el cuarto caso de MHL tratado por el trasplante hepático

Paquimeningitis hipertrófica craneal idiopática diagnosticada tras trombosis venosa / Idiopathic hypertrophic cranial pachymeningitis diagnosed after venous thrombosis

Introducción. La paquimeningitis hipertrófica cranealidiopática (PHCI) es una forma rara y poco conocida de inflamacióncrónica de la duramadre, cuya patogenia permanece sin aclarar.Caso clínico. Se trata de un varón de 77 años de edad, ingresadopor un ictus y que, tras los hallazgos de la RM, fue diagnosticadode PHCI. Tras un tratamiento con corticoides mejoró clínica yradiológicamente. Conclusión. La PHCI produce un engrosamientodural difuso no nodular, hipointenso con respecto al parénquimacerebral en todas las secuencias de RM, con captación de contrasteintravenoso

Introduction. Idiopathic hypertrophic cranial pachymeningitis (IHCP) is a rare and little known form of chronicinflammation of the dura mater, the pathogenesis of which remains unclear. Case report. We report the case of a 77-year-oldmale who was admitted to hospital after suffering a stroke; following the findings in the MR imaging, the patient wasdiagnosed as having IHCP. Treatment with corticoids led to an improvement in the patient’s condition both clinically andradiologically. Conclusions. IHCP produces a non-nodular diffuse dural thickening that is hypointense with respect to thebrain parenchyma in all the MRI sequences with intravenous contrast enhancement

Hallazgos en resonancia magnética en la eclampsia / Magnetic resonance findings in eclampsia

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Baseline concentrations of elements in the Antarctic macrolichen Umbilicaria decussata

Total concentrations of major and trace elements were determined in samples of the epilithic lichen Umbilicaria decussata from 24 ice-free areas in coastal Victoria Land (Antarctica). Overall average concentrations of trace elements except Cd were the lowest ever reported for lichens of the genus Umbilicaria. Specifically, the mean level of Pb in lichens from granitic rocks (0.46 +/- 0.18 microg g(-1) dry wt) was more than four times lower than the lowest record in Arctic lichens. No impact of local human activities was detected, but the elemental composition of U. decussata was affected by entrapment of soil or rock dust particles and probably by uptake of soluble elements from substrate. Relationships between elements and their distribution patterns in the study area indicated that the marine environment is the main source of major ions and perhaps of Cd in lichens. Accumulation of P was detected in samples from coastal sites frequented by seabirds. Although the present results can be taken as baseline levels of major and trace elements in Antarctic U. decussata from substrates with very different geochemical features, further research is necessary to evaluate the relative element contribution from each substrate with respect to those from snow, marine aerosol, salt encrustations and guano.