Pulsed x-rays dose measurements from a hundred joules plasma focus device

Indexación: Scopus.Present work is aimed to perform dosimetric measurements to characterize dosis obtained from pulsed x-rays emitted from a hundred joules plasma focus device PF-400J using thermoluminescent dosimeters (TLD-100). Two dosimeter arrays (containing 21 dosimeters in each) were used. One of the arrays was kept inside the PF-400J vacuum chamber and other outside the vacuum chamber, simultaneously. It was found that dosis obtained from the inside array (∼200.7 mGy) were hundred times larger than the outside array (∼1.1 mGy) for hundred pulses of x-rays. Later, the vacuum window of PF-400J, which was made of 1 mm aluminum, was replaced by a plastic window and a similar dosimeter array was kept outside the chamber over the plastic window. With this arrangement, the obtained doses (100 pulses of x-rays) were of the same order of magnitude (∼106 mGy) as it was inside the vacuum chamber. Later, a lead piece was inserted inside the hollow anode of PF-400J, which increased dose (∼250 mGy) per hundred pulses of x-ray outside the vacuum chamber using plastic vacuum window. Our results suggest that PF-400J could be a useful device to study low dose pulsed radiation effects on cancer cell lines in in vitro experiments. © Published under licence by IOP Publishing Ltd.The work is supported by grant ACT-1115, CONICYT, Chile.https://iopscience.iop.org/article/10.1088/1742-6596/1043/1/01204

Analysis of Deterioration in a Plasma Focus Device

Indexación: Scopus.The Plasma Focus (PF) is a kind of dense transient plasmas in with high-pulsed voltage. To produce devices for eld application it is necessary to obtain PF equipment able to operate for a long period of time. Thus, a reliability analysis is indispensable. In this work a reliability analysis program for plasma focus devices is presented. The program considers a criticality analysis using Failure Modes and Effects Criticality Analysis (FMECA) to identify the most important failure modes of the system. Said failure modes are studied operating the Plasma Focus for many cycles, obtaining from them the characteristic curves of V(t) and İ(t). Feature Extraction (FE) techniques are applied to obtain a list of parameters that correlate to the degrading process. Furthermore, Machine Learning tools are used to learn from the obtained data, linking the changes in these parameters during its life cycle to the decay of the system in hope for future implementation of a predictive maintenance system and a reference for data analysis and prediction in PFs. The study was applied to a portable plasma focus device operated at 2 joules of stored energy. © Published under licence by IOP Publishing Ltd.The work is supported by IAEA CRP contract 20370 and by grant ACT-1115, CONICYT, Chile.https://iopscience.iop.org/article/10.1088/1742-6596/1043/1/01204

Hundred joules plasma focus device as a potential pulsed source for in vitro cancer cell irradiation

Indexación: Web of Science; Scopus.Plasma focus devices may arise as useful source to perform experiments aimed to study the effects of pulsed radiation on human cells in vitro. In the present work, a table top hundred joules plasma focus device, namely "PF-400J", was adapted to irradiate colorectal cancer cell line, DLD-1. For pulsed x-rays, the doses (energy absorbed per unit mass, measured in Gy) were measured using thermoluminescence detectors (TLD-100 dosimeters). The neutron fluence and the average energy were used to estimate the pulsed neutron doses. Fifty pulses of x-rays (0.12 Gy) and fifty pulses of neutrons (3.5 μGy) were used to irradiate the cancer cells. Irradiation-induced DNA damage and cell death were assessed at different time points after irradiation. Cell death was observed using pulsed neutron irradiation, at ultralow doses. Our results indicate that the PF-400J can be used for in vitro assessment of the effect of pulsed radiation in cancer cell research.http://recursosbiblioteca.unab.cl:2296/doi/pdf/10.1063/1.499465

Inference of X-Ray Emission from a Plasma Focus Discharge: Comparison between Characteristic Parameters and Neural Network Analyses

Indexación: Scopus.Pulsed plasma discharges, such as the plasma focus, are a source of pulsed X rays, therefore it is desirable to understand the relationship between this fast transient phenomena and the electrical variables of the discharge. Parameters from the electrical diagnostic signals are typically used to characterize the plasma focus discharge and for the correlations with X rays measurements via scatter plots. To further evaluate relevant information in the electrical signals, besides the characteristic parameters, an implementation of different types of machine learning algorithms, that included deep learning, was performed. A classification of pulses associated with an X rays measurement, in terms of the electrical signals data as input, was carried out. Two approaches were compared: the selection of the characteristic parameters and the use of the entire signals so the algorithms could find additional information for the classification task. The electrical diagnostic signals corresponded to: the voltage at the electrodes of the discharge chamber measured with a resistive voltage divider; time variation of the circuit current measured with a Rogowski coil and an inductive loop sensor; and the electromagnetic burst from the circuit measured with a Vivaldi antenna. The X rays measurement corresponded to the signal obtained from a scintillator-photomultiplier. In terms of the performance of the algorithms models in this classification problem, the results indicated that there is no significative improvements when using the entire signal or the selection of characteristic parameters. The best results were obtained when the following parameters were used: voltage at time of gas breakdown, voltage at time of pinch, current at time of pinch, time derivative of current at time of pinch, time from breakdown to pinch, and the Fast Fourier Transform of the part of the Vivaldi antenna signal related to the pinch event.https://ieeexplore.ieee.org/document/907878

Neuromyopathy with congenital cataracts and glaucoma: A distinct syndrome caused by POLG variants

We identified three non-related patients manifesting a childhood-onset progressive neuromyopathy with congenital cataracts, delayed walking, distal weakness and wasting, glaucoma and swallowing difficulties. Electrophysiology and nerve biopsies showed a mixed axonal and demyelinating neuropathy, while muscle biopsy disclosed both neurogenic and myopathic changes with ragged red fibers, and muscle MRI showed consistent features across patients, with a peculiar concentric disto-proximal gradient of fatty replacement. We used targeted next generation sequencing and candidate gene approach to study these families. Compound biallelic heterozygous variants, p.[(Pro648Arg)]; [(His932Tyr)] and p.[(Thr251Ile),(Pro587Leu)]; [(Arg943Cys)], were found in the three patients causing this homogeneous phenotype. Our report on a subset of unrelated patients, that showed a distinct autosomal recessive childhood-onset neuromyopathy with congenital cataracts and glaucoma, expands the clinical spectrum of POLG-related disorders. It also confirms the association between cataracts and neuropathy with variants in POLG. Early onset cataract is otherwise rare in POLG-related disorders and so far reported only in a few patients with the clinical pattern of distal myopathy or neuromyopathy

Fantoma para punción tiroidea ecoguiada, de elaboración casera y bajo costo

Los procedimientos intervencionistas guiados por imágenes han adquirido importancia en la práctica médica, particularmente para el radiólogo que debe estar familiarizado con estas técnicas para obtener diagnósticos precisos, sin someter al paciente a grandes procedimientos con mayores riesgos asociados. Uno de estos métodos es la punción aspiración con aguja fina (PAAF), que requiere de entrenamiento para adquirir destreza en la obtención de buenas imágenes y una adecuada muestra para la evaluación citológica precisa. Por ello, nos planteamos el desafío de elaborar un fantoma tiroideo, de bajo costo y fácil preparación, que simule contener una glándula tiroides multinodular, además de la tráquea, la vena yugular interna y la arteria carótida común como puntos de referencia anatómicos internos, y que sirva de herramienta de entrenamiento para la práctica de punciones tiroideas en residentes de Radiología

EVALUACIÓN DE LA ANATOMÍA ARTERIAL HEPÁTICA EN TOMOGRAFIA COMPUTADA MULTICORTE DE RUTINA EVALUATION OF HEPATIC ARTERIAL ANATOMY IN RUTINARY MULTISLICE COMPUTED TOMOGRAPHY (MSCT). A PRELIMINARY REPORT

La tomografía computada multicorte (TCM) ha demostrado ventajas en la evaluación de la patología abdominal y en especial del estudio de estructuras vasculares. Optimiza el uso del contraste endovenoso (EV) y tiene una mayor resolución temporal y espacial, permitiendo una resolución isotrópica. Las variantes de la circulación hepática responden al desarrollo embriológico. Objetivos: Demostrar que estudios rutinarios (no vasculares) de TCM con cte. EV, permiten evaluarla circulación arterial hepática, detectando las variantes más frecuentes en nuestra población. Material y Métodos: Análisis retrospectivo de TCM abdominales con uso de contraste EV, desde el 1/6/06 al 26/8/06, en Clínica Indisa. De un total de 102 pacientes, en 100 fue posible evaluar adecuadamente la anatomía arterial hepática. En el análisis de los estudios se revisaron los cortes axiales, reconstrucciones multiplanares, 3D y con modalidad MIP. Para la clasificación se utilizó las variantes descritas por Couinaud y Michels. Resultados: El promedio de edad fue de 57,3 años; 47% fueron hombres y 53% mujeres. En 53 pacientes se pesquisó variante tipo I (53%), 10 tipo II (10%), 10 tipo III (10%), 3 tipo IV (3%), 9 tipo V(9%), 7 tipo VI (7%), 1 tipo Vil (1%), 2 tipo IX (2%) y 5 tipo XI (5%). No se encontraron pacientes con tipo VIII y X. Conclusiones: La TCM abdominal de rutina que utiliza contraste EV permite evaluar adecuadamente la circulación arterial hepática. Un 47% mostró variantes anatómicas, concordante con publicaciones extranjeras. Debido a la alta frecuencia de variantes de la circulación hepática, se hace necesaria la evaluación vascular al planificar procedimientos quirúrgicos hepáticos mayoresIntroduction: Multislice computed tomography (MSCT) appears to provide more advantages in the evaluation of abdominal diseases, and particularly in the study of vascular structures. It optimizes the use of I.V. contrast, and offers a greater temporal and spatial resolution, thus allowing a isotropic resolution. Hepatic circulation variants respond to embryologic development. Objectives: To demonstrate thatrutinary MSCT studies (not vascular) with I.V. contrast allow us to evaluate hepatic arterial circulation by detecting the most frequent variants in our population. Material and Methods: A retrospective analysis of a rutinary abdominal MSCT with I. V. contrast was conducted from June 2006 to August 2006, at Clínica Indisa, Santiago, Chile. In 100 cases out of 102, we could properly assess the hepatic arterial anatomy. Axial cuts, Multi Planar Reconstruction (MPR), Maximum Intensity Projection (MIP), and 3D images were reviewed for study analysis. As for classification purposes, variants described by Couinaud and Michels were used. Results: The mean age was 57.3 years; 47% male and 53% female. Type I variant was found in 53 patients (53%); 10 type II (10%); 10 type III (10%); 3 type IV (3%); 9 type V (9%); 7 type VI (7%); 1 type VII (1%); 2 type IX (2%), and 5 type XI (5%). Type VIII and type X variants were not found. Conclusions: Abdominal MSCT with I.V. contrast has proved to be effective in properly evaluating hepatic arterial circulation in rutinary studies. Forty-seven per cent (47%) of patients presented anatomic variants, which correlates with findings reported in foreign literature. Due to the high frecuency rate of patients with anatomic variation, vascular evaluation has become a must before planning major hepatic surgical procedure

Bayesian inference of plasma parameters from collective Thomson scattering technique on a gas-puff near stagnation

Abstract The Collective Thomson scattering technique has been implemented to study the stagnation of a single liner gas-puff. The plasma parameters are determined by theoretically modelling the scattering form factor in combination with Bayesian inference to provide the set of the most probable parameters that describe the experimental data. Analysis of the data reveal that incoming flows are able to interpenetrate partially. Estimation of the mean free path shows a gradual transition from a weakly collisional to a collisional regime as the plasma gets to the axis. Furthermore, we find that the ion energy at $$\mathrm{r}=2.5\,\mathrm{mm}$$ r = 2.5 mm is $${13.6}_{-0.9}^{+1.0}\,\mathrm{keV}$$ 13.6 - 0.9 + 1.0 keV and is mostly kinetic in nature and represents $${98}_{-9}^{+10} \%$$ 98 - 9 + 10 % of the total energy. This kinetic energy is far greater than the value on axis of $${3.7}_{-0.5}^{+0.4}\,\mathrm{keV}$$ 3.7 - 0.5 + 0.4 keV which is $${84}_{-14}^{+15} \%$$ 84 - 14 + 15 % of the total energy. Energy transfer to the electrons and radiation losses are found to be negligible by this time. A possible explanation for this energy imbalance is the presence of an azimuthal magnetic field larger than $$\sim 4.7\,\mathrm{T}$$ ∼ 4.7 T that deflect the ions vertically. The uncertainties quoted represent 68% credible intervals