Novel imaging and quality assurance techniques for ion beam therapy: a Monte Carlo study

Ion beams exhibit a finite and well defined range in matter together with an “inverted” depth-dose profile, the so-called Bragg peak. These favourable physical properties may enable superior tumour-dose conformality for high precision radiation therapy. On the other hand, they introduce the issue of sensitivity to range uncertainties in ion beam therapy. Although these uncertainties are typically taken into account when planning the treatment, correct delivery of the intended ion beam range has to be assured to prevent undesired underdosage of the tumour or overdosage of critical structures outside the target volume. Therefore, it is necessary to define dedicated Quality Assurance procedures to enable in-vivo range verification before or during therapeutic irradiation. For these purposes, Monte Carlo transport codes are very useful tools to support the development of novel imaging modalities for ion beam therapy. In the present work, we present calculations performed with the FLUKA Monte Carlo code and preliminary experimental studies

Hordeum flexuosum Nees ex Steud.

San Antonio de Areco, Estancia El OmbúpublishedVersio

Different gene expression modulation is the major effect fue to shear stress and stent application in huvecs model: preliminary results

Although it is known that disturbed shear stress may cause endothelial damage, the mechanism by which a stent procedure may affect the endothelium is not yet fully clarify. We present the preliminary data on gene expression analysis of human endothelial cells in a laminar flow bioreactor (LFB) system submitted to different physical (flow changes) and/or mechanical (stent application) stimuli. Our preliminary results show that low shear stress together with stent procedure are the experimental conditions that mainly modulate the highest number of genes in human endothelial model. Those genes belong to pathways specifically involved in the endothelial dysfunctio

Unified Hydrodynamic Theory for Crystals, Liquid Crystals, and Normal Fluids

A unified hydrodynamic theory is presented that is appropriate for crystals; smectic, cholesteric, and nematic liquid crystals; glasses; and normal fluids. In the theory, the increased spatial degeneracy as the system progresses from crystalline and mesomorphic phases to the isotropic fluid phase is marked by successive reductions in the number of firstorder elastic constants and in the number of transport coefficients. Distinction between local lattice dilations and local mass changes, and recognition of processes like vacancy diffusion that this difference makes possible, are crucial for understanding the connection between theories in different phases. Formulas are derived that give the number of hydrodynamic modes and the frequencies, lifetimes, and intensities of these modes in all of the above systems. In the nematic and cholesteric phases, the results agree with some found previously. In more complex systems, they are new. An attempt is made to explain the differences between the present hydrodynamic theory and other phenomenological proposals.Engineering and Applied Science