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

Inflammatory and antioxidant pattern unbalance in "clopidogrel-resistant" patients during acute coronary syndrome.

Background. In acute coronary syndrome (ACS), inflammation and redox response are associated with increased residual platelet reactivity (RPR) on clopidogrel therapy. We investigated whether clopidogrel interaction affects platelet function and modulates factors related to inflammation and oxidation in ACS patients differently responding to clopidogrel. Material andMethods. Platelet aggregation was measured in 29 ACS patients on dual (aspirin/clopidogrel) antiplatelet therapy. Nonresponders (NR) were defined as RPR ≥70% by ADP. Several inflammatory and redox parameters were assayed and platelet proteome was determined. Results. Eight (28%) out of 29 ACS patients resulted NR to clopidogrel. At 24 hours, the levels of Th2-type cytokines IL-4, IFN, andMCP-1 were higher in NR, while blood GSH (r-GSHbl) levels were lower in NR than responders (R). Proteomic analysis evidenced an upregulated level of platelet adhesion molecule, CD226, and a downregulation of the antioxidant peroxiredoxin-4. In R patients the proinflammatory cytokine IL-6 decreased, while the anti-inflammatory cytokine IL-1Ra increased. Conclusions. In patients with high RPR on clopidogrel therapy, an unbalance of inflammatory factors, platelet adhesion molecules, and circulatory and platelet antioxidantmolecules was observed during the acute phase. Proinflammatory milieu persists in nonresponders for a long time after the acute event while antioxidant blood factors tend to conform to normal responsiveness