An automated treatment planning strategy for highly noncoplanar radiotherapy arc trajectories

Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques.     

Chitosan Microspheres as Carriers for pH‐Indicating Species in Corrosion Sensing

Chitosan microspheres containing bromocresol green, cresol red, and phenolphthalein for corrosion detection, through pH change, are synthesized in order to be used in protective coatings for aluminium alloys. Microspheres containing corrosion detection species are characterized morphologically (SEM) and physico‐chemically (FTIR, TGA). Release studies (UV–vis) are performed in corrosion‐promoting conditions (pH, NaCl), and detection studies by immersion in media associated with corrosion activity while microspheres' sensing activity is evaluated visually. Electrochemical characterization of AA2024 substrates in the presence of chitosan spheres is performed to understand material performance, and a color change is observed as a result of local pH increase in cathodic areas when corrosion takes place. These findings can be correlated with the results from release studies and seem a promising approach for corrosion sensing purposes, not only because pH increase is possible to detect due to corrosion, but also because chitosan is considered an environmentally friendly material.     

Design and synthesis of foam glasses from recycled materials

Recycling has emerged as an environmental key point due to the diminishing of natural resources and the generation of ever-increasing amounts of industrial solid wastes. Glass wastes are among the materials that attract great interest in the recycling concept. This work presents the results of foams production from four series of compositions. The first series comprises powders of a sodium-calcium-silicate sheet glass cullet as the main component, an alkali-earth aluminosilicate glass as an additive, and a reagent grade silicon carbide (SiC) powder as gassing agent. In the second series, the glass cullet was used in combination with fly ashes (FLA) as main components, while SiC waste from abrasive paper served as foaming agent. In the third and fourth series, carbonates (calcite and dolomite) were used for foaming powder mixtures composed of sheet glass cullet and FLA, and powdered cathode ray tube panel glasses, respectively. All the processing parameters, including the main components, the nature and content of foaming agents are shown to play a crucial role on the foaming ability and final properties of the glass foams.