A Survey on 4{\pi} Treatment Planning Technique for Radiation Therapy

The challenge of removing cancerous cells lies in the limitation of organ at risk, which restricts the ability to increase the radiation dose adequately for enhancing treatment effectiveness. This survey provides a comprehensive overview of the 4{\pi} planning technique for radiation therapy. In radiation therapy, the gantry of Medical linear accelerators can rotate around the couch to administer radiation from various angles. Researchers have introduced the 4{\pi} technique with the objective of increasing the radiation dose to tumors while minimizing damage to nearby organs. While dose escalation may not be feasible in certain cases due to potential complications in normal tissues, the 4{\pi} technique enables dose escalation for certain types of cancers. The optimization problem formulation constitutes a major innovation in the 4{\pi} technique. In this survey, we went thorough optimization problem of 4{\pi} technique and discussed about the available investigations that have been performed on 4{\pi} technique

Chemical recognition and reactivity of zinc-oxide surfaces

ZnO hat wegen seiner potenziellen Anwendung in elektronischen Geräten und als Katalysator viel Aufmerksamkeit erhalten. Die Struktur und Reaktivität von ZnO-Oberflächen haben eine direkte Bedeutung für die Leistung und Funktionalität dieser Geräte. Daher ist die Definition und das Verständnis der atomistischen Details von ZnO-Oberflächenstrukturen von besonderer Bedeutung. Die atomistischen Details von ZnO-Oberflächen hängen von den Präparationsverfahren ab. Nach der Kristallpräparation ist es notwendig, eine Oberflächencharakterisierung durchzuführen, um eine Verbesserung der Funktionalität und Effizienz von ZnO-basierten opto-elektronischen Bauelementen und Katalysatoren zu erreichen. Die atomistische Wahrnehmung der Reaktion zwischen einem organischen Molekül und ZnO-Oberflächen spielt eine entscheidende Rolle bei der Optimierung der Wasserstoff-on-demand-Lieferung in Brennstoffzellen. Das Verständnis der atomistischen Details von Adsorption, Diffusion und Dissoziation eines organischen Moleküls ebnet den Weg, um die Vorgänge bei der Wasserstofffreisetzung für Brennstoffzellen zu enträtseln. Mit dem Ziel, die Struktur- und Stöchiometriebestimmung mit Hilfe der XPS zu ermöglichen, präsentiere ich in dieser Arbeit die Ergebnisse einer umfassenden theoretischen Studie über die Kernniveauverschiebungen von ZnO-Oberflächenrekonstruktionen. Darüber hinaus biete ich eine gründliche Untersuchung der gemischt-terminierten Oberfläche, indem ich zunächst die Bedingungen untersuche, unter denen sich Methanol-Monolagen auf dieser Kristallfläche bilden können, und dann alle möglichen Wege für deren Reaktion erforsche. Diese Studie liefert ein umfassendes Bild, um die wahrscheinlichsten Reaktionsschritte zu identifizieren, die zur Interpretation der experimentellen Ergebnisse herangezogen werden können. Sie wird zukünftigen theoretischen Studien für ähnliche Reaktionen wie die Dehydrierung und die Kinetik der Monolagenbildung, die hier untersucht wurden, helfen.Zinc-Oxide (ZnO) has been getting much attention over the past decades because of its potential application in electronic devices and as a catalyst. The structure and reactivity of ZnO surfaces have direct relevance for the performance and functionality of these devices. Therefore, defining and understanding the atomistic details of ZnO surface structures is of particular importance. The atomistic details of ZnO surfaces depend on the preparation procedures. After the crystal preparation, it is necessary to perform a surface characterization, to achieve an improvement in the functionality and efficiency of ZnO-based opto-electronic devices and catalysts. The atomistic perception of the reaction between an organic molecule and ZnO surfaces plays a crucial role in optimizing hydrogen-on-demand delivery in fuel cells, and understanding the atomistic details of adsorption, diffusion, and dissociation of a simple organic molecule paves the way towards unraveling the procedures involved in the hydrogen liberation for fuel cells. In this work, with the aim of enabling structure and stoichiometry determination by using X-ray photoelectron spectroscopy, I present the results of a comprehensive theoretical study on the core-level shifts of ZnO surface reconstructions. Moreover, I provide a thorough investigation of the mixed-terminated (10-10) surface by first examining the conditions under which methanol monolayers can form on this crystal face and by then exploring all possible pathways for its adsorption, diffusion, and initial dehydrogenation. This study provides a comprehensive picture to identify the most probable reaction steps that can be used to interpret experimental findings and will help future theoretical studies for reactions similar to dehydrogenation of organic molecules and monolayer-formation kinetics that were studied here

Tabulated square-shaped source model for linear accelerator electron beam simulation

Context: Using this source model, the Monte Carlo (MC) computation becomes much faster for electron beams. Aims: The aim of this study was to present a source model that makes linear accelerator (LINAC) electron beam geometry simulation less complex. Settings and Design: In this study, a tabulated square-shaped source with transversal and axial distribution biasing and semi-Gaussian spectrum was investigated. Subjects and Methods: A low energy photon spectrum was added to the semi-Gaussian beam to correct the bremsstrahlung X-ray contamination. After running the MC code multiple times and optimizing all spectrums for four electron energies in three different medical LINACs (Elekta, Siemens, and Varian), the characteristics of a beam passing through a 10 cm 7 10 cm applicator were obtained. The percentage depth dose and dose profiles at two different depths were measured and simulated. Results: The maximum difference between simulated and measured percentage of depth doses and dose profiles was 1.8% and 4%, respectively. The low energy electron and photon spectrum and the Gaussian spectrum peak energy and associated full width at half of maximum and transversal distribution weightings were obtained for each electron beam. The proposed method yielded a maximum computation time 702 times faster than a complete head simulation. Conclusions: Our study demonstrates that there was an excellent agreement between the results of our proposed model and measured data; furthermore, an optimum calculation speed was achieved because there was no need to define geometry and materials in the LINAC hea