Fast Monte Carlo dose calculation in proton therapy.

This article examines the critical role of fast Monte Carlo dose calculations in advancing proton therapy techniques, particularly in the context of increasing treatment customization and precision. As adaptive radiotherapy and other patient-specific approaches evolve, the need for accurate and precise dose calculations, essential for techniques like proton-based stereotactic radiosurgery, becomes more prominent. These calculations, however, are time-intensive, with the treatment planning/optimization process constrained by the achievable speed of dose computations. Thus, enhancing the speed of Monte Carlo methods is vital, as it not only facilitates the implementation of novel treatment modalities but also leads to more optimal treatment plans. Today, the state-of-the-art in Monte Carlo dose calculation speeds is 106 - 107protons per second. This review highlights the latest advancements in fast Monte Carlo dose calculations that have led to such speeds, including emerging artificial intelligence-based techniques, and discusses their application in both current and emerging proton therapy strategies

Argument structure effects in action verb naming in static and dynamic conditions

Argument structure, as in the participant roles entailed within the lexical representation of verbs, affects verb processing. Recent neuroimaging studies show that when verbs are heard or read, the posterior temporoparietal region shows increased activation for verbs with greater versus lesser argument structure complexity, usually bilaterally. In addition, patients with agrammatic aphasia show verb production deficits, graded based on argument structure complexity. In the present study, we used fMRI to examine the neural correlates of verb production in overt action naming conditions. In addition, we tested the differential effects of naming when verbs were presented dynamically in video segments versus statically in line drawings. Results showed increased neuronal activity associated with production of transitive as compared to intransitive verbs not only in posterior regions, but also in left inferior frontal cortex. We also found significantly greater activation for transitive versus intransitive action naming for videos compared to pictures in the right inferior and superior parietal cortices, areas associated with object manipulation. These findings indicate that verbs with greater argument structure density engender graded activation of both anterior and posterior portions of the language network and support verb naming deficit patterns reported in lesion studies. In addition, the similar findings derived under video and static picture naming conditions provide validity for using videos in neuroimaging studies, which are more naturalistic and perhaps ecologically valid than using static pictures to investigate action naming

Neural plasticity and treatment-induced recovery of sentence processing and production in agrammatism

Six agrammatic speakers were trained on production and processing of object-relative sentence structures, resulting in generalization to less complex sentence structures. The acquired structure-building process reflected by this generalization was shown to be supported by changes in neuronal activation patterns underlying syntactic task execution, as measured with pre and post training functional MRIs. The most prominent neuronal activity upregulation was seen in posterior temporoparietal cortical areas, outside of the core network activated in a group of healthy control subjects during complex syntactic processing