João Costa Seco

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This paper studies specific language level abstractions for component-based programming. We propose a simple model which captures some basic ingredients — like explicit context dependence, dynamic binding and subtype polymorphism, late (dynamic) composition, and avoidance of inheritance in favor of object composition — that several authors have defended to(More)
We present a process-calculus model for expressing and analyzing service-based systems. Our approach addresses central features of the service-oriented computational model such as distribution, process delegation, communication and context sensitiveness, and loose coupling. Distinguishing aspects of our model are the notion of conversation context, the(More)
This paper describes an evolution of the ComponentJ programming language, a component-based Java-like programming language where composition is the chosen structuring mechanism. ComponentJ constructs allow for the high-level specification of component structures, which are the basis for the definition of compound objects. In this paper we present a new(More)
This study focused on predicting the electronic portal imaging device (EPID) image of intensity modulated radiation treatment (IMRT) fields in the absence of attenuation material in the beam with Monte Carlo methods. As IMRT treatments consist of a series of segments of various sizes that are not always delivered on the central axis, large spectral(More)
Treatment delivery with active beam scanning in proton radiation therapy introduces the problem of interplay effects when pencil beam motion occurs on a similar time scale as intra-fractional tumor motion. In situations where fractionation may not provide enough repetition to blur the effects of interplay, repeated delivery or 'repainting' of each field(More)
The enormous advances in the understanding of human anatomy, physiology and pathology in recent decades have led to ever-improving methods of disease prevention, diagnosis and treatment. Many of these achievements have been enabled, at least in part, by advances in ionizing radiation detectors. Radiology has been transformed by the implementation of(More)
The purpose of this study was to assess lateral out-of-field doses in 6 MV IMRT (intensity modulated radiation therapy) and compare them with secondary neutron equivalent dose contributions in proton therapy. We simulated out-of-field photon doses to various organs as a function of distance, patient's age, gender and treatment volumes based on 3, 6, 9 cm(More)
INTRODUCTION The physical properties of proton beam radiation may offer advantages for treating patients with non-small-cell lung cancer (NSCLC). However, its utility for the treatment of medically inoperable stage I NSCLC patients with stereotactic body radiation therapy (SBRT) is unknown. METHODS Outcomes for patients with medically inoperable stage I(More)
We present and validate a computed tomography (CT) metal artifact reduction method that is effective for a wide spectrum of clinical implant materials. Projections through low-Z implants such as titanium were corrected using a novel physics correction algorithm that reduces beam hardening errors. In the case of high-Z implants (dental fillings, gold,(More)