arXiv subjects

Luís Lopes

Publications and source records attributed to Luís Lopes.

7 recordsLinked to original sources

arXiv2026

Curated endoscopic retrograde cholangiopancreatography images dataset

Endoscopic Retrograde Cholangiopancreatography (ERCP) is a key procedure in the diagnosis and treatment of biliary and pancreatic diseases. Artificial intelligence has been pointed as one solution to automatize diagnosis. However, public ERCP datasets are scarce, which limits the use of such approach. Therefore, this study aims to help fill this gap by providing a large and curated dataset. The collection is composed of 19.018 raw images and 19.317 processed from 1.602 patients. 5.519 images are labeled, which provides a ready to use dataset. All images were manually inspected and annotated by two gastroenterologist with more than 5 years of experience and reviewed by another gastroenterologist with more than 20 years of experience, all with more than 400 ERCP procedures annually. The utility and validity of the dataset is proven by a classification experiment. This collection aims to provide or contribute for a benchmark in automatic ERCP analysis and diagnosis of biliary and pancreatic diseases.

cs.CV↗

arXiv2025

Resistive Plate Chambers for brain PET imaging and particle tracking and timing (TOF-tracker)

In this work we explore readout architectures for the simultaneous high-resolution timing and bidimensional tracking of charged particles with Resistive Plate Chambers (TOF-tracker) and for the accurate detection of gamma rays for PET imaging. On 625 $cm^2$ of active area we obtained a time resolution of 61 ps $σ$ and bidimensional position resolution below 150 $μ$m $σ$ for the tracking and timing of charged particles from cosmic rays. An intrinsic precision of 0.49 mm FWHM was determined for the localization of a small $β^+$ source via the detection of its annihilation radiation.

physics.ins-det↗

arXiv2022

A Large-Area RPC Detector for Muography

A muon telescope equipped with four Resistive Plate Chambers of 2 m$^{2}$ per plane was tested with the muon scattering tomography technique. The telescope was operated during several hours with high atomic number materials located at its center with two detector planes on each side. With an intrinsic efficiency above 98%, spatial resolution around 1 cm and detector planes spaced by 45 cm, it was possible to identify the presence of a 5 cm thick tungsten block in 10 minutes of acquisition. The results obtained after five hours of acquisition are also presented in this communication.

physics.ins-det↗

arXiv2022

An RPC-PET brain scanner demonstrator: first results

We present first results from a Positron Emission Tomography (PET) scanner demonstrator based on Resistive Plate Chambers and specialized for brain imaging. The device features a 30 cm wide cubic field-of-view and each detector comprises 40 gas gaps with 3D location of the interaction point of the photon. Besides other imagery, we show that the reconstructed image resolution, as evaluated by a hot-rod phantom, is sub-millimetric, which is beyond the state-of-the-art of the standard PET technology for this application.

physics.ins-det↗

arXiv2022

Advances Towards a Large-Area, Ultra-Low-Gas-Consumption RPC Detector

Large Resistive Plate Chamber systems have their roots in High Energy Physics experiments at the European Organization for Nuclear Research: ATLAS, CMS and ALICE, where hundreds of square meters of both trigger and timing RPCs have been deployed. These devices operate with complex gas systems, equipped with re-circulation and purification units, which require a fresh gas supply of the order of 6 cm$^{3}$/min/m$^{2}$, creating logistical, technical and financial problems. In this communication, we present a new concept in the construction of RPCs which allowed us to operate a detector at ultra-low gas flow regime. With this new approach, the glass stack is encapsulated in a tight plastic box made of polypropylene, which presents excellent water vapor blocking properties as well as a good protection against atmospheric gases.

physics.ins-det↗

arXiv2020

Prototype of an affordable pressure-controlled emergency mechanical ventilator for COVID-19

We present a viable prototype of a simple mechanical ventilator intended as a last resort to ventilate COVID-19 patients. The prototype implements the pressure-controlled continuous mandatory ventilation mode (PC-CMV) with settable breathing rates, inspiration/expiration time ratios and FiO2 modulation. Although safe, the design aims to minimize the use of technical components and those used are common in industry, so its construction may be possible in times of logistical shortage or disruption or in areas with reduced access to technical materials and at a moderate cost, affordable to lower income countries. Most of the device can be manufactured by modest technical means and construction plans are provided.

physics.med-ph↗

arXiv2010

Towards the Safe Programming of Wireless Sensor Networks

Sensor networks are rather challenging to deploy, program, and debug. Current programming languages for these platforms suffer from a significant semantic gap between their specifications and underlying implementations. This fact precludes the development of (type-)safe applications, which would potentially simplify the task of programming and debugging deployed networks. In this paper we define a core calculus for programming sensor networks and propose to use it as an assembly language for developing type-safe, high-level programming languages.

cs.PL↗