FORMAÇÃO E DOCÊNCIA NA EDUCAÇÃO INFANTIL DO CAMPO: DIZERES DOCENTES

Esta pesquisa focaliza a formação e atuação docente na Educação Infantil do Campo, tendo como princípios teórico-metodológicos referenciais bakhtinianos (BAKHTIN,1997, 2010a, 2010b), em interlocução com os referenciais de Nóvoa (1992, 1995, 2008, 2009). Considerando o caráter inicial da temática da Educação Infantil do Campo, a pesquisa, de abordagem qualitativa, de tipo exploratória, utiliza como procedimentos a aplicação de questionário, a realização de entrevistas individual e coletiva e o desenvolvimento de observação atenta à conduta ética na interação com os sujeitos participantes. Os diálogos com as docentes comunicam que a Educação Infantil do Campo vem ganhando uma visibilidade progressiva nas políticas públicas locais, sustentada em diferentes dinâmicas organizativas que se articulam ao movimento da expansão da Educação Infantil. Essa trajetória de pesquisa sinalizou indicativos de avanços relacionados aos aspectos de acompanhamento pedagógico das instituições, manutenção dos espaços físicos e proposta de formação continuada, demonstrando o fortalecimento das políticas voltadas às instituições do campo. Constatou também que esses avanços se associam a desafios e demandas de investimentos, entre os quais se destaca a formação como prioridade para as profissionais da educação infantil do campo, e que essa formação seja específica, assim discutindo os diversos temas vinculados ao contexto em questão, contribuindo para a construção coletiva das instituições do campo

Component characterization and commissioning of a gamma-PET prototype detector system

Hybrid imaging systems, comprising PET and Compton camera modules, have recently gained in interest, due to their capability to simultaneously detect positron annihilation photons and γ-rays from single-photon emitting sources as also used in SPECT. A unique feature of such systems, however, is the capability to also be operated in a so called γ-PET mode. Here, specific β+- emitting radioisotopes (such as 44Sc, 1°C or 14O) are used to detect triple-coincidences between two annihilation γ-rays (in PET imaging) and a third, prompt photon (in Compton imaging), that is emitted by the deexcitation of the decay’s daughter nucleus. Consequently, an intersection between the line-of-response (LOR) and the Compton cone can be determined, which (in principle) allows to localize the photons’ emission vertices on a single decay basis. In practice, however, a few tens of events are required to localize a point source, which still results in a considerable sensitivity improvement compared to conventional PET imaging. For a proof-of-principle study, we used a pixelated GAGG crystal array (16 × 16 crystals; 1.45 × 1.45 × 6 mm3 crystal volume; 25 μm SPAD SiPMs as readout) as Compton camera scatterer and PET detectors, and a three-layered LYSO crystal array (1.2 × 1.2 × 6.66 mm3 crystal volume; 50 μm SPAD SiPMs as readout) as Compton camera absorber. We characterized the individual detector components with regard to their energy resolution and the capability to identify the various scintillator array’s individual crystals. Our first γ-PET prototype was tested in PET-only and Compton-only imaging mode, in which spatial resolutions of 3.2–3.5 mm FWHM (PET-only mode) and 14.4–19.3 mm FWHM (Compton-only mode at 1,274 keV) were achieved, respectively, using a22Na point source and 10 iterations of an ML-EM reconstruction algorithm. By using triple-coincidences in a γ-PET mode (event-wise intersection of the LOR and the Compton cone), we could demonstrate the capability of the prototype to perform a full 3D point source reconstruction using only 77 events

Towards a novel small animal proton irradiation platform: the SIRMIO project

Background: Precision small animal radiotherapy research is a young emerging field aiming to provide new experimental insights into tumor and normal tissue models in different microenvironments, to unravel complex mechanisms of radiation damage in target and non-target tissues and assess efficacy of novel therapeutic strategies. For photon therapy, modern small animal radiotherapy research platforms have been developed over the last years and are meanwhile commercially available. Conversely, for proton therapy, which holds potential for an even superior outcome than photon therapy, no commercial system exists yet. Material and methods: The project SIRMIO (Small Animal Proton Irradiator for Research in Molecular Image-guided Radiation-Oncology) aims at realizing and demonstrating an innovative portable prototype system for precision image-guided small animal proton irradiation, suitable for installation at existing clinical treatment facilities. The proposed design combines precise dose application with in-situ multi-modal anatomical image guidance and in-vivo verification of the actual treatment delivery. Results and conclusions: This manuscript describes the status of the different components under development, featuring a dedicated beamline for degradation and focusing of clinical proton beams, along with novel detector systems for in-situ imaging and range verification. The foreseen workflow includes pre-treatment proton transmission imaging, complemented by ultrasonic tumor localization, for treatment planning and position verification, followed by image-guided delivery with on-site range verification by means of ionoacoustics (for pulsed beams) and positron-emission-tomography (PET, for continuous beams). The proposed compact and cost-effective system promises to open a new era in small animal proton therapy research, contributing to the basic understanding of in-vivo radiation action to identify areas of potential breakthroughs for future translation into innovative clinical strategies

Design study of a novel geometrical arrangement for an in-beam small animal PET scanner

This contribution describes a novel solution for a small animal in-beam positron emission tomography (PET) scanner. Our detector is meant to be used in the SIRMIO project (Small animal proton Irradiator for Research in Molecular Image-guided Radiation-Oncology). The goal of this study is to compare a more conventional dual ring scanner shape (as an in-beam modification of the standard concept of human PET systems) with our novel solution. The conventional one is basically based on a cylindrical shape around the body of the mouse, whereas our shape is based on a so-called spherical design and it takes into account also some additional constraints related to the other components of the SIRMIO project. The system is based on a maximum of 56 scintillator blocks of pixelated LSO (Lu2SiO5). The size of each crystal is 0.9×0.9×6.7 mm3. The pixels are arranged in three layers of 25, 23 and 19 crystals per side to obtain a pyramid-like shape useful for optimizing the geometrical coverage. With this set-up it is possible to reach a good trade-off between a solid angle coverage of more than 44% and sufficient available space for integration of additional imaging components (e.g., ultrasound) and the movement of the mouse holder inside the PET scanner. The detection efficiency is calculated to be between 7% and 12%. The image reconstruction to evaluate the geometrical spatial resolution is done using the MEGAlib software (Medium-Energy Gamma-ray Astronomy library). The physical simulations are based on the GEANT4 software. MEGAlib uses a machine-learning environment based on a ROOT Toolkit for Multivariate Analysis (TMVA) to retrieve the valid events of the PET signal. Image reconstruction is based on a Maximum-Likelihood Expectation Maximization algorithm (EM-LM). According to the preliminary results, the distribution of the crystals on a large coverage of different angles allows us to obtain a spatial resolution of 0.4 - 1 mm (FWHM), consistent with the specification. The thorough characterization of the expected performances of our prototype system for in-beam PET imaging of small animal proton irradiation is still ongoing and will be presented.2019 IEEE Nuclear Science Symposium and Medical Imaging Conferenc

An Advanced Simulation and Reconstruction Framework for a Novel In-Beam PET Scanner for Pre-Clinical Proton Irradiation

Within the project “Small animal proton Irradiator for Research in Molecular Image-guided radiation-Oncology” (SIRMIO) we have designed an in-beam PET scanner for preclinical application. The system is based on a novel spherical geometry, and in order to fully exploit its potential we are developing an integrated computational framework for simulation, image reconstruction and range verification. The software comprises a full Monte Carlo engine to simulate the proton treatment with related detector response, and an image reconstruction tool for simulated and experimental data. The platform is designed to integrate robust analytical reconstruction algorithms and new statistical approaches based on deep learning. The core of the framework is based on MEGAlib (The Medium Energy Gamma-ray Astronomy software library). The physical simulation is based on GEANT4. The machine learning method for the event classification is implemented with the ROOT based Toolkit for Multivariate Data Analysis (TMVA). The first prototype of the SIRMIO irradiation platform foresees a fixed beam, thus requiring the movement of the mouse for scanned beam delivery. Hence, we have extended the MEGAlib image reconstruction algorithm based on maximum-likelihood expectation-maximization (ML-EM) to correct for geometrical efficiency and attenuation taking into account the mouse motion. The goal is to be able to discriminate proton range shifts of ~ 0.5 mm. Moreover, we are augmenting the image reconstruction framework with a new approach based on machine learning, which aims at using all photon events collected during irradiation (dominated by prompt gamma) to retrieve on-the-fly the range of the beam, to complement the PET information