Antecedentes de los Estilos de Aprendizaje para Entornos Virtuales / Background on Learning Styles for Virtual Environments / Antecedentes sobre Estilos de Aprendizagem para Ambientes Virtuais

Resumen Introducción: en el contexto de la educación virtual hacen falta investigaciones sobre los estilos de aprendizaje de cada estudiante, que les ofrezca opciones personalizadas para su proceso de aprendizaje. En este proyecto se busca integrar los estilos de aprendizaje a la educación virtual. Para ello se propone incorporar un componente adaptativo a la herramienta de gestión de aprendizaje para facilitar la personalización de contenidos en función de variables como el ritmo, el estilo y las necesidades del estudiante. Objetivo: desarrollar nuevas funcionalidades para una herramienta de gestión de Aprendizaje Basado en Problemas incorporando un componente adaptativo que potencie la colaboración en cursos virtuales a nivel universitario. Materiales y métodos: el método fue abductivo, dividido en tres fases: apropiación teórica, estructuración de la propuesta, y validación. Además, se tiene una fase transversal denominada Transferencia de conocimiento y gestión del proyecto. A la fecha, el proyecto se encuentra en la fase de validación. Resultados: se presentarán los antecedentes teóricos más importantes en relación con los estilos de aprendizaje vistos desde la historia de la pedagogía, pero reconociendo que para el presente la pregunta por el aprendizaje ya no es un objeto de estudio exclusivo de la pedagogía, pues dicho objeto también hace parte de las teorías sicológicas que se ocupan de procesos cognitivos, tal como ocurre con la teoría de David Kolb. Conclusiones: en este momento serían muy apresuradas, puesto que no se ha terminado de ejecutar la tercera fase del proyecto. Este escrito se ubica en la fase uno: apropiación teórica.

Abstract Introduction: in the context of virtual education, research is needed on the learning styles of each student, which offers them personalized options for their learning process. This project seeks to integrate learning styles to virtual education. For this, it is proposed to incorporate an adaptive component to the learning management tool to facilitate the personalization of content based on variables such as rhythm, style, and student needs. Objective: to develop new functionalities for a Problem Based Learning management tool incorporating an adaptive component that enhances collaboration in virtual courses at the university level. Materials and methods: the method was abductive, divided into three phases: theoretical appropriation, structuring of the proposal, and validation. In addition, there is a transversal phase called Knowledge Transfer and Project Management. To date, the project is in the validation phase. Results: the most important theoretical background in relation to learning styles seen from the history of pedagogy will be presented but recognizing that for the present the question about learning is no longer an exclusive object of study of pedagogy, since said object It is also part of the psychological theories that deal with cognitive processes, as is the case with David Kolb's theory. Conclusions: at this time, they would be very hasty, since the third phase of the project has not been completed. This writing is in phase one: theoretical appropriation.

Resumo Introdução: no contexto da educação virtual, é necessário pesquisar os estilos de aprendizagem de cada aluno, o que lhes oferece opções personalizadas para seu processo de aprendizagem. Este projeto busca integrar estilos de aprendizagem à educação virtual. Para isso, propõe-se incorporar um componente adaptativo à ferramenta de gestão da aprendizagem para facilitar a personalização do conteúdo a partir de variáveis como ritmo, estilo e necessidades do aluno. Objetivo: desenvolver novas funcionalidades para uma ferramenta de gestão da Aprendizagem Baseada em Problemas que incorpore um componente adaptativo que aprimore a colaboração em cursos virtuais de nível universitário. Materiais e métodos: o método foi abdutivo, dividido em três fases: apropriação teórica, estruturação da proposta e validação. Além disso, existe uma fase transversal denominada Transferência de Conhecimento e Gestão de Projetos. Até o momento, o projeto está em fase de validação. Resultados: serão apresentados os fundamentos teóricos mais importantes em relação aos estilos de aprendizagem vistos a partir da história da pedagogia, mas reconhecendo que por ora a questão da aprendizagem não é mais um objeto exclusivo de estudo da pedagogia, visto que esse objeto também faz parte das teorias psicológicas que tratam dos processos cognitivos, como é o caso da teoria de David Kolb. Conclusões: neste momento seriam muito precipitados, pois a terceira fase do projeto ainda não foi concluída. Esta escrita está situada na fase um: apropriação teórica.

A novel extrapolation method using OSL detectors for very small field output factor measurement for stereotactic radiosurgery.

Appropriate methods for the determination of very small X-ray beam output factors are essential to ensure correct clinical outcomes for stereotactic radiosurgery. To date, substantial work has been performed in identifying and quantifying suitable dosimeters for relative output factor (ROF) measurements including recent IAEA published recommendations. In this work, we provide a novel method using optically stimulated luminescent dosimeters (OSLDs) with different effective sizes of the readout area to determine ROFs. This involves applying an extrapolation technique to assess ROFs for 6MV SRS X-ray beams with field diameters ranging from 4 to 30 mm as defined by the Brainlab SRS cones. By combining the use of multiple sized OSLDs and water droplets to remove air gaps located around the OSLD detectors, both volume averaging and density variation effects were minimised to estimate ROFs for an extrapolated zero volume detector. The measured results showed that for a 4 mm diameter cone, the ROF was 0.660 ± 0.032 (2SD) as compared to 0.661 ± 0.01 and 0.651 ± 0.018 for the PTW 600019 microDiamond detector and Gafchromic EBT3 film respectively. Whilst the uncertainties were larger than conventional detectors, the technique shows promise and improvements in accuracy may be obtained by higher quality manufacturing techniques. Based on these results, using OSLDs with different effective sizes of readout area and an extrapolation technique shows promise for use as an independent verification tool for very small X-ray field ROFs in the clinical department.

Monte Carlo calculated output correction factors for Gafchromic EBT3 film for relative dosimetry in small stereotactic radiosurgery fields.

To calculate small field output correction factors, [Formula: see text], for Gafchromic EBT3 film using Monte Carlo simulations. These factors were determined for a Novalis Trilogy linear accelerator equipped with Brainlab circular cones with diameters of 4.0 to 30.0 mm. The BEAMnrc Monte Carlo code was used to simulate the Novalis Trilogy linear accelerator and the Brainlab cones with diameters 4.0 to 30 mm. The DOSXYZnrc code was used to simulate Gafchromic EBT3 film with the atomic composition specified by the manufacturer. Small field correction factors were calculated according to new IAEA TRS-483 Code of Practice for small field dosimetry. The depth of calculation was 10 cm and a source to surface distance of 100 cm. The X-ray beam used in the simulations was a 6 MV SRS. The correction factors were then used to determine field output factors with Gafchromic EBT3 film. These field output factors were validated using three solid state detectors and applying correction factors from the TRS-483 Code of Practice. The solid state detectors were IBA SFD diode, PTW 60018 SRS diode and PTW 60019 microDiamond. The Monte Carlo calculated output correction factors, [Formula: see text], for Gafchromic EBT3 film ranged between 0.998 to 1.004 for Brainlab circular cones with diameters between 4.0 and 30.0 mm. The uncertainty for these factors was 2.0%. The field output factors obtained with Gafchromic EBT3 film were within 2% of the mean results obtained with the three solid state detectors. For field sizes 4 mm diameter and above, Gafchromic EBT3 film has field output correction factors within 1% of unity. Therefore, Gafchromic EBT3 film can be considered to be correction less and supports the assumption made about this film in the TRS-483 Code of Practice.

Skin and build up dose determination for a 2.5 MV medical linear accelerator imaging beam.

The 2.5 MV Imaging beam produced by a Varian TrueBeam linear accelerator produces a dose build up effect at the beam entrance similar to other high energy photon beams. The surface dose values were found to range from 39% of maximum dose at a 5 cm × 5 cm field size up to 69% of maximum at a 40 cm × 40 cm field. The depth of maximum dose deposition was found to range from 5 mm at smaller field sizes to 4 mm at larger field sizes. Whilst large absorbed doses will not be delivered utilizing these beams, the data provided will allow the medical physics community to assess and estimate doses to patient's skin and subcutaneous tissue from low energy MV imaging beams.

Practical time considerations for optically stimulated luminescent dosimetry (OSLD) in total body irradiation.

Total body irradiation (TBI) treatments are used to treat the whole body in preparation for hematopoietic stem cell (or bone marrow) transplantation. Our standard clinical regimen is a 12 Gy in 6 fraction, bi-daily technique using 6 MV X-rays at an extended Source-to-Surface distance (SSD) of 300 cm. Utilizing these characteristics, the beam dose rate is reduced below 7 cGy/min as is standard for TBI treatment. Dose received by the patient is monitored using optically stimulated luminescent dosimetry (OSLD). This work presents some practical calibration corrections based on time-dependant factors for OSLD calibration related to TBI procedure. Results have shown that a negligible difference is seen in OSL sensitivity for 6 MV X-rays irradiated in standard SSD (100 cm) and high dose rate (600 cGy/min) conditions compared to extended SSD (300 cm) and low TBI dose rate (6 cGy/min) conditions. Results have also shown that whilst short term signal fading occurs in the OSL after irradiation at a high dose rate (37% reduction in signal in the first 15 min), thereafter, negligible differences are seen in the OSL signal between 600 and 7 cGy/min irradiations. Thus a direct comparison can be made between calibration OSLs and clinical TBI OSLs between 15 min and 2 h. Finally a table is presented to provide corrections between calibration OSL readout and clinical TBI dose readout for a period up to 7 days. Combining these three results allows users to pre-irradiate their calibration OSLs at standard dose rate and SSD, up to 1 week prior to clinical treatment, and still provide accurate in-vivo dosimetry. This can help with time saving and work efficiency in the clinic.

An experimental extrapolation technique using the Gafchromic EBT3 film for relative output factor measurements in small x-ray fields.

PURPOSE: An experimental extrapolation technique is presented, which can be used to determine the relative output factors for very small x-ray fields using the Gafchromic EBT3 film. METHODS: Relative output factors were measured for the Brainlab SRS cones ranging in diameters from 4 to 30 mm(2) on a Novalis Trilogy linear accelerator with 6 MV SRS x-rays. The relative output factor was determined from an experimental reducing circular region of interest (ROI) extrapolation technique developed to remove the effects of volume averaging. This was achieved by scanning the EBT3 film measurements with a high scanning resolution of 1200 dpi. From the high resolution scans, the size of the circular regions of interest was varied to produce a plot of relative output factors versus area of analysis. The plot was then extrapolated to zero to determine the relative output factor corresponding to zero volume. RESULTS: Results have shown that for a 4 mm field size, the extrapolated relative output factor was measured as a value of 0.651 ± 0.018 as compared to 0.639 ± 0.019 and 0.633 ± 0.021 for 0.5 and 1.0 mm diameter of analysis values, respectively. This showed a change in the relative output factors of 1.8% and 2.8% at these comparative regions of interest sizes. In comparison, the 25 mm cone had negligible differences in the measured output factor between zero extrapolation, 0.5 and 1.0 mm diameter ROIs, respectively. CONCLUSIONS: This work shows that for very small fields such as 4.0 mm cone sizes, a measureable difference can be seen in the relative output factor based on the circular ROI and the size of the area of analysis using radiochromic film dosimetry. The authors recommend to scan the Gafchromic EBT3 film at a resolution of 1200 dpi for cone sizes less than 7.5 mm and to utilize an extrapolation technique for the output factor measurements of very small field dosimetry.

Radiation dose measurements of an on-board imager X-ray unit using optically-stimulated luminescence dosimeters.

Cone beam computed tomography (CBCT) is now widely used to image radiotherapy patients prior to treatment for the purpose of accurate patient setup. However each CBCT image delivered to a patient increases the total radiation dose that they receive. The measurement of the dose delivered from the CBCT images is not readily performed in the clinic. In this study, we have used commercially available optically stimulated luminescence (OSLD) dosimeters to measure the dose delivered by the Varian OBI on a radiotherapy linear accelerator. Calibration of the OSLDs was achieved by using a therapeutic X-ray unit. The dose delivered by a head CBCT scan was found to be 3.2 ± 0.3 mGy which is similar in magnitude to the dose of a head computed tomography (CT) scan. The results of this study suggest that the radiation hazard associated with CBCT is of a similar nature to that of conventional CT scans. We have also demonstrated that the OSLDs are suitable for these low X-ray dose measurements.

Dosimetry of cone-defined stereotactic radiosurgery fields with a commercial synthetic diamond detector.

PURPOSE: Small field x-ray beam dosimetry is difficult due to lack of lateral electronic equilibrium, source occlusion, high dose gradients, and detector volume averaging. Currently, there is no single definitive detector recommended for small field dosimetry. The objective of this work was to evaluate the performance of a new commercial synthetic diamond detector, namely, the PTW 60019 microDiamond, for the dosimetry of small x-ray fields as used in stereotactic radiosurgery (SRS). METHODS: Small field sizes were defined by BrainLAB circular cones (4-30 mm diameter) on a Novalis Trilogy linear accelerator and using the 6 MV SRS x-ray beam mode for all measurements. Percentage depth doses (PDDs) were measured and compared to an IBA SFD and a PTW 60012 E diode. Cross profiles were measured and compared to an IBA SFD diode. Field factors, ΩQclin,Qmsr (fclin,fmsr) , were calculated by Monte Carlo methods using BEAMnrc and correction factors, kQclin,Qmsr (fclin,fmsr) , were derived for the PTW 60019 microDiamond detector. RESULTS: For the small fields of 4-30 mm diameter, there were dose differences in the PDDs of up to 1.5% when compared to an IBA SFD and PTW 60012 E diode detector. For the cross profile measurements the penumbra values varied, depending upon the orientation of the detector. The field factors, ΩQclin,Qmsr (fclin,fmsr) , were calculated for these field diameters at a depth of 1.4 cm in water and they were within 2.7% of published values for a similar linear accelerator. The corrections factors, kQclin,Qmsr (fclin,fmsr) , were derived for the PTW 60019 microDiamond detector. CONCLUSIONS: The authors conclude that the new PTW 60019 microDiamond detector is generally suitable for relative dosimetry in small 6 MV SRS beams for a Novalis Trilogy linear equipped with circular cones.