Robustness of PET Radiomics Features: Impact of Co-Registration with MRI

Radiomics holds great promise in the field of cancer management. However, the clinical application of radiomics has been hampered by uncertainty about the robustness of the features extracted from the images. Previous studies have reported that radiomics features are sensitive to changes in voxel size resampling and interpolation, image perturbation, or slice thickness. This study aims to observe the variability of positron emission tomography (PET) radiomics features under the impact of co-registration with magnetic resonance imaging (MRI) using the difference percentage coefficient, and the Spearman’s correlation coefficient for three groups of images: (i) original PET, (ii) PET after co-registration with T1-weighted MRI and (iii) PET after co-registration with FLAIR MRI. Specifically, seventeen patients with brain cancers undergoing [11C]-Methionine PET were considered. Successively, PET images were co-registered with MRI sequences and 107 features were extracted for each mentioned group of images. The variability analysis revealed that shape features, first-order features and two subgroups of higher-order features possessed a good robustness, unlike the remaining groups of features, which showed large differences in the difference percentage coefficient. Furthermore, using the Spearman’s correlation coefficient, approximately 40% of the selected features differed from the three mentioned groups of images. This is an important consideration for users conducting radiomics studies with image co-registration constraints to avoid errors in cancer diagnosis, prognosis, and clinical outcome prediction

Accurate,robust and harmonized implementation of morpho-functional imaging in treatment planning for personalized radiotherapy

In this work we present a methodology able to use harmonized PET/CT imaging in dose painting by number (DPBN) approach by means of a robust and accurate treatment planning system. Image processing and treatment planning were performed by using a Matlab-based platform, called CARMEN, in which a full Monte Carlo simulation is included. Linear programming formulation was developed for a voxel-by-voxel robust optimization and a specific direct aperture optimization was designed for an efficient adaptive radiotherapy implementation. DPBN approach with our methodology was tested to reduce the uncertainties associated with both, the absolute value and the relative value of the information in the functional image. For the same H&N case, a single robust treatment was planned for dose prescription maps corresponding to standardized uptake value distributions from two different image reconstruction protocols: One to fulfill EARL accreditation for harmonization of [18F]FDG PET/CT image, and the other one to use the highest available spatial resolution. Also, a robust treatment was planned to fulfill dose prescription maps corresponding to both approaches, the dose painting by contour based on volumes and our voxel-by-voxel DPBN. Adaptive planning was also carried out to check the suitability of our proposal. Different plans showed robustness to cover a range of scenarios for implementation of harmonizing strategies by using the highest available resolution. Also, robustness associated to discretization level of dose prescription according to the use of contours or numbers was achieved. All plans showed excellent quality index histogram and quality factors below 2%. Efficient solution for adaptive radiotherapy based directly on changes in functional image was obtained. We proved that by using voxel-by-voxel DPBN approach it is possible to overcome typical drawbacks linked to PET/CT images, providing to the clinical specialist confidence enough for routinely implementation of functional imaging for personalized radiotherapy.Junta de Andalucía (FISEVI, reference project CTS 2482)European Regional Development Fund (FEDER

3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry.

A model based on a specific phantom, called QuAArC, has been designed for the evaluation of planning and verification systems of complex radiotherapy treatments, such as volumetric modulated arc therapy (VMAT). This model uses the high accuracy provided by the Monte Carlo (MC) simulation of log files and allows the experimental feedback from the high spatial resolution of films hosted in QuAArC. This cylindrical phantom was specifically designed to host films rolled at different radial distances able to take into account the entrance fluence and the 3D dose distribution. Ionization chamber measurements are also included in the feedback process for absolute dose considerations. In this way, automated MC simulation of treatment log files is implemented to calculate the actual delivery geometries, while the monitor units are experimentally adjusted to reconstruct the dose-volume histogram (DVH) on the patient CT. Prostate and head and neck clinical cases, previously planned with Monaco and Pinnacle treatment planning systems and verified with two different commercial systems (Delta4 and COMPASS), were selected in order to test operational feasibility of the proposed model. The proper operation of the feedback procedure was proved through the achieved high agreement between reconstructed dose distributions and the film measure- ments (global gamma passing rates > 90% for the 2%/2 mm criteria). The necessary discre- tization level of the log file for dose calculation and the potential mismatching between calculated control points and detection grid in the verification process were discussed. Besides the effect of dose calculation accuracy of the analytic algorithm implemented in treatment planning systems for a dynamic technique, it was discussed the importance of the detection density level and its location in VMAT specific phantom to obtain a more reliable DVH in the patient CT. The proposed model also showed enough robustness and efficiency to be considered as a pre-treatment VMAT verification system.Ministerio de Ciencia y Tecnología SAF2011- 27116; IPT-2011-1480-900000

Tubular micro cell with integrated BESOI BSC-ISFET

Trabajo presentado en la 2ª Conferencia de dispositivos Electrónicos, celebrada en Madrid (España), los días 10 y 11 de junio de 199

Cubeta tubular con sensores químicos de estado integrados para aplicación a sistemas de análisis

Referencia OEPM: P9700443.-- Fecha de solicitud: 28/02/1997.-- Titulares: Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Barcelona (UAB), Biosensores, S.L.Cubeta tubular con sensores químicos de estado integrados para aplicación a sistemas de análisis. Se presenta una microcubeta tubular con sensores ISFET integrados, fabricadas a partir de obleas de silicio y de obleas de vidrio. La cubeta actúa como soporte material y los ISFET como elementos sensibles de un sensor o biosensor capaz de determinar cualquier especie cuya reacción de reconocimiento conlleve la aparición en el medio de un ión, elemento, molécula o compuesto que pueda ser detectado por el sensor. La novedad que presenta esta cubeta es su tamaño, relativamente grande comparado con las obtenidas a partir de obleas de silicio, y las técnicas de fabricación, ya que además de la micromecanización del silicio y de la soldadura anódica se utiliza la mecanización del vidrio. Las cubetas se utilizan en un sistema de análisis por inyeccción en un flujo, FIA (Flow Injection Analysis).Peer reviewe

Microtecnología: Diario de un proceso. Fabricación de un Microacelerómetro

El objetivo de este libro es divulgar las técnicas más utilizadas para fabricar microsistemas basados en silicio. La novedad que aporta este trabajo es describir y mostrar detalladamente el proceso de fabricación de un Microsistema en una Sala Blanca. En la primera parte del libro se hace una introducción teórica a los acelerómetros en general y a los acelerómetros piezorresistivos en particular. En la segunda parte se muestra día a día su proceso de fabricación, en el "Diario del proceso". Para una mayor compresión, esta segunda parte se refuerza con un conjunto de videos, en los cuales se muestran las etapas más importantes en el proceso de fabricación de microacelerómetros

Monocristalline Silicon Micro-Particules for Nano-Devices

Trabajo presentado en el 31st International Conference on Micro- and Nano-Engineering, celebrado en Viena (Austria), del 19 al 22 de septiembre de 200

Actuation unit analysis of a thermo-pneumatic actuated micropump

Trabajo presentado en el 2nd International Conference on Benefiting from Thermal and Mechanical Simulation in (Micro)-Electronics, celebrada en (Francia), del 9 al 11 de abril de 200

An analytical model for passive microvalves

An analytical model of a passive silicon microvalve of the bossed type has been extracted. This model involves three mathematical expressions that must be solved iteratively. They may easily be translated to an analog hardware description language. The main feature of this model consists of the inclusion of the diffuser effect. This effect is considerable at high Re and it has not usually been modeled in previous works. Comparison between the analytical model, FEM and experimental results shows good agreement, although some further improvements are required

Design of a modular micropump based on anodic bonding

A simple and reliable technology for the fabrication of micromachined micropumps is presented. The assembling of different wafers to produce valves and cavities is usually the critical step regarding final yield. Our technology uses exclusively the well known anodic bonding technique for this purpose. The prospective performance of the devices has been evaluated by finite element methods and system level simulations