Estudio dosimétrico de un equipo de tomografía computarizada de haz cónico pararadiología oral y maxilofacial

El radiodiagnòstic en general i la tomografia computada (TC) en particular han patit un important desenvolupament des de la seva implantació. Una conseqüència d'aquest desenvolupament ha estat la recent aparició dels equips denominats CBCT (Cone Beam Computer Tomography, o la seva denominació en català, tomografia computada de feix cònic), introduïts en la radiologia oral i maxil·lofacial perquè que imparteixen menors dosi de radiació als pacients que els equips de TC tradicionals, perquè es poden instal·lar en espais relativament reduïts, sense grans requisits de seguretat, i pel seu baix cost. La bona qualitat d'imatge proporcionada per aquests equips ha facilitat la seva elecció com a modalitat especialment útil per obtenir imatges geomètricament molt precises i amb alta resolució dels teixits durs i les cavitats d'aire de les àrees dentals i en otorinolaringologia. Aquesta tesi doctoral presenta un estudi dosimètric d'un equip de CBCT utilitzat en radiologia dental i maxil·lofacial mitjançant el mètode de Montecarlo aplicat sobre dos maniquins físics (un geomètric i un altre antropomòrfic) i dos maniquins computacionals representatius d'un home i d’una dona adults. L'adaptació i validació d'un programa de simulació per Montecarlo per ser aplicat a aquest equip concret ha permès obtenir les dosis en òrgans i dosis efectives per a un grup d'exploracions de pacients adults. Així mateix, s'ha analitzat la influència de certs paràmetres d'adquisició en relació amb la dosi i s'ha establert el producte dosi-àrea com a valor de referència per fer estimacions dosimètriques aproximades. Aquests resultats han posat en evidència l'efectivitat, precisió i utilitat del mètode utilitzat.El radiodiagnóstico en general y la tomografía computarizada (TC) en particular han sufrido un importante desarrollo desde su implantación. Una consecuencia de este desarrollo ha sido la reciente aparición de los equipos denominados CBCT (Cone Beam Computer Tomography, o su denominación en español, Tomografía Computarizada de haz cónico), introducidos en la radiología oral y maxilofacial debido a que imparten menores dosis de radiación a los pacientes que los equipos de TC tradicionales, que se pueden instalar en espacios relativamente reducidos, sin grandes requisitos de seguridad, y por su bajo coste. La buena calidad de imagen proporcionada por estos equipos ha facilitado su elección como modalidad especialmente útil para obtener imágenes geométricamente muy precisas y con alta resolución de los tejidos duros y las cavidades de aire de las áreas dentales y en otorrinolaringología. Esta tesis doctoral presenta un estudio dosimétrico de un equipo de CBCT utilizado en radiología dental y maxilofacial mediante el método de Montecarlo aplicado sobre dos maniquíes físicos (uno geométrico y otro antropomórfico) y dos maniquíes computacionales representativos de un hombre y una mujer adultos. La adaptación y validación de un programa de simulación por Montecarlo para ser aplicado a ese equipo concreto ha permitido obtener las dosis en órganos y dosis efectivas para un grupo de exploraciones de pacientes adultos. Así mismo, se ha analizado la influencia de ciertos parámetros de adquisición en relación con la dosis y se ha establecido el producto dosis - área como valor de referencia para hacer estimaciones dosimétricas aproximadas. Estos resultadosn general X-ray diagnosis and in particular computed tomography (CT) have undergone an important development since their introduction. A consequence of this development has been the recent appearance of the so called Cone Beam Computed Tomography (CBCT) devices which have been introduced in oral and maxillofacial radiology. This is because they give a lower dose of radiation to the patients than traditional TC equipment and relatively reduced space is needed to install them. There is no need for important safety requirements and the cost is low. Due to the good image quality provided, CBCT is a useful form of technology that obtains high accuracy and good high resolution images of hard tissues and air cavities in the dental region and in otorhinolaryngology. This doctoral thesis presents a radiation dose research within a CBCT system used in dental and maxillofacial radiology using the Monte Carlo (MC) method and different phantoms. A normalized dose phantom and an anthropomorphic phantom were used to validate the MC program whereas two computational phantoms which represent an adult male and female were used to assess doses. The validation of the MC simulating program applied the CBCT system, has allowed us to obtain the dose in organs and subsequent effective doses for a range of examinations of adult patients. In the same way, it has been analyzed the influence of certain acquisition parameters in relation to the dose. The quantity dose-area product has been established as a potential reference index to make approximate estimations of effective dose. The results have revealed the effectiveness, precision and utility of the method employed

Design of anisotropic biomimetic scaffolds for patient-specific heart valve tissue engineering by melt electrospinning writing

Tissue Engineered Heart Valvs (TEHVs) have the potential to replace synthetic and non-bioactive prosthestics which are incapable of supporting tissue remodelling and regeneraition. However, TEHVs need to withstand the severe mechanical loading conditions due to systemic blood cisculation. For this purpose, we have designed biologically inspired electro-spun fibres to mimic the wavy-like orientation of collagen fibres apparent in the Fibrosa and Ventricularis layer recapitulating the composition, dimensions and mechanical properties of the native valve while providing a biomimetic structure for extracellular matrix (ECM) deposition. Leveraging the capabilities of Melt Electrospinning Writing (MEW), medical grade of PCL fibers were deposited in predefined helical patterns with various radius, pore-size and layer number displaying de Jshaped stress-strain curve and anisotropic mechanical characteristics of a native leaflet tissue. Objective: this study will demonstrate the potential of MEW for the fabrication of mechanically viable biomimentic scaffolds for patient-specific heart valve tissue engineering.Outgoin

Estrategias de comunicación con estudiantes

En el I Congreso de reputación de universidades, celebrado en abril de 2015, el vicerrector de Comunicación de esta Universidad, Juan Manuel Mora, expuso el proceso de formación de la reputación. Y para ello empleó la metáfora del iceberg, que era además el logotipo del Congreso. Hoy, en este II Congreso de Reputación, me gustaría usar como marco de mi ponencia esa metáfora, que los profesionales de la Comunicación de nuestra Universidad tenemos como referencia para nuestro trabajo

Biomimetic scaffolds for heart valve tissue engineering

The number of patients who need heart valve replacement is likely to triple over the next five decades due to the continuously increasing aging of the population in developed countries. Several approaches have raised such as synthetic and non-biodegradable prostheses. Nonetheless, their limited lifetime and the fact that they do not support tissue remodelling and regeneration have lead the research field towards regenerative medicine. In that direction, a well established procedure consists on cell-laden hydrogel casting in a polymer scaffold. Melt Electrowriting is a 3D printing novel technique which allows to build biodegradable polymer tubular constructs whose microfibres might mimic the microarchitecture of collagen filaments present in the native aortic valve matrix. In order to make this possible, though, a code needs to be specifically designed for this application and printing technique. In this project, we propose Matlab as a code generator. Several patterns and geometries must be printed in order to mimic the inner architecture of the native aortic valve while preserving its mechanical integrity as well as its macroscopic shape and features. Also, it must respond to the technical requirements of the MEW and translate the desired accuracy to the tubular scaffold. Besides, Mach3 is used as a code reader to translate the commands into movement of the motors in the machine, and therefore validate the performance and printability of the code. The results show the capability and efficiency of Matlab in generating a program which contains the instructions to be followed by MEW machine. The code introduces a maximum error of 4.55% when comparing the code-adjusted parameters with the initially desired values. Furthermore, its customizable character enables to print scaffolds with different specifications in diameter, pore size and leaflet length, among others. The achievement of printing such a complex microarchitecture means a step forward in the way to produce an aortic valve replacement which mimics native mechanical properties while allowing tissue regeneration. Furthermore, this customizable coding approach will be beneficial not only to Heart Valve Tissue Engineering (HVTE) purposes, but also to other applications where Tubular MEW might be needed.Outgoin

Design of anisotropic biomimetic scaffolds for patient-specific heart valve tissue engineering by melt electrospinning writing

Tissue Engineered Heart Valvs (TEHVs) have the potential to replace synthetic and non-bioactive prosthestics which are incapable of supporting tissue remodelling and regeneraition. However, TEHVs need to withstand the severe mechanical loading conditions due to systemic blood cisculation. For this purpose, we have designed biologically inspired electro-spun fibres to mimic the wavy-like orientation of collagen fibres apparent in the Fibrosa and Ventricularis layer recapitulating the composition, dimensions and mechanical properties of the native valve while providing a biomimetic structure for extracellular matrix (ECM) deposition. Leveraging the capabilities of Melt Electrospinning Writing (MEW), medical grade of PCL fibers were deposited in predefined helical patterns with various radius, pore-size and layer number displaying de Jshaped stress-strain curve and anisotropic mechanical characteristics of a native leaflet tissue. Objective: this study will demonstrate the potential of MEW for the fabrication of mechanically viable biomimentic scaffolds for patient-specific heart valve tissue engineering.Outgoin