Development of a Dose Calculation Model as a Supplemental Quality Assurance Tool for TomoTherapy

Helical TomoTherapy is a state-of-the-art delivery technique used in photon radiotherapy. This system relies on the superposition of many small fields to precisely administer the prescribed dose to the patient. This thesis presents a new model that predicts dose distributions delivered by TomoTherapy. The model may be used within a dose verification tool for quality assurance purposes. It is based on so-called "energy deposition kernels" and can accurately predict dose distributions in a homogeneous medium for a broad range of field sizes, down to 2 mm in diameter. The model takes into account the two main effects that influence the dose distribution in small fields: (i) the spatial extension of the radiation source and (ii) the loss of charged particle equilibrium (CPE) within the field. The shape of the source is determined by a combination of a "slit-method" reconstruction and a collimator factor fitting procedure, whereas the loss of CPE is taken into account by the use of a poly-energetic pencil beam kernel. The model was successfully validated for a 6 MV photon beam produced by a conventional linear accelerator. The dose verification tool was evaluated for simple beam configurations and used to study the influence of temporal beam parameter variations on the integral dose. The developed model allows to evaluate the performance of devices applying narrow photon beams in the treatment delivery. Furthermore, it can be used as an alternative to the conventional dosimetry of small fields

Simulation of hypoxia PET-tracer uptake in tumours:Dependence of clinical uptake-values on transport parameters and arterial input function

Poor radiotherapy outcome is in many cases related to hypoxia, due to the increased radioresistance of hypoxic tumour cells. Positron emission tomography may be used to non-invasively assess the oxygenation status of the tumour using hypoxia-specific radiotracers. Quantification and interpretation of these images remains challenging, since radiotracer binding and oxygen tension are not uniquely related. Computer simulation is a useful tool to improve the understanding of tracer dynamics and its relation to clinical uptake parameters currently used to quantify hypoxia. In this study, a model for simulating oxygen and radiotracer distribution in tumours was implemented to analyse the impact of physiological transport parameters and of the arterial input function (AIF) on: oxygenation histograms, time-activity curves, tracer binding and clinical uptake-values (tissue-to-blood ratio, TBR, and a composed hypoxia-perfusion metric, FHP). Results were obtained for parallel and orthogonal vessel architectures and for vascular fractions (VFs) of 1% and 3%. The most sensitive parameters were the AIF and the maximum binding rate (K-max). TBR allowed discriminating VF for different AIF, and FHP for different K-max, but neither TBR nor FHP were unbiased in all cases. Biases may especially occur in the comparison of TBR- or FHP-values between different tumours, where the relation between measured and actual AIF may vary. Thus, these parameters represent only surrogates rather than absolute measurements of hypoxia in tumours.Pontificia Universidad Catolica de Chile (UC) from the German Academic Exchange Service (DAAD) German Cancer Research Center (DKFZ) from the German Academic Exchange Service (DAAD) grant CONICYT Doctorado Nacional 21151353 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 111505601 1117057

Planning a competency evaluation for the human talent in Colombia and Argentina at Sanofi company

El presente trabajo tiene como objetivo crear una evaluación por competencias para los empleados de la empresa Sanofi, donde se puedan evaluar sus fortalezas y sus puntos de mejora. Esto con el fin de poder crear un programa de capacitaciones que les permita crecer en su posición de trabajo y a nivel personal. En los últimos años, la empresa se ha enfrentado en diferentes oportunidades a cambios grandes generando que el rendimiento y las personas se vean afectadas. Por esta razón, se evidencio una oportunidad para poder crear un proyecto que ayude a los colaboradores a asumir con una mejor actitud los diferentes cambios que la empresa puede tener al estar en una industria tan cambiante.The main goal of this project is to create an assessment based on skills for the employees of the Sanofi, where their strengths and points of improvement can be evaluated. This, in order to be able to create a training program that allows them to grow in their job position and on a personal level. In recent years, the company has faced big changes on different occasions, causing performance and people to be affected. For this reason, an opportunity was evidenced to be able to create a project that helps collaborators to assume with a better attitude the different changes that the company can face because of the changing industry in which they are.Administrador (a) de EmpresasPregrad