This paper proposes a more inclusive statistical model for predicting image noise in Computed Tomography (CT), associated with scanning factors, considering the effect of beam hardening and image processing filters. It is based on power functions where the levels of the parameters will determine the rate of noise variation with respect to a given scanning factor. It includes the influence of tube potential, tube current, slice thickness, Field of View (FOV), reconstruction methods and post-processing filters. To validate the model, tomographic measurements were made by using a PMMA phantom that simulates paediatric head and adult abdomen, a PET bottle was used to simulate the head of the newborn. The influence of ROI (Region Of Interest) size over nonlinear model parameters was analysed, and high variations of powers of attenuation and FOV were found depending on ROI size. A nonlinear robust regression method was used. The validation was performed graphically by weighted residual analysis. A nonlinear noise model was obtained with an adjusted coefficient of determination ajNL R 2 > 0.99 for ROI sizes between 10% and 70% of the phantom diameter or FOV. The model confirms the significance of the tube current, slice thickness and beam hardening effect on image. The process of estimation of the parameters of the model by Nonlinear Robust Regression turned out to be optimal.

Los indicadores demográficos han sido empleados por algunos investigadores para estimar el número de personas infectadas por la covid-19. El presente trabajo tiene como primer objetivo determinar en qué medida la incidencia de casos con covid-19 en los municipios de la provincia de Santiago de Cuba puede ser explicada a partir de determinados indicadores demográficos. El segundo objetivo es construir una jerarquía de grupos de municipios de acuerdo al comportamiento diferenciado de los indicadores demográficos seleccionados. Se desarrolló un estudio ecológico, exploratorio, de grupos múltiples, comparando los nueve municipios de la provincia Santiago de Cuba según variables del nivel global, supuestamente relacionadas con la cantidad de casos con covid-19 confirmados desde el 15 de octubre de 2020 hasta el 16 de enero de 2021. Se aplicó el análisis de regresión lineal múltiple para seleccionar el modelo que describiera mejor el comportamiento de los datos y el análisis de clúster para visualizar la agrupación de los municipios. Se evidenció una correlación significativa entre la cantidad de casos con covid-19, la densidad de población y el grado de urbanización. En cambio, en el modelo de regresión solo resultó significativa la densidad poblacional cuando se consideraron los nueve municipios y el índice de masculinidad, cuando se excluyó el municipio atípico, Santiago de Cuba. El índice de masculinidad resultó ser una variable espuria condicionada por la densidad poblacional como variable confusora. El análisis de clúster reveló la formación de tres grupos de municipios, quedando Santiago de Cuba aislado del resto de los municipios.

Background Many variables have been studied in cancer patients. Nevertheless, an study that analyzes simultaneously physical, functional and biological variables in they from clinical, physical and statistical points of views is not reported in the literature. The aim of this study is to propose an integrated analysis of clinical, bioelectrical and functional variables in newly diagnosed lung cancer adult patients for the integral evaluation and possible prognostic of them. Methods This Pilot study was retrospective and cross-sectional and 23 patients aged 53–82 years participated in it. The electrical resistance and capacitive electrical reactance were measured with the Bodystat Quadscan® 4000 analyzer. The electrical impedance modulus and the phase angle were calculated. The serum concentrations of epidermal growth factor, CYFRA21-1 and CA 72–4 were quantified. Correlations/associations among variables and the principal component analysis were suggested. Results The majority of patients had tumor markers, electrical resistance and the phase angle in their respective normal ranges. The capacitive electrical resistance was below its normal range. Minimum, low and moderate grades of linear correlation/association prevailed among studied variables. The principal components I and II were interpreted as prognosis and body energetic reserve of the patient, respectively. Conclusions It is concluded that the clinical, bioelectrical and functional variables allow the integral analysis and possible prognosis of newly diagnosed lung cancer adult patients. The decrease of the capacitive electrical reactance is the most influence to the loss of the body energetic reserve that leads to alterations of the overall health, tiredness and decrease of weight and body mass index of these patients.

Background: Bioelectrical impedance analysis has been used in cancer patients. The aim of this study is to propose an integrated analysis of clinical, bioelectrical and functional variables in newly diagnosed lung cancer adult patients for the integral evaluation and possible prognostic of them.Methods: This Pilot study was retrospective and cross-sectional and 23 patients aged 53-82 years participated in it. The electrical resistance and capacitive electrical reactance were measured with the Bodystat Quadscan® 4000 analyzer. The electrical impedance modulus and the phase angle were calculated. The serum concentrations of epidermal growth factor, CYFRA21-1 and CA 72-4 were quantified. Correlations/associations among variables and the principal component analysis were suggested.Results: The majority of patients had tumor markers, electrical resistance and the phase angle in their respective normal ranges. The capacitive electrical resistance was below its normal range. Minimum, low and moderate grades of linear correlation/association prevailed among studied variables. The principal components I and II were interpreted as prognosis and body energetic reserve of the patient, respectively.Conclusions: It is concluded that the clinical, bioelectrical and functional variables allow the integral analysis and possible prognosis of newly diagnosed lung cancer adult patients. The decrease of the capacitive electrical reactance is the most influence to the loss of the body energetic reserve that leads to alterations of the overall health, tiredness and decrease of weight and body mass index of these patients.

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