Patient exposure monitoring and radiation qualities in two-dimensional digital x-ray imaging

The methods for estimating patient exposure in x-ray imaging are based on the measurement of radiation incident on the patient. In digital imaging, the useful dose range of the detector is large and excessive doses may remain undetected. Therefore, real-time monitoring of radiation exposure is important. According to international recommendations, the measurement uncertainty should be lower than 7% (confidence level 95%). The kerma-area product (KAP) is a measurement quantity used for monitoring patient exposure to radiation. A field KAP meter is typically attached to an x-ray device, and it is important to recognize the effect of this measurement geometry on the response of the meter. In a tandem calibration method, introduced in this study, a field KAP meter is used in its clinical position and calibration is performed with a reference KAP meter. This method provides a practical way to calibrate field KAP meters. However, the reference KAP meters require comprehensive calibration. In the calibration laboratory it is recommended to use standard radiation qualities. These qualities do not entirely correspond to the large range of clinical radiation qualities. In this work, the energy dependence of the response of different KAP meter types was examined. According to our findings, the recommended accuracy in KAP measurements is difficult to achieve with conventional KAP meters because of their strong energy dependence. The energy dependence of the response of a novel large KAP meter was found out to be much lower than with a conventional KAP meter. The accuracy of the tandem method can be improved by using this meter type as a reference meter. A KAP meter cannot be used to determine the radiation exposure of patients in mammography, in which part of the radiation beam is always aimed directly at the detector without attenuation produced by the tissue. This work assessed whether pixel values from this detector area could be used to monitor the radiation beam incident on the patient. The results were congruent with the tube output calculation, which is the method generally used for this purpose. The recommended accuracy can be achieved with the studied method. New optimization of radiation qualities and dose level is needed when other detector types are introduced. In this work, the optimal selections were examined with one direct digital detector type. For this device, the use of radiation qualities with higher energies was recommended and appropriate image quality was achieved by increasing the low dose level of the system.

Prevalencia de síntomas cutáneos asociados a dermatitis de contacto y su relación con factores sociodemográficos y ocupacionales en el personal asistencial de un laboratorio clínico de la ciudad de Bogotá en el año 2012

El objetivo fue determinar la prevalencia de síntomas cutáneos asociados a Dermatitis de Contacto y su relación con factores socios demográficos y ocupacionales, en el personal asistencial de un laboratorio clínico de la ciudad de Bogotá en el año 2012. Es un estudio descriptivo observacional de corte transversal (n= 100) se estimo la prevalencia de síntomas cutáneos de Dermatitis de Contacto y sus factores asociados socio demográficos y ocupacionales en el personal asistencial de un laboratorio clínico de la ciudad de Bogotá en Se usó como instrumento el cuestionario Nórdico para Enfermedades profesionales de la piel (NOQS) en su versión larga validada al español. La sensibilidad y especificidad del cuestionario aplicado en lo referente a las preguntas sobre eczema fue del 96 y 75% respectivamente. Los resultados encontrados fueron que la prevalencia de la sintomatología cutánea de Dermatitis de contacto en la población estudiada fue de 30% para manos y de 16 % para muñecas o antebrazos.

Exploratory Study on Occupational Health Exposure to Chemical Agents, in a Public Hospital in Valencia, Venezuela. Preliminar Assessment

Descriptive study that identified chemical agents (AQ) use and training on risk management and waste disposal techniques in a public Hospital in Valencia. A questionnaire was answered by 48 workers. Information obtained was: personal data, occupational history, AQ used; knowledge of risk management and waste disposal. There were 16 occupations from 12 “High Risk” areas. “Adult emergency” was the one with more workers (11 individuals), followed by “sterilization” and “clinical laboratory” (7 each) and oncology (5). The remained areas had less than 8.3% workers. The most used anesthetic agents were: Halothane, Enfluorane and Isofluorane 4.17% each and main antineoplastics used were: Doxorubicin 16.67% and Paclitaxel, 5-Fluoracil and Etoposide, 8.33% each. The most mentioned substances were: alcohol (70.8%) and Chlorine (64.6%). None of the answers regarding knowledge of AQ’ risk management and waste disposal was satisfactory. Statistical associations between training and several variables such as age, time in their job and being or not a professional, resulted non-significant. The correlation between training and the knowledge of AQ’s management was significant (p < 0.001). Participants showed that their knowledge about chemical occupational risk factors they are exposed to is still insufficient. Therefore, this theme should be included in graduate course curricula. These results provide important data and will serve as a pilot research for the follow up Phase II study that will include clinical aspects and environmental and biological monitoring.

Estrés laboral y su relación con los turnos y áreas de trabajo en el personal que labora en campos de perforación de una empresa del sector hidrocarburos en Colombia

El personal que labora en áreas de campo en las empresas de hidrocarburos se enfrenta de manera sistemática a diferentes exposiciones ocupacionales que pueden estar relacionadas con el estrés laboral o tener algún tipo de incidencia en este sentido. Objetivo: establecer la prevalencia de síntomas de estrés percibidos por un grupo de trabajadores que laboran en cuatro campos de perforación de hidrocarburos e identificar su relación con el turno y área de trabajo (administración y producción) en que desempeñan su labor. Metodología: Estudio de corte transversal, en una empresa del sector hidrocarburos que opera en el municipio de Puerto Boyacá, con una muestra de 115 trabajadores, la información se recolectó a través de la aplicación del cuestionario para la evaluación del estrés – Tercera versión del Ministerio de Salud y Protección Social de la República de Colombia y la Pontificia Universidad Javeriana de Bogotá. Resultados: El género de mayor frecuencia fue el masculino con el 86%, el 39% de los trabajadores se encuentra en el grupo etario entre los 47-57 años refirió un nivel de estrés alto. Se observó que la línea operativa y profesional y los analistas, fueron los que reportaron un nivel de estrés alto. Conclusiones: El trabajo que desarrolla el personal que labora por turnos en campos de perforación, es un generador de estrés por lo que debe ser monitoreado de forma periódica, haciendo énfasis en la promoción de estilos laborales saludables y la prevención de diagnósticos que afecten el componente conductual.

Determinación de las condiciones de trabajo y salud del personal de laboratorios universitarios como estrategia de intervención de riesgos laborales

Introducción: Las condiciones de trabajo y salud de la población trabajadora han sido estudiadas en los diferentes sectores económicos, y para esto se han aplicado diversos instrumentos para la identificación de los factores de riesgo. Sin embargo, el estudio en los trabajadores de las instituciones de educación superior, aún es escaso y limitado. Este trabajo de investigación abordó las condiciones de trabajo y salud y los factores de riesgo asociados de los empleados de laboratorios y de talleres de las diferentes unidades de una Universidad privada en Bogotá D.C. Objetivo: Determinar las condiciones de trabajo y salud del personal de laboratorios y de talleres en el 2014 de las diferentes unidades de una Universidad privada en Bogotá D.C. Métodos: Se realizó un estudio de corte transversal, en una muestra de 87 trabajadores de laboratorios y de talleres. En el análisis univariado se calcularon para las variables cualitativas frecuencias y proporciones, y para las variables cuantitativas medidas de tendencia central y dispersión acorde a la distribución de los datos. Para el análisis bivariado, se realizó la comparación de las prevalencias entre los factores de riesgo locativos, físicos, químicos, biológicos, biomecánicos y psicológicos de cada unidad y las condiciones de trabajo y salud; así como su asociación con los factores sociodemográficos y laborales, por medio de la prueba de asociación Chi-Cuadrado de Pearson. El nivel de significancia establecido fue p<0.05. Resultados: Se encontró que las variables respiración de sustancias y manipulación manual de cargas se encuentran asociadas al cargo de los trabajadores de laboratorios y de talleres. También de la muestra de trabajadores la mayoría infirió no tener una exposición significativa a los riesgos locativo, físico, biológico y psicosocial; mientras que para riesgo químico y biomecánico se encontraron frecuencias de más del 60% entre los participantes. Los hallazgos de este estudio corresponden únicamente a la percepción de los trabajadores frente a sus condiciones de trabajo y salud, puesto que no se realizaron mediciones higiénicas ni exámenes médicos a los participantes. Conclusiones: En este estudio se encontró que la exposición a riesgos locativo, físico, biológico y psicosocial es baja; mientras que es alta para riesgo químico debida a la manipulación e inhalación de sustancias químicas tóxicas, y a riesgo biomecánico a causa de las posturas prolongadas y mantenidas, la manipulación manual de cargas, los movimientos repetitivos y realizar fuerzas. En relación a las condiciones de salud mental, se encontró que la población no presenta algún estado emocional o psicológico que llame la atención, lo que en consecuencia se refleja en el buen estado de salud físico.

Percepción del riesgo biológico en el personal asistencial en un hospital de alta complejidad de la ciudad de Bogotá.

OBJETIVOS: Identificar la percepción del riesgo biológico de los trabajadores asistenciales del Hospital Central de la Policía Nacional en la ciudad de Bogotá. METODOS: se realizó un estudio analítico de corte transversal para describir la percepción acerca del riesgo biológico en 159 trabajadores asistenciales de un hospital de alta complejidad en la ciudad de Bogotá (Colombia), la información se recolectó por medio de la utilización de la encuesta validada nota técnica 578 (Portell M, Solé M, 2001). Se realizó la caracterización de la población por variables de sexo, edad, tiempo de experiencia y servicio al cual pertenece y se promediaron las respuestas obtenidas para cada ítem encuestado, obteniendo una clasificación para cada dimensión de percepción de riesgo baja (1 a 3), media (4 a 5) o alta (6 a 7). Resultados: De los 159 trabajadores asistenciales encuestados el 80.4% eran de género femenino, el 22.2% pertenecían al servicio de urgencias, el 16,5% al servicio de medicina interna y el 9.5% al servicio de pediatría, de los encuestados el 62.9% fueron auxiliares de enfermería, el 21,4% enfermeras jefes y el 6.9% médicos. Se obtuvo una percepción de riesgo alta (media aritmética mayor de 5) para todas las variables incluidas en la encuesta, demostrando conocimiento de todo el personal acerca de la alta exposición a accidentes de tipo biológico. No se encontró asociación entre la labor desempeñada y la percepción del riesgo biológico, sin embargo, se encontró una asociación entre el tiempo de experiencia del trabajador y una disminución en la magnitud del riesgo percibido (Chi cuadrado de asociación, p=0.042). Conclusiones: Los trabajadores asistenciales identifican la magnitud del riesgo biológico al que se encuentran expuestos en sus labores del día a día, sin embargo, es necesaria una mayor participación por parte del personal directivo y de los responsables de la prevención en temas de reacción ante accidentes y en la valoración del riesgo, especialmente en personas que llevan mucho tiempo desempeñando la labor.

Virtual reality Post Traumatic Stress Disorder (PTSD) exposure therapy results with active duty Iraq war combatants

Post Traumatic Stress Disorder (PTSD) is reported to be caused by traumatic events that are outside the range of usual human experience including (but not limited to) military combat, violent personal assault, being kidnapped or taken hostage and terrorist attacks. Initial data suggests that at least 1 out of 6 Iraq War veterans are exhibiting symptoms of depression, anxiety and PTSD. Virtual Reality (VR) delivered exposure therapy for PTSD has been used with reports of positive outcomes. The aim of the current paper is to present the rationale and brief description of a Virtual Iraq PTSD VR therapy application and present initial findings from its use with PTSD patients. Thus far, Virtual Iraq consists of a series of customizable virtual scenarios designed to represent relevant Middle Eastern VR contexts for exposure therapy, including a city and desert road convoy environment. User-centered design feedback needed to iteratively evolve the system was gathered from returning Iraq War veterans in the USA and from a system deployed in Iraq and tested by an Army Combat Stress Control Team. Results from an open clinical trial at San Diego Naval Medical Center of the first 18 treatment completers indicate that 14 no longer meet PTSD diagnostic criteria at post-treatment, with only one not maintaining treatment gains at 3 month follow-up. Clinical tests are also currently underway at Ft. Lewis, Emory University, Weill Cornell Medical College, Walter Reed Army Medical Center and 10 other sites. Other sites are preparing to use the application for a variety of PTSD and VR research purposes.

Virtual reality Post Traumatic Stress Disorder (PTSD) exposure therapy results with active duty OIF/OEF service members

Posttraumatic stress disorder (PTSD) is reported to be caused by exposure to traumatic events including (but not limited to) military combat, violent personal assault, being kidnapped or taken hostage and terrorist attacks. Initial data suggest that at least 1 out of 6 Iraq War veterans are exhibiting symptoms of depression, anxiety and PTSD. Virtual reality (VR) delivered exposure therapy for PTSD has been used with reports of positive outcomes. The aim of the current paper, is to present the rationale and brief description of a Virtual Iraq/Afghanistan PTSD VR therapy application and present initial findings from its use with PTSD patients. Thus far, Virtual Iraq/Afghanistan consists of a series of customizable virtual scenarios designed to represent relevant Middle Eastern VR contexts for exposure therapy, including a city and desert road convoy environment. User-centered design feedback, needed to iteratively evolve the system, was gathered from returning Iraq War veterans in the USA and from a system deployed in Iraq and tested by an Army Combat Stress Control Team. Results from an open clinical trial at San Diego Naval Medical Center of the first 20 treatment completers indicate that 16 no longer met PTSD screening criteria at post-treatment, with only one not maintaining treatment gains at 3 month follow-up.

Exposure to parabens at the concentration of maximal proliferative response increases migratory and invasive activity of human breast cancer cells in vitro

Alkyl esters of p–hydroxybenzoic acid (parabens) are widely used as preservatives in personal care products, foods and pharmaceuticals. Their oestrogenic activity, their measurement in human breast tissue and their ability to drive proliferation of oestrogen-responsive human breast cancer cells has opened a debate on their potential to influence breast cancer development. Since proliferation is not the only hallmark of cancer cells, we have investigated the effects of exposure to parabens at concentrations of maximal proliferative response on migratory and invasive properties using three oestrogen-responsive human breast cancer cell lines (MCF-7, T-47-D, ZR-75-1). Cells were maintained short-term (1 week) or long-term (20±2 weeks) in phenol-red-free medium containing 5% charcoal-stripped serum with no addition, 10-8M 17-oestradiol, 1-5x10-4M methylparaben, 10-5M n-propylparaben or 10-5M n-butylparaben. Long-term exposure (20±2 weeks) of MCF-7 cells to methylparaben, n-propylparaben or n-butylparaben increased migration as measured using a scratch assay, time-lapse microscopy and xCELLigence technology: invasive properties were found to increase in matrix degradation assays and migration through matrigel on xCELLigence. Western immunoblotting showed an associated downregulation of E-cadherin and -catenin in the long-term paraben-exposed cells which could be consistent with a mechanism involving epithelial to mesenchymal transition. Increased migratory activity was demonstrated also in long-term paraben-exposed T-47-D and ZR-75-1 cells using a scratch assay and time-lapse microscopy. This is the first report that in vitro, parabens can influence not only proliferation but also migratory and invasive properties of human breast cancer cells.

Exposure estimation, uncertainty and variability in occupational hygiene retrospective assessment

This thesis reports on a quantitative exposure assessment and on an analysis of the attributes of the data used in the estimations, in particular distinguishing between its uncertainty and variability. A retrospective assessment of exposure to benzene was carried out for a case control study of leukaemia in the Australian petroleum industry. The study used the mean of personal task-based measurements (Base Estimates) in a deterministic algorithm and applied factors to model back to places, times etc for which no exposure measurements were available. Mean daily exposures were estimated, on an individual subject basis, by summing the task-based exposures. These mean exposures were multiplied by the years spent on each job to provide exposure estimates in ppm-years. These were summed to provide a Cumulative Estimate for each subject. Validation was completed for the model and key inputs. Exposures were low, most jobs were below TWA of 5 ppm benzene. Exposures in terminals were generally higher than at refineries. Cumulative Estimates ranged from 0.005 to 50.9 ppm-years, with 84 percent less than 10 ppm-years. Exposure probability distributions were developed for tanker drivers using Monte Carlo simulation of the exposure estimation algorithm. The outcome was a lognormal distribution of exposure for each driver. These provide the basis for alternative risk assessment metrics e.g. the frequency of short but intense exposures which provided only a minimal contribution to the long-term average exposure but may increase risk of leukaemia. The effect of different inputs to the model were examined and their significance assessed using Monte Carlo simulation. The Base Estimates were the most important determinant of exposure in the model. The sources of variability in the measured data were examined, including the effect of having censored data and the between and within-worker variability. The sources of uncertainty in the exposure estimates were analysed and consequential improvements in exposure assessment identified. Monte Carlo sampling was also used to examine the uncertainties and variability associated with the tanker drivers' exposure assessment, to derive an estimate of the range and to put confidence intervals on the daily mean exposures. The identified uncertainty was less than the variability associated with the estimates. The traditional approach to exposure estimation typically derives only point estimates of mean exposure. The approach developed here allows a range of exposure estimates to be made and provides a more flexible and improved basis for risk assessment.

Long-term ethylene oxide exposure trends in US hospitals : relationship with OSHA regulatory and enforcement actions

We assessed long-term trends in ethylene oxide (EtO) worker exposures for the purposes of exposure surveillance and evaluation of the impacts of the Occupational Safety and Health Administration (OSHA) 1984 and 1988 EtO standards. We obtained exposure data from a large commercial vendor and processor of EtO passive dosimeters. Personal samples (87 582 workshift [8-hr] and 46 097 short-term [15-min] samples) from 2265 US hospitals were analyzed for time trends from 1984 through 2001 and compared with OSHA enforcement data. Exposures declined steadily for the first several years after the OSHA standards were set. Workshift exposures continued to taper off and have remained low and constant through 2001. However, since 1996, the probability of exceeding the short-term excursion limit has increased. This trend coincides with a decline in enforcement of the EtO standard. Results indicate the need for renewed intervention efforts to preserve gains made following the passage and implementation of the 1984 and 1988 EtO standards.