Experimental investigation of target and transducer effects on quantitative image reconstruction in photoacoustic tomography

In principle, absorbed energy profiles can be exactly reconstructed from photoacoustic measurements on a closed surface. Clinical applications, however, involve compromises due to transducer focus, frequency characteristics, and incomplete measurement apertures. These tradeoffs introduce artifacts and errors in reconstructed absorption distributions that affect quantitative interpretations as well as qualitative contrast between features. The quantitative effects of target geometry, limited measurement surfaces, and bandpass transducer frequency response have been investigated using a ring transducer system designed for small animal imaging. The directionality of photoacoustic radiation is shown to increase with target aspect ratio, producing proportionate overestimates of absorption values for two-dimension apertures less than approximately 150 degrees. For all target geometries and orientations, mean absorption values approach the full view values for hemicircular measurement surfaces although the true spatial uniformity is recovered only with the complete surface. The bandpass transducer frequency spectrum produces a peaked amplitude response biased toward spatial features ranging from 1 to 8 times the system resolution. We discuss the implications of these results for design of clinical systems

Small animal imaging using a curved array photoacoustic tomography system

We report experimental imaging results with mice using an array-based photoacoustic tomography system designed for small animal imaging. The system features a 128-element curved transducer array with stage rotation to enable complete two-dimensional tomographic imaging in less than 15 seconds. High fidelity imaging of ex vivo mouse brain vasculature was achieved with resolution of vessels less than 200 microns in diameter in the cortex as well as the cerebellum. Images obtained using varying measurement surface angular spans clearly illustrate the impact on feature definition with orientation. The high sensitivity of the system was demonstrated by images of the brain vasculature with an overlying turbid medium (μ_a = 0.03 cm^(-1) and μ_s' ~ 7 cm^(-1) at 780 nm) of over 2 cm depth. In phantom experiments, high-quality images of blood tubing in a turbid medium were achieved at depths greater than 3 cm for incident fluences of less than 15 mJ/cm^2. These results illustrate the suitability for near real-time small animal imaging of deep tissue with high definition

Curved array photoacoustic tomographic system for small animal imaging

We present systematic characterization of a photoacoustic imaging system optimized for rapid, high-resolution tomographic imaging of small animals. The system is based on a 128-element ultrasonic transducer array with a 5-MHz center frequency and 80% bandwidth shaped to a quarter circle of 25mm radius. A 16-channel data-acquisition module and dedicated channel detection electronics enable capture of a 90-deg field-of-view image in less than 1s and a complete 360-deg scan using sample rotation within 15s. Measurements on cylindrical phantom targets demonstrate a resolution of better than 200μm and high-sensitivity detection of 580-μm blood tubing to depths greater than 3cm in a turbid medium with reduced scattering coefficient μ′s =7.8cm^(−1). The system is used to systematically investigate the effects of target size, orientation, and geometry on tomographic imaging. As a demonstration of these effects and the system imaging capabilities, we present tomographic photoacoustic images of the brain vasculature of an ex vivo mouse with varying measurement aperture. For the first time, according to our knowledge, resolution of sub-200-μm vessels with an overlying turbid medium of greater than 2cm depth is demonstrated using only intrinsic biological contrast

A curved array photoacoustic tomography system for small animal imaging

We have developed and tested a photoacoustic imaging system based on a 128 element curved-phased ultrasonic array, which spans a quarter of a complete circle with a radius of curvature equal to 25mm. The center frequency of the array is 5 MHz with 60% bandwidth. The physical dimensions of the elements are 10x0.3mm (elevation x azimuth) with an elevation focus of 19mm. Earlier we reported acoustic measurements of the axial and lateral resolutions of the system that were limited by the impulse response of the narrowband source used in the test. In this paper we discuss photoacoustic characterization of the system including resolution and sensitivity. The array forms the building block for a 512-element ring designed for complete tomographic imaging of small animals. Imaging results of phantoms will be compared with simulations

Small animal imaging using a curved array photoacoustic tomography system

We report experimental imaging results with mice using an array-based photoacoustic tomography system designed for small animal imaging. The system features a 128-element curved transducer array with stage rotation to enable complete two-dimensional tomographic imaging in less than 15 seconds. High fidelity imaging of ex vivo mouse brain vasculature was achieved with resolution of vessels less than 200 microns in diameter in the cortex as well as the cerebellum. Images obtained using varying measurement surface angular spans clearly illustrate the impact on feature definition with orientation. The high sensitivity of the system was demonstrated by images of the brain vasculature with an overlying turbid medium (μ_a = 0.03 cm^(-1) and μ_s' ~ 7 cm^(-1) at 780 nm) of over 2 cm depth. In phantom experiments, high-quality images of blood tubing in a turbid medium were achieved at depths greater than 3 cm for incident fluences of less than 15 mJ/cm^2. These results illustrate the suitability for near real-time small animal imaging of deep tissue with high definition

La imagen y la narrativa como herramientas para el abordaje psicosocial en escenarios de violencia. Municipios de Ricaurte, Sesquilé y Cota Cundinamarca

En el presente trabajo, se logran abordar los contenidos vistos en el Diplomado de Profundización “Acompañamiento Psicosocial en Escenarios de Violencia”, donde se identifican las problemáticas en comunidades de nuestro país víctimas del conflicto armado en Colombia, flagelo que, en el presente, sigue siendo parte de esta realidad y de una guerra sin sentido, que deja a su paso heridas y secuelas tanto físicas como psicológicas; además, de grandes consecuencias psicosociales. Con este material y dicha problemática, se realiza una visión más objetiva y analítica, con la apropiación del enfoque narrativo, la imagen foto voz, la aplicación de preguntas estratégicas, circulares y reflexivas, las cuales permiten ahondar más allá de los relatos de las experiencias vividas, logrando proyectar procesos de acompañamiento psicosocial desde el conocimiento adquirido, a partir de programas de intervención, dirigidos a mejorar la trasferencia positiva de éstos contextos, donde se reconoce la capacidad del ser humano para afrontar las experiencias traumáticas que traen efectos devastadores. Las víctimas logran reestructurar la forma de entender el mundo y construyen nuevos sistemas de valores, por medio de conceptos de resiliencia, que permiten mostrar, que el ser humano, tiene la capacidad de resistir y rehacerse, ante cualquier adversidad en la vida.In this document, it is possible to approach the contents seen in the Diploma of profundization Psychosocial Accompaniment in Scenarios of Violence, where it’s identify the problematic in communities of our country who are victims of the armed conflict in Colombia. This is a problem that in present days continues to be part of this reality and a meaningless war, which leaves wounds and consequences both physically and psychologically, as well as great psychosocial consequences. With this material and the problematic mention before, it is possible to approach from a more objective and analytical vision, with the appropriation of the narrative approach, the photo-voice image, the application of strategic, circular and reflective questions, which allow us to go further from the stories of the lived experiences, making possible to project psychosocial accompaniment processes from the acquired knowledge, from intervention programs aimed at improving the positive transfer of these contexts, where it recognizes the capacity of the human being to face the traumatic experiences that bring devastating effects. The victims manage to restructure the way of understanding the world and build new value systems through concepts of resilience that show that the human being has the ability to resist and to remake himself truth the adversity in life

Plan estratégico para Bell Corporation Inc. 2023-2027

El presente trabajo desarrolla una propuesta de plan estratégico para la empresa Bell Corporation Inc., la cual se dedica a la fabricación y la comercialización de dispositivos móviles para las empresas de telecomunicaciones que operan en las regiones de China, Europa y Estados Unidos. Para el desarrollo de la estrategia se revisaron los aspectos que ayuden a Bell Corporation Inc. A incrementar su participación de mercado y beneficios para sus accionistas. Para esto, se realizó el análisis interno, análisis externo y análisis de mercado, con el fin de estimar correctamente la demanda e identificar el mercado potencial, objetivo y meta para los próximos 5 años. Se desarrollaron los planes funcionales integrados por el plan de Marketing, el plan de Operaciones, el plan de Recursos Humanos, el plan de Responsabilidad Social y el plan de Finanzas; estos planes describen la estrategia para lograr los objetivos de diferenciación y rentabilidad en el negocio, sobre la base de la inversión en investigación y desarrollo acompañado de una configuración organizacional “adhocrática” para el lanzamiento de dispositivos móviles para deportistas con tecnología 5G. Este plan con enfoque en estrategia de diferenciación permite satisfacer tanto la demanda del mercado y el posicionamiento de Bell Corporation Inc. en el mercado asiático