On the Richardson-Lucy Algorithm with A Varying Point Spread Function along The Iterations

Abstract: This work analyses the soundness of two algorithms, Fishsint and Almexp to improve images using the Richardson-Lucy (RL) algorithm under a varying Point Spread Function (PSF) along the iterations. A plethora of methods based on Richardson-Lucy has been published, but no further proposal involving such an alternative has been published. Whereas the unnamed predecessor of Fishsint addressed only small size synthetic images under a blind fashion procedure, Fishsint and Almexp employs an algorithm Wdet to determine the initial PSF and all subsequent values after each iteration, respectively. Fishsint performs a loop, where the last determined PSF improves the previously obtained image and vice versa. Its original unnamed version has been modified in the present work by entering a previously determined initial PSF to accelerate the convergence. The algorithm Almexp, as well, uses the algorithm Wdet to determine the PSF of the last obtained image to deconvolve itself. Therefore, whereas the Fishsint unnamed predecessor used an initial guess PSF - chosen by the customer - Almexp determines the PSF always through the algorithm Wdet. Fishsint and Almexp furnish final images which outperform those obtained with the original Richardson-Lucy approach working under a constant PSF along the iterations. Hence, in order to carry out a comparison between their performances, all the algorithms have been embedded into an ad hoc written Fortran 90 program. The results corroborate the soundness of a varying PSF along the iterations with the Richardson Lucy algorithm. Keywords: Richardson-Lucy, varying PSF along iterations, image improvement, neutron radiograph

Programa computacional para cálculo do tempo de ativação fluxo de nêutron e atividade de amostras

O PARAMETRO é um programa desenvolvido em Turbo-Pascal usado em várias aplicações nucleares onde são envolvidas irradiações de amostras, como análise por ativação com nêutrons. É constituído de 3 programas independentes para determinação do tempo de irradiação, da atividade de amostras ou do fluxo de nêutrons. Consta também de um arquivo de dados denominado LIB contendo informações de 88 isótopos diferentes, alguns dos quais os raios gama de múltiplas energias

Comportamento do fluxo de nêutrons térmicos e epitérmicos na saída do canal J-9 do Reator Argonauta para a obtenção de imagens radiográficas

Neste trabalho foi verificado o comportamento do fluxo de nêutrons térmicos e epitérmicos em toda área de saída do canal J-9 do reator Argonauta para diversos arranjos de colimação. O objetivo principal foi definir um arranjo otimizado para ser utilizado na obtenção de imagens radiográficas com nêutrons, incluindo tomografias e neutrongrafias. Como a homogeneidade do feixe e a energia dos nêutrons são fatores que influenciam na qualidade das imagens de um objeto radiografado, a área do canal foi dividida em treze seções e, em cada uma foi obtido o fluxo absoluto de nêutrons térmicos e epitérmicos para cada arranjo de colimação. Os valores dos fluxos em cada seção foram determinados pela ativação (n,γ) de folhas de índio colocadas em cada posição. O método de diferença de cádmio foi o utilizado para separar a contribuição dos nêutrons térmicos dos epitérmicos

Programa computacional para cálculo de fluxo de neutrons

O valor absoluto do fluxo de nêutrons é um parâmetro importante em Física de Reatores e outras aplicações no campo nuclear. Devido a várias correções necessárias como decaimento radioativo dos nuclídeos produzidos, fatores de normalização entre diferentes irradiações, perturbação do espectro de nêutrons, comportamento da seção de choque, subida de potência do reator e outros, faz com que o cálculo do fluxo de nêutrons seja bastante trabalhoso. O software FLUXO foi desenvolvido para vencer essas dificuldades. É programado em linguagem FORTRAN e tem como objetivo principal o cálculo do fluxo absoluto de nêutrons térmicos, epitérmicos e rápidos através da técnica de ativação de folhas. Essa ativação pode ser medida pela técnica de coincidência 4pb-g ou somente por espectrometria g. O software também calcula, através dessas duas técnicas, a atividade absoluta de fontes radioativas e de amostras irradiadas no reator

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially