Proposta de simulação computacional para avaliação de sistemas de imagem radiológica pelo método das funções de transferência. / A computer simulation proposal for radiographic systems evaluation by the transfer functions method.

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

From the conventional evaluation by the radiological systems Transfer Functions, this work shows that it is necessary to obtain slit images at several field orientations so that this annalysis has a more real significance for non-isotropic systems. This is achieved from the non-linearity on the variations among the MTFs obtained in several directions between 0 and 90°C relative to the X-ray tube axis. This notification, however, represents a serious practical matter, because it shows an increase on the complexity of a method which has been used just by well structured laboratories, although many researchers have considered it the most accurate. Hence, in order to solve this problem, we present a new computer simulation method which calculates the LSF and the MTF due to the focal spot, without all the conventional complex experimental apparatus. This makes the evaluation by the transfer functions suitable to any radiological unit. Finally, it is also part of this work an investigation of the physical meaning of the variations among the MTFs and a formal study about the field characteristics and the lateral magnification concepts.

ASSUNTO(S)

função de transferência óptica radiographic systems quality assurance x-ray tube focal spot avaliação de qualidade em radiodiagnóstico função de transferência de modulação modulation transfer function optical transfer function computer simulation simulação computacional ponto focal de tubos de raios x

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