The modulation transfer functions of x-ray focal spots

Rao, U. V. Gopala; Bates, Lloyd M.

doi:10.1088/0031-9155/14/1/311

Cited by 21 publications

(13 citation statements)

References 3 publications

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“…1943 300 [25,26] 1950 4900 [27] 1951 2000 [28] 1955 2340 [29] 1955 3000 [29] 1956 300 [30] 1957 130 [31] 1957 300 [32] 1957 310 [31] 1957 1200 [33] 1958 400 [15] 1958 16000 [15] 1964 1000 [34] 1964 2000 [34] 1965 2000 [35] 1968 1000 [36] 1968 2000 [36] 1969 50 [37] 1969 340 [37] 1969 360 [38] 1969 500 [39] 1969 2000 [40] 1970 50 [41] 1970 300 [14] 1970 2000 [40] 1971 60 [42] 1971 270 [19] 1971 300 [42] 1971 1000 [42] 1972 2 2 1.0 [43] 1973 1000 1000 1.0 1 -3 √ [44] 1974 600 [45] 1974 2450 [45] 1975 148 [46] 1975 800 0.28 -2.54 [47] 1975 1490 [46] 1975 50 [48] 1977 15 [49] 1979 30 [50] 1980 15 [26] Table 1. X-ray detector sizes and focal spot sizes versus year published.…”

Section: Ct Referencementioning

confidence: 99%

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

Alvare¹,

Gordon²

2017

Radiol Diagn Imaging

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Purpose: In general, there is a reciprocal relationship between the width and flux from an x-ray focal spot (corresponding to spatial resolution and photon noise), so that large focal spots are eschewed in computed tomography (CT) and projection and CT mammography. We wish to overcome this limitation. The goal of foxel based computed tomography (FoxelCT) is to achieve spatial resolution limited by the detector pixel size rather than the focal spot size, and therefore permit the use of much smaller detector pixels and/or larger focal spots in clinical CT. Methods:Rather than using the standard approach of treating the x-ray source as a point, we digitally represent the focal spot as an emission picture consisting of pixels we call foxels (FOcal spot piXELS). Intersections of foxel rays with reconstruction voxels are approximated using the Wu antialiasing line drawing algorithm. All foxel rays in the x-ray light field impinging on a given detector pixel are, in effect, lumped together into a single "passage" or compound ray sum. In this introductory paper noise and other effects that degrade CT are not considered allowing us to demonstrate the upper bound of improvement afforded by the geometry of foxels. The FoxelCT algorithm is a generalization of MART (Multiplicative ART). Results:We show, by simulating a fan beam body scanner configuration, that the loss in resolution versus focal spot size is much slower using foxels compared to the loss when representing the focal spot as a point source. For any given focal spot size, approximating it as a point is always worse than using foxels and furthermore introduces anatomical distortions.Conclusions: Foxels permit the use of larger focal spots and thus greater x-ray photon flux with little loss of resolution. Future scanners could take advantage of foxels to increase the ratio of focal spot size to detector pixel size, via bigger focal spots and/or smaller detector pixels. Existing scanners could be immediately enhanced in image quality via incorporation of foxels in their software. Foxels are applicable to any form of radiological imaging that uses focal spots of finite width, including multisource scanners.

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Section: Ct Referencementioning

confidence: 99%

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

Alvare¹,

Gordon²

2017

Radiol Diagn Imaging

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“…Furthermore, parameters of the recording operation must be chosen so that the x-ray pattern is transferred with a minimum of degradation. The effect 6f many exposing parameters, such as focal spot [1][2][3][4][5][6] size and obiect posi tion, on the x-ray pattern are being studied.…”

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Effect of the X-Ray Spectrum and Screen-Film Unsharpness on the Imaging of Blood Vessels.

Haus¹,

Rossmann²

1972

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“…Função de transferência de fase (FTF) de um sistema isotrópico em duas direções, paralela e perpendicular ao eixo catodo-anodo. As linhas tracejadas indicam a FTF nas mesmas duas direções para um ponto focal perfeitamente quadrado (Rao & Bates, 1969) 3.8. Varredura densitométrica de uma imagem de fenda (Schiabel et al, 1997a)....... 3.10.…”

Section: Figura 34 (A)unclassified

Metodologia baseada nas funções de transferência para pré-processamento de imagens mamográficas digitais e sua aplicação em esquema computacional de auxílio ao diagnóstico

Vieira¹

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Primeiramente, gostaria de agradecer ao Prof. Dr. Homero Schiabel, meu orientador, pela competência e sabedoria com que liderou este projeto, pela paciência com que me orientou nos meus momentos de fraqueza e principalmente por tudo o que me ensinou, como professor e amigo, ao longo de todos esses anos. Um agradecimento muito especial ao amigo Maurício Cunha Escarpinati, pelos ótimos anos de convivência, pelas longas e importantes discussões sobre o desenvolvimento de cada etapa deste projeto e principalmente pela implementação de todos os algoritmos necessários para sua conclusão. Maurício, sem a sua ajuda este trabalho não teria sido realizado. Muito obrigado! À agora Doutora Ana Cláudia Patrocínio, pelo exemplo de pessoa e pesquisadora que acabou me inspirando e motivando em vários aspectos do meu trabalho, pela amizade demonstrada em tantos anos de convivência e pelos momentos agradáveis que passamos juntos no laboratório e também nos congressos. À Ana Claudia Martinez, pela amizade, pelo carinho e pelo apoio incansável no processamento de mais de 400 imagens para a obtenção dos resultados finais desse trabalho. Ao Cláudio Eduardo Góes, pela amizade e companheirismo, pelas importantes discussões sobre filmes, jogos, super-heróis, gravação e impressão de CDs e principalmente pela disposição em solucionar os diversos problemas burocráticos do laboratório. À Vivian Toledo Santos, pela amizade, pelo incentivo e pelo bom humor que acabou tornando alguns momentos no laboratório muito especiais e divertidos.

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The modulation transfer functions of x-ray focal spots

Cited by 21 publications

References 3 publications

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

Effect of the X-Ray Spectrum and Screen-Film Unsharpness on the Imaging of Blood Vessels.

Metodologia baseada nas funções de transferência para pré-processamento de imagens mamográficas digitais e sua aplicação em esquema computacional de auxílio ao diagnóstico

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