Attenuation of X-rays

X-rays are removed from a collimated beam either by scattering out of the beam or by being absorbed. The process is quantized and probabilistic in nature. An X-ray beam can be considered as a flow of discrete photon particles each having a specific 

This leads naturally to the concept of X-ray attenuation, defined as the natural logarithm of the transmitted intensity fraction  

For X-rays from a continuous energy spectrum, p E), passing through a series of materials indexed by i, the formula for attenuation generahzes to 

Note that the order in which the series of materials occurs is immaterial the contribution of each is weighted according to its areal density and mass attenuation coefficient. 

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Methyl chloride, determination by x-ray absorptiometry, 84 Mica, attenuation of x-rays by, 45 Microanalysis, use of x-rays in histo-chemical and eytochemical, 296-305... 

Traditional radiographic methods use two-dimensional film to record the attenuation of X-rays passing through a three-dimensional object. The... 

Special formulations have been developed to visualize the gastrointestinal tract (see below). Magnevist has also been applied succesfully as an X-ray contrast agent in patients who were allergic to iodine because of the attenuation of X-rays by the gadolinium ion [14]. 

The extension of XRD from small samples to extended objects requires two main modifications of Eq. 10 to account for the self-attenuation of X-rays within the object and also to describe the component of scatter signal that suffers more than one interaction within the object. 

Because of the attenuation of x-rays by air, the x-rays interacting with the cloth would convey three-dimensional information. Also because of the emission of x-rays from many point sources, the image is not in sharp focus. Rather the image is diffuse, and it can best be observed from a distance because the eye integrates the intensity of light so that the image then makes sense. 

Soft X-rays E < 1 keV) are rapidly absorbed by matter and have escape depths from a solid surface only a few pm corresponding to approximately the top thousand atomic layers of a sample. Therefore changes in peak profile, satellite peaks, etc., which are informative of chemical effects, can be used to infer chemical changes in sample surfaces. Since the air attenuation of X-ray becomes quite significant at low energies, the entire sample chamber is placed in vacuum. 

Attenuation of x rays by windows around the sampie and extra background scatter ... 

FIGURE 7 Linear attenuation coefficient of water and contribution of each interaction to the attenuation of X rays as a function of the energy. 

X-ray thickness measurement The measurement of the thickness (mass per unit area) by the attenuation of X-rays passing through the material. See also Thickness. 

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