The fraction of photons that interact per unit path length with an absorber.
The calculated remainder of the x-ray beam that is received by the detectors in a computed tomography (CT) unit. This value is used to determine the CT (Hounsfield) number.
The ratio of the change in x-ray beam strength (photons) as it passes through a material, in comparison to a specified attenuation standard, is referred to as the attenuation coefficient.