The Application of Optical Transfer Function in Radiography

The image transfer systems in radiography are classified into four stages corresponding to the tone reproduction characteristics of each element. The optical transfer treatment can be applied to imaging elements at the linear stages effectively. The optical transfer functions of the x ray fluorescent screen, the x ray tube focus and the x ray intensifying screen are obtained experimentally using a direct scanning apparatus which acts as a Fourier transformer. The optical transfer function of the x ray tube focus measured and the line spread function calculated are qualitatively corresponding to the photographs of the Siemens' star and the pin-hole respectively. The optical transfer function of the intensifying screen can be obtained by additive combination of front and back screen. Over-all Optical transfer functions in radiophotography, radiography and fluoroscopy at the linear stage are calculated as an imaging property of image transfer systems.