RELATIONSHIP BETWEEN THE CHARACTERISTICS OF SUBJECT THICKNESS : FILM DENSITY AND CHARACTERISTIC CURVE OF LIGHT A SIMULATED SENSITOMETER FOR CINERADIOGRAPHY

Abstract

When an X-ray cine-camera is used, the characteristics of film density in relation to the change in the thickness of objects could be determined under the same conditions as normal clinical cases. The exposure to film that the X-ray cine-camera has measured at the time of automatic control changed almost linearly in relation to the thickness of the object. However, the correlation of this exposure with the exposure of a light sensitometer is nonlinear;thus the characteristics of this film density differ from the characteristics resulting from light sensitometry. Furthermore, since the relation between the exposures is different according to the film, the differrence of the characteristic curves due to film does not reflect on the differrence of the characteristics regarding the characteristics of film density.