1990 Volume 46 Issue 11 Pages 1731-1737
The characteristic curve of widely used X-ray cinefilm is thought not to be represented precisely when routinely measured by a sensitometer. The main reasons are as follows; the exposure time of the sensitometer is longer than that of the actual exposure time of X-ray cineradiography, and the secondary emitted fluorescent spectrum from the image intensifier (I.I.) does not correspond to the green-filter which is used for simulation. The purpose of this investigation was undertaken to solve these problems using a photo electronic flash (strobe) as the light source which can obtain a shorter flash exposure time than a routinely used sensitometer for X-ray cineradiography. We also investigated the changes of the spectral transmission rate of the green-filter which influenced the characteristic curve when exposed under various kinds of green-filters. The following conclusions were obtained. 1. The flash time of strobe was noted as 2 msec, and it emitted enough light quantity to draw up the characteristic curve. 2. The high voltage direct current was found to be an adequate power supply for strobe flash. 3. The higher reproducibility of the light flash was obtained using constant charging time of the strobe. Also, it could measure average photographic density of the film under multiple exposures. 4. The spectrum distribution of the green-filter must coincident with the fluoresence wave-length of which is a secondary emission of I.I. 5. The characteristic curve which is drawn by our method is closely like that of the X-ray ND method.
