Abstract
This study was carried out in order to obtain good contrast photographs in magnification angiography. First, we compared nine combinations of rare earth intensifying screens (Gd, Ba, La, Y-line) and sixth kinds of film. 1) Comparison of the gradient of characteristic curves by Inverse square sensitometry. 2) Comparison of measured values of photographic density differences by the Al thickness and iodine contrast medium when taking the X-ray photographs of a contrast phantom. 3) Theoretical examination of X-ray spectrum absorbed to intensifying screens of primary X-ray transmitted to contrast phantom and scattered X-rays. Then. we calculated the photographic differences from these data, and compared them with measured values. In the clinical comparison of this system, it is not sufficient to compare the gradients of characteristic curves ; it is also necessary to take X-ray photographs of phantoms with the tube voltage adjusted to the relative photographic sensitivities of the system. This is because film gradients mainly depend on the contrast of X-ray photograghs, and also because element compositions of intensifying screens produce differences to the contrast. Related to this phenomenon is the quality and quantity of scattered X-rays.
