RESUMO
A fundamental study on quasi-parallel radiography using a polycapillary plate and a copper-target x-ray tube is described. In the experiments, the tube voltage was regulated from 12 to 22 kV, and the tube current was regulated within 3.0 mA by the filament temperature. The exposure time was controlled in order to obtain optimum x-ray intensity, and the maximum focal spot dimensions were approximately 2.0 x 1.5 mm. The thickness and the inner capillary tube diameter of the polycapillary were 1.0 mm and 25 microm, respectively. Monochromatic x-rays were produced using a 10 microm-thick nickel filter with a tube voltage of 17 kV, and these rays were formed into quasi-parallel beams by the polycapillary. The radiogram was taken using a computed radiography system utilizing imaging plates. In the measurement of image resolution, the spatial resolution hardly varied according to increases in the distance between the resolution-test chart and imaging plate using a polycapillary. A 50 microm tungsten wire could be observed, and fine blood vessels of approximately 100 microm were visible in angiography.
