Quasi-monochromatic polycapillary imaging utilizing a computed radiography system

摘要

A fundamental study on quasi-monochromatic parallel radiography using a polycapillary plate and a copper-target x-ray tube is described. The x-ray generator consists of a negative high-voltage power supply, a filament (hot cathode) power supply, and an x-ray tube. The negative high-voltage is applied to the cathode electrode, and the anode electrode is connected to the ground. In this experiment, 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 polycapillary plate was J5022-16 (Hamamatsu Photonics Inc.), and the plate thickness was 1.0 mm. The outer, effective, and hole diameters were 33 mm, 27 mm, and 10 μm, respectively. Quasi-monochromatic x-rays were produced using a 10 μm-thick copper filter with a tube voltage of 17 kV, and these rays were formed into parallel beams by the polycapillary. The radiogram was taken using a computed radiography system utilizing imaging plates. In the measurement of image resolution, the resolution hardly varied according to increases in the distance between the chart and imaging plate using a polycapillary. We could observe a 50 μm tungsten wire clearly, and fine blood vessels of approximately 100 μm were visible in angiography.