Quasi-monochromatic parallel radiography utilizing a computed radiography system

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 12-25 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 mm x 1.5 mm. The polycapillary plate was J5022-21 (Hamamatsu Photonics Inc.), and the plate thickness was 1.0 mm. The outer, effective, and hole diameters were 87 mm, 77 mm, and 25 mum, respectively. Quasi-monochromatic X-rays were produced using a 10 mum-thick copper filter, and these rays were formed into parallel beams by the polycapillary, and the radiogram was taken using a computed radiography system utilizing imaging plates. In the measurement of image resolution, the resolution fell according to increases in the distance between the chart and imaging plate using a polycapillary. We could observe a 50 mum tungsten wire clearly, and fine blood vessels of approximately 100 mum were visible in angiography. (C) 2004 Elsevier B.V. All rights reserved.