Real time K-edge subtraction x-ray imaging

Abstract

This paper describes an x-ray K-edge subtraction television system for noninvasive angiography utilizing synchrotron radiation. The phantom, including contrast material (iodine), is irradiated by monochromatized dual-energy x-ray flux, alternately, using a high speed monochromator. The monochromator consists of a silicon crystal plate vibrating at 15 Hz so that the phantom is irradiated by the x-ray flux of 150 eV above and below the K-edge photon energy of iodine, 15 times per second. As an x-ray detector, TV cameras optically coupled to an x-ray image intensifier are used and the video signal is processed to display the subtraction image of pairs of successive images in real time. This system was fully implemented and moving phantoms were examined. Both the time interval between the energy change and the exposure time of each image has been shortened to 2 ms.

Ratio-contrast imaging of dual-energy absorption for element mapping with a scanning transmission X-ray microscope

“…A frequently used method to trace elements by X-ray imaging is K-edge subtraction (KES) (Jacobson, 1953;Kruger et al, 1977;Fukagawa et al, 1989;Elleaume et al, 2000), which involves subtracting the results of the corresponding pixels' signals in the two images. In this method the threshold of the resulting contrast image that is used to determine whether a pixel contains the specified element cannot be determined directly from theory and relies on the different devices and experiment results.…”

Medical Applications with Synchrotron Radiation in Japan

“…Three different techniques for K-edge energy exchange have been developed, namely the oscillatory method (Akisada et al, 1986;Fukagawa et al, 1989;Takeda et al, 1990), the ®lter method (Umetani et al, 1993;Takeda, Itai, Yoshioka et al, 1994), and the use of a dual linearly polarized synchrotron radiation beam from an elliptic multipole wiggler . In the oscillatory method, images above and below the iodine K-edge are obtained by changing the angle of the monochromator, whereas in the ®lter method a small ®lter ®lled with iodine ®ltrates the beam with mixed X-ray energy, and subtraction between the ®ltered and non-®ltered images forms coronary images.…”