Development of Energy Subtraction X-ray Television for diagnosis of cardiopathy

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A K-edge subtraction television system was developed utilizing a high speed monochromator, two CCD camera systems, two laser video disc recorders and an image processing system combined with a synchrotron radiation system. After injection of contrast medium (iodine), the subject is irradiated by monochromatized dual energy X-ray flux closely bracketing the K-edge energy of iodine, alternately. The subtraction images derived from each pair of the X-ray images visualizes contrast medium only. Continuous flow of the contrast medium in vessel can be observed by a serial display of the processed images.The system was improved to obtain clear subtraction images of coronary arteries, as follows:1, An electronic driving monochromator was introduced in order to synchronize the X-ray energy change and the TV frame.2, Frame transfer CCD cameras were utilized to improve vertical resolution.3, The image processing algorithm was investigated to improve image quality, comparing the characteristics of the system with that of a conventional DSA system.This system has been used to display a coronary artery of an anesthetized dog and the obtained images were shown as real time VCR images at the BSR Conference held in Tsukuba, Japan, at Sept. 1992.