Discussion

Abstract

In the measurement system described in this thesis, several advanced techniques are applied to the quantitation of the left heart’s pumping function. This introduces problems of instrumental as well as of methodological nature. As an X-ray installation is used as a part of the measurement installation, its properties have been investigated. The spatial image transfer characteristics of modern image intensifiers pose no principal problems, but the video part of the system may become a limiting factor. Central synchronization of the X-ray-television subsystem, phase-locked to the mains, is required in order to achieve well-determined radiation pulses. From section II.3. it is concluded that jitter in the synchronization is reflected in a frame-to-frame spatial displacement of picture elements of the order of 0.1 mm. This effect can be neglected in comparison with the accuracy of the LV-contour determination. In videosubtraction it results in a “shift unsharpness” which is rather small compared with other sources of error. Raising the master oscillatoa frequency from 10 MHz to about 500 MHz can solve this problem; it should be considered in combination with the properties of all other links in the TV-chain, especially of the recording/reproducing part and of the electronics used for manipulation of the videosignal.