[Measurements in triggered CT imaging of moving objects].

Abstract

This paper describes results of measurements characterising the image properties of a CT apparatus triggered by an "R-peak simulator". For this purpose, a phantom was constructed in which--as straightforward simulation of a cardiac wall movement--a plate made of plexiglass of 5 mm wall thickness moves to and fro with a frequency nu (1 s-1 less than or equal to nu less than or equal to 2 s-1) and an amplitude of A = 10 mm. The number of scanning cycles during a measurement could be varied between 2 and 9. It was evident that the measured density values as well as the positions of the plate which could be ascertained from the CT images in the various phases of movement, especially at low frequencies and a large number of cycles, agree well with the real values; however, it was also found that both at the measured density values and the positions of the plate as seen from the CT images, systematic deviations occur, especially at high frequencies and a small number of scanning cycles.