Motion artifacts in subsecond conventional CT and electron-beam CT: Pictorial demonstration of temporal resolution

To visually demonstrate the effective temporal resolution of subsecond conv entional (slip-ring) and electron-beam computed tomographic (CT) systems, t wo phantoms containing high-contrast test objects were scanned with a slip- ring CT system (effective exposure time, 0.5 second) and an electron-beam C T system (exposure time, 0.1 second). Images were acquired of each phantom at rest, during translation along the x axis at speeds of 10-100 mm/sec, an d during rotation about isocenter at speeds of 0.1 and 0.5 revolution per s econd. Motion artifacts and loss of spatial resolution were judged to be ab sent, noticeable, or severe. For 0.5-second conventional CT images, motion artifacts and loss of spatial resolution were noticeable at 10 mm/sec and 0 .1 revolution per second and were severe at speeds greater than or equal to 20 mm/sec and at 0.5 revolution per second. For 0.1-second electron-beam C T scans, noticeable, but not severe, motion artifacts and loss of spatial r esolution occurred at speeds between 40 and 100 mm/sec and at 0.5 revolutio n per second. Over the range of physiologic speeds examined, the images pro vide visually compelling evidence of the effect of improving temporal resol ution in CT.