Evaluation of the impact of tube current modulation on lesion detectability using model observers.

We use several model observers to evaluate the influence of tube current modulation on lesion detectability in x-ray computed tomography images reconstructed using the classical direct fan-beam filtered backprojection algorithm. Specifically, we compute observer performance for a lesion detection task at various locations in an elliptic water cylinder using simulated x-ray data. The observer performance is computed both with and without x-ray tube current modulation. For different tube current modulation schemes, we find that the Hotelling observer and the channelized Hotelling observer with Gabor channels yield distinctly different qualitative behavior compared to channelized Hotelling observers with circularly symmetric channels and to non-prewhitening observers.