The 1995 and 1998 paper are perception investigations.

1995 Cine Viewing of Spiral Chest CT Images
1998 Influence of CT Image Size and Format on Accuracy of Lung Nodule Detection

The 2008 paper is an attempt to reach closure on my scheme to evaluate CAD systems using the frequency that human observers report suspicious image features

2008 Characteristics of suspicious features in CT lung-cancer screening images