Figure 4.

Simulated images of a background, nonlesion containing phantom. The images were acquired with identical conical slant-hole collimators, with the exception of one having equally spaced cones (a) and the other having cones that were spaced such that the uncovered annular areas at the detector were equal (b). The spacing based on equal annular area provided more uniform background intensity. (The increased intensity in the center is due to a small opening in the collimator where the truncated cones did not come to a point.)