An x-ray tube (16) suitable for use in a computed tomography (CT) scanner
(10) includes an envelope (42) which defines an evacuated chamber. An
anode (40) and a cathode assembly (70) are disposed within the chamber.
The anode defines a target area (56) which is struck by electrons (52)
emitted by a filament (54) of the cathode assembly and emits x-rays (46).
The target area lies partially on a first annular portion (80) which is
disposed at first angle (a) relative to a plane perpendicular to an axis
of rotation (R) of the anode, and partially on a second portion (82,120)
which is radially spaced from the first portion and disposed at a second
angle (.beta.), relative to the plane. The second angle is greater than
the first angle. The portions of different slope allow the x-ray tube to
take advantage of a shallow angle, while minimizing the heel effect.