Cone beam z-axis coverage

A method, comprising:

• collimating a radiation beam emitted from a focal spot on an anode of a radiation source of an imaging system to produce a generally conically shaped radiation beam having an extended cone angle along a longitudinal axis that is greater than an effective maximum cone angle determined by an anode angle of the anode;
• and
• acquiring projection data indicative of the radiation that traverses an examination region and illuminates a detector array.

A computer readable medium encoded with computer readable instructions, which, when executed by a computer processor(s), causes the processor(s) to:

• provide a control signal to position collimator blades of a collimator to collimate a radiation beam emitted from a focal spot on an anode of a radiation source of an imaging system to selectively produce a generally conically shaped radiation beam alternatively having a symmetrically or asymmetrically extended cone angle along a longitudinal axis that is greater than an effective maximum cone angle determined by an anode angle of the anode.