Wide-Field X-Ray Tube Comparisons

X-ray tubes having similar resolution capabilities along the central ray were compared for their wide-field characteristics. It has been suggested that focal spot size, and therefore resolution capability, along the cathode-anode axis may vary in a manner which is dependent upon the tube target angle. The authors show that differences beyond the effects of target angle occur, the extent of those differences varying from tube to tube. Although 2 different-sized focal spots may be adjusted to have equivalent central beam resolution capabilities, they can exhibit different imaging capabilities at wide-angle (off central axis) position. More than one parameter (equivalent focal spot size) is needed to characterize the behavior of a focal spot.