Influence of an object's z-axis location and location on the axial plane on the voxel value representation and uniformity in cone beam computed tomography

Abstract

Objective: This study aimed to determine the influence of an object's z-axis location and location on the axial plane on the voxel values in cone beam computed tomography.

Study design: The CTP401 and CTP486 of the Catphan 500 phantom were scanned with an Alphard-3030 at 6 locations in the z-axis.

Results: In CTP401, the voxel values of 3 inserts showed the lowest values when the center of the radiation field corresponded to under 2 or 4 cm of the z-axis center of CTP401. In CTP486, the voxel values showed the lowest values when the center of the radiation field corresponded to under 2 or 4 cm of the z-axis center of CTP486. On the same axial plane, the voxel values at the center showed significantly lower values than the off-center locations (P = .002).

Conclusions: The voxel values in the Alphard-3030 changed based on the z-axis location of the radiation field and were nonuniform on the same axial plane.