Inherently 3-dimensional method for measurement of computed tomographic resolution anisotropy.
OBJECTIVE
Current techniques to measure computed tomography (CT) spatial resolution use separate methods for in-plane and out-of-plane directions. The growing use of near-isotropic voxel size necessitates a new single method that inherently measures resolution in any direction.


METHODS
We introduce a method using a set of numerous glass microspheres suspended in a small volume from which a mean sphere image is constructed. Projecting asymptotes after imaging different microsphere sets with decreasing diameters provides an inherently 3-dimensional measure of spatial resolution and anisotropy. We apply the method to both a flat-panel and multidetector CT scanner.


RESULTS
The full-width at half-maximum from line profiles through mean sphere in transverse directions corresponds to known microsphere diameters. Increased longitudinal full-width at half-maximum corresponds to known anisotropy, which is larger for a multidetector CT scanner than for a flat-panel CT scanner.


CONCLUSIONS
A new single method to measure CT resolution is inherently isotropic.
Jones
Stephen E
SE
Department of Radiology, Massachusetts General, Hospital, Boston, MA 02114-2698, USA. sejones@partners.org
Grasruck
Michael
M
Schmidt
Bernhard
B
Madisch
Ijad
I
Egeland
Ryan
R
Brady
Tom
T
Gupta
Rajiv
R
D016880:Anisotropy; D021621:Imaging, Three-Dimensional; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*