Reduction of half-scan shading artifact based on full-scan correction.
OBJECTIVE
Temporal studies (such as blood perfusion) commonly are used to measure function. Radiation dosage is a primary limiting factor for these scans. Half-scan reconstruction can decrease dosage and improve temporal resolution, but is not viable for quantitative studies because of shading artifact. We propose a method for identifying the artifact and minimizing its effect.


METHODS
It is possible to measure the shading artifact by producing both a full-scan and a half-scan reconstruction from the same projection data. A correlation was shown between the subset of data used for reconstruction and per-pixel variation. Furthermore, this variation can be parameterized by only the center angle of the projection data. By performing a single full-scan acquisition, it is possible to generate many half-scan reconstructions and measure the artifact; then future half-scan acquisitions can be corrected.


RESULTS
The artifact is caused by the inhomogeneity in the object being scanned. Before correction, the root mean square error between the half-scan reconstruction and the full-scan is 41.0. After correction, the error is decreased to 10.7, or 26% of the original value.


CONCLUSIONS
We present a method that can measure and correct for object-dependent half-scan shading artifact. This can enable half-scan reconstruction for use in quantitative temporal studies.
Meinel
John Arbash
JA
Department of Radiology, University of Iowa, College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242,USA.
Hoffman
Eric
E
Clough
Anne
A
Wang
Ge
G
D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed