The linearity between CT numbers and iodine concentrations is proved analytically provided the correlations between the atoms are negligible. This relationship is applied to correct the CT numbers in the ICA regions in monochromatic images of dual energy CT with the slow kV-switching technique where one scan with a low/high tube voltage follows by another scan with a high/low voltage. The iodine concentration may change significantly during the kV-switching. The resultant CT numbers in ICA regions may not be meaningful in the monochromatic images from pre-reconstruction decompositions because the data with the low/high voltages are not consistent. Using the linearity between CT numbers and iodine concentrations, the CT numbers in ICA regions can be corrected by referring to the CT numbers in the polychromatic images with the low/high voltages. A numerical simulation and a phantom study are performed to examine the linearity between CT numbers and iodine concentrations. The CT number correction by use of the linearity is tested in the numerical simulation study in slow kV-switching dual energy CT. The results show that the corrected CT numbers by use of the linearity are accurate.

Date Published: 13 March 2009
PDF: 8 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72583Z (13 March 2009); doi: 10.1117/12.811709

Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)