CT number variations due to different image acquisition and reconstructionparameters: a thorax phantom study

mA humanoid thorax phantom containing six compartments was scanned with two different computed tomography (CT) scanners using various image acquisitio n and reconstruction parameters. The differences of CT numbers were statist ically significant between the two CT scanners for each compartment (p < 0. 001) except for the "air" compartment. The variabilities of the CT numbers are described for the different parameters. The mean CT numbers of the "wat er" compartment, for instance, ranged from 1 to 15 HU (Hounsfield Units), t hose of the "air" compartment varied from -962 to -990 HU. Knowledge of the se CT number variabilities is necessary when CT numbers are used for tissue characterization. (C) 2000 Elsevier Science Ltd. All rights reserved.