[Simulation and experimental study of cone artifact in spiral CT].

Objective: To study regular patterns of cone artifact resulted from interpolation algorithm of spiral CT.

Methods: Based on the principle of interpolation algorithm and back-projection reconstruction, a mathematical model of the reconstructed image was established to clarify the relation of the scanning parameters and the characteristics of the scanned object with the cone artifact. Experiments were carried out by a set of acrylic phantoms on siemens plus 4 CT scanners.

[High-contrast resolution measurement of CT and phantom testing].

The authors adopted subjective and objective methods for measuring high-contrast resolution (HCR) of CT and explored the parameters in relation to HCR. With Catphan500 and a self-prepared experimental phantom, the two CT sets were tested for HCR with varied slice thickness and kernels. The subjective assessment of the images was carried out by visual detection of HCR, and objective assessment was performed by calculations.

[Evaluation method of CT number linearity].

Objective: To explore the method for computed tomography (CT) number linearity evaluation.

Methods: The model CTP401 of Catphan500 phantom was adopted to test 43 sets of CT scanners under the same scanning conditions. 1- and 2-order curve fitting of the testing results of each scanner were performed, with the bending of the 2-order fitted curve defined as the degree of CT number non-linearity and the slope of the linear fitting as contrast scale.