Noise patches comparison for the four images in <b>Figure 8</b>.

<p>Each sampled region is concatenated with dividing columns (zeros) and displayed in dynamic contrast window to show noticeable differences. From left to right, FBP with sharp kernel filtering, FBP with soft kernel filtering, IRT (LS), and IRT (TV).</p

A modeling effect comparison on LS and TV images: (a) Coronal view of soft contrast section of phantom, (b), (c), and (d) show axial views of line A, B, and C respectively.

<p>The FFS only model (so called Siddon Model, ) shows circular line artifacts in LS and TV as well. In contrast, the proposed model () shows high quality image even in LS without regularization term and significant noise suppression effect on TV.</p

Soft contrast and conspicuity comparison for (a) FBP with sharp kernel filtering, (b) FBP with soft kernel filtering, (c) Least-Squares solution after -iteration, and (d) Total Variation (TV) image after -iteration with (c) initialization .

<p>Soft contrast and conspicuity comparison for (a) FBP with sharp kernel filtering, (b) FBP with soft kernel filtering, (c) Least-Squares solution after -iteration, and (d) Total Variation (TV) image after -iteration with (c) initialization .</p

Consecutive error plot of Siddon and the proposed method .

<p>The NRMSEs of two consecutive images are calculated and displayed in log-log plot. The proposed method exhibits smaller consecutive errors after iterations compared to Siddon method and reaches smaller modeling error.</p

Modular system model effects: (a) Images are displayed in HU and (b) difference maps are displayed in dynamic contrast range.

<p>: : Focal Spot model, : Flying Focal Spot model, and : Detector model.</p

Focal spot area diagram: The length (), width (), and height () of the focal spot area (rectangular shape) are denoted in the diagram.

<p>Focal spot area diagram: The length (), width (), and height () of the focal spot area (rectangular shape) are denoted in the diagram.</p

Spatial resolution bar pattern comparison: (a) FBP (sharp kernel) and (b) TV with high fidelity term image with proposed model (111) are displayed in HU.

<p>(a) shows clear separations of 4, 6, and 8 and (b) presents improved resolution showing 10 and 12 bar patterns. (c) compares profiles of spatial resolution inserts.</p

Flying Focal Spot () modeling: (a) model shows deflected to the angular direction and (b) model shows -directional deflections.

<p>Flying Focal Spot () modeling: (a) model shows deflected to the angular direction and (b) model shows -directional deflections.</p

SNR comparison of the three reconstruction methods for the half-dose dataset in Figure 10.

<p>SNR comparison of the three reconstruction methods for the half-dose dataset in Figure 10.</p

Comparison of reconstruction methods on half-dose images: (a) Reconstructed images, with (L) FBP, (M) IRIS, and (R) TV with advanced system modeling, (b) Zoomed images from different slices; each sub-figure shows (L) FBP, (M) IRIS, and (R) TV with advanced system modeling. Display in HU.

<p>Comparison of reconstruction methods on half-dose images: (a) Reconstructed images, with (L) FBP, (M) IRIS, and (R) TV with advanced system modeling, (b) Zoomed images from different slices; each sub-figure shows (L) FBP, (M) IRIS, and (R) TV with advanced system modeling. Display in HU.</p