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1.
Figure 4

Figure 4. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Spectrum used for the beam hardening study.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
2.
Figure 5

Figure 5. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Attenuation of the head and body bowties used as the static, reference bowties in this work.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
3.
Figure 9

Figure 9. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Beam hardening corrections. (a) A standard bowtie without any beam hardening corrections, (b) a standard bowtie with a water beam hardening correction, (c) a dynamic bowtie with a water beam hardening correction, and (d) the dynamic bowtie with the two-pass correction. [WL, WW] is [0, 200].

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
4.
Figure 3

Figure 3. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Closeup of a single wedge. Each axial cross-section through the wedge is a triangle. (a) The full wedge shape from the front. (b) Full wedge with top third removed. The exposed cross-section is a thin triangle. (c) Full wedge with two thirds removed. The exposed cross-section is a triangle with a greater height.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
5.
Figure 6

Figure 6. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Attenuation sinograms from the dynamic range minimization task. The attenuation sinogram is the attenuation of the object added to the attenuation provided by the system through either the bowtie or the virtual attenuation of tube current modulation. In the dynamic attenuation sinogram, the triangular pieces of the piecewise-linear attenuation function can sometimes be seen (arrows).

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
6.
Figure 7

Figure 7. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Visualization of the relative standard deviation and dose for the dynamic bowtie and reference systems. The dynamic bowtie here minimizes dynamic range everywhere, causing the noise to often be highest near the boundary of the object and the air. This is most cleanly visualized in the adult head. Summary statistics are also provided in Table 3.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
7.
Figure 8

Figure 8. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Visualization of the relative standard deviation and dose for the dynamic bowtie and reference systems. The dynamic bowtie here minimizes dynamic range of rays that pass through the object support eroded by 2 cm. This removes the high noise for pixels near the edge. Summary statistics are also provided in Table 3.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
8.
Figure 1

Figure 1. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Two-dimensional schematics of the traditional bowtie filter and the proposed dynamic bowtie filter, with the square representing the x-ray source, emitting a fan beam of radiation. (a) One possible traditional bowtie filter shape and its corresponding attenuation profile. (b) The proposed bowtie, composed of triangular wedges. In this configuration, the produced attenuation profile is similar to the traditional bowtie. (c) By moving the attenuating wedges into and out of the plane, the heights of the triangles are changed such that a different attenuation profile can be produced.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.
9.
Figure 2

Figure 2. From: The feasibility of a piecewise-linear dynamic bowtie filter.

Three-dimensional rendering of the attenuator wedges. Two layers of wedges, all at the same axial location, are shown in (a) a perspective view and (b) an axial cross-section. The individual wedges may be translated in the longitudinal direction, causing them to shift in (c) the perspective view, and changing the thickness of the triangles are (d) the axial cross-section. In this case, the translation of the sixth wedge from the left downwards in (c) reduces c6, and the translation of the ninth wedge upwards increases c9. When all the wedges are independently translated, a family of piecewise-linear attenuation functions is possible.

Scott S. Hsieh, et al. Med Phys. 2013 March;40(3):031910.

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