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Impact of flat panel-imager veiling glare on scatter-estimation accuracy and image quality of a commercial on-board cone-beam CT imaging system
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Image of FIG. 1.
FIG. 1.

DTF values as function of disc diameter for 80, 100, and 120 kVp.

Image of FIG. 2.
FIG. 2.

(a) Measured ERFs for four beam energies, and (b) MTF curves calculated numerically and by LSF fitting for energies 80 and 120 kVp.

Image of FIG. 3.
FIG. 3.

(a) Comparison of the LSF models derived from fitting Eq. (7) to ERF measurements (red); fitting Eq. (4) to the DTF measurements (blue); and direct differentiation of the ERF (black) for 120 kVp. Because of the logarithm scale at the x-axis, the delta peak of the LSF derived by Eq. (4) is not shown at 0 mm. (b) Ratio of ERF derived by direct and ERF derived from LSF fit.

Image of FIG. 4.
FIG. 4.

FPI central-plane transverse profiles before and after convolution and ratio of the profiles with veiling glare to that without veiling glare, showing the detector signal change with and without BTF.

Image of FIG. 5.
FIG. 5.

(a) Split central slice image, reconstructed from synthetic projections computed without BTF with veiling glare (right half) and without (left half); (b) Profiles through images reconstructed from projections with and without veiling glare PSF convolution. No correction for scatter or beam hardening was made in the polyenergetic case while the monoenergetic simulation assumed perfect scatter compensation, (c) Split image, (veiling glare on right side, no veiling glare on left side), for polyenergetic projections with BTF; and (d) Same as (b) except for projection data assuming BTF.

Image of FIG. 6.
FIG. 6.

(a) Transverse-plane images at the noted axial distance from the bone insert edge reconstructed from synthetic projections including the effect of the veiling glare. The four quadrants of the image show reconstructed planes at the indicated axial distances from the bone insert edge. (b) Reconstructed water attenuation coefficient versus axial distance from the bone insert edge. The coefficients are sampled along the axis of the cylindrical insert.

Image of FIG. 7.
FIG. 7.

Demonstration of the impact of veiling glare on SPR measurements, uncorrected for scatter-volume blocking effects. (a) SPR values for a single beam stop of variable diameter extracted from synthetic projections calculated from Monte Carlo simulation with and without the veiling glare effect included. (b) Data from Fig. 7(a) presented as a ratio, illustrating SPR overestimation due to the veiling glare.

Image of FIG. 8.
FIG. 8.

(a) A Monte Carlo projection of the water phantom, with a beam-stop array of 2 mm diameter discs without BTF and ASG. (b) Comparison between the calculated SPR with and without the veiling glare taken into account. The continuous curve corresponds to the SPR calculated by Monte Carlo simulation, without the beam-stop array.


Generic image for table

Numerical values of the parameters of Eq. (4), determined by fitting on the DTF data. (Average beam energies were calculated by using the Birch–Marshall model and filtration of 3.1 mm of Aluminum for all beams.)

Generic image for table

% contrast values in reconstructed images of the water phantom with 2 cm adipose tissue contrast inserts. Projection data were computed with and without use of the BTF, while veiling glare is introduced to the data by convolving the synthetic projections with the measured detector PSF. Simulated tube voltage: 120 kVp.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Impact of flat panel-imager veiling glare on scatter-estimation accuracy and image quality of a commercial on-board cone-beam CT imaging system