DTF values as function of disc diameter for 80, 100, and 120 kVp.
(a) Measured ERFs for four beam energies, and (b) MTF curves calculated numerically and by LSF fitting for energies 80 and 120 kVp.
(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.
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.
(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.
(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.
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.
(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.
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.)
% 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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