Identification of objects of interest, nonattenuated, and background zones in an image of the PMMA phantom.
(a) Contrast in individual attenuation density images as a function of the iodine mass thickness at 4.4 mGy breast-entrance air kerma. (b) Difference between iodine and adipose tissue mass attenuation coefficient (solid) and between iodine and glandular tissue (dashed). The adipose and glandular tissue curves look indistinguishable in the plot. The vertical lines indicate the mean spectral energies of Mo25 (16.5 keV) and Rh40 (21.0 keV).
Individual raw image information in regions of interest corresponding to background and tubes filled with or water in Mo25 and Rh40 images. The curves are visual guides to data. (a) Signal variances and as a function of their mean values and . Variance was measured either with FINEVIEW activated (on) or deactivated (off). (b) SNR predictions/data in individual raw images.
Best results from the application of the weighted subtraction method. (a) DET-L with Mo25–Rh40 at and (b) DET-H with Rh34–Rh45H at .
Histogram of the background signal in the resulting image sampled in the four . The subtraction modality was DET-L with Mo25–Rh40 at .
Contrast predictions (curves) and data (symbols) in the subtracted images under various subtraction modalities and both subtraction orders as a function of the iodine mass thickness. (a) M25–Rh40, standard order. (b) Rh34–Rh45H, standard order. (c) Mo25–Rh40, inversed order. (d) Rh34–Rh45H, inversed order.
CNR data (symbols) and predictions (curves) for the tube with in the subtracted images under various modalities as a function of . (a) Mo25–Rh40. (b) Rh34–Rh45H, showing experimental CNR for the only technically feasible values (see text).
CNR predictions (solid curves) and data (symbols) in the subtracted images under various subtraction modalities as a function of the iodine mass thickness. (a) Mo25–Rh40 at . (b) Rh34–Rh45H at . The dotted curves correspond to quadratic regressions to DET-L with Mo25–Rh40 and DET-H with Rh34–Rh45H.
FOM experimental values for the tube with as a function of , for all subtraction modalities under both spectral choices. The solid curves are visual guides to data. Uncertainties have been excluded to facilitate visualization.
Beam quality characteristics (identification, HVL in mm Al, equivalent energy , mean energy , and normalized mean glandular dose ) for the mammographic x-ray spectra used in this work.
Spectra used in each subtraction modality, including the experimental values of the weighting factor in the standard subtraction order.
Iodine mass thicknesses of various phantom tubes filled with . Also included are the number of sampled pixels in a tube region in the resultant image ( is the tube mean chord and is an arbitrary sampling length) and the scaling factor .
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