(a) Geometry of the prototype breast tomosynthesis system. (b) A photograph of the prototype tomosynthesis system used in our investigation.
Diagram showing the image sequence used in lag measurement: An offset image was acquired before x-ray exposure, and image frames were acquired after a single x-ray exposure. The x-ray exposure varied from 0.5 to 15 mR. The time intervals between subsequent image views are 0.5 and 0.8 s, respectively, for binning and full resolution modes.
Diagram for ghosting measurement; x-ray sensitivity was measured at a reference exposure before (a) and after (b) ghosting exposures. The exposure for ghosting ranged from 10 to 1000 mR. Ghosting is quantified as ratio of sensitivity at reference exposure before and after ghosting.
(a) Presampling MTF measured from the system; (b) a comparison of MTF due to detector inherent resolution, focal spot blur, and oblique entry angle; and (c) calculated and measured MTF due to oblique x-ray entry alone.
Pixel response of the detector in full resolution and binning modes as a function of x-ray exposure. Measured data are shown with symbols and linear fitting shown with straight lines. for full resolution and 114 for binning mode.
(a) Measured electronic noise NPS (in orthogonal directions of the detector) in both full resolution and pixel binning modes; (b) NPS at different detector exposures for both modes. For clarity, only NPS in the data-line (binning) direction is shown. The Nyquist frequencies of NPS are 5.88 and 2.94 cycles/mm, respectively, for full resolution and binning modes.
Measured detector DQE at different exposures in full resolution and binning modes. Individual symbols are used for the results in full resolution mode, and lines are used for the binning mode.
Lag as a function of frame number measured at different detector exposures for (a) full resolution and (b) binning mode.
Ghosting measurement, quantified as sensitivity at reference exposure as a function of ghosting exposure.
Detector acquisition modes used in the present investigation.
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