Experimental Investigation of the Necessity for Extra Flat Field Corrections in Quality Control of Digital Mammography

摘要

The purpose of this work was to investigate whether extra flat field corrections should be applied prior to the calculations of quality control quantities and whether there are necessary precautions regarding flat fielding in digital mammography. Effects from using one standard flat field correction for all imaging situations or absence of correction procedures were examined using homogenous PMMA slabs. Differences in field profiles for various exposure geometries and breast thicknesses were quantified. For three systems the maximal deviation of averaged pixel values (along a profile of ROIs parallel to the chest wall) varied from 1.3 % to 6.8 % over the whole image and from 0.6 % to 2.6 % if the analysis is limited to the central part. Extra flat field corrections are not necessary for most applications. If required, the corrections should be performed from images acquired with the same manual exposure and not after a time gap.