Assessment of low energies and slice depth in the quantification of breast tomosynthesis

Abstract

This study attempts to assess the quantitative potential of breast tomosynthesis imaging. Tomosynthesis might be a feasible replacement for digital mammography, so it is worthwhile to consider whether it can be quantitative like computed tomography (CT), where the image pixel values are expressed in Hounsfield units. For this investigation, plastic tissue-equivalent breast phantoms with 10 lesions of varying density in the center along with a small density calibration phantom of 5 density-varying lesions were imaged under several different conditions. The measured voxel value for each lesion from a reconstructed slice was linearly rescaled based on the calibration phantom and then plotted against the known glandular fraction of each lesion. It was found that the two different energies and the three different lesion depths all produced linear voxel values versus glandularity relationships. Therefore, tomosynthesis has quantitative potential. However, in order to convert each 3D image's voxel values to values that can be interpreted as a certain glandular fraction, one must consider the x-ray tube energy, slice depth, and many other factors of the imaging system and the breast. © 2008 Springer-Verlag Berlin Heidelberg.