Anthropomorphic software breast phantoms have been introduced as a tool for quantitative validation of breast imaging
systems. Efficacy of the validation results depends on the realism of phantom images. The recursive partitioning
algorithm based upon the octree simulation has been demonstrated as versatile and capable of efficiently generating large
number of phantoms to support virtual clinical trials of breast imaging.
Previously, we have observed specific artifacts, (here labeled “dents”) on the boundaries of simulated Cooper’s
ligaments. In this work, we have demonstrated that these “dents” result from the approximate determination of the
closest simulated ligament to an examined subvolume (i.e., octree node) of the phantom. We propose a modification of
the algorithm that determines the closest ligament by considering a pre-specified number of neighboring ligaments
selected based upon the functions that govern the shape of ligaments simulated in the subvolume.
We have qualitatively and quantitatively demonstrated that the modified algorithm can lead to elimination or reduction
of dent artifacts in software phantoms. In a proof-of concept example, we simulated a 450 ml phantom with 333
compartments at 100 micrometer resolution. After the proposed modification, we corrected 148,105 dents, with an
average size of 5.27 voxels (5.27nl). We have also qualitatively analyzed the corresponding improvement in the
appearance of simulated mammographic images. The proposed algorithm leads to reduction of linear and star-like
artifacts in simulated phantom projections, which can be attributed to dents. Analysis of a larger number of phantoms is