Physical phantoms are needed for the evaluation and optimization of new digital breast tomosynthesis (DBT) systems.
Previously, we developed an anthropomorphic phantom based on human subject breast CT data and fabricated using
commercial 3D printing. We now present three key advancements: voxelized 3D printing, photopolymer material
doping, and 2D inkjet printing of lesion inserts. First, we bypassed the printer’s control software in order to print in
voxelized form instead of conventional STL surfaces, thus improving resolution and allowing dithering to mix the two
photopolymer materials into arbitrary proportions. We demonstrated ability to print details as small as 150μm, and
dithering to combine VeroWhitePlus and TangoPlus in 10% increments. Second, to address the limited attenuation
difference among commercial photopolymers, we evaluated a beta sample from Stratasys with increased TiO2 doping
concentration up to 2.5%, which corresponded to 98% breast density. By spanning 36% to 98% breast density, this
doubles our previous contrast. Third, using inkjet printers modified to print with iopamidol, we created 2D lesion
patterns on paper that can be sandwiched into the phantom. Inkjet printing has advantages of being inexpensive and easy,
and more contrast can be delivered through overprinting. Printing resolution was maintained at 210 μm horizontally and
330 μm vertically even after 10 overprints. Contrast increased linearly with overprinting at 0.7% per overprint. Together,
these three new features provide the basis for creating a new anthropomorphic physical breast phantom with improved
resolution and contrast, as well as the ability to insert 2D lesions for task-based assessment of performance.