Radiological and dosimetric characterization of 3D printing materials.

The aim of this work was to study dosimetric and CT number responses for some Fused Filament Fabrication 3D printing materials, $i.e.$, PoLylActide (PLA) and Acrylonitrile Butadiene Styrene (ABS). The certified phantom CIRS was used as reference. It is composed of several cylindrical inserts of tissue-equivalent materials: dense bone, trabecular, liver, lung (exhale and inhale), adipose, muscle and breast. Using the 3D CAD Inventor and 3D slicing IdeaMaker software, and a RAISE 3D pro2 plus 3D printer, cylindrical samples were designed and printed setting different infill densities to reproduce the CIRS soft tissues. To reproduce CIRS hard tissues, printed hollow cylinders were filled with different mixtures of water and plaster. For each printed sample: Hounsfield Unit (HU) was measured in CT using large and small FOV; charge and dose values ({6\mbox$--$10 ${MV}$ photon beams, $100 {MU}$, TrueBeam LinAc) were measured through a Farmer ionization chamber positioned on 5 slabs of RW3 and under two slabs of RW3 ({$SSD$ = 100 ${cm}$), printed phantom was placed on the RW3 at field centre. 3D printing conditions and mixtures of water and plaster for reproducing CIRS tissue-equivalent materials were obtained.