Radiological properties of 3D printed materials in kilovoltage and megavoltage photon beams

Purpose: This study evaluates the radiological properties of different 3D printing materials for a range of photon energies, including kV and MV CT imaging and MV radiotherapy beams. Methods: The CT values of a number of materials were measured on an Aquilion One CT scanner at 80 kVp, 120 kVp and a Tomotherapy Hi Art MVCT imaging beam. Attenuation of the materials in a 6 MV radiotherapy beam was investigated. Results: Plastic filaments printed with various infill densities have CT values of -743 +/- 4, -580 +/- 1 and -113 +/- 3 in 120 kVp CT images which approximate the CT values of low-density lung, high-density lung and soft tissue respectively. Metal-infused plastic filaments printed with a 90% infill density have CT values of 658 +/- 1 and 739 +/- 6 in MVCT images which approximate the attenuation of cortical bone. The effective relative electron density REDeff is used to describe the attenuation of a megavoltage treatment beam, taking into account effects relating to the atomic number and mass density of the material. Plastic filaments printed with a 90% infill density have REDeff values of 1.02 +/- 0.03 and 0.94 +/- 0.02 which approximate the relative electron density RED of soft tissue. Printed resins have REDeff values of 1.11 +/- 0.03 and 1.09 +/- 0.03 which approximate the RED of bone mineral. Conclusions: 3D printers can model a variety of body tissues which can be used to create phantoms useful for both imaging and dosimetric studies. Crown Copyright (C) 2017 Published by Elsevier Ltd on behalf of Associazione Italiana di Fisica Medica. All rights reserved.