Author: Joseph A. Moore, Paul Rothweiler, Jussi K. Sillanpaa, Adhvaith Sridhar 👨🔬
Affiliation: University of Minnesota 🌍
Purpose: To investigate 3D printed human tissue simulant phantoms for use in radiation therapy and to quantify the mechanical and radiation properties of these phantoms.
Methods: We designed and 3D printed eight phantoms using various mixes of the TissueMatrix, BoneMatrix, RadioMatrix, and Agilus30 materials using a polyjet 3D printer. Phantoms underwent a helical CT scan to measure electron densities at 100kV, 120kV, and 140kV energies as well as MVCT using a tomotherapy machine. Physical mechanical (mass, volume, thickness, and density) and radiation properties (x-ray attenuation) of the phantoms were measured in several trials and compared to expected values calculated from published information on the materials.
Results: Examination of x-ray attenuation results demonstrates the potential for mixes of TissueMatrix, BoneMatrix, and VeroClear materials to be used in 3D printed phantoms for radiation therapy optimization and quality assurance. RadioMatrix was identified as potentially unsuitable due to material composition yielding overestimated densities, consequently leading to inaccurate density assignment and dose calculation.
Conclusion: Traditionally, human tissue simulation in radiation therapy has relied on phantoms composed of materials which approximate the average properties of human tissue but fail to represent tissue heterogeneity or pathological properties. This limits the application of personalized radiotherapy and prevents achievement of the best possible treatment outcomes. Anthropomorphic alternatives are more sophisticated but are associated with high material and manufacturing costs and limited adaptability. We demonstrate the potential for certain 3D printed tissue simulants for use as phantoms in quality assurance. This work indicates the benefits of 3D printed phantoms that can mimic both mechanical properties as well as radiation properties of human tissues. Future work aims to develop complex tissue structures and shapes using layers of compositionally varied material mixes.