Introduction of a Novel Technique in Density-Adjusted 3D Printing for the Manufacture of Soft-Tissue-Equivalent Radiological Phantoms

The aim of this study is to introduce a new filament and novel 3D printing technique to adjust the density of a printing job in order to mimic the radiological properties of different tissues. We used a special filament, Light Weight PLA (LW-PLA), which utilizes foaming technology triggered by temperature. Cylindrical samples were printed at various temperatures, flow rates, print speeds, and diameters. A computed tomography (CT) scan was performed to identify their radiological properties in terms of the mean Hounsfield Unit (HU). The densities of the samples ranged from 0.36 g/cm(3) to 1.21 g/cm(3), corresponding to mean HU values between -702.7 +/- 13.9 HU and +141.4 +/- 7.1 HU. Strong linear correlations were observed between the flow rate and density as well as the flow rate and mean HU. The axial homogeneity of the samples was reported as being comparable to that of distilled water. A reduction in the mean HU was observed at a lower print speed and it changed slightly with respect to the sample size. Reproducibility assessments confirmed consistent results for identical printing jobs. Comparisons with regular PLA samples revealed a superior homogeneity in the LW-PLA samples. The findings of this study suggest a practical and accessible solution for mimicking all of the soft tissues, including the lungs, by using a single filament.