Author: Gisell Ruiz Boiset, Paulo ROBERTO Costa, Wagner Henrique Marques, Raphael Morata, Victor H.F Oliveira 👨🔬
Affiliation: University of São Paulo (USP), Institute of Physics 🌍
Purpose: This study investigates the feasibility of 3D printing materials in creating anthropomorphic kidney phantoms that accurately simulate the radiological properties of human tissues, for applications in abdominal computed tomography (CT). The aim is to optimize diagnostic protocols for conditions such as nephrolithiasis.
Methods: A patient-specific kidney phantom was designed from DICOM CT images using the 3D Slicer software for tissue segmentation and STL file generation. The phantom was fabricated using a combination of hollow 3D-printed structures and low- cost materials, including epoxy resin to fill the prototype. Acrylonitrile Butadiene Styrene (ABS) were printed on a GTMax3D Core H5 printer. The selection of materials was based on linear attenuation coefficients, μ(E), experimentally determined through X-ray spectrometry. Moreover, a mixture of gypsum, water and marble powder rich in calcium carbonate was used to simulate a kidney stone. The μ(E) values were compared to data from the ICRU-44 report to ensure compatibility with the attenuation properties of human tissues. CT numbers were measured using ImageJ software.
Results: The printed phantoms demonstrated radiological equivalence to human tissues. The average CT number, in Hounsfield Units (HU), for epoxy resin was found to be 59 HU, compared to the reference value of 42 HU for soft tissue. The lithiasis simulation was achieved using a prototype that demonstrated nearly 1000 HU. However, the ABS filament exhibited -50 HU, approximately, indicating insufficient radiological equivalence.
Conclusion: Fused Filament Fabrication 3D printing is a highly viable and innovative approach for producing anthropomorphic phantoms in imaging diagnostics. The epoxy resin and the mixture of gypsum and marble powder proved to be a suitable low-cost material for accurately replicating soft tissue, demonstrating a high degree of fidelity in imaging characteristics. Future studies should explore advanced techniques such as dual-extrusion printers and a broader range of materials to evaluate their medical applicability.