Purpose: We are sharing our 3D printing experience from fabricating an anthropomorphic phantom for a dosimetric study in radiotherapy. The goal was to create a phantom which replicates the geometries and densities of a test patient’s body, lung and bone structures.
Methods: In 2021, we purchased a dual-extruder FDM 3D printer (Creatbot Model F430) for creating a custom phantom suitable for film dosimetry. We extracted the body, lung and bone contours from a patient’s CT images. The DICOM-RT contours were converted to volumetric STL files, and then processed by Cura software (Ultimaker B.V) to become printable G-Code files. We divided each body part into 4 pieces with flat interface, so films can be inserted to measure the dose on coronal or sagittal plane. Two kinds of PLA filaments were used. The bone tissue was printed with StoneFil PLA filaments (density 1.6 g/cm3) with 100% infill rate. The lung tissue was printed with EasyFil PLA filaments (density 1.2 g/cm3) with 30% infill rate. To reduce the printing time and prevent the warping effect, the body was printed with 3mm walls and 0% infill rate. After the phantom is printed, we filled the empty space inside the body with epoxy resin (density 1.0 g/cm3) to mimic the soft tissue.
Results: The head and thorax sections were printed as our plan. The densities of bone and lung tissue were close to our expectation. The printing time was about 15 to 35 hours for one piece depending on the size and complexity. The accuracy of phantom dimension and interface matching are great.
Conclusion: Although we had some failures and frustrations at the beginning, but the final products were very satisfying. We believe 3D printing is an excellent technology for creating custom phantom, bolus or tools in radiotherapy.
TH- Radiation Dose Measurement Devices: Development (new technology and techniques)