Properties of irradiated Bi2O3 and TiO2 enriched 3D printing polymers for fabrication of patient specific immobilization devices in radiotherapy

The main objective of this work was to investigate the radiation hardness and mechanical properties of newly developed 3D printing polymer acrylonitrile butadiene styrene (ABS) enriched with Bi2O3 and TiO2 for its possible application for the manufacturing of patient-specific immobilization masks in radiotherapy. To achieve this primary purpose, the work was performed in 4 steps: (1) fabrication of the new Bi2O3 and TiO2 enriched ABS filaments; (2) investigation of radiation interaction with 3D printed samples; (3) evaluation of mechanical properties of the samples; the stiffness and robustness of the customized immobilization device through mechanical testing of different 3D samples and (4) assessment of radiation impact on the properties of the newly developed 3D materials. More homogeneous dispersion of filler material in the polymer matrix was observed in the case of ABS/Bi2O3 samples, also indicating more uniform changes in the sample's radio densityy corresponding to the filler's concentration, as compared to ABS/TiO2 samples, where clusters of filler material and air voids were present in the 3D printed structures. Radiation-caused variations of mechanical properties were minimal and indicated only a small reduction in UTS and Young's Modulus values for the 3D printed samples irradiated to high doses with 6 MeV X-ray photons. The average surface roughness of irradiated ABS/Bi2O3 decreased indicating saturation tendency at high irradiation doses. Investigation revealed that radiation-induced variations of ABS/Bi2O3 sample properties were not significant to make an impact on the patient's treatment procedure, and surface smoothening to some extent was achieved. Therefore, this composite can be a promising candidate for the printing of precise, accurate, and biocomfortable individual immobilization masks for radiotherapy treatment.