The feasibility of fabricated 3D-printed immobilization masks for radiotherapy: mechanical and dosimetric analysis

Background: 3D printing technology is becoming widely popular in the medical field, particularly in radiotherapy, where it is used to fabricate immobilization masks from thermoplastic materials because it can generate geometric figures and produce sophisticated templates eligible for individual patients. Objectives: This study aims to evaluate the mechanical and dosimetric properties of three types of plastic: polylactic acid (PLA), polyethylene terephthalate glycolmodified (PETG), and acrylonitrile styrene acrylate (ASA) to identify an appropriate material for use as a 3D-printed thermoplastic mask in radiotherapy. Materials and methods: The 3D-printed square plastic samples were designed with four infill patterns: triangle, honeycomb, gyroid, and honeycomb-gyroid, and were manufactured using fused deposition modeling (FDM) 3D printing technology. This study analyzed the characteristics regarding mechanics, uniformity, and radiation transmission. Results: Mechanical testing demonstrated that PETG provided high strength (10.88 MPa with gyroid pattern) and flexibility (7.36% with honeycomb pattern). The mean uniformity across tests ranged from 84.80 to 85.03, with a standard deviation between 5.93 and 7.53. All plastic types have Hounsfield units (HU) ranging from -774.88 to -620.21. The 3D-printed plate demonstrated radiation transmission like the efficiency of a commercial thermoplastic mask, in the range of 99.30% to 99.91%. Conclusion: All three types of plastic have proven to be appropriate alternative materials for the integration of an immobilization mask. PLA plates displayed advantageous results in terms of radiation transmission, while PETG emerged as the most balanced performer in terms of mechanical properties, showing high strength and flexibility. ASA, a polymer confirmed by FTIR analysis that contains a benzene ring, demonstrated that it is more resistant to radiation. The 3D-printed masks provide a viable alternative to traditional thermoplastic mask systems. Nevertheless, further investigation is required.