A Study of Feasibility for Reusing Thermoplastic Masks - Toward a Green Environment.

Aim: This study evaluated the feasibility of reusing thermoplastic masks in radiation oncology to reduce environmental waste and financial costs. Materials and Methods: The study conducted from July 2024 to December 2024 involved 70 thermoplastic masks across three types: 3-clamp brain masks, 5-clamp head-and-neck masks, and 4-clamp chest/abdomen/pelvis masks. Measurements of fresh masks were compared to those after molding and re-flattening post-treatment. Dimensions were recorded in superior-inferior (SI) and lateral directions at specific anatomical levels. Results: The 3-clamp brain thermoplastic cast expanded 46% ± 7% in SI directions postmolding. Width increased by 63% ± 16% (chin) and 75% ± 10% (forehead). Re-flattened casts showed 25% ± 4% SI reduction and 19% ± 8% (chin) and 26% ± 5% (forehead) contraction in width. The 5-clamp head-and-neck thermoplastic cast expanded 16% ± 3% SI postmolding, with width expansion of 54% ± 15% (chest), 62% ± 10% (forehead), and 66% ± 5% (chin). Re-flattened casts showed 6% ± 3% SI expansion and 26% ± 5.5%, 40% ± 16%, and 37% ± 17% width enlargement at chest, chin, and forehead levels, respectively. The 4-clamp chest/abdomen/pelvis thermoplastic casts expanded 3% ± 5% (SI) in 26 casts and contracted by 7.5% ± 2.5% in 2 casts postmolding. Conclusion: Thermoplastic masks demonstrated acceptable dimensional changes while reusing, with consistent structural integrity and minimal compromise in functionality. Single reuse could significantly reduce costs and waste, particularly in resource-limited settings, making this practice a viable option for sustainable health care.