Realization of a 3D-printed custom-made immobilization facemask for head and neck radiation therapy using selective laser sintering

This study introduces an alternative workflow for the design and fabrication of a custom immobilization device for head and neck radiotherapy. The proposed process integrates additive manufacturing technologies with medical imaging to overcome limitations associated with conventional immobilization devices, such as patient discomfort and variability in performance. The workflow comprises patient-specific anatomical segmentation, computer aided design (CAD) modeling, and fabrication using powder bed fusion - specifically, Selective Laser Sintering. Segmentation was performed on medical imaging data to extract precise patient-specific geometries, forming the basis of the immobilization device design. Meshmixer was employed for CAD modeling due to its versatility and capability to handle complex meshes. The design phase included structural optimization, such as incorporating a honeycomb pattern to enhance patient comfort, reduce material consumption, and maintain device functionality. Challenges experienced during this phase included splitting the model into two parts due to size constraints of the printer and ensuring robust connections between the semi-masks. A tenon/mortise bonding system, reinforced with epoxy resin and improved through iterative testing, provided a reliable solution for assembling the device. The device was fabricated using PA2200 nylon on an EOS P396 printer; for this purpose, printing parameters were carefully selected to ensure high precision and structural integrity. Despite encountering software and hardware limitations, the final prototype provided evidence about the feasibility, reproducibility, and precision of the proposed workflow. The results suggest that the workflow is effective not only in achieving a high-quality immobilization device, but also in ensuring consistent outcomes across different operators. While this study serves as an exploratory analysis, it highlights the potential of additive manufacturing to revolutionize radiotherapy by enabling the prototypation of customized, patient-specific devices. Future work will involve dosimetric evaluations, mechanical validation, and clinical trials to further assess the effectiveness and scalability of the proposed workflow for clinical applications.