Design, characterization, and fabrication of a 3D-printed patient-specific and personalized cranial immobilization system for radiotherapy treatment

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Abstract

Accurate immobilization is essential in cranial radiotherapy because modern treatment techniques rely on high geometric precision and tight setup tolerances. Conventional thermoplastic masks remain the clinical standard, but they may be uncomfortable, anxiety-provoking, and insufficiently adapted to individual facial anatomy. This study investigates the design, fabrication, and preclinical validation of a personalized immobilization system composed of a facial shell and fixation belts. The necessary facial surface was acquired using an EinScan Pro+ scanner. The facial shell was designed in Meshmixer, while the fixation belts and hooks were modeled in Fusion 360 according to the geometry of a Klarity Optek™ indexing board. Final components were sliced in Cura and fabricated on an Artillery Sidewinder X1 printer. Polylactic acid (PLA) and thermoplastic polyurethane (TPU) were numerically evaluated in COMSOL Multiphysics 6.3 for thermal phase transition during printing, irradiation-induced heating under a 6 MV radiotherapy photon beam (400 MU/min for 15 min), and tensile mechanical behavior of the fixation belts. The workflow successfully produced a 2.5-mm-thick patient-specific immobilization device with excellent anatomical conformity and compatibility with the clinical support system. Simulated peak temperatures remained low for both PLA (27.85 °C) and TPU (28.45 °C), indicating thermal stability during photon irradiation. Mechanical simulations showed peak stress of approximately 0.7 MPa and maximum displacement (deformation) of 0.012 mm for PLA and 0.4 mm for TPU, both below a 1-mm tolerance threshold. The proposed workflow supports the feasibility of personalized 3D-printed cranial immobilization devices, with TPU emerging as a promising material because it combines structural stability with greater flexibility and patient comfort.

Graphical abstract

Keywords

Radiotherapy

Cranial immobilization

Personalized medicine

3D printing

Structured-light scanning

Patient-specific device

COMSOL Multiphysics simulation

Funding

None.

Conflict of interest

The authors declare they have no competing interests.

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Advances in Radiotherapy & Nuclear Medicine, Electronic ISSN: 2972-4392 Print ISSN: 3060-8554, Published by AccScience Publishing