A 3D printed patient-specific vaginal mould for brachytherapy

Abstract

Patient specific applicators are needed for vaginal brachytherapy treatments in cases where conventional cylindrical applicators are unsuitable or unusable. These applicators are often produced using a time-consuming and comparatively imprecise moulding method. This proof-of-concept study used Monte Carlo calculations to investigate potential dosimetric effects from creating applicators using several common 3D printing materials. A sample mould was then replicated using a fused deposition modelling (FDM) technique, which allowed catheter channels to be precisely placed with reference to treatment goals, before 3D printing from thermoplastic using a consumer-grade 3D printer. The Monte Carlo results indicated that several FDM filaments caused substantial dose depletions (up to 6%) within the model applicators while having a minor effect (less than 1%) on dose in surrounding tissue. Compared to the sample mould, the 3D printed applicator achieved superior dosimetry in terms of target coverage, while also passing manual tests of smoothness and usability. This study demonstrated an overall process by which 3D printing could replace an imprecise and time-consuming manual process and potentially achieve improved dosimetry in brachytherapy treatments of irregular vaginal anatomy.