S106
Brachytherapy - Head & neck, skin, eye
ESTRO 2026
Digital Poster 4349 Proof of concept: a 3D-printed modular applicator for intensity-modulated interventional radiotherapy (modern brachytherapy) Bruno Fionda 1 , Elisa Placidi 1 , Enrico Rosa 1,2 , Maria Vaccaro 1 , Valentina Lancellotta 1 , Pierpaolo Dragonetti 1 , Maria Concetta La Milia 1 , Gabriele Ciasca 3 , Maria Antonietta Gambacorta 1,4 , Marco De Spirito 1,3 , Luca Tagliaferri 1,4 1 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 2 Department of Theoretical and Applied Sciences, eCampus University, Rome, Italy. 3 Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, Rome, Italy. 4 Dipartimento di Scienze Radiologiche, Università Cattolica del Sacro Cuore, Rome, Italy
Conclusion: This study demonstrates the feasibility of 3D-printed modular applicators for intensity modulation in IRT. Integrating multilayer catheter configurations and shielding elements enables flexible dose shaping and paves the way for patient-specific optimization in clinical brachytherapy applications. Keywords: skin, 3d-printing, interventional [1] Nath R, Anderson LL, Luxton G et al. Dosimetry of interstitial brachytherapy sources: Recommendations of the AAPM Radiation Therapy Committee Task Group No. 43. Med Phys 1995; 22: 209-234. [2] Beaulieu, L.; Carlsson Tedgren, Å.; Carrier, J.F.; Davis, S.D.; Mourtada, F.; Rivard, M.J.; Thomson, R.M.; radiotherapy References: Verhaegen, F.; Wareing, T.A.; Williamson, J.F. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: Current status and recommendations for clinical implementation. Med. Phys. 2012, 39, 6208– 6236 Applicator Curvature Influence on the Efficacy of Contact Interventional Radiotherapy (Modern Brachytherapy) Bruno Fionda 1 , Enrico Rosa 1,2 , Elisa Placidi 1 , Sofia Raponi 3 , Maria Vaccaro 1 , Valentina Lancellotta 1 , Maria Concetta La Milia 1 , Pierpaolo Dragonetti 1 , Lucia Di Maio 1 , Maria Antonietta Gambacorta 1,4 , Marco De Spirito 1,3 , Luca Tagliaferri 1,4 1 Dipartimento di Diagnostica per Immagini e Radioterapia Oncologica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 2 Department of Theoretical and Applied Sciences, eCampus University, Novedrate, Italy. 3 Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, Digital Poster 4365
Purpose/Objective: Interventional radiotherapy (IRT, modern
brachytherapy), enables highly localized dose delivery while sparing surrounding healthy tissues. We present a proof of concept for a 3D-printed modular applicator designed to achieve intensity-modulated IRT through variable geometries, multilayer catheter layouts, and
integrated shielding. Material/Methods:
The applicator, fabricated in polylactic acid, was tested in four configurations (A–D). A: Unshielded setup, dose calculated with TG-43 [1].B: Identical geometry as in A, evaluated with TG-186 [2], incorporating a cadmium–lead shielding insert (density 8 g/cm ³ ). C and D: Dual-layer catheter arrangements with 7.5 mm and 10 mm interlayer spacing, respectively. Each configuration included two catheters (50 dwell positions each, 2.6 s dwell time). The therapeutic window (TW) was defined as the 100%–150% isodose distance. Results: Shielding in configuration B (TG-186) reduced the TW compared with the unshielded TG-43 calculation (configuration A), confirming attenuation by the high- density alloy. Multilayer setups (C and D) expanded the TW and improved dose uniformity, particularly with 10 mm spacing (table 1 and figure 1).
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