Are Water-Based Algorithms Still Adequate for Dose Calculation in Modern HDR Interventional Radiotherapy? A Review with Special Focus on 3D-Printed Applicators and Heterogeneous Materials

Rosa E, Fionda B, Vaccaro M, Lancellotta V, Placidi E, La Milia MC, Ciasca G, Dragonetti P, Karius A, Siebert FA, Tagliaferri L, De Spirito M (2026)

Publication Type: Journal article, Review article

Publication year: 2026

Journal

Radiation MDPI

Book Volume: 6

Article Number: 29

Journal Issue: 3

DOI: 10.3390/radiation6030029

Abstract

Background: High-dose-rate interventional radiotherapy (HDR IRT) relies on accurate dose calculations to ensure safe and effective treatment. The AAPM TG-43 formalism, based on homogeneous water assumptions, has long been the clinical standard, but the growing use of patient-specific applicators and heterogeneous materials challenges its accuracy. Materials and Methods: A literature narrative review was performed using PubMed and Scopus to identify studies comparing TG-43 and model-based dose calculation algorithms (MBDCAs), including deterministic methods (ACE, Acuros BV) and Monte Carlo simulations. Thirty-five studies were selected and qualitatively analyzed. Results: TG-43 yielded higher dose compared with MBDCAs, particularly in the presence of tissue heterogeneities, air gaps, shielding materials, and limited scatter conditions. Differences ranged from 2 to 5% in relatively homogeneous settings to more than 10–20% in complex geometries such as superficial mould treatments and head-and-neck IRT. Model-based approaches showed better agreement with Monte Carlo simulations and experimental measurements, especially in contact HDR IRT and applications involving 3D-printed applicators. Conclusion: While TG-43 remains clinically established and widely used, its limitations are increasingly evident in modern personalized HDR IRT. Model-based dose calculation algorithms provide greater dosimetric accuracy and should be progressively integrated into clinical practice, particularly in treatments involving significant heterogeneities.

Authors with CRIS profile

Andre Karius Department of Radiation Oncology

Involved external institutions

Fondazione Policlinico Universitario Agostino Gemelli IRCCS IT Italy (IT) Catholic University of the Sacred Heart / Università Cattolica del Sacro Cuore IT Italy (IT) Universitätsklinikum Schleswig-Holstein (UKSH) DE Germany (DE)

How to cite

APA:

Rosa, E., Fionda, B., Vaccaro, M., Lancellotta, V., Placidi, E., La Milia, M.C.,... De Spirito, M. (2026). Are Water-Based Algorithms Still Adequate for Dose Calculation in Modern HDR Interventional Radiotherapy? A Review with Special Focus on 3D-Printed Applicators and Heterogeneous Materials. Radiation, 6(3). https://doi.org/10.3390/radiation6030029

MLA:

Rosa, Enrico, et al. "Are Water-Based Algorithms Still Adequate for Dose Calculation in Modern HDR Interventional Radiotherapy? A Review with Special Focus on 3D-Printed Applicators and Heterogeneous Materials." Radiation 6.3 (2026).

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