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Updated: Sep 29, 2026
Irradiator Commissioning and Dosimetry for Assessment of LQ α and β Parameters, Radiation Dosing Schema, and in vivo Dose Deposition
Published on: March 11, 2021
Preliminary feasibility results for implementing a phantom model for external auditing of HDR brachytherapy with an
N Briggs1, A C F Silva2, S P Leite3
1Universidade Federal Do Rio de Janeiro/Coordenação Dos Programas de Pós Graduação e Pesquisa de Engenharia da Universidade Federal Do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, 21941-616, Brazil; Universidade Do Estado Do Rio de Janeiro/Laboratório de Ciências Radiológicas, Departamento de Ciências Radiológicas, R. São Francisco Xavier, 524, CEP, Maracanã, Rio de Janeiro, 20550-900, Brazil.
Abstract:
Accuracy in dose delivery in brachytherapy treatments is a critical component for clinical success and patient safety, requiring a rigorous quality assurance system. The implementation of external dosimetric audits plays a fundamental role in verifying the planned and delivered doses, allowing the identification of discrepancies that could compromise tumor control or increase toxicity in healthy tissues, as well as ensuring compliance with national and international recommendations and standards. This work presents the development and validation of a methodology for external auditing in high-dose-rate (HDR) brachytherapy using an Ir-192 source, conducted within the scope of a research project coordinated by the International Atomic Energy Agency (IAEA), with the participation of nine countries. A positioning phantom, manufactured through 3D printing, was designed to accommodate various models of intracavitary applicators, allowing adaptable and reproducible assembly conditions for dosimetric evaluation. Optically Stimulated Luminescence (OSL) dosimeters (nanoDot model) were used for point dose measurements around the applicator, in configurations previously standardized based on the results obtained from earlier tests leading to the final prototype. The coordinates of these points were registered in the Treatment Planning System (TPS) and used as a reference for experimental comparison, respecting distances and depths equivalent to those defined in the planning. The applied methodology allowed the comparison between the experimental data obtained with NanoDot OSL dosimeters and the doses calculated by the TPS. The dosimeters were positioned in a cross-shaped configuration around the applicator, maintaining a distance of 2 cm from the ring and 2 cm from the probe (tandem), ensuring a standardized and reproducible geometric arrangement. The project was funded by project E24023, International Atomic Energy Agency (IAEA), Contract number 24544.
