ESTRO 2025 - Abstract Book

S321

Brachytherapy - Physics

ESTRO 2025

Keywords: Mixed reality, Intraoperative visual support

References: 1. Milgram P, Kishino F. A Taxonomy of Mixed Reality Visual Displays. IEICE Transactions on Information and Systems 1994; 12:1321–9.

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Digital Poster Study of effect of the transfer tube curvature on the position of radiation source inside brachytherapy applicator Vladimir Stserbakov Radiotherapy, North-Estonia Medical Centre Foundation, Tallinn, Estonia Purpose/Objective: To answer the question: what happens to the delivered treatment dose if the afterloader is connected to the brachytherapy applicator via a transfer tube on the other side of the patient couch (a clinically possible situation)? In this case, the source will travel through a differently covered transfer tube and enter the applicator in different ways, i.e. where the mechanical “resistance” or friction force may be different, and respectively, which may cause fluctuations of dwell-positions inside the applicator. Material/Methods: The method is well suited for studying such delicate effects is the technique using PTW OCTAVIUS 1600 SRS 2D dimensional array. Venezia 26 (Flexitron, Elekta) applicator is taken as an example. The applicator was fixed on central part of 2D-dimensional array during all circle of measurements but location of afterloader relatively to applicator was different (Fig. 1,A). Time of collecting charge is ~10 s per dwell-position. Radiation source step is 1 mm. Measured files ( .mcc format) were imported to Excel program to perform quick results processing (2 min/25 dwell-position). The positioning of found source coordinates relatively to the library coordinates was performed by matching these source pathways in 1 cm range close to the tip of the applicator channel.

Figure. A – The scheme of measurements. Different locations of afterloader relatively to applicator/patient side: Right, Left, Direct. B – The comparing measured and library dwell-positions in Ovoid (Channel 2) of the Venezia 26 applicator for different setups. Circle r=13 mm illustrate middle line of the applicator source travel pathway.