ESTRO 2025 - Abstract Book

S329

Brachytherapy - Physics

ESTRO 2025

1796

Digital Poster Characterization of TULIP Ring applicators for gynaecological brachytherapy with interstitial component and MRI imaging Guillermo Veiguela, Silvia Fernandez, Daniel Rodriguez, Diego Piedrafita, Alvaro Garcia Medical Physics, Hospital Universitario Central de Asturias, Oviedo, Spain Purpose/Objective: High-dose-rate (HDR) gynaecological brachytherapy often requires an interstitial component to deliver optimal treatments. The TULIP add-ons (Bebig Medical) LCF013-10 configuration 02 (standard), 03 (oblique extended) and 04 (lower extended) for MICK ring applicator show three different needle positions to adapt to the clinical needs. The aim of this study is to characterize the needle insertion depth in all three configurations using CT and MR images.

Material/Methods:

The needle depth with the 10 different channels and the 3 configurations of the TULIP add-ons measured in CT and MR images was compared with the nominal depth measured with a ruler. The slice thickness was 2 mm for CT and 1 mm for 3D T2 MRI images. Sagiplan 2.2 TPS ruler was used to measure depths in both CT and MR. With MR, the lengths were measured from the observed tip in the image to the surface of the applicator, while with CT, the tip was located using the TPS applicator library. We positioned the first dwell position at the center of the first radiopaque marker and measured from the applicator tip to the surface of the TULIP. Additionally, we assessed the differences in measured length between both types of imaging modalities and the resulting adjustments to the TPS TULIP templates.