ESTRO 2025 - Abstract Book

S241

Brachytherapy - Gynaecology

ESTRO 2025

In terms of distance rectum, sigmoid and bowel are significantly closer to the target in the MRL situation compared to BT (with applicator).

Conclusion: BT plans resulted in similar or better target coverage and similar or lower OAR dose compared to MRL plans. For MRL plans a PTV-margin of 3mm is used, decreasing this may improve MRL target coverage towards BT. With an applicator in situ, distance of target to OARs can be increased, which is more favorable for dose planning. Dosimetrically BT boost is the modality of choice, while in certain clinical situations it is possible to create a clinically acceptable MRL plan as an alternative for BT.

Keywords: Brachytherapy, MRLinac, gynaecology

References: [1] Pötter, R., Tanderup, K., Kirisits, C., de Leeuw, A., Kirchheiner, K., Nout, R., Tan, L. T., Haie-Meder, C., Mahantshetty, U., Segedin, B., Hoskin, P., Bruheim, K., Rai, B., Huang, F., van Limbergen, E., Schmid, M., Nesvacil, N., Sturdza, A., Fokdal, L., … Jürgenliemk-Schulz, I. (2018). The EMBRACE II study: The outcome and prospect of two decades of evolution within the GEC-ESTRO GYN working group and the EMBRACE studies. In Clinical and Translational Radiation Oncology (Vol. 9, pp. 48–60). Elsevier Ireland Ltd. https://doi.org/10.1016/j.ctro.2018.01.001

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Poster Discussion Dosimetric and clinical outcomes of hyaluronic acid rectal spacer in MRI-guided adaptive brachytherapy for cervical cancer: a phase II RCT Jiraporn Suntiruamjairucksa 1,2 , Napapat Amornwichet 1 , Petch Alisanant 2 , Kanokphorn Thonglert 2 , Chonlakiet Khorprasert 1 1 Radiation Oncology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. 2 Radiation Oncology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand Purpose/Objective: Benefits of rectal spacer in cervical cancer treatment remain inconclusive and there is a lack of studies in MRI guided adaptive brachytherapy (MR-IGABT). This study aims to evaluate the effect of hyaluronate gel injection (HGI)