ESTRO 2023 - Abstract Book

S1929

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ESTRO 2023

In variances across the BV groups, the mean doses of bladder and rectum doses showed a significant difference according to BV (P<0.001). The group A had the lowest D2cc of bladder with an average of 3.89±0.7 Gy and the highest D90 of HR- CTV with an average of 5.54±1.4 Gy. The D2cc of bowel was 2.03±.0.8 Gy, which was slightly higher than the EMBRACE guideline (D2cc<1.95 Gy). This showed analogous results as a previously reported cross-group comparison studies for BV and dose of OARs. In applying the ToBF classification, the type T (tilted) showed optimal results in the group C (BV > 300 cc) for bladder and bowel dose (P<0.05). The type C (curved) showed the best results in the group B and C (BV > 200 cc) (P<0.05), whereas the type R showed no statistically significant association between BV and bowel dose in group B and C (p>0.05).

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Table 1. Results of DVH parameters of CTV and OARs

Conclusion In analysis of the ToBF model, it was confirmed that the appropriate BV for DVH parameters differs according to the type of bladder. In conclusion, further studies are necessary on the potential dose-reducing effects between the ToBF and BV.

PO-2144 Image-guided intracavitary and interstitial brachytherapy in locally advanced cervical cancer

P. Chitmanee 1

1 Ratchaburi hospital, Radiation therapy and oncology center, Ratchaburi, Thailand

Purpose or Objective to report clinical outcomes and side effect of CT-based image-guided combined high-dose-rate intracavitary and interstitial (IC/IS) brachytherapy Materials and Methods A total of 341 patients with FIGO stage IB1 to IVA were treated with chemoradiation and high-dose-rate brachytherapy between 2014 and 2022. Computed tomography (CT) and/or magnetic resonance imaging (MRI) were done at baseline and before brachytherapy to plan implantation. The main applicators were Vienna-ring, Fletcher and Venezia applicators.