ESTRO 2024 - Abstract Book

S1947

Clinical - Mixed sites, palliation

ESTRO 2024

reaching the temperature of 41 degrees. The tumor temperatures were reported as T10, T50 and T90, (i.e. the temperature at least achieved in 10%, 50% and 90% of the target volume, respectively).

Results:

The median RT-HTtime was 30.5 minutes (range, 21 – 50), while the median pre-HTtime was 6.5 minutes (range, 3.6 – 19.2). In patients treated with invasive thermometry, the RT-HTtime was 5 minutes longer than in patients treated without (35.3 vs 30.3 minutes, respectively). Temperature index measured in the 60% of treatments delivered with invasive thermometry were T10: 42.19±0.50°C SD; T50: 41.25±0.51°C SD; T90: 40.03±0.91°C SD. Minimal, average, and maximal mean temperatures were 39.40±1.09°C SD, 41.50±0.70°C SD, and 42.77±0.69°C SD, respectively. The online/in-vivo/real-time temperature measurements were similar to the simulated/estimated temperatures from Plan2Heat.

Conclusion:

In our series, we demonstrated an easy and efficient clinical workflow for combined thermo-radiotherapy treatments, allowing us to deliver HT in a median interval time of approximately 30minutes from the end of the RT session. Moreover, the in-vivo thermometric quality of our treatments was optimal and consistent with the simulated HT plans. Shortening the interval between HT and RT and achieving high intra-tumoral temperatures are essential goals for improving treatment outcomes.

Keywords: Radiotherapy, Hyperthermia, Time interval

1837

Digital Poster

Impact of target volume definition on LC in postoperative palliative RT for spinal metastases

Maria Waltenberger 1,2 , Ferdinand Hohmann 1 , Marco M. E. Vogel 1 , Christian Diehl 1,3 , Bernhard Meyer 4 , Stephanie E. Combs 1,2,3 1 Klinikum rechts der Isar, Technical University of Munich (TUM), Department of Radiation Oncology, Munich, Germany. 2 German Cancer Consortium (DKTK), Partner site Munich, Munich, Germany. 3 Institute of Radiation Medicine (IRM), Helmholtz Zentrum, Munich, Germany. 4 Klinikum rechts der Isar, Technical University of Munich (TUM), Department of Neurosurgery, Munich, Germany

Purpose/Objective:

No level I data or consensus recommendations are available to guide target volume definition (TVD) in palliative RT (pRT) after stabilization surgery for spinal metastases. A common approach is to include all vertebral heights over which the surgical instrumentation extends, but reduced volume pRT e.g., only to the vertebrae affected by