ESTRO 2024 - Abstract Book

S388

Beachytherapy - Physics

ESTRO 2024

Results:

For a single-source configuration, we observed a linear increase in the therapeutic window (TW) with the catheter to-skin distance (Figure 1C). The range of TW varied between 0.6 and 11.7 mm for catheter-to-skin distances ranging from 1.9 to 53.1 mm. Figure 1A-B offers a comparison between standard and multilayer configurations. The standard configuration, featuring five activated catheters in the lower flap, achieved a CTV coverage of V95 (CTV) equal to 81.84%. In contrast, the multilayer configuration achieved a higher V95 (CTV) equal to 95.68%, with a V150 (CTV) set at 1.5% for both configurations. The results for the plans applied to patients show a better coverage of the target volume with a less 150% isodose in patient skin.

Conclusion:

This study sought to present a novel approach for treating NMSC lesions thicker than 5 mm by implementing a multilayer arrangement of catheters. It serves as an illustrative instance of dynamic intensity-modulated IRT by varying catheter-to-skin distances of radiation sources to attain optimal CTV coverage while substantially mitigating excessive skin dose. This arrangement can be used also for the clinical application with a reasonable better coverage of the target volume.

Keywords: Interventional Radiotherapy, NMSC, Multilayer flap

References:

[1] Tagliaferri L, Ciardo FG, Fionda B et al. Non-melanoma skin cancer treated by contact high-dose-rate radiotherapy (brachytherapy): A mono-institutional series and literature review. In Vivo 2021; 35: 2313-2319.

[2] Skowronek J. Brachytherapy in the treatment of skin cancer: an overview. Postepy Dermatol Alergol 2015; 32: 362-367.

3251

Digital Poster

Evaluation of INTRABEAM dosimetry characterization in intraoperative radiotherapy of glioblastoma

David Santiago Ayala Alvarez 1 , Peter G F Watson 2 , Marija Popovic 2 , Veng Jean Heng 1 , Michael D C Evans 2 , Valerie Panet-Raymond 3 , Jan Seuntjens 2,4 1 McGill University, Department of Physics and Medical Physics, Montreal, Canada. 2 McGill University Health Centre, Medical Physics Unit, Montreal, Canada. 3 McGill University Health Centre, Department of Radiation Oncology, Montreal, Canada. 4 Princess Margaret Cancer Centre, Radiation Medicine Program, University Health Network, Toronto, Canada

Purpose/Objective: