ESTRO 2024 - Abstract Book

S4086

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

If we compare both workflows in a paired setup and use the median residual setup errors per patient for both techniques, we do observe statistically significant differences in the lateral and longitudinal directions (respectively p=0.018 and p=0.028). Both for the lateral and the longitudinal shift, we observed a somewhat smaller shift in the ExacTrac DIBH workflow compared to the CBCT workflow (respectively, 0.19 (0.09) vs. 0.28 (0.11) mm for the lateral direction and 0.18 (0.10) vs. 0.24 (0.11) mm for the longitudinal direction). For residual setup errors observed in the vertical direction and for yaw, pitch, and roll between both workflows no statistically significant differences were found (p>0.05).

Conclusion:

This study demonstrated that residual setup errors in stereoscopic x-rays' accuracy is in the same line as gated CBCT positioning for left sided breast DIBH treatments. Furthermore, x-ray imaging offers the benefit of being able to evaluate the intra-DIBH stability to control the thoracical wall during irradiation. The clinical integration of SGRT with IGRT with ExacTrac Dynamic enables a stable and reliable consecutive breath-holds since upstroke of simulation is considered and used for guidance. This study additionally demonstrated a marginal gain in accuracy in both the lateral and longitudinal direction for the stereoscopic x-rays obtained in the Exactrac DIBH workflow.

Keywords: Breast cancer, CBCT X-rays, accuracy

2368

Digital Poster

Commissioning of an Adaptive Radiation Therapy module for Tomotherapy treatments

Josefina Mateus 1 , Mariana Girão 2 , Miguel Capela 1 , Tania Santos 1 , Tiago Ventura 1 , Maria do Carmo Lopes 1

1 IPO Coimbra, Medical Physics Department, Coimbra, Portugal. 2 University of Coimbra, Physics Department, Coimbra, Portugal

Purpose/Objective:

The iDMS system of Tomotherapy incorporates a module (PreciseART) for offline adaptive radiation therapy (ART). The objective of this study was to validate this ART module and establish a protocol for its clinical use in head and neck patients.

Material/Methods:

In PreciseART, a merged image set is created from the registration of the daily acquired MVCT images with the planning CT. The dose of the day and total accumulated dose are automatically calculated for each patient based on the merged image set. Alerts can also be reported concerning dosimetric and/or geometric parameters.