ESTRO 2024 - Abstract Book

S668

Clinical - Breast

ESTRO 2024

2722

Digital Poster

Dose to heart and lung from VMAT radiotherapy for challenging anatomies in left sided breast cancer

Henrik D Nissen, Else Maae, Martin Berg, Mads M Kjeldsen

Vejle Hospital, University Hospital of Southern Denmark, Oncology, Vejle, Denmark

Purpose/Objective:

Volumetric-modulated arc therapy (VMAT) is increasingly popular as a treatment planning technique for breast cancer patients where 3D conformal techniques (3DCRT) is inadequate due to challenging anatomy, e.g. with the heart close to the chest wall. Figure 1 shows an example of such an anatomy. Different techniques (with gating/breath hold and prone positioning as the most common) are available to aid in reducing anatomical challenges but in some patients, this is not possible or not enough, and proton therapy may not be an option. In these treatment planning-wise challenging cases, the standard solution in tangential 3DCRT has been to compromise target coverage or dose to organs-at-risk (OAR). VMAT may provide an option for both maintaining target coverage and keeping OAR dose acceptable. However, dose distributions in VMAT can be very different from 3DCRT and hence attention must be paid to especially OAR low dose and OARs not typically within the treatment fields. Variations in dose distribution with VMAT planning are many but need to be considered weighing in the clinical benefit of the increased target coverage when making the decision to treat these cases.

Here we present data from a single institution on dose parameters for VMAT plans for challenging anatomies as a reference for other sites working on similar cases.

Material/Methods:

For breast cancer patients treated in our institution between October 2018 to October 2023 treatment plan data were extracted from the Record and Verify system using an automated script scraping data from pdf printouts of