Purpose: The aim of this study was to evaluate the effect of decreasing the irradiated cardiac volume in breast-conserving therapy (BCT) using breath-adapted radiation therapy (BART).
Materials and methods: The radiation therapy (RT)-computed tomography (CT) of 21 patients with left breast cancer during free breathing (FB), end-inspiration gating (IG) with audio-prompting, and deep inspiration breath-hold (DIBH) were subjected to BART planning analysis. Respiratory movement was monitored during CT scanning with the respiratory-gating system. The opposing tangential fields were planned for each respiratory-gated CT. The dose-volume histograms (DVHs) of the heart, lung, and breast of each respiratory phase were compared.
Results: The median respiratory movement of the right chest wall was 5.6 mm with FB CT, 10.9 mm with audioprompting CT, and 21.3 mm from end-inspiration to DIBH. The median left ventricular volume receiving >50% of the prescribed dose was 2.9% for FB, 0.2% for IG, and 0% for DIBH. DIBH led to significant cardiac spattering effect compared with FB or IG (P < 0.01). The median lung volume receiving 20 Gy or more was 5.0% for FB, 4.7% for IG, and 4.3% for DIBH. There were no significant differences between each respiratory phase.
Conclusion: We concluded that radiotherapy on the DIBH facilitates a reduction of the irradiated heart volume compared to FB and IG.