Cardiac-sparing radiotherapy for the left breast cancer with deep breath-holding

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). 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. The median respiratory movement of the right chest wall was 5.6 mm with FB CT, 10.9 mm with audio-prompting 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. We concluded that radiotherapy on the DIBH facilitates a reduction of the irradiated heart volume compared to FB and IG. (author)