Deep inspiration breath hold to reduce irradiated heart volume in breast cancer patients

Adjuvant radiation therapy can significantly increase both disease-free and overall survival for breast cancer patients. However, long-term complications resulting from cardiac toxicity are a serious concern, especially for young patients with left-sided tumours. This issue becomes critical when patients are treated with wide tangents in order to include internal mammary nodes in the radiation field, thus increasing the amount of heart irradiated. Our postulate is that deep inspiration hold will maximize the distance between chest wall and heart during tangential breast irradiation and will therefore minimize the irradiated cardiac volume. In this study, the Active Breath Control device (ABC) designed at William Beaumont Hospital, Michigan was used to quantify the potential effect of treating during breath hold for five left-sided breast cancer patients. This device forces breath hold at a predefined, reproducible lung volume. For each patient, two CT scans were acquired respectively with and without breath hold, and virtual simulation was performed for regular tangent and wide tangent techniques. The resulting dose volume histograms were calculated, and the volume of heart irradiated to 25 Gy or more was assessed. Our results show that the use of the ABC can decrease the portion of irradiated heart from 6% to 1% if treating with regular tangents and from 16% to 4% with wide tangents in the most significant case. The methodology used and detailed results far the five patients will be presented in this feasibility study.