PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s): Patients undergoing radiation for breast cancer are at risk of long-term cardiac morbidity and radiation-related coronary artery disease, which is correlated with dose to the heart. Deep inspiration breath-hold (DIBH) technique reduces dose to organs at risk for patients undergoing left breast radiation. The role of DIBH in reducing dose to coronaries, heart, and lungs for right-sided breast cancers is less clear. We evaluated whether treatment planning using DIBH produces significant reduction in right coronary artery (RCA), heart, and lung dose as compared to free breathing (FB) for patients receiving radiation to the breast and regional lymph nodes lymph nodes for right-sided breast cancer.
Materials/Methods: We compared 8 consecutive right-sided breast cancer patients planned with modified wide tangent plans to cover the breast, levels I-III of the axilla, and supraclavicular and internal mammary lymph nodes on paired DIBH and FB CT scans. Lymph nodes were contoured according to the RTOG atlas. RCA was contoured according to the RADCOMP breast atlas available on the RTOG website. All patients were planned to receive 50 Gy in 25 fractions. We compared dose-volume data for DIBH versus FB for RCA, heart, right lung, and total lung. Plan metrics were compared using Wilcoxon signed-rank testing on SPSS.
Results: DIBH significantly decreased RCA mean dose, heart maximum point dose, mean heart dose, and heart V5 (Table 1). The difference in maximum point dose and V5 for RCA approached statistical significance (p=0.063 and 0.068, respectively). Mean lung dose for the right lung and total lung were significantly improved with DIBH, as were V20 for the right lung and total lung (Table 1).
Conclusion: DIBH resulted in a significantly decreased RCA mean dose as well as a decrease in multiple cardiac and lung dose metrics. DIBH should be considered for right-sided breast cancer patients undergoing radiation to the breast and regional lymph nodes via partial wide tangents. Table 1. Organ at risk dose-volume comparison between FB versus DIBH
|FB Mean||BH Mean||p-value|
|RCA D(0.03cc) (cGy)||1199||333||.063|
|RCA D(mean) (cGy)||251||140||.025|
|Heart D(0.03cc) (cGy)||1710||552||.036|
|Heart D(mean) (cGy)||93||56||.012|
|Heart V5 (%)||2||0||.027|
|Right Lung D(mean) (cGy)||1524||1202||.036|
|Total Lung D(mean) (cGy)||886||678||.036|
|Right Lung V20 (%)||31||24||.025|
|Total Lung V20 (%)||18||13||.025|
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