RESUMO
Objective:To explore the effects of the deep inspiration breath-hold (DIBH) technique on cardiac dosimetry in internal mammary node irradiation with intensity-modulated radiation therapy (IMN-IMRT) for postoperative left breast cancer.Methods:Totally 23 left breast cancer patients in the First Affiliated Hospital of Bengbu Medical College from Octorber 2021 to July 2022 receiving postoperative IMN-IMRT were enrolled in this study. The changes in dosimetric parameters for their heart and left anterior descending coronary artery (LAD) in the DIBH mode were observed, and the potential factors affecting DIBH effects were analyzed.Results:Compared with the free breath (FB) mode, the DIBH mode manifested a heart volume decrease by 18% ( t = 10.47, P < 0.001), a left lung volume increase by 42% ( t = -14.55, P < 0.001), and significantly reduced dosimetric parameters ( Dmean, Dmax, V5- V30) for the heart and LAD, exhibiting statistically significant differences ( t=-13.38 to -3.30, P<0.05). As indicated by the Pearson correlation analysis, the relative ratio of cardiac dose reduction was positively correlated with that of left lung expansion ( r = 0.82, P < 0.001) and negatively correlated with the patient′age ( r = -0.56, P = 0.005). Conclusions:DIBH can effectively reduce the heart and LAD radiation doses in IMN-IMRT for postoperative left breast cancer and that the patient's age, and the DIBH effects might be affected by the vital capacity.