RESUMEN
BACKGROUND: The deep inspiration breath hold (DIBH) technique is effective for heart dose reduction in patients with left-sided breast cancer. In deep breathing, some women breathe in thoracic respiration; and others, in abdominal respiration. This study evaluated differences in dose reduction in organs at risk (OAR) and reproducibilities of the target and OAR between thoracic DIBH (T-DIBH) and abdominal DIBH (A-DIBH). METHODS: Fourteen patients with left-sided breast cancer who had planned to receive whole-breast irradiation were included. Computed tomography (CT) was performed in free breathing (FB), T-DIBH, and A-DIBH, and the dosimetric indexes of the target and OAR for three treatment plans were compared. In T-DIBH and A-DIBH, two series CTs were taken in each breathing method and the displacements of the target and heart were calculated. RESULTS: The averaged mean heart doses (MHDs) were 1.5 Gy and 1.6 Gy in T-DIBH and A-DIBH, respectively, significantly lower than 2.7 Gy in FB (p < 0.001 for both breathing methods). Between T-DIBH and A-DIBH, no significant difference in MHD was found (p = 0.95); however, the percentage increase in lung volume positively moderately correlated with the reduction in MHD (R = 0.68). The three-dimensional target displacements were 2.3 mm in T-DIBH and 2.0 mm in A-DIBH (p = 0.64). The three-dimensional heart displacements were 1.7 mm in T-DIBH and 1.8 mm in A-DIBH (p = 0.85). CONCLUSION: The present study demonstrates that the MHD and reproducibility did not differ between T-DIBH and A-DIBH. However, the superior breathing method for increasing lung volume should be determined for each patient.
