Abdominal DIBH reduces the cardiac dose even further: a prospective analysis

Abstract

Background: Deep inspiration breath hold (DIBH) can be performed using different breathing maneuvers, such as DIBH with a thoracic breathing maneuver (T-DIBH) and DIBH with an abdominal breathing maneuver (A-DIBH). Dosimetric benefits of A-DIBH were investigated in the treatment of left-sided breast cancer radiotherapy (RT) with both 3-Dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques.

Methods: Twenty-two patients with left-sided breast cancer were enrolled in this study. 3D-CRT and IMRT plans were generated for each patient with three different CT scans of free breathing (FB), T-DIBH and A-DIBH. There were total of six treatment plans generated for each patient: FB_3D-CRT; TDIBH_3D-CRT; ADIBH_3D-CRT; FB-IMRT; TDIBH-IMRT; ADIBH-IMRT. Doses to the heart, left anterior descending coronary artery (LADCA), and ipsilateral lung were evaluated and compared using the Wilcoxon signed-rank test.

Results: The mean doses to the heart, LADCA and ipsilateral lung in 3D-CRT plans generated from 3D-CRT with FB, T-DIBH and A-DIBH were (2.89 ± 1.30), (1.67 ± 0.90) and (1.34 ± 0.43) Gy (all P < 0.05), respectively, with FB; (29.08 ± 16.72), (13.94 ± 14.74) and (10.22 ± 10.30) Gy (all P < 0.05), respectively, with T-DIBH; and (7.77 ± 2.71), (7.32 ± 1.42) and (6.90 ± 1.60) Gy (all P < 0.05), respectively, with A-DIBH. The mean doses to the heart, LADCA and ipsilateral lung in IMRT plans were generated from IMRT with FB, T-DIBH and A-DIBH were (1.96 ± 2.25), (1.37 ± 0.44) and (1.18 ± 0.26) Gy (all P < 0.05), respectively, with FB; (16.10 ± 7.45), (8.6 ± 6.60) and (7.35 ± 5.42) Gy (all P < 0.05), respectively, with T-DIBH; and (5.90 ± 2.24), (5.65 ± 1.58) and (5.62 ± 1.05) Gy (all P > 0.05), respectively, with A-DIBH.

Conclusions: This study indicates that both 3D-CRT and IMRT plans with A-DIBH achieved lower cardiac and LADCA doses than plans with FB and T-DIBH; 3D-CRT plans with A-DIBH achieved lower ipsilateral lung doses than plans with FB and T-DIBH; and IMRT plans with A-DIBH had better outcomes than 3D-CRT plans with A-DIBH with respect to the mean dose to the heart, LADCA and ipsilateral lung. IMRT plans with A-DIBH should be incorporated into the daily routine for left-sided breast RT.

Keywords: 3-dimensional conformal radiation therapy (3D-CRT); Breast cancer; Breath holding; Intensity-modulated radiation therapy (IMRT); Organs at risk; Radiotherapy dosage.

Fig. 1

The relative spatial position relationships of the breast CTV (orange), left lung (blue), heart (red), LMCA (green), and LADCA (yellow) in a typical patient during FB (a), T-DIBH (b) and A-DIBH (c). A vertebral body T7 (blue) is contoured as a position marker in the shown case. During T-DIBH, due to expansion of the left lung (B), the heart, LMCA, and LADCA are moved caudally compared with during FB (a). During A-DIBH (c), the heart, LMCA, and LADCA are moved farther caudally than during T-DIBH (b). During T-DIBH (b) and A-DIBH (c), the breast CTV is moved cranioventrally compared with during FB (a) due to the expansion of the left lung

Fig. 2

Mean doses to the heart (a, d, g), LADCA (b, e, h) and left lung (c, f, i) in Gy following 3D-CRT and IMRT plans during FB (upper row), T-DIBH (middle row) and A-DIBH (lower row). ∆: mean dose difference between 3D-CRT and IMRT plans