Dosimetric Benefit and Clinical Feasibility of Deep Inspiratory Breath-Hold and Volumetric Modulated Arc Therapy Based Postmastectomy Radiotherapy for Left-Sided Breast Cancer

• DOI: 10.1016/j.ijrobp.2024.07.749
• Publication Date: 2024-09-27T22:44:01Z
• Authors: S.J. Wang; H. Jing; Y. Zhai; W. Zhang; S. Chen; S. Qin; H. Fang; Y. Tang; Y. Song; Y. Liu; B. Chen; S. Qi; Y. Tang; N. Lu; Y. LI; S. Wang
• Keywords: Adult; Left-sided breast cancer; Science; Setup error; Deep inspiratory breath-hold; Article; Breath Holding; Cardiopulmonary dose; Unilateral Breast Neoplasms; Humans; Prospective Studies; Radiometry; Lung; Mastectomy; Aged; Radiotherapy Planning, Computer-Assisted; Q; R; Radiotherapy Dosage; Heart; Postmastectomy radiotherapy; Middle Aged; Cone-Beam Computed Tomography; Inhalation; Medicine; Feasibility Studies; Female; Radiotherapy, Intensity-Modulated

To evaluate the dosimetric benefits and clinical feasibility of deep inspiratory breath-hold (DIBH) combined with volumetric modulated arc therapy (VMAT) in left-sided postmastectomy radiotherapy (PMRT). Eligible patients with left-sided breast cancer undergoing DIBH-based PMRT were prospectively included. Chest wall, supra/infraclavicular fossa, and/or internal mammary node irradiation (IMNI) were planned with a prescription dose of 43.5 Gy in 15 fractions. VMAT plans were designed on free breathing (FB)-and DIBH-CT to compare dosimetric parameters in heart, left anterior descending artery (LAD) and lung. Cone-beam computed tomography (CBCT) was performed before and after treatment to evaluate inter- and intra-fractional setup errors. Heart position and dose variations during treatment were estimated by fusing CBCT with DIBH-CT scans.Twenty patients were included with 10 receiving IMNI. In total, 193 pre-treatment and 39 pairs pre- and post-treatment CBCT scans were analyzed. The Dmean, Dmax, and V5-40 of the heart, LAD, and left lung were significantly lower in DIBH than FB (p < 0.05 for all), except for V5 of LAD (p = 0.167). The cardiopulmonary dosimetric benefits were maintained regardless of IMNI. The inter- and intra-fractional setup errors were < 0.3 cm; and the overall estimated PTV margins were < 1.0 cm. During treatment, the mean dice similarity coefficient of heart position and the mean ratio of heart Dmean between CBCT and DIBH-CT plans was 0.95 (0.88-1.00) and 100% (70.6-119.5%), respectively. DIBH-VMAT could effectively reduce the cardiopulmonary doses with acceptable reproducibility and stability in left-sided PMRT regardless of IMNI.