A Comparative Dosimetric Study for the Treatment of Left-Sided Breast Cancer using Three-Dimensional Conformal Deep Inspiration Breath-Hold and Free-Breathing Intensity-Modulated Radiotherapy Techniques

Introduction: Most women with left-sided breast cancer are at an increased risk of heartmorbidity and mortality from the adjuvant radiotherapy due to an increase in heart absorbed dose during radiotherapy treatment. This study aimed to compare free-breathing intensity-modulated radiotherapy (FB-IMRT) and three-dimensional conformal deep inspiration breath-hold (3DCRT-DIBH) techniques in terms of the cardiac dose. Material and Methods: In total, 15 women with left-sided breast cancer underwent FB and DIBH computed tomography (CT) scans in the same supine position. For DIBH CT, 3D-CRT plans were created using two opposing wedged tangential fields and for FB-CT, 4-5 IMRT optimized tangential fields were created. All plans were evaluated using the dose-volume histogram. The data were analyzed in SPSS software version 20 (IBM, IL). Results: The FB-IMRT plans were more homogeneous and had more dose coverage and fewer hotspots, than the 3DCRT-DIBH plans; however, the planning target volume V95% was clinically acceptable for both techniques. Furthermore, the 3DCRT-DIBH plans were much faster and require fewer monitor units. A significantly lower mean dose of heart, left lung, left anterior descending coronary artery, right lung, and V10% left lung were observed in 3DCRT-DIBH plans, compared to FB-IMRT plans. Moreover, FB-IMRT plans showed a significant further dose reduction in heart V25% and V30%. Conclusion: The majority of the patients with left-sided breast cancer who treated with the DIBH technique were getting sufficient benefits of radiotherapy, and DIBH was a comprehensive strategy for reducing cardiac doses during radiotherapy treatment.