Comparison of the Dosimetric Parameters of Free Breathing versus Deep Inspiration Breath Hold for Left-sided Breast Cancer

A BSTRACT Background: Deep inspiration breath hold (DIBH) synchronizes radiation therapy with the breathing cycle, thereby reducing dose to the normal tissues, especially the heart. The objective of this study was to compare the dosimetric parameters of free breathing (FB) and DIBH treatment plans in patients with left-sided breast carcinoma. Materials and Methods: Thirty-one patients aged <65 years who underwent breast conservation surgery (BCS) for early stage left-sided breast cancer were included in this prospective study. After breath hold coaching, computed tomography (CT) simulation was performed with both FB and DIBH techniques. Two treatment plans were generated for each patient using the respective CT image sets, with a prescribed dose of 40 Gray (4000 centi-Gray) in 15 fractions followed sequentially by 10 Gray (1000 centi-Gray) in 5 fractions lumpectomy boost. The plans were compared with respect to the cardiac and lung dosimetric parameters and paired t -test was used to test for significant differences. Results: Mean heart dose was reduced from 279.83 ± 106.6 centi-Gray (cGy) in FB to 213.24 ± 91.59 cGy in DIBH ( P < 0.001). There was a 29% reduction in the mean left anterior descending coronary artery dose with the use of DIBH (515.94 ± 294.48 cGy FB vs. 365.93 ± 171.62 cGy DIBH, P < 0.001). There was no significant difference in the mean left lung dose, left lung V20, and the total lung V20; however, there was an increase in both the left lung volume and the total lung volume by DIBH method compared to FB. Conclusion: Deep inspiratory breath hold technique significantly reduced the cardiac dose compared to FB in left-sided breast cancer patients; however, there was no significant reduction in the lung dose.