Free Breathing versus Deep Inspiration Breath Hold Technique in Post-mastectomy Radiotherapy for Left Sided Breast Cancer: A Dosimetric Comparison of Target Volumes, Heart and Left Lung
Authors: Dr. Nishat Tasnim
Institution: 250 Bedded Mohammad Ali Hospital, Bogura
Introduction
Radiotherapy (RT) is an important part of treatment for breast cancer. But it may cause late cardiac and pulmonary toxicities, especially in left sided cases due to proximity to these vital organs. Deep inspiration breath hold (DIBH) is a newer RT technique that can reduce radiation dose to the heart and lungs compared with free breathing (FB) without compromising target coverage.
Methods
This quasi-experimental study was conducted at Bangladesh Medical University (BMU) and Combined Military Hospital (CMH), Dhaka, from August 2024 to September 2025. Fifty women with left sided invasive breast cancer requiring PMRT with regional nodal irradiation (RNI) were enrolled and equally divided into Arm A (FB) and Arm B (DIBH). All of them received 4005 cGy in 15 fractions over three weeks by intensity-modulated RT (IMRT) technique. Dose-volume histograms (DVH) and statistical graphs for PTV, heart, and left lung were analyzed from treatment planning system (TPS).
Results
DIBH significantly reduced cardiac and pulmonary doses compared to FB mainly by increasing intervening lung volume (p < 0.001). For the heart; Dmean, Dmax, and V25Gy were all lower in DIBH (p < 0.001). Left lung Dmean and V20Gy were also significantly reduced (p = 0.003 and < 0.001, respectively). No significant difference was observed in PTV dosimetry between the two techniques. Univariate analysis showed left lung volume as most important predictor of cardiopulmonary sparing. Regression model explained 64.4% of the variance in mean heart dose (MHD) and 14.5% of the variance in mean left lung dose (MLLD) with left lung volume.
Conclusion
DIBH technique results in a remarkable decrease in cardiac and ipsilateral pulmonary doses than FB technique during PMRT for left sided breast carcinoma cases while maintaining equivalent PTV coverage.