A prospective dosimetric study comparing thoracic and abdominal deep inspiratory breath hold techniques in left-sided breast cancer

INTRODUCTION The deep inspiratory breath hold (DIBH) technique has been recognized as a practical approach for reducing radiation doses to the heart in patients with left-sided breast cancer. DIBH can be achieved through thoracic (T-DIBH) or abdominal (A-DIBH) manoeuvres. In this study, we conducted a dosimetric analysis at our institute to compare the two DIBH techniques. MATERIAL AND METHODS A total of 5 diagnosed cases of left-sided breast cancer, who were advised for adjuvant radiotherapy (RT), were taken up for this prospective study. Before the planning simulation scan, all patients underwent training for T-DIBH and A-DIBH techniques over 5 consecutive days. Only patients who could perform DIBH using both manoeuvres were included in the study. Two planning CT scans were conducted with the patient's written consent on the final training day. Target delineation was performed on both planning scans following the Radiation Therapy Oncology Group (RTOG) standard guidelines. All plans were created using the forward intensity-modulated radiation therapy (IMRT) technique. A radiation oncologist evaluated the plans. The doses received by the heart, ipsilateral lung, and planning target volume (PTV) were compared using the Wilcoxon signed-rank test. Statistical analyses were conducted using SPSS version 26. RESULTS The mean dose received by the heart in the thoracic DIBH plans was 2.56±1.1, whereas, in the abdominal DIBH plans, it was 2.05±0.89. The mean lung dose achieved in the thoracic DIBH plans was 11.89±2.31, compared to 10.43±1.90 in the abdominal DIBH plans. Furthermore, the mean dose received by the PTV in the thoracic DIBH plans was 39.67±0.45, while in the abdominal DIBH plans, it was 39.89±0.39. CONCLUSION Based on findings, abdominal DIBH is a viable alternative to thoracic DIBH in patients with left-sided breast cancer. This technique offers comparable dosimetric coverage for the PTV while providing relative sparing of the heart and ipsilateral lung.