A dosimetric analysis of cardiac dose with or without active breath coordinator moderate deep inspiratory breath hold in left sided breast cancer radiotherapy.

Abstract

Cardiac toxicity is a major concern for left breast tangential field irradiation. The left ventricle and left anterior descending (LAD) artery are suggested to be radiosensitive and radiation to these structures leads to late lethal cardiotoxicity. Moderate deep inspiration breath hold (mDIBH) during radiation treatment delivery helps in reducing the cardiac dose. This study compares dosimetric parameters of heart with and without active breath coordinator (ABC) mDIBH during tangential field breast cancer radiation. This is a dosimetric comparative study. Forty-five consecutive patients with left-sided breast cancer who underwent breast-conserving surgery and adjuvant tangential field and radiotherapy with ABC mDIBH between November 2013 and September 2015 in our center were analyzed in this study. The ABC device was used for respiratory control and patients who could hold their breath for 20-30 s were considered for radiation with ABC mDIBH. Simulation scans of both free breathing (FB) and ABC mDIBH were done. Tangent field treatment plans with a dose prescription of 40 Gy/15 Fr were generated for each patient, in both scans. Target coverage, dose to the heart, LAD, and the left lung were documented with dose-volume histograms. Statistical Package for the Social Sciences, version 20 software, was used for analysis and the level of significance was set at P < 0.05. Mean heart dose was 308.5cGy with FB and 159cGy with ABC (P < 0.0001). Mean dose to the LAD was reduced by 53.81% (1320.64 cGy vs. 606.56 cGy, P < 0.001). Target coverage was equal in both the plans. We report that the use of ABC mDIBH technique resulted in a significant reduction in cardiac dose and hence can be considered as a promising tool for cardiac sparing.