14P - The impact of the deep inspiration breath-hold (DIBH) technique in the heart and other organ-at-risk (OAR) dose sparing in the postoperative radiotherapy to the left early breast cancer

Background

Under the deep inspiration breath hold (DIBH) technique a considerable volume of the heart can be reduced to the high radiation doses. To investigate whether implementing DIBH to the hybrid technique will further reduce the cardiac doses, we compared the dosimetry characteristics of hybrid and VMAT treatment planning under DIBH and free breath.

Methods

Twenty patients with left-sided breast cancer who underwent breast-conserving surgery were selected for this study. Two sets of CT images were already acquired under deep-inspiration breath-hold (DIBH) and free-breathing(FB) before treatment. The same contours based on the original DIBH CT data sets were used for the modified Hybrid-technique and VMAT technique re-planning for the comparison of the original Hybrid planning. All plans were optimized to cover 100% of the PTV by 95% of the prescribed dose while minimizing the doses to the OAR as much as possible. The dosimetric differences among the 3 treatment plans for the 20 patients were analyzed using the Wilcoxon signed-rank test, the p value<0.05 were considered statistically significant. All analyses were performed using SPSS software, version 19.0.

Results

The mean heart dose was reduced from 3.2Gy and 5.38Gy, respectively (p value=0.002) and the LAD0.03cc dose was reduced from 14.85Gy and 24.91Gy, respectively (p value=0.001) by modified Hybrid-technique on DIBH and FB conditions. No statistically significant dose difference (p value>0.05) was found in the tumor conformity and homogeneity, and the critical organ on the affected side by the modified Hybrid-technique of VMAT under DIBH. In the contralateral critical organ, the modified Hybrid-tech showed better dose sparing than VMAT on the average dose of the contralateral lung, and the average dose of the contralateral breast.

Conclusions

Modified Hybrid-technique provides the best benefits for heart and OAR radiation dose sparing effect on DIBH condition.

Clinical trial identification

This clinical trial is approved by the institution review board of Taichung Veterans General Hospital (CE21447B).

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.