Quantifying benefit of deep inspiration breath hold technique in reducing cardiac avoidance area (CAA) and liver doses for right-sided breast cancer patients

Abstract

Introduction: The present study aimed to observe the difference in dosimetry between Deep inspiration breath hold (DIBH) and Free breathing (FB) in patients who received right-sided breast radiotherapy with Intensity-Modulated Radiotherapy (IMRT), focusing on the cardiac avoidance area (CAA) and liver doses.

Materials and methods: This retrospective study analyzed twenty-one right-sided breast cancer patients from 2018 to 2023 at our centre. Tangential multiple-field IMRT plans were generated using two scan datasets with identical field arrangements. Dose-volume histograms (DVH) were analyzed to compare dose to target volume and organs at risk. The mean and standard deviation represent continuous variables. Pairwise, Wilcoxon signed rank tests with two tails were used to compare the groups. The Statistical Package for the Social Sciences (SPSS) version 21 was used for all statistical calculations.

Results: The study found that PTV coverage was similar for both FB and DIBH. Most patients are stage II (52.4%) with invasive ductal carcinoma histology. Over half had undergone mastectomy. The primary endpoint of CAA exposure and liver doses was significantly lower in DIBH than in FB. The maximum dose to the CAA was 5.23 (0.00-11.09) with DIBH compared to 6.35 (2.89-14.32) with FB (p=0.05). The mean dose of the liver was 2.27 (0.45-6.38) with DIBH compared to 3.91 (0.95-10.36) with FB (p =0.001); similar trends were observed across other liver volumes. The mean dose to the right lung was 6.38 (1.88-12.94) with DIBH compared to 6.92 (1.66-16.09) with FB (p=0.018); similar trends were observed across other lung volumes. The mean dose to right coronary artery and contralateral breast was less with DIBH, but not statistically significant.

Conclusion: DIBH for right-sided breast irradiation effectively reduces CAA and liver exposure while maintaining target volume coverage. However, larger studies are needed to determine clinical benefits.