# Dosimetric impact of deep inspiration breath hold (DIBH) technique in right-sided breast cancer radiotherapy: a retrospective analysis

## TL;DR

This study shows that using a deep breath hold technique during radiotherapy for right-sided breast cancer reduces doses to critical organs without affecting treatment coverage.

## Contribution

The study is the first to demonstrate dosimetric benefits of DIBH for right-sided breast cancer and identifies BMI as a factor influencing liver dose reduction.

## Key findings

- DIBH significantly reduced doses to the right lung, heart, RCA, and liver in right-sided breast cancer patients.
- Higher BMI correlated with greater liver dose reduction in patients undergoing DIBH.
- Contralateral breast dose was significantly reduced in both treatment groups using DIBH.

## Abstract

While deep-inspiration breath hold (DIBH) is widely used to reduce cardiac dose in left-sided breast cancer radiotherapy, its dosimetric benefits for right-sided cases remain underexplored. This study evaluated DIBH’s impact on target coverage and organs at risk (OARs) in right-sided breast cancer, and investigated associations between dose-volume changes, lung volume, and anthropometric indices.

We retrospectively analyzed 33 patients with right-sided breast cancer treated using DIBH. Seventeen patients received whole-breast (WB) irradiation following post–breast-conserving surgery, and sixteen received chest wall (CW) plus internal mammary node (IMN) and supraclavicular (SC) irradiation post-mastectomy. Computed tomography (CT) scans acquired under free breathing (FB) and DIBH were used to generate separate treatment plans. Dose-volume parameters for target volumes and OARs were compared, and correlations between FB-to-DIBH changes and body mass index (BMI) and body surface area (BSA) were analyzed.

Compared with FB, DIBH significantly reduced doses to the right lung, heart, right coronary artery (RCA), and liver in both cohorts (all P < 0.05), while planning target volume (PTV) coverage remained unchanged. The maximum dose to the contralateral breast (Dmax) also decreased under DIBH, with reductions of 22.7% in the WB group (P = 0.02) and 37.76% in the CW+IMN+SC group (P < 0.001). Body mass index (BMI) showed a significant association with DIBH induced liver dose reduction in the WB cohort (liver mean dose, Dmean: r = 0.622, P = 0.008; liver volume receiving > =5Gy, V5Gy: r = 0.483, P = 0.05). In contrast, no meaningful correlations with dosimetric parameters were observed for BSA (all P > 0.05).

DIBH effectively reduced OAR doses in right-sided breast cancer radiotherapy while maintaining target coverage. Patients with higher BMI derived greater hepatic dose sparing, suggesting that BMI-informed patient selection may enhance the clinical utility of DIBH.