Respiratory Instability-driven Cardiac Dose Deviation in Postmastectomy Deep Inspiration Breath-hold Volumetric Modulated Arc Therapy (DIBH VMAT): Development and External Validation of a Respiratory-informed Predictive Framework
In brief
A breathing-pattern model predicts heart-dose shifts within 0.58 cGy
In an external test of 20 patients receiving left-sided breast radiotherapy, a model predicted treatment-day changes in mean heart dose with an average error of 0.58 cGy. It was less accurate for dose changes to the left anterior descending artery, and the framework still needs further validation before clinical use.
- Journal
- Clinical oncology (Royal College of Radiologists (Great Britain)) (Q1)
- Published
- 1 October 2026
- Study design
- Retrospective cohort
- Evidence level
- Level 3, Low (CEBM 3b)
- Authors
- S Singh, S Sen, A K Singh, Dipesh, M Bhushan, S Pal, et al.
- PMID
- 42913341
- DOI
- 10.1016/j.clon.2026.104353
Why clinicians should know about it
- Picked for Medical Physics (top studies of the week, 25 October 2026): DIBH VMAT fraction-level cardiac dose prediction externally validated
Abstract
AIMS: Deep inspiration breath-hold (DIBH) reduces cardiac exposure during left-sided breast radiotherapy; however, treatment-day cardiac dose may differ from the planned dose because of variations in respiratory reproducibility and anatomy. The aim of this study was to develop and validate a framework for predicting fraction-level cardiac dose variation using routinely acquired respiratory, anatomical, and dosimetric information. MATERIALS AND METHODS: A retrospective cohort of 150 patients treated with postmastectomy DIBH VMAT (volumetric modulated arc therapy) was analyzed. Models were developed using a 30-patient development cohort with patient-wise-nested cross-validation, externally validated in 20 independent patients using cone-beam CT-derived synthetic CT dose recalculation, and applied to a 100-patient deployment cohort. Separate models predicted deviation from planned per-fraction mean heart dose (ΔMHD) and left anterior descending coronary artery dose (ΔLADCA D0.03 cc) using treatment-day real-time position management (RPM)--derived respiratory features, planning computed tomography (CT)-derived geometric variables, and plan-derived dosimetric parameters. SHAP-based analysis was performed to identify influential predictors. RESULTS: The final Gradient Boosting model for ΔMHD achieved an internal validation mean absolute error (MAE) of 0.541 ± 0.035 centigray (cGy) and coefficient of determination (R2) of 0.642 ± 0.069. The Ridge Regression model for left anterior descending coronary artery (ΔLADCA) achieved an MAE of 23.413 ± 1.617 cGy and R2 of 0.413 ± 0.082. External validation demonstrated good agreement for ΔMHD (MAE 0.58 cGy, R2 = 0.641), whereas ΔLADCA showed lower performance (MAE 24.14 cGy, R2 = 0.435). Stability index and baseline drift were key predictors. CONCLUSION: Treatment-day-respiratory characteristics combined with anatomical and dosimetric variables can estimate fraction-level cardiac dose variation during DIBH radiotherapy. The framework may support verification-based clinical review, with further validation required before implementation.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.