Cardiac Substructure Dose Quantification and Optimization in Left-Sided Lung Cancer Radiotherapy
In brief
Replanning lowers left anterior descending artery high-dose volume from 84% to 14%
In 50 left-sided lung cancer patients, eleven cardiac substructures received mean doses above the institutional whole-heart limit, with the left anterior descending artery exposed to 15 Gy in 84% of its volume. Strategic replanning reduced that exposure to 14% of the artery, showing that substructure-sparing plans are feasible and may lessen radiation-induced heart injury.
- Journal
- Practical radiation oncology (Q1)
- Published
- 11 September 2026
- Study design
- Unclassified
- Evidence level
- Level 5, Expert Opinion (CEBM 5)
- Authors
- Vanessa L Wildman, Richard L J Qiu, Kirk Luca, Mokshad P Gaonkar, Mojtaba Safari, Luke Del Balzo, et al.
- PMID
- 42727773
- DOI
- 10.1016/j.prro.2026.08.011
Why clinicians should know about it
- Picked for Radiation Oncology (paper of the day, 15 September 2026): Cardiac substructure dose optimization in left‑lung RT
Abstract
BACKGROUND: As curative-intent radiation therapy provides excellent local control for lung tumors, patients are surviving longer to experience treatment-associated adverse cardiac events. Patients treated for left-lung tumors are particularly vulnerable due to the heart's anatomical proximity. While the whole heart is conventionally contoured as an organ-at-risk, emerging research highlights cardiac substructure doses better predict cardiotoxicity post-radiotherapy than mean heart dose. METHODS: An institutional dataset of 50 contrast-enhanced CT scans was compiled from patients treated between 2015 and 2025 for left-sided locally advanced primary lung cancers with definitive photon radiotherapy to 60 Gy in 30 fractions. Twenty-one cardiac substructures were manually contoured on each CT per gold-standard atlases and novel protocols. Mean and maximum substructure doses were extracted from treatment dose-volume histograms, and associations between substructure dose, target volume, tumor location, and demographics were analyzed. Strategic treatment replanning of the 15 cases exceeding a mean whole heart dose of 9 Gy evaluated feasibility of substructure dose reduction. RESULTS: Mean substructure radiation doses were compared against the optimal institutional whole-heart mean dose constraint of 10 Gy. The four highest average mean dose results with 95% confidence intervals were: Aortic Arch 38.6 [32.7-43.8] Gy, Pulmonary Artery 33.3 [29.4-36.8] Gy, Pulmonary Veins 28.8 [24.9-32.4] Gy, and Left Circumflex Coronary Artery 27.3 [21.8-32.7] Gy. In the full cohort, average LAD V15 Gy was 52.7%; in the elevated heart dose cohort, it reached 83.8%. Following replanning, LAD V15 Gy was reduced to 13.7%. CONCLUSION: This is one of few quantifications of substructure dosimetry in left-sided lung radiotherapy. Eleven substructures received mean doses exceeding the institutional whole-heart threshold, underscoring the need to consider substructures treatment planning. Strategic replanning demonstrates clinical feasibility in reducing substructure doses, particularly the left-sided coronary arteries. The resulting contour and dose datasets provide a foundation for predictive modeling and substructure-sparing treatment strategies.
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.