Cardio-respiratory-gated proton pencil beam scanning for cardiac ablation: workflow and end-to-end validation

@article{depauw2026cardiorespiratorygated,
  title = {{Cardio-respiratory-gated proton pencil beam scanning for cardiac ablation: workflow and end-to-end validation}},
  author = {Nicolas Depauw and Felicitas Bijari and Ethan Cascio and Evan Driscoll and Adriano Garonna and Jagdip Kang and Helen Deng and Hyeongseok Kim and Marina Macdonald-Soccorso and Willian Nett and Marc Normandin and Matthieu Pellissier-Tanon and Rebecca Woodcock and Koushiar Yaghoubian and Georges El Fakhri and Robert Levine and H.Immo Lehmann and Yen-Lin Chen and Kyung-Wook Jee},
  journal = {Frontiers in Oncology},
  year = {2026},
  month = oct,
  doi = {10.3389/fonc.2026.1923998},
  url = {https://www.frontiersin.org/articles/10.3389/fonc.2026.1923998/full},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Cardio-respiratory-gated proton pencil beam scanning for cardiac ablation: workflow and end-to-end validation
AU  - Nicolas Depauw
AU  - Felicitas Bijari
AU  - Ethan Cascio
AU  - Evan Driscoll
AU  - Adriano Garonna
AU  - Jagdip Kang
AU  - Helen Deng
AU  - Hyeongseok Kim
AU  - Marina Macdonald-Soccorso
AU  - Willian Nett
AU  - Marc Normandin
AU  - Matthieu Pellissier-Tanon
AU  - Rebecca Woodcock
AU  - Koushiar Yaghoubian
AU  - Georges El Fakhri
AU  - Robert Levine
AU  - H.Immo Lehmann
AU  - Yen-Lin Chen
AU  - Kyung-Wook Jee
PY  - 2026
DA  - 2026/10/23
JO  - Frontiers in Oncology
DO  - 10.3389/fonc.2026.1923998
UR  - https://www.frontiersin.org/articles/10.3389/fonc.2026.1923998/full
AB  - Background: Stereotactic Arrhythmia Radiotherapy (STAR) offers a non-invasive alternative for ventricular tachycardia ablation, yet motion management remains a critical challenge. While respiratory gating is established, cardiac gating requires a dedicated workflow and gating device.  Methods: This study establishes and validates an end-to-end workflow for cardiorespiratory gated proton STAR in six healthy swine. Key innovations include a novel pencil-beam scanning (PBS) controller enabling mid-spot beam pausing and resumption, and the integration of CardioKit, an ultrasound-based image-guidance system for real-time soft-tissue tracking. The workflow was evaluated by comparing single-gated (respiratory only) and dual-gated (cardiorespiratory) delivery strategies, assessing system latency, dosimetric accuracy on dynamic phantoms, and motion tracking fidelity against 4D-CT benchmarks.  Results: The upgraded PBS system demonstrated a gate response latency of <550 µs, effectively mitigating interplay effects in dynamic phantom measurements through gated beam deliveries. CardioKit provided respiratory motion traces highly correlated with 4D-CT data (Pearson r > 0.97) and responded to arrhythmic events within 5 ms. In vivo , dual-gating restricted delivery to the diastolic window (70–100% R–R), which resulted in a reduction in the Internal Target Volume (ITV) expansion by a mean of 45% compared to single-gating (19% vs. 64%), thereby substantially sparing healthy myocardium. Although dual-gating increased total beam-on time, the mid-spot interrupt capability ensured robust dose accumulation without treatment aborts.  Conclusion: The workflow for imaging, treatment planning, and cardiorespiratory-gated beam delivery was viable for treating all six subjects. The PBS system responded to gating commands < 550 µs and CardioKit responded to irregularities in heartbeat in <5 ms. Cardiorespiratory gating enabled an average 45% reduction in target expansion due to cardiac motion. Comparison of CardioKit respiratory motion traces with respiratory 4D-CT yielded differences of 1.1-1.4 mm in total motion amplitude and 0.97-0.99 Pearson correlation factor. These findings are valuable for establishing a workflow for cardiorespiratory-gated STAR treatment with CardioKit.
SN  - 2234-943X
ER  -