Key result
Proton stereotactic arrhythmia radioablation reduces radiation to non-target cardiac structures versus photon therapy.
Why the study?
Most stereotactic arrhythmia radioablation treatments have used photons, but protons have advantageous ballistic properties that could potentially improve the sparing of organs at risk.
Does proton radiotherapy reduce radiation dose to organs at risk compared to photon radiotherapy in in silico planning for stereotactic arrhythmia radioablation?
Cohort (n=23)
Does proton radiotherapy reduce radiation dose to organs at risk compared to photon radiotherapy in in silico planning for stereotactic arrhythmia radioablation?
In silico dosimetric analysis suggests proton beam stereotactic arrhythmia radioablation significantly reduces radiation exposure to non-target cardiac and extracardiac structures compared to photon therapy.
Proton plans were associated with lower OAR doses than photons in STAR; hypothesis-generating and requires prospective trials before clinical adoption.
BACKGROUND: Stereotactic arrhythmia radioablation (STAR) may represent an alternative to standard catheter ablation (CA) for treatment of refractory ventricular arrhythmias (VA). Most STAR treatments performed to date have used photon radiotherapy. However, protons have advantageous ballistic properties suitable for this application, potentially improving sparing of organs at risk (OARs). METHODS: ECG-gated CT scans and electroanatomical mapping were performed to reconstruct a 3D bipolar voltage map and identify ablation targets in a cohort of patients with VA candidates for CA. Three radiation treatment modalities were investigated/compared using the breath-hold technique: photon volumetric modulated arc therapy (VMAT) and proton active pencil beam scanning delivered with/without cardiac gating. When cardiac gating was applied, the diastolic phase-longer and more stable than the systolic one-was selected as the reference. RESULTS: Twenty-three patients were enrolled, and three presented multifocal ventricular arrhythmias, resulting in a total of 27 treatment targets. Both photon and proton plans achieved adequate target coverage. Compared with photon plans, proton therapy showed a statistically significant reduction in the mean maximum dose to several OARs and to important non-target cardiac structures (coronary arteries, valvular apparatus and right atrium) while maintaining comparable target coverage. These findings were consistent for proton plans with and without cardiac gating. In a subset of 14 patients, cardiac gating provided additional reductions in dose to healthy cardiac tissue. CONCLUSIONS: This in-silico study suggests that STAR using proton beams may significantly reduce radiation exposure to non-target cardiac substructures and surrounding extracardiac OARs, regardless of the cardiac motion management strategy adopted.
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Mirandola et al. (2026) conducted a cohort in Ventricular tachycardia (n=23). Proton active pencil beam scanning vs. Photon volumetric modulated arc therapy (VMAT) was evaluated on Target coverage and dose to organs at risk and non-target cardiac structures. Proton therapy for stereotactic arrhythmia radioablation significantly reduced the mean maximum radiation dose to non-target cardiac structures and organs at risk compared with photon therapy.
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