Development of a prospective clinical workflow for proton beam therapy of ventricular tachycardia

This study presents a prospective preclinical workflow for proton beam therapy of refractory ventricular tachycardia (VT), covering target transfer, treatment planning (TP), and beam gating.

Photon-based stereotactic arrhythmia radioablation (STAR) protocols were adapted to proton beam therapy, encompassing (i) target transfer from electroanatomical mapping (EAM) onto planning computed tomography (CT), (ii) simulation of three TP cases from the Standardized Treatment and Outcome Platform for Stereotactic Therapy of Re-Entrant Tachycardia by a Multidisciplinary (STOPSTORM.eu) benchmark, and (iii) evaluation of trigger events and delays for synchrotron beam delivery control using gating.

CARDIO-RT enabled electroanatomical mapping to computed tomography (EAM-to-CT) target transfer; two experienced cardiologists qualitatively judged the transferred targets as clinically acceptable by visual inspection. Treatment plans demonstrated effective organ at risk (OAR) sparing and clinical adequacy. The planning target volume (PTV) D_95% ranged from 23.3 to 23.9 Gy relative biological effectiveness (RBE) and the clinical target volume electrophysiology (CTV [EP]) D_95% from 30.9 to 31.6 Gy (RBE); underdosage was permitted where anatomical compromise was unavoidable. No CTV(EP) hotspot exceeded 33.5 Gy (RBE). Optical trigger signals are supported for beam gating; the total cardiac gating chain latency was below 30 ms.

This technical feasibility study demonstrates a prospective preclinical workflow for proton beam STAR, covering EAM-to-CT target transfer, TP across three benchmark clinical cases, and accelerator-side optical gating integration at a synchrotron-based facility. The workflow demonstrates technical feasibility; however, full clinical translation still requires patient positioning and verification, motion characterization, and end-to-end validation. Future work will employ a dynamic anthropomorphic phantom to characterize motion-induced dosimetric changes and assess plan robustness for proton and carbon ion beam delivery.