Clinical Application of Heart Digital Twin–Based Cardiac SBRT for Ventricular Tachycardia Using VMAT with High-Definition Mlc
Abstract
Purpose
SBRT is an emerging noninvasive treatment for refractory ventricular tachycardia. Precise target delineation and highly conformal dose delivery are critical due to cardiac motion and the close proximity. This study evaluates the clinical application of cardiac SBRT planned using a heart digital twin and delivered with VMAT utilizing HD MLC.
Methods
Two patients with refractory VT were included. In the first patient, a left ventricular assist device (LVAD) was present and incorporated into planning as a critical avoidance structure. In the second patient, SBRT targets were refined using noninvasive electrocardiographic mapping of VT induced through the patient’s implantable cardioverter-defibrillator (ICD). A dedicated cardiac modeling software analyzed cardiac CT/MRI to construct a three-dimensional heart digital twin, enabling identification of myocardial scar, arrhythmogenic substrates, and adjacent organs at risk (OARs) for target delineation. Target structures were imported into a commercial treatment planning system. Treatment plans were generated using VMAT with 6 MV flattening filter-free beams and HD MLC on a linear accelerator. A prescription dose of 25 Gy in a single fraction was planned. Dosimetric endpoints included target coverage, conformity, and OAR doses (lungs, esophagus, spinal cord, coronary arteries, and implanted devices). Patient-specific quality assurance was performed using standard measurement-based techniques.
Results
Both plans achieved ≥95% target coverage with the prescription dose and demonstrated high conformity (CI₁₀₀% ≤ 1.1) with steep dose gradients. The HD MLC enabled precise shaping of complex cardiac targets while maintaining OAR and implanted-device doses within institutional and published constraints. VMAT delivery provided efficient treatment times compatible with motion-managed workflows.
Conclusion
Heart digital twin–based target delineation combined with VMAT and HD MLC enables accurate, highly conformal, and clinically feasible cardiac SBRT for VT ablation, including complex scenarios involving LVADs and ICD-guided target refinement. This approach supports safe treatment delivery and demonstrates potential for broader clinical implementation.