Linac-based STereotactic Arrhythmia Radioablation (STAR) for ventricular tachycardia: a treatment planning study

Area of Science:

• Medical Physics
• Radiation Oncology
• Cardiology

Background:

• Ventricular tachycardia (VT) poses a significant clinical challenge.
• Linear accelerator (Linac)-based STereotactic Arrhythmia Radioablation (STAR) is an emerging technique for VT treatment.
• Optimizing geometrical approaches and delivery parameters is crucial for STAR efficacy and safety.

Purpose of the Study:

• To analyze geometrical strategies, dose prescription methods, and delivery efficiency of Linac-based STAR for ventricular tachycardia.
• To compare different treatment planning parameters for STAR to determine optimal configurations.

Main Methods:

• Utilized patient anatomy and planning target volume (PTV) data from the first Italian STAR patient.
• Generated and compared three plans (Plans#1-3) with varying arc numbers, lengths, and couch rotations using 6-MV flattening-filter-free (FFF) volumetric-arc therapy.
• Evaluated prescription modalities and delivery efficiency by comparing the best geometrical plan against plans with different isodose prescriptions (70%, 65%, 60%) and a 10MV-FFF beam (Plans#4-7).

Main Results:

• Plans#1-3 achieved PTV coverage of 96-98.5%, with mean cardiac dose of 4.9-5.2 Gy, MUs of 7047-7790, and beam-delivery-time (BDT) of 5-6 minutes.
• Plans#4-7 showed comparable mean cardiac dose, MUs, and BDT to Plans#1-3.
• The 10MV-FFF plan demonstrated a lower delivery time but potentially higher maximum dose.

Conclusions:

• Linac-based STAR is a safe and efficient treatment modality for VT, characterized by acceptable beam-delivery-time and monitor units.
• Careful consideration of dose prescription modalities is necessary to achieve adequate PTV coverage.
• While 10MV-FFF beams offer faster delivery, their suitability is limited in patients with cardiac implantable electronic devices.