motion; radioablation; ventricular-tachycardia

Stereotactic arrhythmia radioablation (STAR) has been suggested as a promising alternative in cases of failed catheter ablation for recurrent ventricular tachycardias in patients with structural heart disease. When delivering STAR, specific challenging conditions include extreme hypo-fractionation with typical single fraction prescription doses of 25 Gy and the target location in the left ventricle which makes it susceptible to cardiorespiratory intrafractional motion. The general objective of this work is to estimate the delivered dose based on data not explicitly considered and/or available for treatment planning. This includes situations where data was included only partially such as respiratory 4DCT or ECG-gated CT applied for target definition but not for dose calculation/optimization. In this initial study we analysed clinical available data of one STAR patient following a Cyberknife-specific workflow. In line with the general objective, the specific task was to provide a more accurate dose estimation by accounting for anatomical and dosimetric variations at complementary respiratory phases sampling free breathing during dose delivery.