PO-04-095 ACCURATE EAM-BASED TARGET DELINEATION IN STEREOTACTIC ARRHYTHMIA RADIOABLATION OF VT

Stereotactic Arrhythmia Radiotherapy (STAR) aided by precise image-guided delivery and respiratory motion management has been used successfully for experimental treatment of refractory VT. However, accurate target selection remains challenging. Current methods often rely on manual delineation and/or visual estimation predefined cardiac segments. Develop a systematic process registering VT targets from electroanatomic maps (EAM) to reference imaging coordinates the planning CT (pCT) radiation treatment. The goal is minimize potential variations in site as well treated volumes. In patients antiarrhythmic undergoing 2nd unsuccessful ablation, EA LV (and LA/RV when possible) more focal sites were acquired (CARTO®3, Biosense-Webster, CA, USA) exported. In-house software was register these image set convert them DICOM structure files (Fig 1). Dice similarity coefficients calculated between ventricular mesh data corresponding contours. Initial (GTV) expanded include internal volumes (ITV) (PTV) account residual uncertainties, with minor adjustments guided consensus among electrophysiologists, oncologists medical physicists. STAR delivered single fraction 25 Gy using volumetric-modulated arc therapy or dynamic conformal depending shape. 7 defining based individualized EAM images. indices transferred map contours 0.83 ± 0.04 0.72 LA/RV, respectively (table median clinical 22cc, PTVs ranging 62.4 199.6 cc. All demonstrated significant reduction events 6 weeks post STAR. We have developed an effective methodology direct registration selected STAR, anatomic during ablation procedures. This offers way efficiently delineate variable boundaries semi-automated way, which advantageous unusual make standard segmentation inaccurate difficult. rigorous comparison other approaches be done.Tabled 1Patient-specific metrics1234567Dice, LV0.8680.8450.7910.8060.7210.8720.794Dice, LA/RV0.7520.6670.734N/A0.382N/A0.338GTV (cc)22.313.526.520.759.863.927.2ITV (cc)45.529.142.230.959.8127.829.6PTV (cc)98.662.488.275.5166.8199.672.8 Open table new tab