Exhibit Hall | Forum 2
Purpose: To report the variability of target volumes in single fraction stereotactic arrhythmia radioablation (STAR) in patients with refractory ventricular tachycardia (VT) between comparing the traditional 17-segment model to direct registration of electroanatomic (EA) maps to a planning image set.
Methods: To compare target variability, four refractory VT patients treated with standard STAR technique (a single fraction of 25-Gy) were considered in this study. The treatment plan was generated based on direct target definition which defined the target by registering EA maps of the left-ventricle and treatment area to a planning image. For comparison, two cardiac electrophysiologists (EPs) retrospectively defined the target volume using the traditional 17-segment model. They selected the target region on the 17-segment model with the data such as EKG, EA maps and MR image. Then the target was delineated on the planning image based on the selected segments. For comparison, three targets per patient were overlaid; The EA map based target (clinical target), the 1st EP defined target (EP1), and the 2nd EP defined target (EP2). The target volumes and the location on 3D space were compared.
Results: The target variability study between experts showed that EPs chose a relatively similar area, however EP2 defined additional segments. The EP1 and EP2 target volume range was 11% to 154% and 123% to 299% of the clinical target volume, respectively. The target location on 3D space is inconsistent among the three targets.
Conclusion: In an EA map versus 17 segment model comparison of VT targets, there is inter-user variability. The directly registering EA map of treatment area could be the more accurate target definition method.
Localization, Conformal Radiotherapy, Heart