A recent Phase I/II trial demonstrated safety and efficacy of non-invasive cardiac radioablation for patients with treatment refractory ventricular tachycardia (VT). An increasing number of domestic and international centers are using this approach as a salvage therapy. However, the variability in target volume selection by physicians currently using or planning to use cardiac radioablation is not known. During the 2019 Symposium for Noninvasive Radioablation (SNORAD), teams of cardiac electrophysiologists (EPs) and radiation oncologists were given two patient datasets for analysis. Participants were asked five questions regarding gross target volume (GTV) selection using a 17-segment left ventricular cardiac model after being given: 1) previous electrocardiograms and catheter mapping studies, 2) noninvasive electrocardiographic imaging (ECGI) of patients during VT, 3) anatomic imaging for scar identification with CT and cardiac MRI, 4) metabolic imaging with PET/SPECT for viable myocardium identification and 5) final volume based on all data sources. We analyzed the range of GTV values and agreement between the two-person teams. There were 32 responses for Case 1 and 34 responses for Case 2. For both Case 1 and 2, the smallest target volume estimates came from PET/CT imaging: mean volume 11.4cc (range 3.5 – 35.5cc) for Case 1 and 14.4cc (4.9 – 42.8cc) for Case 2. The largest GTV estimates came from CT/MRI for Case 1 (mean 19.9cc, 3.6 – 50.4cc) and ECGI for Case 2 (20.9cc, 3.6 – 57.0). Final mean GTV values once all data was reviewed was 15.8cc (3.6 – 39.0) for Case 1 and 20.5cc (5.0cc – 42.8cc) for Case 2. For Case 1, 75% of the teams could not agree on a common volume based on individual data from questions 1-4, and even with all data available, could only agree on a single cardiac segment (3.6cc). With Case 2, only question 1 showed no common volume, while questions 2-4 showed increased consensus of a common 5cc volume with PET/CT and 9.9cc for ECGI and CT/MRI each. The final consensus volume for 75% of the observers was 9.9cc for Case 2. GTV delineation for ventricular tachycardia represents a novel challenge for EPs and radiation oncologists alike as it involves the integration of imaging and electrophysiological information not conventionally used by either specialty. This analysis demonstrates that there can be substantial variability in the size and location of GTV selection, and that a learning curve is likely present.