Fig. 2

Example of noninvasive cardiac radio-ablation using the linear accelerator (LA) and CyberKnife (CK)-based radiosurgery systems. Patient No. 10 was a 61-year-old man with recurrent sustained ventricular tachycardia (VT) related to left apical ventricular hypertrophy refractory to antiarrhythmic medication and an implantable cardiac defibrillator. Electro-anatomical mapping revealed that the substrate originated from the apical junction of the right coronary commissure (RCC) and left coronary commissure (LCC). He underwent multiple sessions of CARTO-guided cardiac ablation of the apical junction of the LCC-RCC and the right ventricular outflow tract posterior septal area. He developed recurrent VT, and noninvasive cardiac radio-ablation was performed using an LA-based 6-MV flattening filter-free photon beam and stereotactic volumetric modulated arc radiotherapy technique to the posterior-septal wall at 25 Gy in 1 fraction. The VT burden was reduced after noninvasive cardiac radio-ablation, and the patient was followed up at the clinic. The CK plan was generated for dosimetric comparison. The homogeneity indices, conformity indices, gradient indices, gradient measures, and maximum doses at 2 cm from the planning target volume (PTV) of the LA and CK plans are shown in Table 1. The beam arrangement is shown in the upper panels of the figure. a Four coplanar arcs and three non-coplanar arcs are presented in the LA plan. b A total of 253 non-coplanar beams are presented in the CK plan. The isodose curves are shown in the lower panel for the LA plan (c) and the CK plan (d). Green areas indicate the PTV. The orange, red, and blue lines represent the isodose curves at 2875, 2500, and 1250 cGy, respectively