Room: Exhibit Hall | Forum 6
Purpose: To establish a protocol regarding stereotactic body radiotherapy (SBRT) for ventricular arrhythmias (VA) with co-registration of electrophysiological maps
Methods: The protocol for VA SBRT consisted of four parts: 1) defining the target area using an electrophysiological map, 2) registering the defined target area to a planning image by using in-house software to read the non-DICOM format mesh files, 3) converting the contours of the cardiac structures in non-DICOM format and saving in DICOM format for planning, and 4) optimizing a SBRT plan. An in-house software was developed for steps 2 and 3. An interventional cardiologist generated the electrophysiological map of the target and adjacent cardiac structures using CARTO (Biosense-Webster, Diamond Bar, CA), and a radiation oncologist drew contours of ventricles on the planning images for registration. The electrophysiological map data was registered to planning images using an iterative closest point algorithm with modification of the resampled target as necessary. The resampled target and structures were saved in DICOM-RT structure format. As a proof of concept, the map data and 4D MR images from a patient who underwent conventional radiofrequency ablation were used.
Results: A radiation oncologist defined the inner surface of the left ventricle on 3-consecutive MR axial images at the end of the atrial systolic phase, and the electrophysiological maps were registered with those contours. The root-mean-square error of registration was 7.4-mm after 101-iterations. Eight cardiac structures on the electrophysiological map were resampled on the MR images, and the resampled contours were saved as a DICOM-RT structure. The DICOM-file was successfully imported into a commercial treatment planning software for optimizing a SBRT plan.
Conclusion: The protocol for treating ventricular arrhythmias using radiation was proposed and was verified using a sample patient data set. The quality of the contours on the image was sufficient for optimizing a plan.