Room: AAPM ePoster Library
Sudden cardiac death caused by ventricular tachycardia (VT) results in >150,000 deaths/year in U.S. Noninvasive Cardiac Radio-Ablation (NCRA) was recently reported as a novel noninvasive alternative treatment to treat VT refractory to the anti-arrhythmogenic drugs and catheter ablation. Under-managed heart and respiratory motions can significantly affect multiple-modal images that are involved in target definition and treatment planning, and jeopardize the precision of image-guided target localization and radiation delivery. A heart motion phantom is needed to provide simultaneous cardiac and respiratory motions to support motion-compensated 4DCT and 4DMR studies, and allows end-to-end radiation dosimetry testing of NCRA.
A heart motion phantom with multiple components was constructed. Two double-layered balloons were filled with ~350 ml water to simulate the blood-flow. Each balloon was narrowed in its upper middle by a rubber band to separate upper and lower chambers simulating the dynamics of blood-flow between atrium and ventricle. Two such balloons wrapped by an air bag and packed in a container simulated four chambers of a heart. The air bag, inflated and deflated at 1 Hz by an air pump, squeezed the lower chambers rhythmically to create heart beating and blood-flow between atria and ventricles. The balloon and air bag assembly was placed on the motion platform which provided respiratory motion in superior-inferior at 0.25 Hz. Both the respiratory and cardiac cycle frequencies are adjustable.
The phantom was imaged with MR, helical CT and CBCT. All three scans showed clear 5D motion (3D + cardiac + respiratory motions). Landmarks placed on the balloon, air bag and motion platform were visible and trackable.
A 5D motion phantom supporting simultaneous cardiac and respiratory motions was constructed. It will be useful for imaging, motion-management and dosimetry research studies for NCRA.