(Wednesday, 8/1/2018) 1:45 PM - 3:45 PM
Room: Davidson Ballroom A
Purpose: Conformal delivery of radiation to a cardiac target is challenging due to respiratory and cardiac motion and the proximity to radiation sensitive organs-at-risk (OARs) including right coronary and left anterior descending arteries. Although recent studies showed non-invasive cardiac arrhythmia ablation for atrial fibrillation and ventricular tachycardia with radiotherapy modalities, mitigation techniques for cardiac motion have not been studied thoroughly. The purpose of this study is to evaluate the dosimetric advantage of using cardiac gating on ECG signals as a motion mitigation method for proton radiotherapy of targets in the heart.
Methods: Cardiac gated 4D CTs were obtained at end-expiration, resulting in 10 cardiac phase CTs. OARs and seven different targets were contoured on each phase for 4D planning, and 3D target volumes were generated on the average intensity-projection for a non-cardiac gated comparison. For each target, a reference cardiac phase was selected to determine optimal beam angles for double-scatter proton radiotherapy in terms of target coverage and OAR sparing. Dosimetric parameters for cardiac gated and non-gated plans were compared. Target size and location were also evaluated to investigate the feasibility of a respiratory and cardiac double gating delivery.
Results: Due to the anatomical location of the heart, the angle of incoming beams played an important role in dose homogeneity and OARs dose. Targets in the left ventricle and interventricular septum benefit the most from cardiac gating, showing a reduction in OAR doses of up to 35% and minimizing the mean heart and left ventricle doses.
Conclusion: This work evaluated cardiac gating on ECG signals as a motion mitigation technique for proton radiotherapy. It demonstrated that the choice of beam angle is important to spare OARs, and that cardiac gating may be beneficial for some targets out of the seven studied target locations in the heart to reduce cardiac toxicity.
Keywords
Not Applicable / None Entered.
Taxonomy
Not Applicable / None Entered.
Contact Email
