Radiation exposure with cardiac interventional procedures is an emerging concern. Patients receiving radiofrequency ablation for atrial fibrillation (AF) still routinely undergo pre-ablation computed tomography (CT) scans for definition of left atrial and pulmonary vein anatomy, as well as creation of a surrogate geometry. In an effort to decrease ionizing radiation associated with AF ablation, an ultrasound-guided surrogate geometry approach is proposed as an alternative to routine CT imaging. Ten patients underwent AF ablation using intracardiac ultrasound for the creation of a surrogate left atrial geometry (CartoSound, Biosense Webster, CA); and ten control-cases who had conventional CT-guided imaging (CartoMerge, Biosense Webster, CA) were matched for age, gender, and type of catheter ablation. Sources of radiation included 1) intraprocedural fluoroscopy (CartoSound: 151 ± 43 mGray*cm^2, CartoMerge: 174 ± 130 mGray*cm^2; p=0.6) and 2) CT ionizing radiation (CartoSound: 0 mSv, CartoMerge 9.4 ± 2.3 mSv/CT scan.) When comparing clinical success rates after a trial of previously ineffective anti-arrhythmic drugs, ultrasound-guided AF ablation was non-inferior to a CT-guided approach. This potentially obviates the need for CT-guided imaging, therefore reducing doses of ionizing radiation by nearly 10 mSv per AF catheter ablation.