A method of adjusting an ablation field radiating into tissue includes the initial step of providing a handheld device including a phased antenna array and an ultrasound transducer array. The method includes the steps of positioning a tissue-contact surface of the handheld device adjacent to tissue, activating the phased antenna array to deliver energy through the tissue-contact surface to generate an ablation field in targeted tissue, activating the ultrasound transducer array to acquire ultrasound image data representative of the targeted tissue during energy delivery into the targeted tissue by the phased antenna array, and selectively steering the focal point of energy delivery in tissue to adjust the ablation field radiating into tissue.
