Two Treatment Strategies Using a Therapy / Imaging Rotating Transducer

Deep‐seated tumours can be treated by high intensity interstitial ultrasound using a miniature transducer brought in contact with the target. A dual mode transducer was designed for performing simultaneous imaging. Two therapeutic strategies are envisaged in this study. First, the transducer can be rotated step‐by‐step and therapy interrupted periodically for acquiring echo lines. In a second approach, fast rotation of the transducer allows 2D‐imaging and therapy is applied transiently over a small angular sector. Simultaneous imaging and therapy were performed in vitro with the designed transducer (2.5×7.5mm2, cylindrically focused at 10mm, 11MHz) following these two approaches. Up to 10mm deep lesions were obtained with the immobile transducer emitting an intensity of 17W/cm2 for 120s. M‐mode images were constructed on‐line during treatment. For the second strategy, the transducer rotated at a 7 rotations per second pace. Each turn, imaging was interrupted for ≈0.02s in order to perform therapy at insta...