Dual-mode capacitive micromachined ultrasonic transducer arrays for high intensity focused ultrasound and imaging

Abstract

High Intensity Focused Ultrasound (HIFU) therapy requires imaging guidance to ensure that the correct area is treated. Guidance may be provided by magnetic resonance imaging or ultrasound imaging. With piezoelectric transducers, ultrasound imaging guidance is typically done with a separate transducer array since it is difficult to obtain sufficient imaging and HIFU performance with the same transducers. However, Capacitive Micromachined Ultrasonic Transducers (CMUTs) can have sufficient bandwidth and efficiency to allow both HIFU therapy and imaging to be done with the same transducer array. Additionally, CMUTs have much lower self-heating than piezoelectric transducers and require less cooling when used for HIFU. This means that CMUT-based HIFU systems can be made smaller than other HIFU systems to date, allowing access to treatment areas that were not previously possible. In addition, using the same array for imaging and treatment eliminates challenges with co-registration. We have constructed a dual-mode HIFU and imaging probe using a 32x32 CMUT array integrated with an application-specific integrated circuit. Ultrasound imaging guided ablation of ex-vivo tissue has been demonstrated with the probe, with rapid switching between HIFU and imaging mode.