Suppression of Radiated Emissions from Interventional Ultrasound Catheter Using Impedance Control Method: Simulation and Verification

Interventional ultrasound imaging technology is widely utilized for the diagnosis of a diverse range of diseases. A slender interventional catheter is an essential component of such an apparatus. The combination of a universal main unit and multiple single-frequency catheters is the development trend of such instruments to meet the increasingly complicated clinical requirements. However, significant electromagnetic interference (EMI) would probably be generated during its operation, as the single-grounded catheter may exhibit characteristics similar to those of a monopole antenna. The critical clinical significance and specific usage scenarios render the electromagnetic compatibility safety concerns of this category of equipment indispensable. Meanwhile, the low signal-to-noise ratio (SNR) of high-frequency ultrasound makes any modulation of the electric insertion likely to affect the fragile acoustic echo signal and impact the image quality. Therefore, it remains a worthwhile pursuit to develop a general method that effectively suppresses electromagnetic radiation while preserving high-frequency ultrasonic signals for different frequencies in interventional scenarios. This paper proposes an electromagnetic radiation suppression technique for interventional ultrasound catheters based on impedance control methods. By designing an impedance matching network, the method achieves impedance matching within the working frequency band and intentional impedance mismatch in the non-operational frequency band of the catheter, thereby effectively suppressing electromagnetic emissions from catheters with different operating frequencies. Simulation and experimental results demonstrate that this approach not only significantly reduces the catheter’s radiated emissions to meet the CISPR11:2016 standard but also enhances the electro-acoustic conversion efficiency of the transducer and improves imaging quality in different ultrasound frequencies.