EMI caused artifact removal in LED-based photoacoustic tomography system for image quality enhancement

Abstract

The Light Emitting Diode (LED) based photoacoustic computed tomography (PACT) system offers advantages such as safety, low cost, portability, and wavelength adjustability. In order to obtain high-quality photoacoustic signals, LEDs are driven by periodic nanosecond pulses. This results in a significant variation in the current flowing through the LEDs during the turn-on and turn-off moments, generating strong electromagnetic interference (EMI) around the LED circuit. In LED-based PACT systems, the light source is typically placed near the ultrasound transducer. Under the influence of the EMI emitted from the LEDs, the coil in the ultrasound transducer picks up induced currents, causing the transducer to emit ultrasonic signals. The ultrasonic echoes are received by the transducer, mixing with the photoacoustic signals and resulting in image artifacts. In this study, we propose an optimized design for the LED-based PACT system that suppresses EMI, thereby reducing image artifacts. We designed several circuit modules to reduce EMI and incorporated external electromagnetic wave absorption techniques, then conducted EMI measurements and imaging comparison experiments to demonstrate the effectiveness of this design. The proposed approach is expected to advance the application of LED-based PACT systems in fields such as surface vascular imaging and photoacoustic endoscopy.