Author(s): Avishek Das, Manojit Pramanik
ABSTRACT
Light-emitting diodes (LEDs) emerge as a viable alternative to pulsed lasers in photoacoustic computed tomography (PACT) due to their low cost, compact form factor, wavelength flexibility, and reduced safety concerns. Unlike class-IV laser systems, LED-based excitation eliminates regulatory constraints while enabling high pulse-repetition rates (PRRs) and flexible modulation for improved signal averaging and contrast. We present a high-speed nanosecond pulsed LEDbased PACT (LED-PACT) system optimized for rapid tomographic imaging using multiple single-element ultrasound transducers (USTs) arranged in a circular geometry. A custom nanosecond pulsed current source (NSPCS) drives 37 infrared LEDs at 850 nm, delivering ~0.19 mJ per pulse. Sub-100 ns excitation enables PRRs ≥10 kHz, allowing fast data acquisition with reduced motion artifacts. Imaging speed is further increased by employing eight single-element USTs that rotate mechanically around the target. This configuration reduces the effective angular step size to 360˚/n, where n is the number of transducers, achieving substantially faster full-angle coverage than conventional single-UST systems. The system performance was evaluated using absorbing phantoms. Delay-and-sum (DAS) reconstructed images demonstrate clear visualization of target geometry at scan times as short as 0.25 s, corresponding to a frame rate of 4 Hz. These results confirm that the combined use of high-PRR nanosecond LED excitation and multi-UST acquisition enables sub-second PACT imaging while maintaining stable signal generation and sufficient image contrast. The proposed architecture provides a compact, scalable, and cost-effective pathway toward high-speed PACT systems for dynamic biomedical imaging applications.
Citation
A. Das and M. Pramanik, Nanosecond Pulsed Light Emitting Diode (LED) Based High-Speed Photoacoustic Computed Tomography Using Multiple Single-Element Ultrasound Transducers (SPIE BiOS). SPIE, 2026. doi: 10.1117/12.3079921.
