Development of an Integrated Gamma-Ultrasound (γ -US) Probe Detector and Multiplexed Readout for Simultaneous γ -US Detection

This article presents the first fully integrated, highly compact single-element integrated gammaultrasound ( $\gamma $ -US) probe for simultaneous molecular and anatomical imaging. The probe integrates a PZT-5A ultrasound (US) transducer with a Ce:GAGG scintillator and silicon photomultiplier (SiPM), enabling dual-modality detection along the same line-of-sight (LOS). The tungsten-epoxy composite serves dual roles as both the US backing layer and $\gamma $ collimator, making it innovative and significantly reduces size and complexity. Furthermore, a single-channel frequency-based multiplexed circuit enables real-time dual-modality data acquisition (DAQ). The $\gamma $ part of the probe achieves 17.3% energy resolution (FWHM at 122 keV), 80.0 cps/MBq sensitivity, and 2.69 mm spatial resolution at 1 cm distance in air. The US component provides a 36.0% fractional bandwidth (FBW), 5.95 dB signal-to-noise ratio (SNR), 1.32 mm axial resolution, and 4.90 mm lateral resolution at 5 cm depth in water. Finally, a fused B-mode image of a breast phantom validates the probe's imaging capability. This integrated probe design offers a compact, cost-effective solution for handheld medical diagnostics and nondestructive testing (NDT), with minimal performance trade-offs compared to standalone systems.