The POSiCS handheld gamma-ray camera for radio-guided surgery

¹ Dept. of Nuclear and Corpuscular Physics (DPNC), Université de Genève, Switzerland
² Center for Sensors and Devices (SD), Fondazione Bruno Kessler (FBK), Italy
³ Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Switzerland

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 6 November 2025

Abstract

Intraoperative imaging techniques such as Sentinel Lymph Node Biopsy (SLNB) and Radio Occult Lesion Localization (ROLL) are adopted as a standard in breast cancer and melanoma surgery. Traditional 1D gamma probes, while widely used, lack spatial imaging capability, limiting their effectiveness near injection sites. To address this, we present POSiCS: a compact, wireless gamma camera designed for real-time intraoperative imaging. POSiCS employs a high-density scintillator and novel position-sensitive SiPMs developed by FBK, enabling sub-millimeter spatial resolution with only 8 readout channels. The device supports interchangeable collimators for adjustable sensitivity and resolution, and is optimized for detection of ^99mTc. Performance tests demonstrate a spatial resolution of 1.4 mm and a sensitivity of up to 481 cps/MBq, as well as reliable energy discrimination at 140 keV. Phantom studies confirm the system’s ability to resolve closely spaced sources with low activity levels, reinforcing its suitability for SLNB and ROLL. With a patent filed and promising initial results, POSiCS offers a portable, high-performance solution that enhances surgical precision and reduces procedure time.