Performance Evaluation of a Position-Sensitive SiPM-based Gamma Camera for Intraoperative Imaging

TL;DR

This paper presents the development and evaluation of a compact, handheld gamma camera using SiPM technology for intraoperative imaging, aiming to improve surgical guidance and reduce invasiveness.

Contribution

The paper introduces a novel portable gamma camera with high spatial resolution and sensitivity, optimized for intraoperative use in radio-guided surgery.

Findings

Spatial resolution of 1.9 mm (high sensitivity) and 1.4 mm (high resolution).

Sensitivity of 481 cps/MBq (high sensitivity) and 134 cps/MBq (high resolution).

Energy resolution around 20% for both modes.

Abstract

The POSiCS camera is a handheld, small field-of-view gamma camera developed for multipurpose use in radio-guided surgery (RGS), with sentinel lymph node biopsy (SLNB) as its benchmark application. This compact and lightweight detector (weighing approximately 350 g) can map tissues labeled with Tc-99m nanocolloids and guide surgeons to the location of target lesions. By enabling intraoperative visualization in close proximity to the surgical field, its primary objective is to minimize surgical interventional invasiveness and operative time, thereby enhancing localization accuracy and reducing the incidence of post-operative complications. The design and components of the POSiCS camera emphasize ergonomic handling and compactness, providing, at the same time, rapid image formation and a spatial resolution of a few millimeters. These features are compatible with routine operating-room workflow, including wireless communication with the computer and a real-time display to support surgeon decision-making. The spatial resolution measured at a source-detector distance of 0 cm was 1.9 +/- 0.1 mm for the high-sensitivity mode and 1.4 +/- 0.1 mm for the high-resolution mode. The system sensitivity at 2 cm was evaluated as 481 +/- 14 cps/MBq (high sensitivity) and 134 +/- 8 cps/MBq (high resolution). For both working modes, we report an energy resolution of approximately 20 percent, even though the high-resolution collimator exhibits an increased scattered component due to the larger amount of tungsten.