Evaluation of a compact, general-purpose Germanium Gamma Camera

Technological advances in High-Purity Germanium (HPGe) detectors have given rise to compact, mechanically cooled gamma cameras that do not require bulky liquid nitrogen dewars to operate. When used in the double-sided strip configuration, spatial resolution finer than the strip width can be obtained using pulse signal analysis for position interpolation. With 3D position sensitivity and excellent energy resolution (1% FWHM at 140 keV), HPGe detectors have many possible applications in biomedical imaging. Here, we introduce the Germanium Gamma Camera (GGC1.1), a fully integrated imaging system incorporating a 90-mm diameter, 10-mm thick germanium detector with 16 × 16 orthogonal strips of 5-mm pitch having 0.25-mm wide gaps between the strips. All data acquisition, system control, and system monitoring functions are accessed through a single USB-2.0 port. An integrated assembly also allows for interchangeable mounting of parallel-hole and pinhole collimators. The intrinsic properties of the GGC1.1 detector system are measured according to the NEMA NU 1-2007 standards for gamma cameras, including detector efficiency, spatial resolution, energy resolution, and uniformity. In addition, we demonstrate the planar imaging capabilities of the GGC1.1 with the parallel-hole and pinhole collimators by scanning line sources, as well as a phantom comprised of spherical hot spots in a warm background.