Basic performance and stability of a CdTe solid-state detector panel

Area of Science:

• Medical Imaging Technology
• Nuclear Medicine Instrumentation
• Semiconductor Detector Physics

Background:

• Developing advanced gamma camera systems is crucial for improving diagnostic accuracy in nuclear medicine.
• Cadmium Telluride (CdTe) detectors offer potential advantages in terms of compactness and energy resolution compared to traditional scintillation cameras.

Purpose of the Study:

• To develop and evaluate a prototype gamma camera system (R1-M) utilizing a CdTe detector panel.
• To assess the fundamental performance characteristics and spectral stability of the R1-M system.

Main Methods:

• The R1-M system features a 5-mm thick CdTe detector panel with 18,432 pixels (1.4 mm pitch) and replaceable modules.
• Readout electronics utilize ASICs for compact design, and a cold-air cooling system maintains optimal operating conditions (20°C, <70% RH).
• CdTe polarization is mitigated using a bias refresh technique, and performance is evaluated with three dedicated collimators (LEGP, LEHR, LEUHR).

Main Results:

• The system achieved an intrinsic energy resolution (FWHM) of 6.6% with Tc-99m.
• Spatial resolutions ranged from 4.2 to 5.7 mm (FWHM at 100 mm) with different collimators, and sensitivities were 23-71 cps/MBq.
• Spectral stability was excellent, with peak position variation <0.2% and resolution variation ~0.3% over extended periods (hours and over a year).

Conclusions:

• The developed CdTe gamma camera system (R1-M) demonstrates robust basic performance and verified spectral stability.
• The system's stability allows for daily operation over several months without the need for recalibration, indicating its practical viability.