Design and Development of a High-Resolution Handheld Gamma Camera for Thyroid and Sentinel Nodes Imaging

The purpose of this study is to design and develop a high-resolution handheld gamma camera for thyroid and sentinel lymph nodes imaging. The detector of the camera is based on a continuous NaI(Tl) crystal directly coupled to a Position Sensitive Photo Multiplier Tube (PSPMT) with a highly integrated readout circuit to achieve an intrinsic spatial resolution, Ri, at ~1 mm at a much lower cost than a pixelated CZT detector based camera with similar Ri. A novel readout electronic system based on the scintillation light distribution function and least square estimation (LSE) positioning algorithm implemented on a previously developed FPGA board to provide the high Ri, throughout the entire detector area. Two prototype parallel-hole collimators were designed and fabricated for general purpose and high sensitivity thyroid and sentinel imaging. Preliminary test results show that the Ri of our detector meet the designed target, which has exceeded that of most commercially available handheld gamma cameras. The other imaging characteristics are compatible to the designed parameters. In conclusion, the new handheld gamma camera has the potential for small organ imaging with higher performance characteristics at a lower cost than those that are currently available.