Performance Evaluation of a Newly Proposed Novel L-SPECT System for SPECT Imaging

The importance of pre-clinical research of single photon emission computed tomography(SPECT) imaging is now widely recognized. For the demand of high resolution and high detection efficiency, SPECT has been developed in several ways and it is simultaneously making demand for high quality imaging. This paper introduces the newly proposed dual-head L-SPECT system and investigates the initial performance of the system having an array of pinholes as a collimator. The proposed L-SPECT system is based on the concept of light field imaging allowing the refocusing of images after exposure. A microlens array is placed just before the imaging sensor to simultaneously record the direction of incident light rays and their intensities. We are proposing a detector module with 48mm by 48mm of active area behind an array of 100×100 pinholes for gamma rays instead of microlenses. The system is based on a pixelated array of NaI crystals (10×10×10 mm elements) coupled with an array of position sensitive photomultiplier tubes (PSPMTs). The basic characteristics of this system were evaluated with pinhole radii of 50μm, 60μm and 100μm. The measurements of system sensitivity, system spatial resolution, energy resolution, volume sensitivity and uniformity were evaluated for 99mTc (140keV) solution where reconstructed images are well visualized. Monte Carlo simulation studies using the Geant4 Application for Tomographic Emission (GATE) software package validate the performance of this novel dual head L-SPECT where a general cylindrical water phantom is used to evaluate its performance. The analysis results show the combination of excellent spatial resolution and high detection efficiency over an energy range between 20-160 keV.