Introduction: Nuclear medicine imaging has become a common technique for functional imaging in small animals [1]. Mouse and rat models have become popular for studying human diseases because of their physiologic similarities [2]. Several attempts have been made for high quality small animal brain imaging, however yet drawbacks of pinhole SPECT include low sensitivity and poor resolution, which also require higher radiological doses [3].
Objectives: This study investigates the feasibility of quantitative mouse brain imaging using a dual head L-SPECT system having an array of pinholes as collimators. Monte Carlo simulations are performed using GATE. A mouse brain XCAT phantom and various diameters cold-rod phantoms are used to evaluate its initial performance.
Methods: The proposed L-SPECT system is based on the concept of light field imaging allowing the refocusing of images after exposure [4]. We are proposing a detector module with 48mm by 48mm active area behind an array of 100×100 pinholes for gamma rays. The system is based on a pixelated array of NaI crystals coupled with an array of position sensitive photomultiplier tubes (PSPMTs) [5]. The basic characteristics of this system were evaluated with pinhole radii of 50µm and 60µm. The system sensitivity, system spatial resolution and image quality based on the NEMA standard are evaluated with 99mTc solution.
Results: The sensitivity at a radial rotation of 10 cm using 60 µm pinhole aperture was 1250 cps/µCi and its reconstructed axial spatial resolution was 0.8 mm full width at half-maximum (FWHM). More analysis is done with the image quality phantom.
Conclusion: We simulated a compact design L-SPECT imaging system with a high performance pinhole array detector module, which is feasible for high quality small animal brain imaging with favorable combination of spatial resolution and sensitivity, and can be used to reduce the radiological dose.