Performance evaluation of a multipinhole small animal SPECT system

S. R. Meikle, Royal Prince Alfred Hospital, Sydney
P. Kench, University of Sydney
R. Wojcik, Thomas Jefferson National Accelerator Facility, Virginia, USA
M. F. Smith, Thomas Jefferson National Accelerator Facility, Virginia, USA
A. G. Weisenberger, Thomas Jefferson National Accelerator Facility, Virginia, USA
S. Majewski, Thomas Jefferson National Accelerator Facility, Virginia, USA
M. L. Lerch, University of Wollongong
A. Rosenfeld, University of Wollongong

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This paper originally appeared as: Meikle, SR, Kench, P, Wojcik, R et al, Performance evaluation of a multipinhole small animal SPECT system, IEEE Nuclear Science Symposium Conference Record, 19-25 October 2003, vol 3, 1988-1992. Copyright IEEE 2003.

Abstract

We have designed and constructed a small animal SPECT system based on compact, high resolution detectors and multipinhole apertures. The scanner is currently configured with two detectors mounted on a rotating gantry. Each detector comprises a NaI(Tl) crystal array (1/spl times/1/spl times/5 mm elements), a 12 cm diameter position-sensitive photomultiplier tube (Hamamatsu R3292) and a tungsten aperture with 1 or more pinholes. In this study, we performed phantom experiments to characterise the planar and tomographic performance of the scanner. Intrinsic resolution measured with a highly collimated /sup 99m/Tc point source stepped across the detector face was 1.0 /spl plusmn/ 0;.1 FWHM and 2.9 /spl plusmn/ 0.1 mm FWTM. Energy resolution at 140 keV varied from 14% FWIIM for central crystals to 19% for edge crystals and was 20% FWHM for the whole detector normalised spectrum. Intrinsic uniformity for the central field of view was 2.4% differential and 3.8% integral. Reconstructed spatial resolution was 1.2 mm FWHM at the centre of the field of view and 1.2, 1.7 mm FWHM (radial, tangential) at 10 mm off-axis, using typical geometric parameters for mouse and rat brain imaging. Reconstructed images of a micro deluxe hot rod phantom demonstrate the high resolution of the system and indicate similar resolution and improved signal-to-noise is obtained with a 2 pinhole aperture compared with a single pinhole. We conclude that the performance characteristics of this system make it suitable for high resolution imaging of small laboratory animals.