Performance evaluation of a newly developed high-resolution, dual-head animal SPECT system based on the NEMA NU1-2007 standard.

Small-animal single-photon emission computed tomography (SPECT) system plays an important role in the field of drug development and investigation of potential drugs in the preclinical phase. The small-animal High-Resolution SPECT (HiReSPECT) scanner has been recently designed and developed based on compact and high-resolution detectors. The detectors are based on a high-resolution parallel hole collimator, a cesium iodide (sodium-activated) pixelated crystal array and two H8500 position-sensitive photomultiplier tubes. In this system, a full set of data corrections such as energy, linearity, and uniformity, together with resolution recovery option in reconstruction algorithms, are available. In this study, we assessed the performance of the system based on NEMA-NU1-2007 standards for pixelated detector cameras. Characterization of the HiReSPECT was performed by measurement of the physical parameters including planar and tomographic performance. The planar performance of the system was characterized with flood-field phantom for energy resolution and uniformity. Spatial resolution and sensitivity were evaluated as functions of distance with capillary tube and cylindrical source, respectively. Tomographic spatial resolution was characterized as a function of radius of rotation (ROR). A dedicated hot rod phantom and image quality phantom was used for the evaluation of overall tomographic quality of the HiReSPECT. The results showed that the planar spatial resolution was similar to 1.6 mm and similar to 2.3 mm in terms of full-width at half-maximum (FWHM) along short-and long-axis dimensions, respectively, when the source was placed on the detector surface. The integral uniformity of the system after uniformity correction was 1.7% and 1.2% in useful field of view (UFOV) and central field of view (CFOV), respectively. System sensitivity on the collimator surface was 1.31 cps/mu Ci and didn't vary significantly with distance. Mean tomographic spatial resolution was measured similar to 1.7 mm FWHM at the radius of rotation of 25 mm with dual-head configuration. The measured performance demonstrated that the HiReSPECT scanner has acceptable image quality and, hence, is well suited for preclinical molecular imaging research.