Thick Silicon Strip Detectors for Small-Animal SPECT Imaging

In this work we report first experimental characterization of the detectors for an ultra-high-resolution, dual-headed, stationary SPECT system for ¹²⁵I imaging. The detectors used for this purpose are one millimeter thick silicon double-sided strip detectors (DSSD) that have a measured intrinsic resolution of 59 mum. Such a high resolution allows the use of pinhole collimators at low magnification and very small pinhole diameters. The new detector is the second generation of silicon DSSD being investigated by our group for this application. Because the stopping power of silicon in the neighborhood of 30 keV is modest, significant increase in detection efficiency can be obtained by increasing the detector thickness from the standard thickness from 300 mum in the prototype detector to one mm in the current detector. Further improvements in SPECT imaging capabilities result from the increase in active area from 28 mm times 63 mm to 60 mm times 60 mm.