Toward the development of a microcrystal element scanner (MiCES): quickPET II

This work reports on the development and the imaging characteristics of a single ring version of the microcrystal element scanner (MiCES). We refer to this evaluation system as quickPET II The key component of the system is our microcrystal element (MiCE) detectors. Each MiCE detector consists of a 22×22 array of polished 0.8×0.8×10 mm mixed lutetium silicate (MLS) crystals. The crystals are placed within a grid made of a highly reflective polymer film material. The grid optically isolates the crystals and additionally functions as a reflective wrap. The detector unit is directly coupled to a 6+6 cross-anode position sensitive PMT. The PMT signals are fed to a simple resistor network and front-end amplifier card that produces four (X+, X-, Y+, Y-) position and the summed energy signals. QuickPET II is an interim step to the development of the complete MiCES imaging system. It supports whole body static ¹⁸F imaging protocols. QuickPET II consists of 18 MiCE detector modules mounted as a single ring to a vertical gantry. The gantry can rotate ± 20 degrees. Line source and mouse images have been acquired. Using filtered backprojection (FBP) the resolution for a reconstructed line source has been measured at 1.1 ±0.1 mm FWHM. We have also developed a 2D OSEM reconstruction that includes a model of the system´s 2D detector response function. Mouse heart images reconstructed with FBP, OSEM and OSEM with a model for detector blurring (OSEM(DB)) are provided. The final MiCES system will consist of four rings of detectors mounted on a fully rotating gantry; utilize a high bandwidth IEEE 1394a based acquisition system; and support whole body dynamic imaging protocols.