No abstract

This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

A prototype Direct Detection Device (DDD) camera system has shown great promise in improving both the spatial resolution and the signal to noise ratio for electron microscopy at 120-400 keV beam energies (Xuong, et al., 2007. Methods in Cell Biology, 79, 721-739). Without the need for a resolution-limiting scintillation screen as in the charge coupled device (CCD), the DDD camera can outperform CCD based systems in terms of spatial resolution, due to its small pixel size (5 μm). In this paper, the modulation transfer function (MTF) of the DDD prototype is measured and compared with the specifications of commercial scientific CCD camera systems. Combining the fast speed of the DDD with image mosaic techniques, fast wide-area imaging is now possible. In this paper, the first large area mosaic image and the first tomography dataset from the DDD camera are presented, along with an image processing algorithm to correct the specimen drift utilizing the fast readout of the DDD system.

No abstract

As a part of our teams' efforts in developing ultra-high resolution PET systems, this paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors capable of positioning the 3-D coordinates of individual 511 keY photon interactions. The detectors are 40 mm x 40 mm x 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found the best-case single anode FWHM energy resolution of 2.7±0.2% at 511 keY, and neighborsummed FWHM energy resolution of approximately 4.64±0.35% at 511 keY. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating full charge collection across anodes, as well as a spatial resolution of 1 mm in the direction perpendicular to the electrode planes. Finally, measurements based on coincidence electronic collimation demonstrated a spatial resolution of 1 mm transverse to the anodes -as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high resolution PET system.