This paper presents a feasibility study of using emission tomography (ET) systems for synchrotron X-ray fluorescence
computer tomography (XFCT). The proposed detection system combines high-resolution semiconductor detectors with
multiple-pinhole apertures. The key advantage of using an ET-based detection system is that 3D distributions of trace
elements can be built up with much reduced scanning motion and potentially without need for tomographic
reconstruction. In comparison to the conventional line-by-line scanning scheme, the ET-based imaging system allows
a great reduction in imaging time, which has been one of the major hurdles for current XFCT studies. In order to
compare different imaging schemes for XFCT studies, we developed an analytical performance index that is based on
the fundamental tradeoffs between image noise and spatial resolution achievable with given detection configurations.
To further demonstrate the feasibility of using SPECT apertures for XFCT, a prototype CCD-based multiple-pinhole
imaging system was set up at the Advanced Photon Source (APS) for imaging phantoms that contain solutions of
several trace metals. Simultaneously acquired 3D distributions of these elements are presented.
In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting
(ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4 cm x 4.4
cm, which is pixelated into 128 x 128 square pixels with a pitch size of 350 μm 350 μm. The current detector consists
of multiple detector hybrids, each with a CdTe crystal of 1.1 cm x 2.2 cm x 1 mm, bump-bonded onto a customdesigned
application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 3264
array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry, and an analog-todigital
converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two
8-bit DACs are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a
high spatial resolution, a wide dynamic range of 12-200 keV and a good energy resolution of 3-4 keV. The hybrid
detector configuration provides a flexible detection area that can be easily tailored for different imaging applications.
The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results