Emerging cancer therapies—such as photothermal ablation therapy and metal-mediated radiation therapy—utilize low concentrations of Gold Nanoparticles (GNPs). For safe and effective treatment, the spatial distribution and concentration of GNPs must be known. However, current clinical imaging modalities cannot simultaneously image both the concentration and spatial distribution of GNPs relevant to these therapies. This study presents a novel metal-mapping imaging modality, X-ray Fluorescence Emission Tomography (XFET), that addresses this need by directly detecting x-ray fluorescence emitted from GNPs after interaction with an x-ray pencil beam. This study compares XFET to Computed Tomography (CT) for trace metal mapping by comparing a realistic XFET Monte Carlo simulation to idealized, approximately dose-matched CT acquisitions. The Monte Carlo XFET simulation was performed on a digital MOBY mouse phantom containing gold concentrations ranging from 0.12% to 4% by weight in the kidneys, hind-leg tumor, and other organs. Contrast-to-Noise Ratios (CNRs) of the gold-containing kidneys and tumor were compared between XFET and CT images. XFET produced superior CNR values (CNRs = 24.5, 21.6, 3.4) compared to CT images obtained with both energy-integrating (CNR = 4.4, 4.6, 1.5) and photon-counting (CNR = 6.5, 7.7, 2.0) detection systems. The CNR improvements of XFET averaged 315% and 175%, respectively. Because the gold concentrations imaged here are modeled after a previous preclinical study, this work shows XFET’s feasibility for metal mapping in future preclinical applications and warrants further study to demonstrate proof of benefit and quantification of XFET’s detection limit.
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
are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.