L-shell x-ray fluorescence computed tomography (XFCT) imaging of Cisplatin
X-ray fluorescence computed tomography (XFCT) imaging has been focused on the detection of K-shell x-rays. The potential utility of L-shell x-ray XFCT is, however, not well studied. Here we report the first Monte Carlo (MC) simulation of preclinical L-shell XFCT imaging of Cisplatin. We built MC models for both L- and K-shell XFCT with different excitation energies (15 and 30 keV for L-shell and 80 keV for K-shell XFCT). Two small-animal sized imaging phantoms of 2 and 4 cm diameter containing a series of objects of 0.6 to 2.7 mm in diameter at 0.7 to 16 mm depths with 10 to 250 µg mL(-1) concentrations of Pt are used in the study. Transmitted and scattered x-rays were collected with photon-integrating transmission detector and photon-counting detector arc, respectively. Collected data were rearranged into XFCT and transmission CT sinograms for image reconstruction. XFCT images were reconstructed with filtered back-projection and with iterative maximum-likelihood expectation maximization without and with attenuation correction. While K-shell XFCT was capable of providing an accurate measurement of Cisplatin concentration, its sensitivity was 4.4 and 3.0 times lower than that of L-shell XFCT with 15 keV excitation beam for the 2 cm and 4 cm diameter phantom, respectively. With the inclusion of excitation and fluorescence beam attenuation correction, we found that L-shell XFCT was capable of providing fairly accurate information of Cisplatin concentration distribution. With a dose of 29 and 58 mGy, clinically relevant Cisplatin Pt concentrations of 10 µg mg(-1) could be imaged with L-shell XFCT inside a 2 cm and 4 cm diameter object, respectively.
Available from: Moiz Ahmad
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ABSTRACT: X-ray luminescence and X-ray fluorescence computed tomography (CT) are two emerging technologies in X-ray imaging that provide functional and molecular imaging capability. Both emission-type tomographic imaging modalities use external X-rays to stimulate secondary emissions, either light or secondary X-rays, which are then acquired for tomographic reconstruction. These modalities surpass the limits of sensitivity in current X-ray imaging and have the potential of enabling X-ray imaging to extract molecular imaging information. These new modalities also promise to break through the spatial resolution limits of other in vivo molecular imaging modalities. This paper reviews the development of X-ray luminescence and X-ray fluorescence CT and their relative merits. The discussion includes current problems and future research directions and the role of these modalities in future molecular imaging applications.
01/2014; 2:1051-1061. DOI:10.1109/ACCESS.2014.2353041
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ABSTRACT: A theme that emerges from this year's Update is that of ‘green’ chemistry. This, in part, explains the larger than usual number of publications focussing on sample preparation, especially those concerned with the analysis of foods. Procedures that involved dilute acids while still achieving digestion of the specimens were reported by various workers. Meanwhile the trend towards smaller and smaller volumes continues with developments on the micro-scale. These aspects were noted in both the original work and in reviews. Last year saw the large number of papers concerned with metallic prostheses and this topic continues to attract interest. In possibly the first publication in which ICP-MS/MS was used for a clinical application, concentrations of Ti were determined in serum from healthy subjects and patients with hip implants. Concern is evident over the toxicological implications of consumption of rice grown in regions where water is contaminated with As. This has led to several reports of analytical methods and of concentrations in foods and total diets. Localisation of the As into different parts of the plant and the rice was also investigated and, in some reports this included speciation as well as the total As concentrations. Compared with the last few years, Se longer dominates the speciation work reported in this Update and there are more reports relating to As and Hg. A new class of arsenolipids, cationic trimethylarsenio fatty alcohols, were discovered in Capelin Oil. The number of publications applying XRF spectrometry to imaging elements within tissues appears to be increasing with localisation in bone of particular interest. Laser ablation ICP-MS in combination with other techniques, TOF-SIMS, XRD or XPS was also noted, to increase the information obtained.
Journal of Analytical Atomic Spectrometry 03/2014; 29(3):386. DOI:10.1039/c4ja90001d · 3.47 Impact Factor
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ABSTRACT: A novel x-ray fluorescence imaging setup for the in vivo detection of high-Z tracer distributions is investigated for its application in molecular imaging. The setup uses an energy resolved detection method based on a Bragg reflecting analyzer array together with a multiple scatter reducing radial collimator. The aim of this work is to investigate the potential application of this imaging method to in vivo imaging in humans. A proof of principle experiment modeling a partial setup for the detection of gold nano-particles was conducted in order to test the feasibility of the proposed imaging method. Furthermore a Monte Carlo simulation of the complete setup was created in order to quantify the dependence of the image quality on the applied radiation dose and on the geometrical collimator parameters as well as on the analyzer crystal parameters. The Monte Carlo simulation quantifies the signal-to-noise ratio per radiation dose and its dependence on the collimator parameters. Thereby the parameters needed for a dose efficient in vivo imaging of gold nano-particle based tracer distributions are quantified. However also a number of problems are found like the fluorescence emission as well as scatter from the collimator material obscuring the tracer fluorescence and the potentially large scan time.
SPIE Medical Imaging; 03/2014
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