Topic
Imaging phantom
About: Imaging phantom is a research topic. Over the lifetime, 28170 publications have been published within this topic receiving 510003 citations. The topic is also known as: phantom.
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TL;DR: A phantom that simulates CT measurements in patients and permits comparison of CT density of each nodule with a physical standard derived from clinical experience is designed and facilitates standardized quantitative analysis of pulmonary nodules with current scanners.
Abstract: The CT density of the same pulmonary nodule can vary significantly between scanners or with the same scanner because several independent factors besides partial volume averaging can affect its determination. Hence a single CT number cannot be used to distinguish calcified from noncalcified nodules, ruling out direct extrapolation of quantitative data between scanners. The authors designed a phantom that simulates CT measurements in patients and permits comparison of CT density of each nodule with a physical standard derived from clinical experience. Tests on 35 patients using a GE 8800 showed that no malignant nodules and 65% of benign lesions were more dense than the phantom nodule. This method is independent of inter- and intra-scanner variation and facilitates standardized quantitative analysis of pulmonary nodules with current scanners.
104 citations
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TL;DR: The reconstruction method makes use of all coincidence data acquired by high-sensitivity PET systems that do not have inter-slice absorbers to restrict the axial acceptance angle, making it well suited for dynamic and whole-body studies.
Abstract: A fast method is described for reconstructing volume images from three-dimensional (3D) coincidence data in positron emission tomography (PET). The reconstruction method makes use of all coincidence data acquired by high-sensitivity PET systems that do not have inter-slice absorbers (septa) to restrict the axial acceptance angle. The reconstruction method requires only a small amount of storage and computation, making it well suited for dynamic and whole-body studies. The method consists of three steps: (i) rebinning of coincidence data into a stack of 2D sinograms; (ii) slice-by-slice reconstruction of the sinogram associated with each slice to produce a preliminary 3D image having strong blurring in the axial (z) direction, but with different blurring at different z positions; and (iii) spatially variant filtering of the 3D image in the axial direction (i.e. 1D filtering in z for each x-y column) to produce the final image. The first step involves a new form of the rebinning operation in which multiple sinograms are incremented for each oblique coincidence line (multi-slice rebinning). The axial filtering step is formulated and implemented using the singular value decomposition. The method has been applied successfully to simulated data and to measured data for different kinds of phantom (multiple point sources, multiple discs, a cylinder with cold spheres, and a 3D brain phantom).
104 citations
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TL;DR: High resolution and contrast of a first-of-its-kind intravascular optical-resolution photoacoustic tomography system with a 1.1 mm diameter catheter can enable improved stent implantation guidance and lipid identification of vulnerable atherosclerotic plaques.
Abstract: Photoacoustic imaging is an emerging technology that can provide anatomic, functional, and molecular information about biological tissue. Intravascular spectroscopic and molecular photoacoustic imaging can potentially improve the identification of atherosclerotic plaque composition, the detection of inflammation, and ultimately the risk stratification of atherosclerosis. In this study, a first-of-its-kind intravascular optical-resolution photoacoustic tomography (OR-PAT) system with a 1.1 mm diameter catheter is developed, offering optical-diffraction limited transverse resolution as fine as 19.6 μm, ∼ 10-fold finer than that of conventional intravascular photoacoustic and ultrasonic imaging. To offer complementary imaging information and depth, the system also acquires co-registered intravascular ultrasound images in parallel. Imaging of an iliac stent and a lipid phantom shows that the high resolution and contrast of OR-PAT can enable improved stent implantation guidance and lipid identification. In the future, these capabilities may ultimately improve the diagnosis and interventional treatment of vulnerable atherosclerotic plaques, which are prone to cause thrombotic complications such as myocardial infarction and stroke.
104 citations
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TL;DR: Correct quantitation can be obtained with TDCS(Gauss), with a relatively small reduction in S/N ratio, according to Monte Carlo simulations.
Abstract: Scatter correction is a prerequisite for quantitative SPECT, but potentially increases noise. Monte Carlo simulations (EGS4) and physical phantom measurements were used to compare accuracy and noise properties of two scatter correction techniques: the triple-energy window (TEW), and the transmission dependent convolution subtraction (TDCS) techniques. Two scatter functions were investigated for TDCS: (i) the originally proposed mono-exponential function and (ii) an exponential plus Gaussian scatter function demonstrated to be superior from our Monte Carlo simulations. Signal to noise ratio (S/N) and accuracy were investigated in cylindrical phantoms and a chest phantom. Results from each method were compared to the true primary counts (simulations), or known activity concentrations (phantom studies). was used in all cases. The optimized method overall performed best, with an accuracy of better than 4% for all simulations and physical phantom studies. Maximum errors for TEW and of -30 and -22%, respectively, were observed in the heart chamber of the simulated chest phantom. TEW had the worst S/N ratio of the three techniques. The S/N ratios of the two TDCS methods were similar and only slightly lower than those of simulated true primary data. Thus, accurate quantitation can be obtained with , with a relatively small reduction in S/N ratio.
104 citations
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TL;DR: The effect of different mAs settings on computed tomobraphy (CT) image quality was evaluated by a clinical study and phantom studies; there appeared to be a linear relationship between noise, as measured by RMSD, and body size.
Abstract: The effect of different mAs settings on computed tomobraphy (CT) image quality was evaluated by a clinical study and phantom studies. In the clinical portion of this study, a number of CT images, obtained at various mAs settings, were reviewed by experienced CT interpreters. From these same images, graphs were charted of the root-mean-standard deviation (RMSD) vs. body size; there appeared to be a linear relationship between noise, as measured by RMSD, and body size. A performance phantom was used to evaluate the effect of the different mAs settings on resolution. There was some loss in low contrast resolution at 6 and 20 mAs; however, the resolution was identical at 40 and 100 mAs.
104 citations