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We are developing an analytic breast phantom that allows for quantitative comparison of reconstruction algorithms for digital breast tomosynthesis. The phantom consists of simple shapes and aims at capturing the main features of the breast. Projection data can be computed analytically. We present volumes reconstructed from the phantom data using the filtered backprojection, expectation maximization...
The reduction of detectors in PET systems, without significantly compromising the PET utility, is an important cost consideration in a PET-system design. Recent advances in algorithm development can be used for enabling the design and assessment of innovative PET systems. In this work, we investigate PET configurations with reduced number of detectors by using the ASD-POCS algorithm that was developed...
Cone-beam CT (CBCT) has gained considerable popularity in dentistry over the past decade. The increasing use of dental CBCT also raised concern about potential radiation risk. It is thus desirable to lower the radiation dose in CBCT data acquisition. However, image quality may be degraded when current analytic-based algorithms are used for reconstructing images from low-dose CBCT data. Recently, optimization-based...
For certain applications in tomographic imaging, precise knowledge of the image within a regions of interest (ROI) is often desired, while rough knowledge outside the ROI is sufficient. Conventional iterative algorithms can only yield image values on uniform grids. It is of practical merit to develop iterative algorithms for image reconstruction with variable resolutions — a high-resolution ROI image...
Advanced diagnostic CT scanners acquire data at a large number of projections. Conventional image reconstruction algorithms, such as FDK algorithm, are analytic-based. Recently, optimization-based algorithms have been under investigation because they may reconstruct images with improved quality, and has the potential and flexibility for image reconstruction from data in non-conventional configurations,...
Tomographic imaging modalities sample subjects with a discrete, finite set of measurements, while the underlying object function is continuous. Because of this, inversion of the imaging model, even under ideal conditions, necessarily entails approximation. The error incurred by this approximation can be important when there is rapid variation in the object function or when the objects of interest...
Micro-computed tomography (micro-CT) is an important tool in biomedical research and preclinical applications that can provide visual inspection of and quantitative information about imaged small animals and biological samples such as vasculature specimens. Currently, micro-CT imaging uses projection data acquired at a large number (300-1000) of views, which can limit system throughput and potentially...
Flat-panel-based X-ray cone-beam computed tomography (CBCT) can provide images of high utility in medical applications such as image-guided surgery and radiotherapy by offering location and contrast information concerning the target and surrounding region. A potential issue in these applications of CBCT is the imaging dose involved because repeated scans are necessary in the image-guided procedures...
Advanced single-photon emission computed tomography (SPECT) includes a cone-beam computed tomography (CBCT) unit for acquisition of anatomic information about the imaged subject. CT images obtained can be used for attenuation correction in SPECT and localization determination. Hardware considerations have led to the use of an imaging configuration in which the CBCT field of view (FOV) is extended...
Micro-CT is a useful imaging tool for a wide range of biomedical research and preclinical applications. Accurate three-dimensional images of the subject such as vasculature specimens can be obtained and further be used to derive quantitative anatomic and physiologic information. In this work, we applied the adaptive-steepest-descent-projection-onto-convex-sets (ASD-POCS) algorithm to reconstructing...
This work is concerned with applying iterative image reconstruction, based on constrained total-variation minimization, to low-intensity X-ray CT systems that have a high sampling rate. Such systems pose a challenge for iterative image reconstruction, because a very fine image grid is needed to realize the resolution inherent in such scanners. These image arrays lead to under-determined imaging models...
Current cone-beam CT imaging requires dense angular sampling that is imposed by the FDK-type image-reconstruction algorithm. In an attempt to investigate the possibility of low-dose CBCT by reducing the number of projection views, we applied the adaptive-steepest-descent-projection-onto-convex-sets (ASD-POCS) algorithm for CBCT image reconstruction. Given a reduced amount of total radiation-dose,...
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