A bs tra c t We have developed a dynamic SPECT method which allows the prevalent rotating camera systems to be used. In this method, the parameters of the time-activity curve in each pixel are recovered directly from the projection data, without first reconstructing a series of static images. Preliminary test results show that we can accurately recover time-activity curves for a simple model based on activity values expected for myocardial viability studies with fatty acid tracers.
A bs tra c t We have developed a dynamic SPECT method which allows the prevalent rotating camera systems to be used. In this method, the parameters of the time-activity curve in each pixel are recovered directly from the projection data, without first reconstructing a series of static images. Preliminary test results show that we can accurately recover time-activity curves for a simple model based on activity values expected for myocardial viability studies with fatty acid tracers.
The sampled Radon transform of a 2D function can be represented as a continuous linear map A : L 2 () ! R N , where (Au) j = hu; j i and j is the characteristic function of a strip through approximating the set of line integrals in the sample. The image reconstruction problem is: given a vector b 2 R N , nd an image (or density function) u(x; y) such that Au = b. In general there are in nitely many solutions; we seek the solution with minimal 2-norm, which leads to a matrix equation Bw = b, where B is a square dense matrix with several convenient properties. We analyze the use of Gauss-Seidel iteration applied to the problem, observing that while the iteration formally converges, there exists a near null space into which the error vectors migrate, after which the iteration stalls. The null space and near null space of B are characterized in order to develop a multilevel scheme. Based on the principles of the Multilevel Projection Method (PML), this scheme leads to somewhat improved performance. Its primary utility, however, is that it facilitates the development of a PML-based method for spotlight tomography, that is, local grid re nement over a portion of the image in which features of interest can be resolved at ner scale than is possible globally.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.