Gabor T. Herman

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We give a ncw method for direct reconstruction of threc-dimcnsional objects from a fcw electron micrographs taken at angles which nced not exceed a range of 60 degrees. Thc method works for totally asymmctric objects, and rcquircs littlc computer timc or storage. It is also applicable to X-ray photography. and may greatly reduce the exposurc compared to(More)
A prospective sample of 69 healthy adults, age range 18-80 years, was studied with magnetic resonance imaging scans (T2 weighted, 5 mm thick) of the entire cranium. Volumes were obtained by a segmentation algorithm that uses proton density and T2 pixel values to correct field inhomogeneities ("shading"). Average (+/- SD) brain volume, excluding cerebellum,(More)
Although three-dimensional electron microscopy (3D-EM) permits structural characterization of macromolecular assemblies in distinct functional states, the inability to classify projections from structurally heterogeneous samples has severely limited its application. We present a maximum likelihood-based classification method that does not depend on prior(More)
Algebraic reconstruction techniques (ART) are iterative procedures for recovering objects from their projections. It is claimed that by a careful adjustment of the order in which the collected data are accessed during the reconstruction procedure and of the so-called relaxation parameters that are to be chosen in an algebraic reconstruction technique, ART(More)
Algebraic reconstruction techniques (ART) are iterative procedures for solving systems of linear equations. They have been used in tomography to recover objects from their projections. In this work we apply an ART approach in which the basis functions used to describe the objects are not based on voxels, but are much smoother functions named "blobs". The(More)
Desirable properties of color scales are examined, and a linearized optimal color scale (LOCS) is introduced. The merits of color scales for medical image data were studied, and it was found that, in tests, although observers performed somewhat better with the newly developed LOCS than with the previously advocated heated-object color scale, they performed(More)
The relative performance of five fully 3D PET reconstruction algorithms is evaluated. The algorithms are a filtered backprojection (FBP) method and two variants each of the EM-ML and ART iterative methods. For each of the iterative methods, one variant makes use of voxels and the other makes use of 'blobs' (spherically symmetric functions smoothly decaying(More)
The notion of a linogram is introduced. It corresponds to the notion of a sinogram in the conventional representation of projection data in image reconstruction. In the sinogram, points which correspond to rays which go through a fixed point in the cross section to be reconstructed all fall on a sinusoidal curve. In the linogram, however, these points fall(More)