Classification and Analysis of Morphological Edge Detectors

In this paper we critically examine various morphologic edge detectors, the methods they apply, their orientation in detecting the edges accurately and to raise the de-noising capacity. Comparative analysis of these edge detectors reveals the various advantages and disadvantages of one approach over the other

Thorotrast and in vivo thorium dioxide: numerical simulation of 30 years of alpha radiation absorption by the tissues near a large compact source

Background: The epidemiology of the slightly radioactive contrast agent named Thorotrast presents a very long latency period between the injection and the development of the related pathologies. It is an example of the more general problem posed by a radioactive internal contaminant whose effects are not noteworthy in the short term but become dramatic in the long period. A point that is still to be explored is fluctuations (in space and time) in the localized absorption of radiation by the tissues. Methods: A Monte Carlo simulation code has been developed to study over a 30 year period the daily absorption of alpha radiation by micrometer sized portions of tissue placed at a distance of 0-100 micrometers from a model source, that approximates a compact thorium dioxide source in liver or spleen whose size is larger or equal to 20 micrometers. The biological depletion of the daughter nuclei of the thorium series is taken into account. The initial condition assumes chemically purified natural thorium. Results: Most of the absorbed dose is concentrated in a 25 micrometer thick layer of tissue, adjacent to the source boundary. Fluctuations where a target region with a volume of 1 cube micrometer is hit by 3-5 alpha particles in a day or in a shorter period of time are relevant in a 1-10 micrometer thick layer of tissue adjacent to the source boundary, where their frequency is larger than the Poisson law prediction.Comment: In press on Physica Medica, available online at the journal site since february 21th, 201

A Nonlinear Directional Derivative Scheme for Edge Detection

In this paper, a new one-stage nonlinear directional derivative scheme has been proposed for edge detection. The directional edge detection method was applied to gray and color images. The results were compared to three well-known conventional edge detectors namely Canny, Prewitt, and Sobel. The directional derivative method is an efficient edge detection tool especially in capturing details.DOI:http://dx.doi.org/10.11591/ijece.v2i4.75