wcq 5 Characterization and

lica he ctal s, riz enome d, man 0; Fris there h great n viours ematic icate o fluid mechanics. To this end, Mandelbrot introduced the notion of fractal sets (Mandelbrot, 1977), which enables to take into ac-count the degree of regularity of the organizational structure re-lated to the physical system’s behaviour. Fractal geometry is widely used in image analysis problems in general and especially in the medical field. It is applied in different ways with different results. However, there has been no review pa-per to digest these different methods and their application. The R can be arbitrary. Here, of importance is only the dependence ofR on the sphere radius after averaging over the element put in its ori-gin. This definition takes into account the fact that the relevant dimension of an object depends on the spatial scale. A fundamental characteristic of fractal objects is that their mea-sured metric properties, such as length or area, are a function of the scale of measurement. A classical example to illustrate this prop-erty is the ‘‘length ” of a coastline (Mandelbrot, 1967). When mea-sured at a given spatial scale d, the total length of a crooked coastline L(d) is estimated as a set of N straightline segments o