Fractal exponents for the upper airways of mammalian lungs

Abstract This paper studies the applicability of fractal geometry to morphological data of mammalian lungs. We use the data of upper airways of a human lung and a beagle lung measured by Phalen et al. In addition to Weibel's binary lung model we introduce a new lung model. It turns out that the branching exponent defined by Mandelbrot takes values in a range from one up to infinity and can not be determined in a reliable way. Instead, we suggest fractal exponents for diameters and lengths of lung segments. These exponents were derived both from a theoretical viewpoint and by linear regression.