Abstract: A computer-implementable method for estimating the surface area to volume ratio and the surface area of a lung based on x-ray attenuation data obtained from a computed tomography (CT) scan of the lung is disclosed. The method includes obtaining a plurality of CT images that include a lung image from a plurality of subjects. Each of the resulting CT images is displayed such that an x-ray attenuation value is associated with each pixel. Thereafter the lung image is extracted from the CT image. Then, the volume of each lung is calculated based on the plurality of lung images extracted from the plurality of CT images. Also, the volume-of-gas to weight-of-tissue ratio for all of the pixels included in each of the lung images is calculated using the x-ray attenuation value associated with the pixel. The pixel ratio values are used to determine the median volume-of-gas to weight-of tissue ratio for all the pixels included in all the lung images for each lung.