Organ contouring for prostate cancer: interobserver and internal organ motion variability.

The purpose of this study is to assess the uncertainties that arise in locating the boundaries of anatomical structures, such as the prostate and the bladder, due to interobserver variability in the delineation of the structures and to internal organ motion. The variabilities are computed in all the radial directions and this information is used to obtain the margins, following the techniques and limitations imposed by medical practice. The margins obtained from the organ motions are significantly greater than those arising from interobserver variability. The developed tools, allow us to obtain the required margins in an efficient way.