an algorithm is disclosed that recovers regions of possible pleural nodules left out of an organ field or otherwise undetected due to the nature of low level image processing in the organ field . a morphological closing with an elliptical structuring element is performed on a region to detect nodules within the size of the ellipsoid . a deformable surface - based analysis is performed in distinctive regions for the identification of larger nodules . the integrated use of a deformable surface model and chamfer distance potential enables explicit representation of regularized , or smoothed , surfaces within which nodule candidates may be detected .