NIST scientists are applying measurement science to medical images of lung tumors. The change in pulmonary nodules over time is an extremely important indicator of tumor malignancy and rate of growth. With current technology, tumor sizes, from which changes in size over time are calculated, are measured through computed tomography (CT), though often on different CT machines, with different operators, at different times of the day, and with patients in different physical positions relative to the CT equipment. Our long-term goal is to be able to make lung tumor measurements that are independent of these operating conditions. We are working on two projects to achieve this goal: (1) developing a volumetric measurement technique that is completely automated, independent of any user input parameters; and (2) creating standardized lung tumor data sets to test measurement techniques. For the latter, our approach is to embed known geometric objects into clinical lung tumor data, taking into account the noise of the data and the error involved with the gridded data. We will recreate the complications that arise in clinical tumor measurements by embedding synthetic tumors into areas of high vasculature and onto the pleural lung linings to use as standards to compare measurement techniques.