T. B. Nyeng, J. F. Kallehauge, M. Høyer, J. B. B. Petersen, P. R. Poulsen, and L. P. Muren, “Clinical validation of a 4D-CT based method for lung ventilation measurement in phantoms and patients”, AO, vol. 50, no. 6, pp. 897–907, Aug. 2011.