Multi-modality medical imaging enables measurement of the three-dimensional spatial distribution of inhaled, radiolabelled aerosol within the human lung. Using a conceptual model of spatial lung morphology, this data may be transformed to provide information on deposition by airway generation in the conducting airways. This methodology has been used to study intrapulmonary deposition patterns in control subjects for two polydisperse aerosols produced by jet-type nebulisers of mass median aerodynamic diameter (MMAD) 1.8 and 6.8 mu m. Comparison between derived experimental results and those from computer modelling shows reasonable agreement for total body, oropharynx and lung deposition and also for the difference in deposition pattern between the two aerosols. However, experiment suggests significantly less deposition in the central airways than is predicted by modelling. The new methodology has considerable potential in the fields of inhalation therapy and deposition modelling though more detailed validation is still required.