A method for assessing the efficacy of a treatment for a respiratory condition in a subject is disclosed. Data concerning a pre-treatment three-dimensional image of the subject’s respiratory system and a post-treatment three-dimensional image of the subject’s respiratory system is obtained. A specific three-dimensional structural model of the subject’s lung structure from each of the pre- and post-treatment image data is calculated. A specific three-dimensional structural model of the subject’s airway structure from each of the pre- and post-treatment image data is calculated. A patient-specific three-dimensional structural model of the subject’s lobar structure from each of the pre- and post-treatment lung structure models is calculated. The air flow through the airway at pre- and post-treatment states, using the respective pre- and post-treatment models of the airway and lobar structure of the subject is modelled by a computer and the structural behaviour of the airway and the interaction with the flow at pre- and post-treatment states, using the respective pre- and post-treatment models of the airway and lobar structure of the subject is modelled by a computer. The modelled airflow and structural behaviour pre- and post-treatment are compared to determine the efficacy of a treatment. An efficacious treatment is one that decreases the airway resistance, thereby increasing the lobar mass for the same driving pressure thereby determining the efficacy of the treatment for the respiratory condition.
