ABSTRACT
One of the most convenient methods to assess the pattern of distribution of therapeutic aerosols in the lung is by the use of gamma scintigraphy18. This can measure deposition in the lung, oropharynx and stomach. A critical feature for the success of gamma scintigraphy is a meticulously validated radiolabelling process to give confidence that the radiolabel is behaving in a manner which is representative of the system under study. Conventional planar gamma scintigraphy does not allow clear distinction between central and peripheral deposition since there is an overlay of structures e.g. alveoli, small and large airways, which is most marked centrally. Single photon emission computed tomography (SPECT)19 and positron emission tomography, (PET) have the potential to give more detailed data on regional lung deposition as the image they provide is three-dimensional. Currently these techniques are more expensive and employ higher radiation doses, so are less widely used than planar imaging.
