Since more than five years the research group on spatial statistics and image analysis at Mathematical statistics, Chalmers, have a cooperation with AstraZeneca on colloidal particle tracking and diffusion estimation using microscopy. This has e.g. resulted in the PhD thesis Kvarnström (2005) and the recent paper Kvarnström and Glasbey (2006). The data modelled and analysed are sequences of microscope images obtained at AstraZeneca of diffusing polystyrene particles of diameter 500 nm. This system is used as a model for describing release of medical drugs in pharmacy, where the understanding of interaction and mobility of the active drug substances is of crucial importance. The positioning methods developed can be used for 3-D tracking from sequences of 2-D images of diffusing particles and the accuracy of the position estimates goes well beyond sub-pixel accuracy. The same principle for tracking can be used in virtually any application where the depicted objects are roughly rotationally symmetric.
Figure: An image from a video sequence of diffusing polystyrene particles. The particles are all of the same size; their difference in appearance is due to an out-of-focus effect, which is used for depth estimation.
Kvarnström, M. (2005). Position Estimation and Tracking in Colloidal Particle Microscopy. PhD thesis, Chalmers University of Technology.
Kvarnström, M. and Glasbey, C. A. (2006). Estimation of centres and radial intensity profiles of spherical nanoparticles in digital microscopy. To appear in Biometrical Journal.