Spatial and temporal stability of tissue induced aberration
Real-time adaptive imaging systems employ near-field phase correction techniques, which are desired because of their computational simplicity and compatibility with current imaging system architectures. Aberrator stability is essential to adaptive imaging because it defines the spatial and temporal limits for which the near-field phase estimates are valid. In this study, the spatial and temporal stability of clinical aberrations is measured in breast, liver, and thyroid tissue and discussed in relation to real-time adpative imaging. Azimuthal isoplanatic patch sizes of 1.1, 0.44, and 1.0 mm were measured for breast, liver, and thyroid tissue, respectively, using a 70% correlation limit. Axial isoplanatic patch sizes were 2.0, 1.2, and 2.9 mm for the same tissue, respectively. Temporal stability was determined to be greater than 1.5 seconds for breast and thyroid tissue, and 1.2 seconds in the liver. The effects of noise, motion, and target non-uniformity on aberrator stability are characterized with simulations and experiments in tissue mimicking phantoms. © 2004 IEEE.
