The gamma scan can observe when the internal conditions are clearly separated regarding to the density of medium. Fouling on trays may not be explicitly identified throughout the gamma scanning, however, it gives a tentative results since the fouling of trays shall give a response to the liquid in terms of liquid phase quality density. Consequently, the scanning profile may slightly drop due to higher density of medium (low gas phase).
If fouling on tray is partially, it is difficult to be identified and confidence of interpretation would be low krab.