X‐ray Computed Tomography: A 3D method for characterising inhalation powders

Accurate characterisation of the microstructure of inhaled powders is an essential element in our understanding of dry powder inhalers, yet current methods for measuring critical material attributes such as the particle size and shape suffer from low resolution, image in 2D or make shape assumptions. In this work, we demonstrate how X‐ray Computed Tomography (XCT) is a non‐destructive, fully three‐dimensional technique for characterising inhalation powder blends. Particle size distributions produced through XCT are shown to have good correspondence with those produced through laser diffraction and optical microscopy, whilst XCT sphericity distributions provide a more accurate reflection of the powder shape. This shows the promise for XCT as a valuable powder characterisation technique that develops our fundamental understanding of powder microstructure, a descriptor now required from the United States Food and Drug Administration (Q3 equivalence).