Quantitative measurement of total aerosol lung deposition: Comparison of three different techniques

The recent development of radiolabelled, monodisperse, sebacate aerosols has allowed the simultaneous quantitative measurement of aerosol lung deposition using Tyndallometry (continuous concentration measurement at the mouth), gamma camera imaging, and filter collection of exhaled aerosol. This study demonstrates a close correlation between Tyndallometry and the other two techniques (r = 0.965, p < 0.001 and r = 0.934, p < 0.001, respectively). Systematic differences were observed between the gamma camera and Tyndallometric measurement which could be explained by regional inhomogeneities in gamma camera calibration. Similar differences were observed when comparing Tyndallometry to collected exhaled aerosol which could be explained by aerosol losses in the experimental apparatus. The accuracy and reproducibility of the Tyndallometric technique suggests that it is the best method for measurement of total aerosol deposition and can be combined with nuclear imaging for quantitative regional studies.