Evaluating the Aging of Multiple Emulsions Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry.

Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry was applied to measurements of multiple emulsions with no pretreatment; a method for the quantitative evaluation of aging was proposed. We prepared water-in-oil-in-water (W/O/W) multiple emulsions containing toluene and m-phenylenediamine. The samples were measured immediately following both preparation and after having been stirred for 24 h. Time profiles of the peak areas for each analyte species were obtained, and several intense spikes for toluene could be detected from each sample after stirring, which suggests that the concentration of toluene in the middle phase had increased during stirring. On the other hand, in the case of a W/O/W multiple emulsion containing phenol and m-phenylenediamine, spikes for m-phenylenediamine, rather than phenol, were detected after stirring. In the present study, the time-profile data were converted into a scatter plot in order to quantitatively evaluate the aging. As a result, the ratio of the plots where strong signal intensities of toluene were detected increased from 8.4% before stirring to 33.2% after stirring for 24 h. The present method could be a powerful tool for evaluating multiple emulsions, such as studies on the kinetics of the encapsulation and release of active ingredients.

The development and use of a chest phantom for optimizing scanning techniques on a variety of low-dose helical computed tomography devices.

PURPOSE: To develop a chest phantom for determining the optimal scan conditions for chest computed tomography (CT) screening. METHODS: The basic structure of the phantom is an arms-elevated-positioned anthropomorphic chest phantom. The internal structure includes simulated tumors (which are assumed to be the target lesions of chest CT screening examinations) placed at the levels of the lung apex, the bifurcation of the trachea, and the lung base of both simulated lungs. The image contrast of the simulated tumors is taken as the difference in CT value and is specified as 1 of 2 target values: Delta270 and Delta100. An opening for placement of a dosimeter is provided on the central axis of the phantom. Initial field tests were conducted focusing on the scan conditions for chest CT screening. RESULTS: Images similar to those obtained in chest CT screening examinations and clearly showing pathologic changes were obtained. The dose measurement at the center was 2.0 mGy. The diameters of the simulated tumors that could be detected were 6 mm for Delta270 and 10 mm for Delta100. CONCLUSION: The use of this phantom makes it possible to determine the optimal scan conditions for chest CT screening based on objective evaluation criteria.