On reducing radiographic dosages in pellet-tracking experiments

Abstract

Radiographic dosage levels continue to present an increasingly difficult barrier to obtaining valuable data on the movements of pellets attached to internal articulatory structures during speech production. Two methods of reducing dosage have been explored. The first method involves the use of a high-speed recording film (Kodak 2475) in conjunction with a “normal extended” commercial cine-developing process, A test run was made in which a head and neck phantom and small lead pellets suspended on a moving wooden pendulum were exposed at normal and reduced cineradiographic dosage levels. It was found that the high-speed film and extended development allowed for perfect pellet visualization at dosage levels one-fourth as great as those normally delivered by the apparatus with conventional cineradiographic filming and developing techniques. The second method used videotape of a fluoroscopic image of a human subject and tracings of “field-by-field” photographic transparencies made from a video monitor. Initial results suggest that even lower dosages may be obtained with this method, but at the cost of decreased resolution and increased effort or expense in obtaining data. [This work was supported by the National Institutes of Health Grant NS04332.]