Eligibility is limited to people with disabilities such that a wheelchair is used for daily mobility - more specifically, those who are non-ambulant or can walk only very short distances.

Reflux of radiolabelled food and liquids can be measured using the technique of gamma scintigraph; however, in this procedure the subjects are non-ambulant as they have to be continually monitored by standing in front of, or lying under, a gammacamera to detect the reflux event.