Adult participants who have completed radiation therapy for oropharyngeal cancer within the past 3 months will undergo a swallowing x-ray study in which they will swallow up to 15 liquid stimuli prepared to different consistencies using starch and gum based thickeners.

Barium will be thickened to slightly, mildly, moderately and extremely thick consistences as defined by the International Dysphagia Diet Standardisation Initiative flow test.

Swallowing safety was measured using the Penetration-Aspiration Scale, an 8-point categorical scale which captures the depth to which any material enters the airway and whether or not the material is ejected. Levels 1 and 2 on the scale are considered safe, while levels > 2 are considered unsafe. Actual scale scores (1-8) will be recorded and then converted to binary categorical scores (< 3 vs >/= 3). We will report the frequency (count) of participants showing scores > 2 by bolus consistency.

Residue is material remaining behind in the pharynx after the swallow. We measured residue by tracing the area of barium visible on a lateral view x-ray (in pixels, using ImageJ software) and dividing that area by the squared length C2-C4 cervical spine. This cervical spine scalar provides a common anatomical reference that is a proxy for pharyngeal size, and enables the comparison of residue severity across different people with different neck length and pharynx size. In healthy swallowing, residue is expected to be minimal. We report mean values and standard deviations for amount of residue by consistency (thin, slightly thick, and mildly thick liquids).

Participants rated the palatability of lemon flavored water and liquid barium stimuli in slightly thick, mildly thick and moderately thick consistencies. Palatability was scored using a 9-point hedonic categorical rating system previously described by Pelletier et al. The ratings use 9 descriptors to capture the degree to which a participant likes a stimulus, with anchors of "Dislike extremely" and "Like extremely". Scores of 1-4 indicate liking of a stimulus, a score of 5 is neutral while scores of 6-9 indicate dislike. We dichotomized this scale between scores of 1-4 (liking) and scores of 5-9 and report the number of participants reporting scores of 6-9 (dislike).

Adult participants who have completed radiation therapy for oropharyngeal cancer within the past 3 months.

Swallowing safety was measured using the Penetration-Aspiration Scale, an 8-point categorical scale which captures the depth to which any material enters the airway and whether or not the material is ejected. Levels 1 and 2 on the scale are considered safe, while levels > 2 are considered unsafe. Actual scale scores (1-8) will be recorded and then converted to binary categorical scores (< 3 vs >/= 3). We will report the frequency (count) of participants showing scores > 2 by bolus consistency.

Adult participants who had completed radiation therapy for oropharyngeal cancer within the past 3 months. A sample of 12 adults was enrolled. The thickened consistencies were only administered (and analyzed) for the 6 participants who displayed obvious unsafe swallowing on the thin liquid stimuli during data collection. A further 3 participants were determined to have shown unsafe swallowing on thin liquids during post-hoc analysis, but this was not recognized at the time of data collection.

Adult participants who have completed radiation therapy for oropharyngeal cancer within the past 3 months will undergo a swallowing x-ray study in which they will swallow liquid stimuli prepared to different consistencies.