In order to accurately determine objective measures from fluoroscopic examinations, the studies must be acquired with uniform body positioning, barium density, distance to the imaging source, consistent resolution and capture rates, and the use of quality recording and reviewing equipment. Performing each study according to a standardized protocol is essential to ensure a high degree of precision and reproducibility (Chap. 2) . Most measures are made from the sequence when the largest bolus (usually 20 cc) is swallowed. Although normative data are available for smaller bolus sizes, these measurements have less clinical utility than assessment with larger volumes. Acquiring timing measures requires a counter that displays time to the hundredth second superimposed on the fluoroscopic recording; we use the Horita Video Stopwatch VS-50 (Horita, Mission Vijeo, CA) (Fig. 7.1). If this equipment is not available, timing measures may be calculated by hand when frame number and rates are known. Most measures are obtained in the lateral fluoroscopic view and require two frames for comparison. The first frame is the “hold” or “pseudo-rest” position, which is obtained while the subject holds a 1 cc bolus in the mouth (Fig. 7.1a). Holding the 1 cc bolus in the oral cavity provides a standardized anatomic position for reproducible assessment . The comparison image is the frame at maximum displacement of the structure of interest (hyoid, larynx, pharynx). Obtaining displacement measures requires the use of digital measuring software; at our center, we use Universal Desktop Ruler for distance determination (http://​www.​avp.​soft) and ImageJ for area calculation (http://​rsbweb.​nih.​gov/​ij). Pixels that are digitally measured using these programs are converted to centimeters through calibration. In order to calibrate the onscreen tools, a ring of known diameter is placed on the chin (lateral view, Fig. 7.1a) or neck (anterior–posterior view) for reference. A keychain, washer, or coin may be used for this purpose (Fig. 7.1b) .

The objective assessment of the VFSS is broadly classified into measurements of timing, displacement, and area (Table 7.2). Timing measures (in seconds) are further subclassified into bolus transit times and timing of anatomic structure movement .