Page 88 - Organ motion in children for high-precision radiotherapy - Sophie Huijskens

5.3 | Results
Over all patients, average amplitude and cycle time were 10.7 mm (range 4.1–17.4 mm) and 2.9 s (range 2.1–3.9 s). Intrafractional variabilities were larger (2.4 mm amplitude, 0.5 s cycle time) than interfractional variabilities (1.4 mm amplitude, 0.4 s cycle time). Interpatient variabilities were 2.9 mm and 0.5 s for amplitude and cycle time, respectively.
An overview of the findings regarding the investigation of the possible correlation between the mean, inter- and intrafractional amplitude and cycle time variabilities, on the one hand, and age, height, and weight, on the other hand, is given in Figure 5.1 and Supplementary Figure 5.2. A significant, but weak correlation was found between mean amplitude, on the one hand, and age, height, and weight, on the other hand, (ρ = 0.40, 0.45, 0.33, respectively). Correlations between inter- and intrafractional variability of amplitude and cycle time, on the one hand, and age, height, and weight, on the other hand, were very weak and insignificant.
Intrafractional amplitude variability was significantly smaller in children treated under GA (1.6 mm) than in children of similar ages treated without GA (2.4 mm), whereas other respiratory-induced diaphragm motion characteristics did not differ (Figure 5.2).
Figure 5.2 | Boxplots describing differences between patients treated under general anaesthesia (GA, n = 7) and patients without GA within the same age range (no GA, n = 12). Boxes: median value and upper and lower quartiles; whiskers: lowest and highest data point within 1.5 x interquartile range; circles: outliers. Note: y-axes differ in range. *Significant differences (p<0.05).
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