Part I | Chapter 4 72 axes than the prostate, especially about the left-right (pitch) rotation axis (Figure 2). A distribution of the included number of samples in this analysis (cine-MR dynamics) over time is provided in Figure S4 in Supplementary E. Pearson's correlation coefficients between the seminal vesicles with respect to the prostate in the left-right, anterior-posterior, and caudal-cranial translation direction were 0.63, 0.74 and 0.72, respectively. The complete set of the Pearson's correlation coefficients with the 95-percentile confidence interval are provided in Table S3 and Table S4 in Supplementary F. Pearson scatter graphs for all translation and rotation directions are provided in Figure S5 and Figure S6 in Supplementary F. In addition, histograms showing the distribution of intrafraction motion results of each target in the translation and rotation directions are provided in Figure S7 and Figure S8 in Supplementary F. Results of the two-sample Kolmogorov-Smirnov test indicate that that for almost all time points the intrafraction motion of the seminal vesicles come from populations with the same distribution at 5% significance level. However, this is not the case for the time points after 5 min for the anteriorposterior (roll) rotation direction and the caudal-cranial (yaw) rotation direction. Full details are provided in Table S5 (Supplementary G). The most commonly observed major motion component was peristalsis, observed in 40% of all fractions and in 84% of all patients. Drift was observed in 30% of all fractions and in 76% of all patients. Interestingly, gas pockets were found to be the major motion component in 18% of the fractions, but were observed in 50% of the patients. Only 12% of the fractions were labelled to have a stable anatomy, with less than 2 mm intrafraction motion (Table 1). Exemplary paths of these motion types are provided in Figure 3. The case with the gas pocket as plotted in Figure 3 is also provided as a movie as part of the (online) supplementary material. A visual example of the principle of the isometric volume expansion analysis is provided in Figure 4. The prostate and vesicles can be seen reaching outside the 5 mm boundaries as an effect of intrafraction motion. Results from the corresponding coverage probability analysis show that 99% of the percentage of volume of the seminal vesicles can be covered at least 95% of the time when using 5 mm isometric volume expansion (Table 2).
RkJQdWJsaXNoZXIy MTk4NDMw