Seminal vesicle intrafraction motion 71 Results In total, three complete fractions (1.2%) were excluded. This was due to failed acquisition of the cineMR imaging due to human error (two fractions). In one fraction, the patient moved substantially during treatment, leading to significant image blurring. As an effect, the tracking algorithm was unable to analyse this specific dataset. The adopted Kalman filter flagged 139 cine-MR dynamics over 33 fractions of 18 patients. The results of 16 out of 15954 cine-MR dynamics (0.1%) involving six fractions of five patients were removed due to detected mis-registrations. In all these specific dynamics, the results were visually verified and found to be incorrect. The following results cover the remaining 247 fractions containing a total of 15938 cine-MR dynamics. The mean cine-MR acquisition duration was 10.1 ± 1.1 min (one standard deviation [SD]). The results indicate that the prostate shows larger translational spread in the posterior and caudal translation direction (Figure 2). However, the seminal vesicles show larger rotation about all Figure 2 – Overview of the population translation and rotation results, with the intrafraction motion of the prostate (green), left seminal vesicle (blue) and right seminal vesicle (red). The area containing the 90 percentile intervals are shown as the clouds in the respective colours. The lines in the respective colours in the centre of these areas describe the population mean. Results provided over 247 fractions and 50 patients and these results describe intrafraction motion during each fraction with respect to the first cine-MR dynamic acquired in that fraction. 4
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