Determination of Multileaf Collimator Positional Errors as a Function of Dose Rate, Speed, and Delivery Interruption for Volumetric-Modulated Arc Therapy Delivery.

Figures

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  Figure 1. MLC velocity (cm/s) as a function of time (s) for circular, parabolic and linear MLC velocities. MLC Multi leaf collimator

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  Figure 2. Independent sub group analysis of MLC-PE for four tested velocities: circular, parabolic, linear motion single interruption and linear motion multiple interruption, for two tested dependent variables of DR and MLC speed. Where M corresponds to MLC Number, DR corresponds to DR. (a to d and e to h) corresponds to the dependency of the MLC-PE on MLC speed and DR respectively. MLC: Multi leaf collimator, MLC-PE: MLC positional error, DR: Dose rate

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  Figure 3. (a) Independent subgroup analysis: Mean MLC-PE with 95% CI plotted as a function of DR and MLC speed obtained for MU DR 140 MU/min where 0.85 ± 0.2 mm, and for PV speed 1.41 cm/s 0.84 ± 0.21 mm. The mean MLC-PE for all subgroup analysis was within ±1 mm, (b) Dependent subgroup analysis. CI: Confidence interval, MLC: Multi leaf collimator, MLC-PE: MLC positional error, PV: Parabolic velocity, DR: Dose rate

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  Figure 4. Histograms analysis of MLC-PE for linear MLC motion with single interruption (LMSI) (a) Linear MLC motion with multiple interruption (LMMI) (b) Circular speed MLC speed (c) And parabolic speed MLC speed (d) MLC: Multi leaf collimator, MLC-PE: MLC positional error, LMSI: Linear motion single interruption, LMMI: Linear motion multiple interruption

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  Figure 5. Individual histograms analysis of MLC-PE for linear MLC motion with single interruption (LMSI) (a) Linear MLC motion with multiple interruption (LMMI) (b) Circular speed MLC speed (c) And parabolic speed MLC speed (d) Histogram rows are paneled by the DR and columns are paneled by the MLC velocity. MLC: Multi leaf collimator, MLC-PE: MLC positional error, LMSI: Linear motion single interruption, LMMI: Linear motion multiple interruption, DR: Dose rate