A comparison of the dose distributions for various movements of the multileaf collimators by using a two-dimensional ionization chamber in a medical linear accelerator

초록

This study conducted a comparative analysis on the dose distribution between the SS (step and shoot) method and the SW (sliding window) method for various movements of a multi-leaf collimator (MLC) by utilizing the two-dimensional ionization chamber called MatriXX. The tolerance ranges of the flatness and the symmetry is ±2 percent, and ±3 percent, respectively. The flatness resulting from the therapeutic plan was 1.487 percent; however, the flatness of the symmetry was 0.966 percent. This study found that both methods fell within the tolerance range. Moreover, the flatness obtained from the actual measurement by using MatriXX was 1.491 percent whereas the symmetry was 0.485 percent. Again, both methods were in the tolerance range. The standard deviations of the flatnesses of the SS and the SW methods in the measurements using the MatriXX were 0.166 and 0.158 percent, respectively. The standard deviations of the symmetries of the SS and the SW methods were 0.563 and 0.542 percent, respectively.

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