Quality Assurance of the Dosimetric Characteristics of the Multileaf Collimator for the VERO 4D-IGRT System

다국어 초록 (Multilingual Abstract)

To qualify the dosimetric characterization of the multileaf collimator (MLC) for the VERO 4D IGRT System, we performed quality assurance (QA), including the field characteristics, leaf position accuracy, leakage, and picket fence test, using a 6-MV photon beam, an electronic portal imaging device (EPID), Gafchromic EBT2 films and a water phantom. The leaf leakage was up to 0.47%, and the tolerance (T) was up to 0.63 for the picket fence test. The dose profile exhibited regions of underdose due to the tongue and groove effect. The mean value of the underdose was 12.3%.
Regarding the deviation between the actual and the ideal MLC leaf positions at the end of each segment, the maximum deviation was 0.2 mm in plan 1 and 0.1 mm in plan 2. Regarding the irradiated dose and the gantry movement, the maximum deviations were 3.35% in plan 1 and 0.23% in plan 2. Regarding the deviation between the actual and the plan irradiated dose per unit angle, the maximum deviation was 0.02% in plan 1 and 0.01% in plan 2. Despite the fact that independent jaws not exist in the VERO system due to insufficient space and, therefore, only the MLC represents a specific field shape, QA revealed a dosimetric characterization of high accuracy.

참고문헌 (Reference)

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