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Table 2 Uncertainty components for the verification method.

From: Two years experience with quality assurance protocol for patient related Rapid Arc treatment plan verification using a two dimensional ionization chamber array

Uncertainty budget
Components for measurement Uncertainty
MatriXX Ionization chambers 2%
broadening of penumbra (low pass filter) 1 mm
positioning of IMRT-MatriXX 1 mm
monitur output fluctuation 0.75%
dose stability during gantry rotation 2%
stability gantry, collimator, and couch rotation 0.75 mm
MLC positioning 1 mm
Total 2.9%, 1.9 mm
Components for calculation Uncertainty
dose calculation of treatment planning system 1%
Basic data measurements 2 mm
Total 1%, 2 mm