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Table 4 The uncertainty components for measurements of the FWHM and penumbra

From: Development of a PMMA phantom as a practical alternative for quality control of gamma knife® dosimetry

Uncertainty component Type A (%) Type B (%)
Optical density measurement 0.10 0.02
Intensity resolution   0.002
Uniformity of the radiochromic film   0.50
Temperature and relative humidity measurements   0.056
Alignment of the PMMA phantom with the PPS calibration center   0.20
Positioning of the radiochromic film inside the phantom   0.16
Calibration curve fitting   1.33
Measurements of FWHM and penumbra 0.02 0.01
Standard relative combined uncertainty 1.45
  1. Legend: GafChromic™ MD-V3 films were used for the measurement of absorbed dose rate to water at the patient positioning system (PPS) calibration center