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Table 3 The uncertainty components for measurement of the absorbed dose rate to water

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

Uncertainty component Type A (%) Type B (%)
Calibration factor of the ionization chamber, \( {N}_{D_w,{Q}_0}^c \)   0.50
Ionization current measurement 0.01 0.02
Temperature and pressure measurement   0.056
Scattered photon contribution 0.01 1.28
Displacement of the ionization chamber 0.01 0.15
Alignment of the PMMA phantom with the PPS calibration center   0.20
Long-term stability of the ionization chamber   0.12
Standard relative combined uncertainty 1.40
  1. Legend: A PTW TN31010 ionization chamber was used for measurements of the FWHM and penumbra at the patient positioning system (PPS) calibration center