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Table 2 Patient specific IMRT QA absolute dose measurement analysis

From: A systematic approach to statistical analysis in dosimetry and patient-specific IMRT plan verification measurements

Meas. num (n) Measurement result (Gy) Mean value (1 to n) Result standard deviation (1 to n) Estimated dose delivery standard deviation Probability for the mean to be within 3% accuracy (1 to n) Probability for the mean to be within 5% accuracy (1 to n)
a. Chamber 1: corresponding plan dose was 1.702 Gy
1 1.689 1.689 -   - -
2 1.706 1.698 0.012 0.015 89.62% 93.73%
3 1.550 1.648 0.086 0.097 57.74% 76.25%
4 1.700 1.661 0.075 0.081 72.60% 88.76%
5 1.678 1.665 0.065 0.069 83.87% 95.41%
b. Chamber 2: corresponding plan dose was 0.546 Gy
1 0.502 0.502 -   - -
2 0.466 0.484 0.025 0.032 43.55% 59.61%
3 0.457 0.475 0.024 0.027 59.52% 77.70%
4 0.465 0.473 0.020 0.022 75.01% 90.16%
5 0.453 0.469 0.019 0.021 82.01% 94.62%
  1. The measurements were conducted with the QA phantom re-setup and re-aligned between each measurement and the statistical analysis was for the accuracy of measurement itself. The accuracy is defined as percent difference between the expected value and measurement mean value.