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Table 1 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 2% accuracy (1 to n) Probability for the mean to be within 3% accuracy (1 to n)
a. Chamber 1: corresponding plan dose was 1.702 Gy
1 1.706 1.706 -   - -
2 1.695 1.700 0.008 0.010 89.63% 93.05%
3 1.695 1.699 0.006 0.007 98.85% 99.50%
4 1.689 1.696 0.007 0.008 99.76% 99.93%
5 1.689 1.695 0.007 0.007 99.96% 99.98%
b. Chamber 2: corresponding plan dose was 0.546 Gy
1 0.513 0.513 -   - -
2 0.507 0.510 0.005 0.006 80.50% 86.76%
3 0.504 0.508 0.005 0.006 93.11% 96.77%
4 0.504 0.507 0.005 0.005 97.94% 99.33%
5 0.502 0.506 0.005 0.005 99.25% 99.83%
  1. The measurements were conducted without the QA phantom re-setup 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.