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Table 3 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) Percent difference between the mean and plan dose (%, 1 to n) Probability for the mean to be within 3% of plan value (1 to n) Probability for the mean to be within 5% of plan value (1 to n)
a. Chamber 1: corresponding plan dose was 1.702 Gy. No QA phantom re-setup between each measurement.
1 0.232 - -
2 -0.095 93.05% 95.81%
3 -0.205 99.49% 99.84%
4 -0.341 99.93% 99.97%
5 -0.423 99.98% 99.98%
b. Chamber 2: corresponding plan dose was 0.546 Gy. No QA phantom re-setup between each measurement.
1 -5.960 - -
2 -6.551 3.28% 9.96%
3 -6.939 0.70% 3.12%
4 -7.132 0.10% 0.70%
5 -7.319 0.02% 0.17%
c. Chamber 1: corresponding plan dose was 1.702 Gy. The QA phantom was re-setup between each measurement.
1 -0.751 - -
2 -0.259 89.57% 93.72%
3 -3.153 39.74% 65.16%
4 -2.388 55.53% 81.86%
5 -2.193 65.01% 90.52%
d. Chamber 2: corresponding plan dose was 0.546 Gy. The QA phantom was re-setup between each measurement.
1 -8.065 - -
2 -11.327 4.76% 8.88%
3 -12.963 1.69% 3.35%
4 -13.432 0.39% 0.85%
5 -14.164 0.07% 0.18%
  1. Statistical analysis results for the percent difference between the expected delivery value and given (plan) value.