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Table 4 Statistical estimation of the difference between planned dose and the average dose delivered over a treatment course

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

Number of fractions (N) Probability for the mean to be within 1% of plan value Probability for the mean to be within 3% of plan value Probability for the mean to be within 5% of plan value
a. Estimation at the point corresponding to Chamber 1: corresponding plan dose was 1.702 Gy. No QA phantom re-setup between each measurement. The mean measured value used was 1.684 Gy.
36 20.23% 100.00% 100.00%
3 40.59% 100.00% 100.00%
b. Estimation at the point corresponding to Chamber 2: corresponding plan dose was 0.546 Gy. No QA phantom re-setup between each measurement. The mean measured value used was 0.503 Gy.
36 0.00% 0.00% 0.00%
3 0.00% 0.00% 0.00%
c. Estimation at the point corresponding to Chamber 1: corresponding plan dose was 1.702 Gy. The QA phantom was re-setup between each measurement. The mean measured value used was 1.669 Gy.
36 8.21% 94.12% 100.00%
3 23.89% 65.58% 90.16%
d. Estimation at the point corresponding to Chamber 2: corresponding plan dose was 0.546 Gy. The QA phantom was re-setup between each measurement. The mean measured value used was 0.471 Gy.
36 0.00% 0.00% 0.00%
3 0.00% 0.00% 0.00%
e. Estimation at the point corresponding to Chamber 1: corresponding plan dose was 1.702 Gy. The QA phantom was re-setup between eachmeasurement and additional 5% uncertainty was included. The mean measured value used was 1.669 Gy.
36 18.55% 84.00% 99.80%
3 18.69% 52.33% 76.72%
f. Estimation at the point corresponding to Chamber 2: corresponding plan dose was 0.546 Gy. The QA phantom was re-setup between each measurement and additional 5% uncertainty was included. The mean measured value used was 0.471 Gy.
36 0.00% 0.00% 0.00%
3 0.01% 0.06% 0.40%