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