Table 2.
Patient specific IMRT QA absolute dose measurement analysis
| 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% |
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.