Table 1.
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 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% |
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.