Table 2.
Offsets between the planned and imaged target positions for the two platforms. For each target, the distance from the isocenter (in cm) and the average and maximum offsets between the planned and imaged targets (in mm) with the standard deviation in the 35 measurements for each target. The 95% confidence limit is approximated by the last column, which sums the average offset with twice the standard deviation. (A) for the iX with ExacTrac and (B) for the TrueBeam with CBCT
| Target | Distance from isocenter (cm) | Average offset (mm) | Maximum offset (mm) | Std Dev (mm) | Avg + 2SD (mm) |
|---|---|---|---|---|---|
| (A) iX/ExacTrac platform | |||||
| T0 | 0 | 0.5 | 1.1 | 0.2 | 1.0 |
| T4 | 3.1 | 0.5 | 1.0 | 0.2 | 0.9 |
| T3 | 3.3 | 0.5 | 1.0 | 0.2 | 1.0 |
| T5 | 6.7 | 0.5 | 1.0 | 0.3 | 1.0 |
| T2 | 7.2 | 0.4 | 0.8 | 0.2 | 0.9 |
| T6 | 9.9 | 0.6 | 1.1 | 0.3 | 1.1 |
| T1 | 10.2 | 0.4 | 0.9 | 0.2 | 0.9 |
| T11 | 10.5 | 1.1 | 1.8 | 0.4 | 2.0 |
| T10 | 10.9 | 1.2 | 2.0 | 0.5 | 2.2 |
| T8 | 11.6 | 0.9 | 1.6 | 0.3 | 1.6 |
| T9 | 13.8 | 0.8 | 1.7 | 0.4 | 1.6 |
| T7 | 13.8 | 1.1 | 1.8 | 0.4 | 1.8 |
| (B) TrueBeam/CBCT platform | |||||
| T0 | 0 | 0.3 | 0.7 | 0.2 | 0.6 |
| T4 | 3.1 | 0.5 | 1.2 | 0.3 | 1.1 |
| T3 | 3.3 | 0.5 | 0.9 | 0.2 | 0.9 |
| T5 | 6.7 | 0.4 | 0.8 | 0.2 | 0.7 |
| T2 | 7.2 | 0.5 | 0.8 | 0.2 | 0.9 |
| T6 | 9.9 | 0.7 | 1.1 | 0.2 | 1.1 |
| T1 | 10.2 | 0.7 | 1.1 | 0.2 | 1.1 |
| T11 | 10.5 | 0.5 | 0.8 | 0.2 | 0.9 |
| T10 | 10.9 | 0.4 | 0.8 | 0.2 | 0.8 |
| T8 | 11.6 | 0.3 | 0.7 | 0.2 | 0.6 |
| T9 | 13.8 | 0.7 | 1.2 | 0.2 | 1.1 |
| T7 | 13.8 | 0.6 | 1.3 | 0.2 | 1.1 |