Background
Methods
Patients
Cross-modality comparison of CBCT, and ExacTrac
Intra-modality improvement after correction and re-verification by ExacTrac
Intra-modality repeatability of position detection by ExacTrac
Phantoms
Ball bearing phantom
Head phantom
Results
Patient characteristics and treatment parameters
Cross-modality comparison of CBCT and ExacTrac
mean ± SD | median | range | 95% (abs.) | |
---|---|---|---|---|
lateral | +0.1 ± 0.3 | +0.1 | –0.9 to +0.8 | <0.8 |
longitudinal | –0.5 ± 0.4 | –0.4 | –1.6 to +0.2 | <1.2 |
vertical | –0.3 ± 0.5 | –0.4 | –1.4 to +0.8 | <1.0 |
radial | 0.8 ± 0.3 | 0.8 | 0.3 to 1.8 | <1.4 |
Intra-modality improvement after correction and re-verification by ExacTrac
mean ± SD | median | range | 95% (abs.) | |
---|---|---|---|---|
Before correction by ExacTrac | ||||
lateral | –0.7 ± 2.3 | –0.7 | –7.7 to +5.9 | <5.2 |
longitudinal | +0.3 ± 1.5 | +0.2 | –3.6 to +4.6 | <3.5 |
vertical | –1.2 ± 1.8 | –0.8 | –10.7 to +1.3 | <3.1 |
radial | 2.9 ± 2.0 | 2.3 | 0.2 to 11.8 | <6.1 |
After correction by ExacTrac | ||||
lateral | +0.03 ± 0.25 | +0.02 | –0.40 to +1.13 | <0.38 |
longitudinal | –0.02 ± 0.21 | –0.04 | –0.54 to +0.95 | <0.40 |
vertical | +0.01 ± 0.22 | +0.01 | –0.67 to +0.56 | <0.51 |
radial | 0.32 ± 0.22 | 0.26 | 0.07 to 1.33 | <0.69 |
Intra-modality repeatability of position detection by ExacTrac
mean ± SD | range | 95% (abs.) | 50% (abs.) | |
---|---|---|---|---|
Difference before – after | ||||
lateral | –0.08 ± 0.52 | –0.94 to +0.53 | <0.8 | <0.5 |
longitudinal | –0.05 ± 0.70 | –0.74 to +1.01 | <0.8 | <0.1 |
vertical | –0.03 ± 0.42 | –0.67 to +0.83 | <0.7 | <0.3 |
radial | 0.73 ± 0.32 | 0.26 to 1.28 | <1.2 | <0.7 |
Confirmation of absolute accuracy and precision in a phantom measurement
Ball bearing phantom
Head phantom
Discrepancy between … | … ExacTrac and robotic couch | … CBCT and robotic couch | … ExacTrac and CBCT |
---|---|---|---|
lateral | 0.0 ± 0.5 (p = 0.9) | 0.0 ± 0.6 (p = 1.0) | 0.0 ± 0.1 (p = 0.5) |
longitudinal | 0.4 ± 0.3 (p = 0.1) | 0.3 ± 0.3 (p = 0.1) | 0.1 ± 0.1 (p = 0.3) |
vertical | 0.0 ± 0.4 (p = 0.9) | 0.0 ± 0.4 (p = 1.0) | 0.0 ± 0.1 (p = 0.5) |
radial | 0.7 ± 0.3 (p = 0.007) | 0.7 ± 0.3 (p = 0.006) | 0.1 ± 0.0 (p < 0.001) |
Gantry in position | Scan | Registration | |
---|---|---|---|
ExacTrac | 15.7 ± 2.9 | 6,8 ± 0.3 | 4.1 ± 0.2 |
CBCT | 25.1 ± 1.1 | 41.2 ± 0.2 | 8.2 ± 2.0 |