Table 3.
Comparison of dosimetric indices for PTV and spinal cord as a result of different grid sizes for Eclipse and Velocity. Mean ± standard deviation with ranges given in parentheses (minimum, maximum). Average percent difference for all fifty cases between Velocity and Eclipse dosimetric parameters.
| Grid Size | PTV_D99% (Gy) | PTV_D95% (Gy) | PTV_D5% (Gy) | PTV_D0.03cc (Gy) | Cord_D10% (Gy) | Cord_D0.03cc (Gy) | |
| 1mm | 16.59±1.89 (11.57, 17.82) |
17.49±1.98 (12.16, 18.73) |
19.82±2.34 (13.61, 21.63) |
20.45±2.37 (14.15, 22.32) |
9.24±1.26 (6.25, 10.64) |
11.27±1.50 (7.59, 12.78) |
|
| Eclipse | 1.5mm | 17.07±1.98 (11.86, 18.43) |
17.82±2.06 (12.32, 19.01) |
20.19±2.44 (12.32, 19.32) |
20.93±2.49 (14.32, 23.14) |
8.76±1.22 (5.94, 10.11) |
10.81±1.54 (7.37, 12.5) |
| 2.5mm | 16.73±1.95 (11.66, 18.18) |
17.34±1.200 (12.03, 18.61) |
19.93±2.42 (12.16, 19.03) |
20.83±2.54 (14.12, 23.08) |
7.93±1.11 (5.39, 9.25) |
9.9±1.46 (6.78, 11.79) |
|
| 1mm | 16.39±1.90 (11.44, 17.56) |
17.41±1.97 (12.11, 18.61) |
19.86±2.35 (13.64, 21.76) |
20.49±2.37 (14.22, 22.44) |
9.23±1.29 (6.12, 10.50) |
11.24±1.62 (7.43, 12.87) |
|
| Velocity | 1.5mm | 16.91±2.05 (11.73, 18.39) |
17.76±2.06 (12.27, 19.02) |
20.25±2.44 (13.81, 22.11) |
21.02±2.49 (14.38, 23.11) |
8.67±1.22 (5.78, 9.99) |
10.73±1.54 (7.22, 12.64) |
| 2.5mm | 16.54±2.00 (11.5, 18.11) |
17.29±2.00 (11.98, 18.58) |
19.88±2.40 (13.55, 21.71) |
20.74±2.49 (14.13, 22.91) |
7.95±1.11 (5.37, 9.22) |
9.93±1.46 (6.72, 11.88) |
|
| 1mm | -1.2% (-3.3%, 0.1%) |
-0.4% (-0.8%, 0%) |
0.2% (0, 0.6%) |
0.2% (-0.2%, 0.5%) |
-0.2% (-2.1%, 2.1%) |
-0.5% (-5.9%, 2.5%) |
|
| % Difference (Velocity – Eclipse) |
1.5mm | -1.0% (-5.1%, 0.6%) |
-0.3% (-0.6%, 0.1%) |
0.31% (0.1%-0.5%) |
0.4% (-0.1%, 1.0%) |
-1.1% (-3.5%, 1.3%) |
-0.8% (-3.4%, 2.5%) |
| 2.5mm | -1.2% (-5.2%, 0.2%) |
-0.30% (-0.6%, 0%) |
-0.3% (-0.6%, 0) |
-0.4% (-1.6%, 0.2%) |
0.3% (-2.0%, 2.2%) |
0.3% (-2.7%, 4.1%) |
|
| 1mm | 94.3±6.0 | 1.22±1.8 | 11’36’’±2’48’’ | ||||
| 1.5mm | 95.9±5.4 | -0.06±2.03 | 4’30’’± 47’’ | ||||
| 2.5mm | 93.6±5.4 | 0.40±2.09 | 1’53’’ ± 32’’ | ||||
| 1vs1.5 mm | -1.6% | 1.28% | 61% | ||||
| 1.5vs2.5 mm | 2.3% | -0.46% | 58% | ||||
| 2.5vs1 mm | -0.7% | -0.82% | 84% | ||||