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Evaluation of PDDs
Build-up region (0-2 cm)
Field size
Field size
Field size
Field size
5x5 cm
2
10x10 cm
2
15x15 cm
2
20x20 cm
2
Average deviation (%)
3.7
0.7
- 1.3
- 3.7
Standard deviation (%)
6.2
2.1
2.4
5.1
Confidence limit (%
)
13.0
3.9
5.0
11.3
Remaining curve (2-25 cm)
5x5 cm
2
10x10 cm
2
15x15 cm
2
20x20 cm
2
Tol. 10 %
13
Statistical evaluation of the deviations between calculated and measured
data of the four 6 MV depth dose curves. Note that the confidence limits
for the 5x5 cm
2
and 20x20 cm
2
do not fulfill the recommended 10%
accuracy requirement of dose calculations of a TPS in the build-up region.
Average deviation (%)
- 0.1
0.2
0.1
- 0.6
Standard deviation (%)
0.3
0.3
0.3
0.5
Confidence limit (%
)
0.5
0.7
0.6
1.4
Tol. 2 %
Utrecht 2016