Dose Course 2018_Flipping book

14

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

Tol. 10 %

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. 2 %

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

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 cm2 and 20x20 cm2 do not fulfill the recommended 10% accuracy requirement of dose calculations of a TPS in the build-up region.

Dublin 2018