Dose Course 2018_Flipping book

11

Tolerances δ for the local dose deviation d%(i)

Region

Homogenous, simple geometry

Complex geometry (wedge, inhomogeneity, asymmetry, blocks / MLC)

More complex geometries****

Central beam axis data – high dose, low dose gradient Build-up region of central axis beam, penumbra region of the profiles - high dose, high dose gradient Outside central beam axis region - high dose, low dose gradient Outside beam edges – low dose, low dose gradient Radiological width – high dose, high dose gradient. Beam fringe – high dose, high dose gradient 2 mm or 10% The tolerances, if applied to the confidence limit, can be exceeded in two ways; either because the mean deviation of all points is too large or because a few data points show extreme deviations and therefore the SD is too large. 3 mm or 15% 3 mm or 15% 3% 3% 4% 30% (3%) 40% (4%) 2 mm or 1% 2 mm or 1% 2 mm 3 mm 3 mm 2% 3% 4%

δ 1

δ 2

*

δ 3

δ 4

**

50% (5%)

RW 50 *** δ 50-90

2 mm or 1%

(normalized at central axis same depth)

Adopted from Venselaar, 2001

Dublin 2018