Dose Course 2018_Flipping book

Causes of differences between TPS & measured dose Source Unintentional Errors

Accepted Limitations

Beam data incorrectly measured such as small field output factors, MLC Transmission

Accepted TPS Beam Model Limitations ex.T&G modelling inaccurate

TPS

Settings changed accidently ex. gantry resolution for VMAT calculation

Continuous treatment segmented into static fields at a pre-set gantry resolution

Dynamic Gantry Tolerance = 0.5°

Data transfer errors

Dynamic MU Tolerance = 0.2 MU

Dynamic MLC Tolerance = 5mm

Linac

Linac component fall’s out of specification (MLC calibration, Energy, Flatness/Symmetry)

Tolerance on Symmetry/Flatness with rotation and @ low DR’s

Tolerance on MLC calibration