ESTRO course Dose Modelling and Verification 2017

18 MV X-rays

Physical quantity of procedure

Relative standard uncertainty (%)

TLD

Ans Swinen

PhD thesis

2005

TLD calibration with IC

1.7%

TLD reading of “unknown detector”

1.0%

Non-lineality

0.5%

Fading

<0.5%

Combined standard uncertainty of step 1

2.1%

Step 2: Correction factors

Field correction factor

1.5%

SSD correction factor

1.5%

Combined standard uncertainty of step 2

2.1%

Step 3: measure on the patient

Reading of the in vivo detector

1.2%

Combined standard uncertainty of step 3

1.2%

Combined standard uncertainty of steps 1+2+3

3.2%

reproducibility on positioning on patients was not tested.

Uncertainty in entrance dose measurements