Dose Course 2018_Flipping book
Uncertainty in entrance dose measurements
18 MV X-rays
Physical quantity of procedure
Relative standard uncertainty (%)
OneDosePlus
MOSFET (T&N)
diode
Step 1: Calibration under reference conditions Dose measured with the ionisation chamber
2.0% 2.6%
2.0% 0.7% 0.5% 2.2%
2.0% 0.1% 0.3% 2.0%
Reading of the in vivo detector Reproducibility of the setting
Combined standard uncertainty of step 1
3.3%
Step 2: Correction factors Field correction factor
3.0% 2.0% 3.6%
0.8% 0.8% 1.1%
0.1% 0.2% 0.2%
SSD correction factor
Combined standard uncertainty of step 2
Step 3: measure on the patient Reading of the in vivo detector 1
3.3% 3.3%
0.7% 0.7%
0.1% 0.1%
Combined standard uncertainty of step 3
Combined standard uncertainty of steps 1+2+3
5.9%
2.6%
2.0%
1 reproducibility on positioning on patients was not tested.
Made with FlippingBook HTML5