Question
What are the differences between the ELM and the DLG approach in regards to the beam data requirements and beam modelling for myQA iON?
Answer
ELM (Enhanced Leaf Modelling) or DLG (Dosimetric Leaf Gap): There is no impact on the myQA iON beam modeling process or on the results.
The DLG value calculation requires to measure the transmission vs. leaf gap (usually 10 measurement points). A linear fit is used to estimate the DLG value.
The approach for the myQA iON modelling is the same, the same DLG value is used (if it is based on the actual measurements).
For the ELM, Varian requests only 6 measurement points, and these are entered directly in the software which calculates the ELM value - this does not correspond to the DLG value!
Even though 10 points are recommended, also the 6 points measured for the ELM can be used to calculate the actual DLG value which is used for the myQA iON beam model.