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Recently… New identical Linac…
Why did QART fail?
•
Also weekly Matrix measurements are performed.
But
a
different algoritm is used for this.
•
MU-check accepts 10% deviations. In general, for the existing
HD MLC with 2.5 mm leaves the deviations were already a bit
bigger than for other linacs with other MLCs.
•
The institution started to use another HD MLC model. Looking
back at all the data, a systematic deviation could be detected.
( this is a strong argument for statistical proces analysis, SPC!)
•
An RPC audit had been conducted.
But
the MU’s needed were
based on the measurements, not on the TPS calculation. (not
mandatory for RPC check).