SBRT 2016

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).