Quality Management 2017
A NALYZE
12. Control charts building: Moving-Range
Type of drifts to detect
Control charts
Part 1 :
Introduction to SPC
Ex.: wrong adjustment of linac’s parameters, errors during measurement…
Large and Fast
Individual value / Moving Range Individual value / o i nge
(I- MR )
Part 2 :
Patient number
Diff. mes/calc. (%)
Essential concepts to start with SPC
EWMA - Exponentially Weighted Moving Average -
Ex.: drift of the detector’s dose response
Small and slow
Part 3 :
Patient number Diff. mes/calc. (%)
SPC in practice
Example of a measurement logbook
Patient #
1
2
3
4
5
Beam #
1
1,00% -1,80% 1,68% -1,07% 3,20%
2
2,02% -1,27% -1,15% -0,55% 3,58%
3
0,20% 2,10% 2,83% -0,52% 5,49%
Part 4
4
2,11% -2,06 % 0,64%
-
3,68%
Conclusion
5
4,61%
5 0,78%
-0,39%
-
-
MEAN
1,99% -0,45% 0,72% -0,72% 3,99%
03/10/17
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