Quality Management 2017

A NALYZE

13. Control charts building: EWMA

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

4%

EWMA control chart

N ° patient

3%

EWMA control chart

2%

coefficient

coefficient

Part 4

1%



1i ) 1( x M    M

Conclusion

i

i

0%

EWMA

-1%

Résultat en cours

Historique des données

-2%

-3%

Patients #

03/10/17

33

2