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…

Individual value / Moving Range 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

Patient #

Moving-range control chart

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%

Part 4

3

0,20% 2,10% 2,83% -0,52% 5,49%

4

2,11% -2,06 % 0,64%

-

3,68%

Conclusion

5

4,61% 0,78% -0,39%

-

-

MEAN

1,99% -0,45% 0,72% -0,72% 3,99% Patients #

Moving-ranges. (%)

MOVING-RANGES

-

2,44% 1,17% 1,44% 4,70%

03/10/17

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