66 Inspection and maintenance
MOBILETT XP Digital SPR8-230.831.30.03.02 Siemens AG
11.05 CS SD 24
Page 66 of 74
Medical Solutions
The following shows an example of the procedure. Follow this procedure and record the
result in the protocol.
Coefficient of variation C must be ≤ 0.045.
If the value obtained is > 0.045, locate and correct the cause according to the trouble-
shooting instructions.
QSQ Determine coefficient of variation C.
Example for determining coefficient of variation C:
Step 1)
• 10 exposures with recorded measurements (fictitious measured values).
Step 2)
• Addition of measured values:
∑ = 1.01 + 1.02 + 1.03 + 1.04 + 1.03 + 1.02 + 1.02 + 1.01 + 1.03 + 1.04 = 10.25
Fig. 32:
Step 3)
Calculation of the standard deviation:
Exposure
(n=10)
Measured val-
ues
(xi)
11.01
21.02
31.03
41.04
51.03
61.02
71.02
81.01
91.03
10 1.04
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