Ziehm Imaging, Inc. VISION, Руководство по установке

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Ziehm Imaging, Inc. Vision Installation Manual MAN 06-0015, Rev. A Page 17
M a i n t e n a n c e R e p o r t : C h e c k R e p r o d u c i b i l i t y
Calculating the Coefficient C
For n individual measurements, the variation of the coefficient C is obtained from.
1. Calculate the average
Add the four dose values and divide the sum by four.
X1 + X2 + X3 + X4 = X (Average)
n
2. Calculate the difference
Subtract each measured value from the average.
X
i
- X =
∆
(Difference)
3. Calculate the difference squared
Multiply the difference by itself.
(X
i
- X)
2
=
∆
2
4. Calculate the square root
Add the sum of the four differences squared and divide by 3. Write the result below.
S =
5. Calculate the variation coefficient
Divide the sum (obtained in step 4) by the average value (obtained in step 1).
S
= calculated standard deviation
X
= average value of all individual measurements
X
i
=
measured value of the
i
th
measurement
n
= number of individual measurements
∆
= difference
∆
2
= difference squared
Measurement Radiation
Exposure
Average (X) = Difference Difference
Squared
Sum = Sum divided by 3 =