Ziehm Imaging, Inc. VISION - Page 30

Ziehm Imaging, Inc. Vision Installation Manual MAN 06-0015, Rev. A Page 17
Maintenance Report: Check Reproducibility
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 =