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Reproducibility, Linearity, & HVL Testing
CPI Canada Inc
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Page 6
Rev. C X-Ray Generator Service Manual Supplement 740917-00
3.0 REPRODUCIBILITY
(Cont)
3 point = 80% of maximum kV, 250 ms, mA to give 100 - 500 mR (0.9 – 4.4 mGy) dose.
2 point = 80% of maximum kV, mAs to give 100 - 500 mR (0.9 – 4.4 mGy) dose. mAs = __________
EXP No.
DOSE (K)
mGy
DIFFERENCE DIFFERENCE
2
1
2
3
4
5
K =
________
Calculate each of the differences
ie: DIFF
1
= K
1
- K.
Repeat for each remaining K
value.
Square each difference. Then
calculate the sum of the difference
2
.
Sum of difference
2
= _________
Calculate standard deviation (S) using formula at beginning of this section: S = __________
Calculate reproducibility = S = _________ (not to exceed 0.045)
K
Table 4: Reproducibility
EXAMPLE
mAs = _20_
EXP No.
DOSE (K)
mGy
DIFFERENCE DIFFERENCE
2
1 2.17
0.036
0.001296
2 2.14
0.006
0.000036
3 2.13
0.004
0.000016
4 2.11
0.024
0.000576
5 2.12
0.014
0.000196
K =
_2.134_
Calculate each of the differences
ie: DIFF
1
= K
1
- K.
Repeat for each remaining K
value.
Square each difference. Then
calculate the sum of the difference
2
.
Sum of difference
2
= _0.00212_
Calculate standard deviation (s) using formula at beginning of this section: S = _0.0230_
Calculate reproducibility = S = _0.011_ (not to exceed 0.045)
K
Table 5: Reproducibility