Cluster 3 Conclusion
The
three quality control tests our group did are linearity, reproducibility and
dark noise. Linearity is to test the
accuracy of linear output according to changes in mAs with a fixed kVp and
reciprocity between mA and exposure time.
For the first part of the linearity test, although the results show there
was a variance in mR/mAs, all the results were well within the acceptable range
suggested by SC 35 and HARP act. For the second part of the linearity test, a
different combination of mA and time were used to test the linearity of
mR/mAs. Again, the results showed a
slightly variation of mR/mAs but they were all within the acceptable range of
SC 35 and HARP act. The second quality control test is reproducibility, the
test is to check whether the mammo unit and an x-ray unit produce a consistent
exposures. Since the mammo unit did not
allow us to alter mAs settings, we used the same technique in all 10
exposures. The coefficient of radiation
from the mammo unit was 0.0053457 and the coefficient of radiation in the x-ray
unit is 0.03294. According to SC 35 and HARP act, the coefficient of radiation
should not be greater than 0.05 and 0.08 respectively. In a result, our mammo
and x-ray units both passed the reproducibility control test. Note that the
x-ray unit has a higher coefficient than the mammo unit and that is because the
mammo unit was using the same mAs and kVp throughout the ten exposures while a
different combination of mAs and kVp was used in the x-ray unit. The last
quality control test was dark noise and the purpose is to test the uniformity
of the CR processor. The CR reader did not show any artifacts while having a
low EI value, which was 10, on the image. The acceptable range of the dark
noise test was anything less than 80. Thus, the CR processor passed the test. Though all the units are functioning properly,
quality control tests should be done frequently to ensure the equipments keep
up the same level of performance.
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