SCYM Quality Control & Assurance 2

Question 1

Which metric is used to assess the day-to-day reproducibility of a flow cytometer's fluorescence measurements?

Accepted Answer

Coefficient of variation (CV) of bead populations

Answer

CV of fluorescent bead populations measured daily quantifies instrument reproducibility and flags instrument drift.

Question 2

A lab notices that the CV for their daily QC beads has increased from 2% to 6% over one week. The most likely cause is:

Accepted Answer

Laser power instability or a failing detector

Answer

Widening bead CVs typically indicate laser instability, detector degradation, or optical misalignment.

Question 3

What is the purpose of running an unstained control in cytometry QC?

Accepted Answer

To establish the autofluorescence baseline of the cell population

Answer

Unstained controls define the autofluorescence level, enabling proper gating of negative populations.

Question 4

Which of the following best describes the role of a fluorescence-minus-one (FMO) control?

Accepted Answer

It identifies the spread of fluorescence into a channel of interest from all other fluorochromes except one

Answer

FMO controls capture spillover spread from all other channels into the channel of interest, defining the true negative boundary.

Question 5

A flow cytometry lab implements Levey-Jennings charts for QC bead data. A data point falling 3 standard deviations from the mean indicates:

Accepted Answer

An out-of-control condition requiring investigation before patient samples are reported

Answer

Per Westgard rules, a 3SD exceedance is an out-of-control signal mandating investigation and corrective action.

(SCYM) Specialist in Cytometry Practice Test