SCYM Quality Control & Assurance 5

Question 1

A flow cytometer's photomultiplier tube (PMT) voltage is adjusted upward. The primary effect on QC bead data will be:

Accepted Answer

A shift of bead populations to higher MFI values

Answer

Increasing PMT voltage amplifies the signal, shifting populations to higher MFI without changing the coefficient of variation proportionally.

Question 2

Which of the following scenarios represents a random error in flow cytometry QC?

Accepted Answer

A single QC bead result that is high, followed by results within normal range

Answer

Random errors produce isolated, non-directional excursions that return to expected range, unlike systematic errors that cause trends or shifts.

Question 3

The purpose of including a viability dye in a cytometry staining protocol relates to QC because:

Accepted Answer

It excludes dead cells that non-specifically bind antibodies and inflate false-positive signals

Answer

Dead cells non-specifically bind antibodies, so excluding them with a viability dye improves staining specificity and data quality.

Question 4

Which of the following defines 'precision' as validated in a clinical flow cytometry assay?

Accepted Answer

The closeness of repeated measurements of the same sample under defined conditions

Answer

Precision (reproducibility) measures how consistently an assay returns the same result when the same sample is tested multiple times.

Question 5

A laboratory discovers that two operators consistently report different CD34+ stem cell percentages on split aliquots. This most likely reflects a problem with:

Accepted Answer

Inter-operator variability in gating strategy

Answer

Inconsistent results between operators on the same sample typically indicate non-standardized gating strategies requiring harmonization.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Quality Control & Assurance 5