Abbott CELL-DYN 3000 Operator's Manual - Plt Measurement
3-22
CELL-DYN
3000 System Operator’s Manual
9140240E — May 1995
Principles of Operation Chapter 3
PLT Measurement
Pulses counted in the RBC/PLT dilution between 1 and 35 fL are
included in the PLT data. If the raw PLT count is estimated to be below a
predetermined value, the instrument automatically continues to count
PLTs for an extended count period. The results from the two count
periods are averaged. The PLT data is plotted as a histogram. An
algorithm analyzes the histogram to eliminate interference and thus
determine the lower and upper thresholds for the count.
If no interference is detected, the lower and upper thresholds are set at 2
and 30 fL respectively. If interference is detected, the thresholds float to
determine the best separation between the interference and the PLT
population. The lower threshold floats in the 1–3 fL region and the upper
threshold floats in the 15–35 fL region. Once the thresholds have been
determined, the PLT count is derived from the data between them.
Interference in the upper threshold region is generally caused by
microcytic RBCs. Therefore, after the PLT upper threshold has been
determined, the data between it and the RBC lower threshold is
reevaluated. If the PLT upper threshold is less than 35 fL, the counts
above it (but less than the RBC lower threshold) are added to the RBC
count.
If the interference in either threshold region exceeds a predetermined
limit, the PLT count is flagged accordingly. The flags are discussed in the
last section of this chapter.
Platelet Parameters
All numeric and frequency size distribution data are automatically
displayed on the Data Station RUN Screen in the format selected. The
size distribution data for the platelets is displayed graphically as a
histogram with the size distribution data plotted on the X axis and the
relative number of cells normalized and plotted on the Y axis. The
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