FUNCTIONAL DESCRIPTION
9-20 Sysmex KX-21 Operator’s Manual -- Revised October 1998
6.2 Analysis of RBC/PLT Histogram
1. RBC Histogram
As mentioned earlier, RBC are determined as particle counts between two
discriminators (LD) and (UD) which are automatically counted in the ranges of 25 - 75
fL and 200 - 250 fL, respectively.
As to histogram, check is made for relative frequency errors on respective
discriminator levels, for more than one peak, and for distribution width error.
In addition, this instrument is capable of expressing RBC distribution width (RDW) by
two methods below:
RDW-CV (RBC Distribution Width - Coefficient of Variation) is calculated by the
formula below, after determining points L1 and L2 for 68.26% of the entire particle
area:
• Calculation of RDW-CV
RDW-CV (%) =
L
2
- L
1
L
2
+ L
1
×100
L2L1
68.26% of Entire Distribution Area
Figure 9-6-13: Calculation of RDW-CV
RDW-SD (RBC Distribution Width - Standard Deviation) is set on 20% frequency
level with the peak taken as 100%.
• Definition of RDW-SD
100%
20%
RDW-SD
Figure 9-6-14: Definition of RDW-SD
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