1024 vs 256 channels

VSH - Tech Support tech at vsh.com
Thu Mar 28 16:42:57 EST 2002


I thought it might be useful to add a little more information on this
subject.  I presented a poster at the last ISAC meeting that discussed
several of the parameters often associated with determining histogram
quality.  One of these parameters was the number of events, or to be more
exact the number of events in the cycling population.  I found that it was
important to maintain an average of 200 events per channel over the cycling
population to obtain good S-phase results.  The DNA Consensus Conference
Guidelines (1) indicated that 10,000 events (excluding debris and
aggregates)  were required for proper S-phase analysis. According to our
work,  this value is correct but only as long as the number of channels
between the first G0G1 and the last G2M is 50 or less.	This would only be
true for DNA Diploid samples with the DNA Diploid G0G1 set at channel 50
(normally only used when collecting at 256 channel resolution).  My
experience is that operators frequently use  "10,000" as a general guide for
any collection resolution.   Instead users should adjust the number of
events collected to insure that a minimum of 200 events per channel in the
cell cycle when analyzed .  For example, when collecting at 1024 channels
with the DNA Diploid G0G1 mean set at channel 200  you would need a minimum
of 40,000 events just in the cell cycle (remember to exclude the debris and
aggregate events).

Based on extensive DNA Cell Cycle analysis and correlating the results with
known outcome, we have found that in the majority of cases, 256 channels are
sufficient.  However collecting at 1024 channel resolution and analyzing
using a 256 channel histogram has a lot of merit.  You can keep the number
of events needed lower and while being able to go back to the higher
resolution if needed.

I have attached some of the panels of my poster in a zipped PowerPoint file.
If you wish more information or a copy of the full poster I would be happy
to send it to you.

Best regards

 Don

Donald J. Herbert
Technical Support Manager
Verity Software House, Inc.
PO Box 247
45A Augusta Road
Topsham, ME, USA  04086

Phone: (207) 729-6767 ext.190
Fax:   (207) 729-5443
email:	tech at vsh.com
web: www.vsh.com

1. T. Vincent Shankey, Peter S. Rabinovitch, Bruce Bagwell, Kenneth D.
Bauer, Ricardo E. Duque, David Hedley, Brian H. Mayall, and Leon Wheeless:
Guidelines for Implementation of Clinical DNA Cytometry. Cytometry
14:442-447, 1993
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