Phosphoroimagers vs Instantimager Experiences Saught

[Brian Foley]

Roland J Saldanha (rsaldanh at magnus.acs.ohio-state.edu) wrote:
: We are considering purchasing a phosphorimager or Beta imager 
: specifically the 
: Packard Instantimager.  We have mostly had continuous exposure to a Betagen  
: Beta imager and are most familiar with it.  I would be very grateful for 
: comments positive & negative about the BIO-RAD phosphorimager, the Molecular 
: Dynamics Phosphorimager, & the Packard Instantimager.  

	I have used a Betagen beta imager and the Bio-Rad phosphorimager
quite a bit, but have not tried the others.
1)	The phosphorimager gives a much sharper image, and better 
resolution because the radioactive source (gel or blot) is pressed 
directly against the imaging screen, whereas the beta detector in the 
Betagen is not in direct contact with the source.
2)      While the expense of the machine may be similar, the 
phosphorimager is a much better value, because the machine is not tied up 
durring exposure, only during the read of the screen.  You can buy many 
screens and just one imager.  We find we can serve about 10X as many
people with one phosphorimager as we could with our Betagen.
3)      We have been happy with the software for both the Betagen and the
phosphorimager.  The phosphorimage comes in either Mac or Windows flavors.
The phosphorimager software was updated recently and is quite improved, 
so if you saw a demo a few months ago and didn't like it, you might try 
again now.
4)     I have no hard data comparing the Betagen to the phosphoimager.  I 
have never put the same gel through both imagers to compare.  One 
disadvantage of the phosphoimager is that the Luminescent units are 
dependent on exposure time, and the screen reader cannot know how long 
the screen was exposed.  Thus, one cannot compare one blot to another, 
unless they are exposed together, or some other control is run.  In the 
Betagen, the counts are read directly, so you can get a CPM reading.  In 
the phosphorimager, the screen is read after being exposed for some time.

: I am most interested in 
: general satisfaction with the product, reliability, ease of use, cost of 
: maintenance

	The Betagen was continually getting abused and broken.  People 
would load gels and contaminate the machine, we had trouble with the 
vacuum needed to hold gels down on the platter, etc...  The phosphoimager 
has been maintenance-free except for the software upgrade.  Each user 
owns his/her own screen so if they contaminate it, it only affects them.  
There is much less potential to contaminate the reader.

: (screens, optical backup devices etc for the phosphorimagers), 

	We use a tape drive (6 gigabytes per tape, I think each tape 
costs about $15) to back up and store data.  The phophoimager hard disk 
was partitioned to have software on one partition and user space on 
another.  We then allow each user to have up to 10 megabytes of hard disk 
storage.  We do a daily backup to the tape and purge files that are more 
than two weeks old.

: product support & service etc.

	We tend to service such things ourselves as much as possible.  
Being out in Vermont makes it tough to get rapid service from anyone.
The phosphoimager has needed much less baby-sitting than the Betagen.

--
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*  Brian Foley               *     If we knew what we were doing   *
*  Molecular Genetics Dept.  *     it wouldn't be called research  *
*  University of Vermont     *                                     *
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