Scanning blots and films etc for quantification - (Mar/24/2011 )
A few years ago, I scanned blots using a regular office scanner and found that the final numerical results differed depending on the contrast settings etc, and decided it would be better to scan them all using a dedicated scientific scanner. I now have an exposed film that I want to scan; one of my supervisors doesn't think it matters what scanner I use, but of course I disagree. Would you not get different results however, even between dedicated scientific scanners? Is there no objective way to scan images?
Depends on what you intend to do with the results. If I were you I would not complicate too much. Western blots especially from scanned films are far from quantitative measures of the amount of protein in your sample. Therefore it doesn't really matter where you scan them. I mean once a band is black it's black and all you can do is overexpose the film. You might use the best scanner currently available and still not be able to use the data for anything.
a dedicated scientific scanner is pretty much the same as a regular office scanner. the scientific supply company just wants you to think there is a difference. at one time there may have been. we looked at a wet gel scanner that was sealed to prevent the works from contact with moisture.
look at the specifications for scientific scanners and compare them to those of regular office scanners and you should be able to match (if not better) them for a lower price.
software may be where you find the difference but imagej pretty much nullifies that difference.
mdfenko on Fri Mar 25 14:47:46 2011 said:
a dedicated scientific scanner is pretty much the same as a regular office scanner. the scientific supply company just wants you to think there is a difference. at one time there may have been. we looked at a wet gel scanner that was sealed to prevent the works from contact with moisture.
look at the specifications for scientific scanners and compare them to those of regular office scanners and you should be able to match (if not better) them for a lower price.
software may be where you find the difference but imagej pretty much nullifies that difference.
Okay, for my film, I've found that we have a "film digitiser" (a scanner for transparencies) so I'll be using that.
What I think makes the difference is the dynamic range achievable by the system. Our gel imaging system for example, shows you when an area has reached saturation so you can adjust exposure to get maximum range without reaching saturation. I think scanning softwares for scientific purposes could do with such a feature. Ideally, it would optimise itself, because I think that doing it manually may yield the differences in final quantitations I wrote about above.
the dynamic range is determined by the bit depth of the scanner. that is one of the parameters to consider when you compare the specifications of the scientific scanner with those of the office scanner.
what it boils down to, at least for me, is price.