Tuesday, July 22, 2008

What is a "Micron"?

I was at a conference yesterday and one of the doctors asked about the resolution of my i-CAT images. I told him they were .4mm. He said, "but what is the resolution??" I explained to him the voxel size was .4mm. He said, "but what is the resolution in microns???". I told him I didn't know microns, only voxel size.

Anybody out there know "microns?"


Blogger Tim said...

Here is a link to a pp presentation for imaging sciences that discusses microns. It has to do with the pixel size. I believe it stated it is 125 microns (0.125mm).
Hope this helps,

10:02 AM  
Blogger Amnon said...

He ment the flat panel pixel size.
but I don't belive he understands what is binning, we are binning 2x2 or 4x4 depends on the protocol, which makes a huge difference & that the number of exposures is also important.
see you in October

1:37 PM  
Blogger M CARPENTER said...

what is binning?

8:12 AM  
Blogger Arun said...

"Micron" is nothing more than a unit of distance measurement. It is a 1000th of a millimeter, or a millionth of a meter. In other words, 0.4mm is 400 microns. In that sense, the doctor's question was not meaningful.

The confusion might have been caused by the doctor's perception that "micron" is automatically tied to the pixel size on the flat panel. If that was his question, the pixel size on the iCAT panel is 127 microns (0.127mm) to be exact. However, this does not directly specify the resolution of the images.

That's where Amnon comes in, and the question on "binning". We do not read the 127 micron pixels individually. There are over 3 million pixels on the panel, reading them individually would take too long, prolonging scan and reconstruction times, with accompanying hugely inflated data sizes, not to mention lower signal to noise ratios. To overcome all this, we "bin" the pixels in groups of 4 (2x2 binning, making it 254 microns), or groups of 16 (4x4 binning, making it 508 microns), for high or normal res scans respectively. The corresponding voxel sizes define the image resolution.


8:51 AM  
Blogger Merry Hampton said...

Since I have the Next generation-flat panal that rotates to the 17cm. Does it have the same number of microns- 127 or (0.127mm)? Or are the panaels the same size?

2:40 PM  
Blogger Arun said...

Hi Merry:

The flat panels are identical in the 14-bit Classic and Next Gen iCATs. The "flip panel" mechanism is unique to the next gen, but the panel is not.


8:17 AM  

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