Here is Arun’s answer:
An explanation is in order on the matrix sizes.
Even though the reconstructed volume is cylindrical, each axial slice is stored as a square array or pixels (rows and columns) in the database, also defined as the “matrix size”. This is necessary since a common computer database does not provide a mechanism to store a circular array of pixels. Obviously, there are some wasted pixels when a circular image is fitted inside a square frame, those extra pixels are filled with “blanks”. To minimize the file sizes, we have chosen matrix sizes where the side of the square is the same as the diameter of the circle, enabling the tightest possible fit. This was the reason for going from 512x512 matrix to 400x400 matrix, for 0.4 voxel, covering exactly 16cm of diameter.
This caused compatibility issues with I-Dent, DenX and certain other systems, since they have “hard-coded” their import modules for the common 512 matrix, disallowing or crashing on everything else. They are all expected to support other matrices in the future, but for the time being the file sizes must be over 50% larger, filling the extra pixels with blanks, whenever exporting to these systems. Nobel system does work with 512 or anything smaller, but not larger. This eliminates everything but 0.4 voxel at this time.
You can certainly use the I-Dent protocols for Nobel, as there is no other difference besides what’s described above. However, if you would like to economize on the file sizes when using Nobel, we can add 2 additional protocols for 6cm height, name them Nobel (or stay with a generic name), and change the matrix back to 400. Please let us know.
Many thanks to Arun for his very detailed and clear explanation of matrix. For more information about iDent and the required scan protocols, their website is http://www.ident-surgical.com/ Under the Frequently Asked questions (FAQ) site, they state that the i-CAT cone beam unit is the only cone beam unit currently approved for iDent imaging. That is not going to last long, so take advantage of this opportunity to get the word out about your i-CAT -now!