reading siemens CT from an MO drive

Robert Day robday at
Mon Jan 24 21:59:59 EST 2000

The MOD problem is well known, as several people have written.
The devices themselves are not un-readable, nor un-mountable.

However, the way the data is written to the MOD does not usually conform to 
anyone's idea of a standard file system.  Re-formatting the disk will work, 
under any operating system that supports the hardware (I have done this on 
SGI, Mac and DOS machines), just like any other media.  But of course you 
lose the data on the disk.

It is possible to write custom code to read the data off the disk, if you 
have access to the low level SCSI driver or some other way to read raw 
blocks.  Doing this is a pain, mostly because you have to reverse engineer 
the disk format.  GE do supply the specs, and we have had some success 
reading their disks.

Siemens have not seen fit to release the spec of their MOD layout, despite 
several requests.  Even worse, I have made some attempt to reverse engineer 
the format for some Siemens disks, and found that they seem to be going out 
of their way to make the disk un-readable.  Basically, after a single block 
with header information they write a big area of bad blocks onto the disk, 
then the data.  This means any attempt to scan through the disk will fail 
when it gets to the bad area.  This is not a problem with the disk or the 
drive, but something Siemens deliberately does; I'm not sure why.

In any event, I did get around this, but only partly decoded the format for 
_one_ type of Siemens drive before I convinced the clinical people to go 
another way.

In summary, I agree the best (only ?) way to read a Siemens MOD is on a 
Siemens scanner, then transfer the data off over the network or to other 
DICOM compatible media as quickly as possible.

Sorry for the longish Off-Topic rant, but I have wasted months on this kind 
of thing over the years.


Robert Day		robday at
Project Bioengineer	ph  +61 8 9224 3227
Royal Perth Hospital	fax +61 8 9224 1138

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