reading siemens CT from an MO drive

[fmri]

Robert,

I feel this is a very helpful posting providing lots of technical background one
is only able to acquire through painful personal experience otherwise.
As lots of medical imaging data (partly due to medicolegal aspects as well) is
stored on MOD companies like Siemens are really a pain in the ass.
Your posting also seems to explain why I often get a "Drive not ready"/ "Unknown
Device" etc. message by Windoze No Title when inserting a MO from a Siemens
machine when the medium used to be perfectly sane when reading it in the scanner.

As one uses those expensive MOs for longterm storage of sensitive data the
paradoxon of not being able to read it later on is even aggravated. Medical
imaging professionals should point out these and other cost increasing rubbish
when it comes to buying the next scannner at the hospital/university ...

Arno

Robert Day wrote:

> 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.
>
> Rob.
>
> --
> Robert Day              robday at rph.health.wa.gov.au
> Project Bioengineer     ph  +61 8 9224 3227
> Royal Perth Hospital    fax +61 8 9224 1138
>
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