Almos Elekes (almos@milwaukee.sgi.com)
Thu, 14 Oct 1999 16:02:05 -0500
Jeff Potter wrote:
> http://www.vitalimages.com/
>
> ----------
> >From: bond@stereosgi.neur.cwru.edu (Angus Bond)
> >To: Mark Davey <mkd@medphys.ucl.ac.uk>
> >Cc: info-volumizer <info-volumizer@corp.sgi.com>
> >Subject: Re: Fly-through suggestions
> >Date: Thu, Oct 14, 1999, 1:22 PM
> >
>
> >> Message-ID: <38061800.A98BE7D5@medphys.ucl.ac.uk>
> >> Date: Thu, 14 Oct 1999 10:50:56 -0700
> >> From: Mark Davey <mkd@medphys.ucl.ac.uk>
> >> To: info-volumizer <info-volumizer@corp.sgi.com>
> >> Subject: Fly-through suggestions
> >>
> >> Hi..
> >> I am looking to use Volumizer to effectively 'fly-through' a CT or MRI
> >> volume. For instance, this could be used as a teaching aid for
> >> endoscopic surgery. Does anyone have any ideas concerning steps that
> >> should be taken to do this using Volumizer. My initial attempts have
> >> been less than satisfactory resulting in quite blurred, very aliased
> >> images.
> >> Regards
> >> Mark
> >>
> >> --
> >> From: Mark Davey
> >> Dept. of Medical Physics, UCL.
> >>
> >> TEL: +44 (0)171 915 1673.
> >> FAX: +44 (0)171 837 9279.
> >>
> >> Institute of Laryngology and Otology,
> >> 330 Gray's Inn Road,
> >> London.
> >> WC1X 8GE.
> >
> > Hello Mark,
> >
> > I do not have the answer you seek, but I can tell you that, if you
> > are emulating an endoscope, you can expect to see blurred and/or
> > aliased images.
> >
> > The problem has to do with image resolution. CT and MR scans are
> > usually 512 pixels across a field-of-view of 240 mm and the slices
> > are usually 1 to 2 mm apart. That means that each voxel is about
> > 0.5x0.5x1.0 mm at best. An endoscope usually has a field-of-view
> > of about 10 to 20 mm, so you will be looking at a field of about
> > 40x40 voxels at best and 20x10 voxels at worst. I can guarantee
> > that the result will be blurred and/or aliased.
> >
> > A good rendering system will produce an anti-aliased image so that
> > you get an understanding of what you are seeing. You may also be
> > able to get a crude surface rendering. The rendering system cannot
> > create data that was not in the original CT or MR scan, so the very
> > best it can do is approximate reality. Once you understand this,
> > you can find a rendering system that will give you a good
> > representation of the volume. For that, you will have to talk to
> > the other members of this mailing list.
> >
> > Good luck!
> > Angus
> > -----------------------------------
> > Angus Bond
> > bond@stereosgi.neur.cwru.edu
> > bond@modex.com
> > +1 216 844-8963 lab/office
> > +1 440 834-1414 answering machine/fax
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