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List:       insight-users
Subject:    Re: [Insight-users] Measuring tumor diameter
From:       "Steve M. Robbins" <steve () sumost ! ca>
Date:       2008-12-28 4:15:41
Message-ID: 20081228041541.GQ5408 () sumost ! ca
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On Sun, Dec 21, 2008 at 05:34:54PM -0500, Andriy Fedorov wrote:

> To understand maximum diameter, as I understand it, imagine the
> contour of the tumor segmented in a 2d slice. Then take a set of
> segments connecting all possible combinations of the contour points.
> For each segment, subtract the subsegment which is outside tumor
> contour (this will happen only for concave shapes). The updated this
> way length of the longest segment will be the maximum diameter.

OK, so it sounds something like "find the largest line segment that
lies inside the contour".  The computational geometry community calls
this "The Biggest Stick Problem" [1]; however, at first glance the
algorithm looks a bit involved.

In addition, I suspect that various unspoken heuristics are 
used in practice.  For example, a "C" shaped tumour with a 
thin body along the "C" will admit only a small stick, whereas
I'd bet a medical person would draw a line more like the chord
from the middle to one of the points of the "C".

So in the end, I don't have anything to suggest.

-Steve

[1] http://www.stolaf.edu/people/olaf/papers/potato.pdf

P.S.  Thanks, Celina Imielinska, for the book reference.


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