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Formula for calculating tumor volume?

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HeadCase2:
Windsong,
  Here's an example.  If an AN was measured to be 1.5 cm x 1.0 cm x 0.8 cm, we can divide each "diameter" by 2 to convert them to radius measurements, giving 0.75 cm, 0.5 cm, and 0.4 cm.  We can plug these radii into the formula listed in the earlier note, using 3.1416 for the value of pi.
4/3 x 3.1416 x 0.75 cm x 0.5 cm x 0.4 cm = 0.62832 cubic cm.
  It should be noted that there is some error involved in measuring dimensions on MRIs, and trying to represent a complex shape as an ellipsoid.  I am not knowledable about radiation therapy, but the error involved is probably not significant in calculating radiation dosages.
Regards,
 Rob
PS: measuring ellipsoid dimensions is an interesting exercise, and involves tensor mathematics with eigen vectors, etc.  Tensor mathematics is used by scientists to descibe physical properties in the natural world, for example how a rock allows fluids to flow through it at different rates in differenet directions.

arcteryx:
This was the reason why doctors recommended against radiation for me (even though I would've preferred it).  You'll notice that as the two-dimensional size of the tumor increases, its volume (i.e., radiation required) is cubed.  So:

...for a 1cm AN, its volume is 0.52 cubic centimeters:
4/3 * 3.14 * 1cm/2 * 1cm/2 * 1cm/2 = 0.52cc

...for a 2cm AN, its volume is 4.18 cubic centimeters:
4/3 * 3.14 * 2cm/2 * 2cm/2 * 2cm/2 = 4.18cc

...for a 3cm CN, its volume is 14.12 cubic centimeters:
4/3 * 3.14 * 3cm/2 * 3cm/2 * 3cm/2 = 14.12cc

Windsong:
Thank you.

That explains why when i tried all these numerous formulae for varius volume type things, i never could approximate a volume no. that made sense for my An.... but then I am not a mathemetician nor a physiscist nor a radiooncologist lol..... i think i'd leave these kinds of math calcs to them.....

best wishes,
Windsong

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