# Bone Mineral Density (BMD) measurement method

**URL:** <https://discourse.slicer.org/t/bone-mineral-density-bmd-measurement-method/11010>\
**Category:** Support\
**Created:** [April 6, 2020, 8:23am UTC](https://discourse.slicer.org/t/bone-mineral-density-bmd-measurement-method/11010 "2020-04-06T08:23:51Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [April 6, 2020, 2:10pm UTC](https://discourse.slicer.org/t/bone-mineral-density-bmd-measurement-method/11010/2 "2020-04-06T14:10:16Z")

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> [@manjula](#):
>
> in the segment statistics module, the value that come as the mean in the scalar volume statistics, is it the mean hounsfield ?

You get results in the same unit as the input image. In case of a calibrated CT, it is Hounsfield unit. In case of a non-calibrated system, it can be anything.

> [@manjula](#):
>
> Is the method of trying to arrive at BMD in this way is accurate ?

3 measurement points are very few. At least for initial exploration, I would add at least 5-10 points, just to have an idea about shape and amount of noise in the curve. It is highly unlikely that the calibration curve would be a line, so fitting a line to 3 points is a potential source of error.

[GelDosimetry extension](https://www.slicer.org/wiki/Documentation/Nightly/Modules/GelDosimetry) contains an automatic image intensity calibration and evaluation workflow that should be directly usable. @cpinter do you have any advice?

> [@manjula](#):
>
> What is the reason for the slight difference in the mean values between the 3D Slicer and the other program ?

There could be many reasons, but I don’t know what that software does. Is that software open-source? Do they describe somewhere what they do?

How much is the difference? If it’s small then it may be due to forcing the calibration curve to be a line.

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