Intensity calculations

[framezani]

Hi everyone ,
im very new in imageJ and im not even sure what im gonna ask makes any sense or not but here is the question :
my project is about determining the bone mineral density of the lumbar spine , to do that I took x-ray images and now I need to analyse them with imageJ to extract to BMD at the end.
to do so I need to have the intensity of the beam , which I passed through my phantom and I need the intensity in keV at the end . Is it possible to get the intensity using imageJ ?

[ph73nt]

I think it depends on the file format.

My experience of BMD is from DXA scanners, which typically save images in a
proprietary format. The X-ray energy at the source should be in a narrow
band so the spectrum would be the same at the detector (although lower in
intensity). You'd get an image for each high and low source energy
(actually I think three images per energy on Hologic DXA scanners).

If you're doing something novel with plain X-ray, then saved DICOM data
would be unlikely to have this sort of spectral data, you'd need to have
acquired list-mode data. Again this is usually a proprietary format.

Perhaps you're using transmission CT?

What have you got?

Neil
On 21 Jun 2014 15:50, "framezani" <[hidden email]> wrote:

> Hi everyone ,
> im very new in imageJ and im not even sure what im gonna ask makes any
> sense
> or not but here is the question :
> my project is about determining the bone mineral density of the lumbar
> spine
> , to do that I took x-ray images and now I need to analyse them with imageJ
> to extract to BMD at the end.
> to do so I need to have the intensity of the beam , which I passed through
> my phantom and I need the intensity in keV at the end . Is it possible to
> get the intensity using imageJ ?
>
>
>
>
> --
> View this message in context:
> http://imagej.1557.x6.nabble.com/Intensity-calculations-tp5008357.html
> Sent from the ImageJ mailing list archive at Nabble.com.
>
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> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>
>

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[Michael Doube-4]

Hi Framezani,

> my project is about determining the bone mineral density of the lumbar spine
> , to do that I took x-ray images

With what kind of source? Are they plain radiographs or X-ray microtomography reconstructions?

> and now I need to analyse them with imageJ
> to extract to BMD at the end.

You will need to make a calibration curve, using phantoms of known BMD-equivalence, which will result in a function that relates pixel values to BMD values. Use ImageJ's built in calibration function to do that, once you have the image of the phantoms. Some of the commercial XMT manufacturers have a streamlined way to do this, so talk to your local expert / sales rep / service engineer.

Michael

<http://www.rvc.ac.uk>

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