Size volume reconstruction

[LeidyMoraV]

I'm attempting to reconstruct the volume of a spine phantom. I'm using equipment including the Ascension Trackstar, Siemens P300 ultrasound, and the Epiphan frame grabber VGA2USB. However, after completing the volume reconstruction, the images of the vertebrae appear too closely spaced together, almost as if the spacing between them is incorrect. Could this issue be related to calibration? What other factors might be influencing the outcome?

[Sunderlandkyl]

I think that it is likely related to the calibration, it seems like the ultrasound image spacing is too large.

[LeidyMoraV]

The data is here: https://pennstateoffice365-my.sharepoint.com/:f:/g/personal/lfm5705_psu_edu/Euc_NmkZvkpBjNjDO8OUV8UBCyPQYKAv1oTKQxlxZnqViA?e=t7P5MT
The sequence is named SequenceBrowser_1

[Sunderlandkyl]

Ok, I see the problem now. Your Slicer scene is not taking ImageToProbe into account. You'll need to either change the reference coordinate system of your image to Image_Probe, or add the ImageToProbe transform to the outgoing server and adjust your transform hierarchy so that it goes Image_Image -> ImageToProbe -> ProbeToTracker.

You should probably also do the volume reconstruction in the Reference coordinate system in case the phantom is moved accidentally. You can just add ProbeToReference to the config file and use that instead of ProbeToTracker.

[LeidyMoraV]

Do you have any config files example of the changes I need to make?

[Sunderlandkyl]

Actually I realized there's an easier way. You can just change the parent transform of Image_Image to ImageToReference and use that instead, or use the Image_Reference volume for reconstruction instead.

Just don't try to record a sequence in the future using Image_Reference since the saved sequence will not contain the position information.

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In any case here's some examples of other changes that you could make:

Change the EmbeddedTransformToFrame to "Probe" so that the image calibration is applied.

  <Image Name="Image" EmbeddedTransformToFrame="Probe" />

Add ProbeToReference to this section to get the "ProbeToReference" transform in Slicer.

      <TransformNames>
        <Transform Name="ProbeToTracker" />
        <Transform Name="ReferenceToTracker" />
        <Transform Name="StylusToTracker" />
        <Transform Name="ImageToReference" />
        <Transform Name="ProbeToReference" />
      </TransformNames>

[LeidyMoraV]

It worked, thank you!