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Gantry tilt interpolation should respect pixel padding value #262

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alund opened this issue Jan 31, 2019 · 1 comment
Closed

Gantry tilt interpolation should respect pixel padding value #262

alund opened this issue Jan 31, 2019 · 1 comment

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@alund
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alund commented Jan 31, 2019

DICOM tags (0028, 0120), (0028, 0122) or (0028, 0123) can be used to specify pixel padding values. The presence of these values in the image itself indicate pixels without valid data, for example outside the cylindrical acquisition volume of a CT.

When interpolating, these pixels should not be treated as "normal" values that can be used in linear interpolation. My suggestion is, when at least one of the two values used in the interpolation equals the padding value, to use nearest neighbor interpolation instead.

While the effects of this are limited to the border between the padding and real pixels, it changes the intensity histogram enough to confuse our code for a couple of images.

I will submit a pull request with a proposed fix.
alund added a commit to alund/dcm2niix that referenced this issue Jan 31, 2019
@alund
Respect pixel padding value during interpolation
c3f450d 
* Fixes rordenlab#262
@alund alund mentioned this issue Jan 31, 2019
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alund added a commit to alund/dcm2niix that referenced this issue Feb 1, 2019
@alund
Respect pixel padding value during interpolation
7f378ce 
* Fixes rordenlab#262
* Use a single float pixelPaddingValue in TDICOMData rather than
  pixelPaddingValue, floatPixelPaddingValue, isHasPixelPaddingValue and
  isHasFloatPixelPaddingValue
* Read kFloatPixelPaddingValue with dcmFloat() rather than dcmStrFloat()
* Use pixel padding value when available for padding added during tilt
  correction.
@neurolabusc
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Fixed with pull request 246

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@alund @neurolabusc