Add FOV to the header?

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Active
Tech stack
python
Domain
data

Research direction

Read the ExamInformation definition and the ETSI discussion referenced in the issue. The proposal to add expected FOV shape and transform was rejected as duplicative and potentially impossible to determine during live writing when the gantry tracks movement; the issue leaves reconsideration to a future hackathon, so the desired change and completion criteria are unresolved.

Written by the indexing model from the issue text.

Description

question

It would be convenient for the reconstruction people to have upfront information on the actual FOV to reconstruct. At the moment, they need to

  1. read the scanner geometry.
  2. figure out what the FOV is in the "reference" position for the gantry.
  3. read the stream to get the information on the gantry and bed movements.
  4. figure out what the final FOV is.

This isn't so easy and also time-consuming.

One potential solution is to add the following to ExamInformation

    # Expected Field of View shape (including bed position movements)
    # The "axis" of the shape is defined as the "axis" of the scanner.
    expected_FOV_shape: GeometricShape

    # Expected Field of View transform (including bed position movements)
    # After applying the transform, the shape coordinates are
    # specified w.r.t. the CT/MR gantry, not the PET gantry.
    expected_FOV_transform: RigidTransformation

This was discussed at ETSI meeting 6Nov2026. Most people found this is duplication of information, and therefore error-prone. Other things like this could be added as well then (such as total duration, if known, or total counts if that's the stopping criterium). It was therefore decided not to include this information, but to be discussed at the 5th ETSI hackathon.

@KrisThielemans afterwards also realised that knowing the expected FOV might be impossible to know upfront in case the gantry is tracking any movement. (Obviously, it would be available for a converter, but not "live" writing of the PETSIRD file).

Dominant language
Python
Stars
15
Forks
18
Avg merge
1d 11h
Merged PRs (30d)
12

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