PyTomography / PyTomography/PyTomography
DVF volume ratio (Jacobian) correction commented out in MotionTransform
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- Python
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Description
Hi, I noticed that in transforms/shared/motion.py:22-25 the volume
ratio computed by _get_vol_ratio is commented out and hardcoded to
_apply_dvfmultiplies by this ratio, so for non-volume-preserving
DVFs the total counts are not conserved between the forward and
backward passes, which would affect quantitative reconstruction. I'm
not sure if this was intentional - just wanted to flag it in case the
missing Jacobian term matters for the gated OSEM/BSREM workflows.
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Research direction
Read transforms/shared/motion.py:22-25, including _get_vol_ratio and _apply_dvf, to determine whether the commented-out volume-ratio correction is intentional. Check how gated OSEM/BSREM workflows use MotionTransform and define a reproducible conservation check for forward and backward passes; done means the intended behavior is documented and covered by an appropriate test.
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Assessment
- Tech stack
- python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100