MONAI-Physio 2026.09.0

Highlights

• TCIA-4DLung is now the lung tutorials' primary dataset, replacing
  DirLab-4DCT, and downloads automatically with one CLI call
  (monai-physio-download-data TCIA-4DLung) instead of a manual DICOM
  download + conversion step. (#141)
• Physics-informed cardiac motion, tutorials 16-18, with a neo-Hookean
  loss term. (#126)
• Cohort-based evaluation and distributed training, plus tutorials
  14-15 and a new cookbook. (#123)

Enhancements

• Training now warns when it stalls. (#140)
• 4D CT reconstruction supports Mean/Max-over-time compositing, not just a
  single reference frame. (#132)
• Tutorials can point at custom data/output directories instead of the
  repo-relative defaults. (#125)
• Tetmesh quality is verified after fitting the statistical model to a
  patient. (#135)
• Physics-informed motion training is more robust (PhysicsNeMo fixes).
  (#138)
• GPU test run time reduced. (#127)

Breaking changes

See docs/developer/migration_2026.09.0.md for full before/after code and
automated-conversion scripts:

• Registration transform results renamed forward/inverse →
  fixed_to_moving_transform/moving_to_fixed_transform (asymmetric
  between image and PCA/ICP registration - read the table before
  find-replacing).
• WorkflowCreateStatisticalModel.inverse_transforms removed (unused,
  was doubling peak memory).
• Install extras collapsed to cuda12/cuda13/dev/dev_cuda12/
  dev_cuda13; all, physicsnemo, docs, test are gone, and the
  AI-surrogate packages are now base dependencies.
• physicsnemo_tools.py free functions moved onto a new
  PhysicsNemoTools class.
• The *_tools/*Tools module and class family renamed to
  process_*/Process* (ContourTools → ProcessContours, etc.);
  utils/rename_tools_to_process.py automates the migration.
• Project renamed PhysioTwin4D → MONAI Physio. (#133)

Fixes

• Nightly test failures from stale/old tests resolved. (#128)

Docs

• Installation procedure and docs refined. (#134)
• Docs updated for new tutorials and issue templates. (#131)
• data/TCIA-4DLung/README.md added (was a dangling link); every doc
  referencing TCIA-4DLung's download method updated.

Details

• Update installation.rst by @aylward in #122
• ENH: Cohort-based evaluation, distributed training, tutorials 14-15, cookbook by @aylward in #123
• DOC: Prefer API compatibility, log unavoidable breaks in a migration guide by @aylward in #124
• ENH: Allow data and output directories of tutorials to be specified by @aylward in #125
• ENH: address long run-time of GPU tests by @aylward in #127
• BUG: Address nightly failures due to stale/old tests by @aylward in #128
• ENH: Physics-informed cardiac motion with a neo-Hookean loss, tutorials 16-18 by @aylward in #126
• ENH: Enable reconstruction using Mean/Max over time by @aylward in #132
• DOC: Update docs for new tutorials, issues templates by @aylward in #131
• ENH: Rename the project from PhysioTwin4D to MONAI Physio by @aylward in #133
• ENH: Refined installation procedure and documentation by @aylward in #134
• ENH: Verify tetmesh quality after fit to patient by @aylward in #135
• ENH: Fixed naming of transforms to standard to/from by @aylward in #136
• ENH: Physics-informed motion training fixes - PhysicsNeMo robustness by @aylward in #138
• ENH: Rename tools modules and classes to process naming convention by @aylward in #139
• ENH: Warn when physics-informed motion training collapses to the trivial solution by @aylward in #140
• ENH: Switch lung tutorials to TCIA-4DLung and automate its download by @aylward in #141
• ENH: Release 2026.09.0 by @aylward in #142
• ENH: 2026.09.0 Migration Guide by @aylward in #143

Full Changelog: 2026.08.0...2026.09.0