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fix(data): avoid divide-by-zero in pydicom affine for single-slice volumes #8956

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Merged
ericspod merged 5 commits into from
Jul 5, 2026
Merged

fix(data): avoid divide-by-zero in pydicom affine for single-slice volumes #8956

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a4ed8a6
test(data): add affine regression coverage for single-slice pydicom m…
SID-6921 Jun 30, 2026
42517f5
test(data): use lowercase pydicom module name in SkipIfNoModule
SID-6921 Jun 30, 2026
88ffd80
Merge branch 'dev' into fix/pydicom-affine-single-slice-zero-div
ericspod Jul 3, 2026
789e533
Potential fix for pull request finding
SID-6921 Jul 3, 2026
a8da817
Merge branch 'dev' into fix/pydicom-affine-single-slice-zero-div
ericspod Jul 5, 2026
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37 changes: 36 additions & 1 deletion tests/data/test_init_reader.py
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@

from monai.data import ITKReader, NibabelReader, NrrdReader, NumpyReader, PILReader, PydicomReader
from monai.transforms import LoadImage, LoadImaged
from monai.utils import MetaKeys
from tests.test_utils import SkipIfNoModule


Expand Down Expand Up @@ -48,7 +49,7 @@ def test_load_image_to_gpu(self):
@SkipIfNoModule("nibabel")
@SkipIfNoModule("PIL")
@SkipIfNoModule("nrrd")
@SkipIfNoModule("Pydicom")
@SkipIfNoModule("pydicom")
def test_readers(self):
inst = ITKReader()
self.assertIsInstance(inst, ITKReader)
Expand Down Expand Up @@ -100,6 +101,40 @@ def test_nibabel_reader_avoids_eager_c_order_copy(self):
# (F-order) layout from nibabel should be preserved here.
self.assertFalse(data.flags.c_contiguous)

@SkipIfNoModule("pydicom")
def test_pydicom_reader_get_affine_single_slice_with_last_position(self):
reader = PydicomReader()
metadata = {
"00200037": {"Value": [1.0, 0.0, 0.0, 0.0, 1.0, 0.0]},
"00200032": {"Value": [10.0, 20.0, 30.0]},
"00280030": {"Value": [0.5, 0.25]},
"lastImagePositionPatient": np.array([10.0, 20.0, 30.0]),
MetaKeys.SPATIAL_SHAPE: np.array([64, 64, 1]),
}

affine = reader._get_affine(metadata, lps_to_ras=False)

np.testing.assert_allclose(affine[0, 2], 0.0)
np.testing.assert_allclose(affine[1, 2], 0.0)
np.testing.assert_allclose(affine[2, 2], 1.0)

@SkipIfNoModule("pydicom")
def test_pydicom_reader_get_affine_multi_slice_uses_last_position(self):
reader = PydicomReader()
metadata = {
"00200037": {"Value": [1.0, 0.0, 0.0, 0.0, 1.0, 0.0]},
"00200032": {"Value": [0.0, 0.0, 0.0]},
"00280030": {"Value": [1.0, 1.0]},
"lastImagePositionPatient": np.array([0.0, 0.0, 8.0]),
MetaKeys.SPATIAL_SHAPE: np.array([8, 8, 5]),
}

affine = reader._get_affine(metadata, lps_to_ras=False)

np.testing.assert_allclose(affine[0, 2], 0.0)
np.testing.assert_allclose(affine[1, 2], 0.0)
np.testing.assert_allclose(affine[2, 2], 2.0)

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if __name__ == "__main__":
unittest.main()
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