Merged in feature/RAM-3186_writing_to_lazy_stacks (pull request #319)

RAM-3186 Allow writing to lazy dicom stacks

Approved-by: Randy Taylor

docs/source/changelog.rst

@@ -2,6 +2,15 @@
 Changelog
 =========
 
+v 3.19.0
+--------
+
+Core
+^^^^
+
+* The efficient DICOM stack introduced in the last version did not allow for writing images back to the stack
+  (e.g. when manipulating the image). Images can now be written back to efficient stacks.
+
 v 3.18.0
 --------
 

pylinac/core/image.py

@@ -1658,6 +1658,11 @@ def metadata(self) -> pydicom.FileDataset:
     def __getitem__(self, item: int) -> DicomImage:
         return DicomImage(self._image_path_keys[item], dtype=self.dtype)
 
+    def __setitem__(self, key: int, value: DicomImage):
+        """Save the passed image to disk in place of the current image."""
+        current_path = self._image_path_keys[key]
+        value.save(current_path)
+
     def __len__(self):
         return len(self._image_path_keys)
 

tests_basic/core/test_image.py

@@ -787,6 +787,16 @@ def test_mixed_studies(self):
         with self.assertRaises(ValueError):
             DicomImageStack.from_zip(mixed_study_zip)
 
+    def test_writing_back_to_lazy_stack(self):
+        dstack_lazy = LazyDicomImageStack.from_zip(self.stack_location)
+        original_offset = np.copy(dstack_lazy[0].array) + 50
+        for idx, img in enumerate(dstack_lazy):
+            img.array += 50
+            dstack_lazy[idx] = img
+        manipulated_offset = np.copy(dstack_lazy[0].array)
+        # assert that writing back to the stack works
+        assert_array_almost_equal(manipulated_offset, original_offset)
+
 
 class TestGamma2D(TestCase):
     def test_perfect_match_is_0(self):