[Bug] Segmentation is not removed from the viewport when the same segmentation is loaded again.

[nithin-trenser]

Describe the Bug

Segmentation is not removed from the viewport when the same segmentation is loaded again.

Note : This issue is reproducible in OSS 3.12

Steps to Reproduce

• Launch the study.
• Load the segmentation.
• Remove the loaded Segmentation.
• Load the same segmentation again.
• Remove the same segmentation.
• Observe that the segmentation remains in the viewport.

The current behavior

Segmentation is not removed from the viewport when the same segmentation is loaded again.

Current.behavior.mp4

The expected behavior

The segmentation should be removed from the viewport when the same segmentation is loaded again.

System Information

System:
OS: Windows 11 10.0.22631
CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
Memory: 8.68 GB / 31.74 GB
Binaries:
Node: 20.17.0 - C:\Program Files\nodejs\node.EXE
Yarn: 1.22.22 - C:\Users\1497\AppData\Roaming\npm\yarn.CMD
npm: 11.1.0 - C:\Program Files\nodejs\npm.CMD
Browsers:
Chrome: 143.0.7499.170
Edge: Chromium (143.0.3650.96)
Internet Explorer: 11.0.22621.3527

[linear]

OHIF-2409

[nithin-trenser]

Findings

On the initial load, the segmentation representation and its corresponding actor are created as expected. However, after removing the segmentation and re-adding it, a new label map entry is added to labelMapActorEntries, resulting in the creation of an additional actor.

At this stage, the actor list contains multiple entries, including:

• the image set actor,
• the actor created during the initial load (which should have been removed), and
• the newly created actor.

When the segmentation is removed, only one of these actors is deleted, while the remaining actor continues to exist and is still rendered in the viewport.

With each subsequent re-addition of the same segmentation, a new actor is created without properly cleaning up the previously created ones. For example:

• loading the segmentation a third time results in four actors in the actor list,
• deleting and re-adding it again increases the actor count to five.

This indicates that actor creation continues to grow with each add/remove cycle.

As a result, the segmentation appears as an overlay spanning multiple slices, even though the original segmentation is defined for a specific image slice only. When the same segmentation is loaded and removed multiple times, it may remain visible in the viewport. However, switching the layout (for example, to an MPR viewport) clears the segmentation from the viewport and removes the remaining actors.

The primary issue appears to be in the actor cleanup logic within the imageChangeEventListener.ts file. When segmentations are removed and re-added, the cleanup mechanism does not properly remove all actors, leading to actor accumulation and incorrect rendering behavior.

@sedghi Could you please look into this?