SQ sequence item structural editing

Add, remove, or reorder items inside a nested sequence (SQ) tag.

Problem

DICOM SQ (Sequence) tags contain nested datasets — arrays of items, each holding its own sub-tree of tags. You need to structurally edit these sequences: add items, delete items, reorder items, or edit tags within a specific sequence item. This is common when fixing modality worklist entries, structured reports, or radiation therapy plan fractions.

Steps

1. Open the file (⌘O) and switch to Edit mode (⌘3).

2. Locate an SQ tag in the tag tree (e.g. (0040,0275) Request Attributes Sequence). The row displays the item count.

3. Expand the sequence — click the disclosure triangle to reveal nested items and their sub-tags.

4. Edit a tag inside a sequence item — double-click a nested tag, modify its value, and save. The gold modified highlight appears.

5. Add or remove items using the sequence toolbar controls that appear when an SQ tag is selected.

6. Undo (⌘Z) reverts any sequence structural edit.

Expected Result

• SQ tags expand to reveal nested items and their sub-tags.
• Tags within sequence items are editable and track modifications individually.
• Item-level structural changes (add, delete, reorder) are reflected in the item count.
• Undo restores the sequence to its previous state.