DICOM Explorer

Structure and display of Patients/Studies/Series

DICOM Explorer

The DICOM Explorer is the panel on the left that displays the Patient/Study/Series representation defined in the DICOM standard.

The data displayed in the DICOM Explorer can be imported form different ways.

Tip

You can navigate through the Patient/Study/Series/Image structure using only keyboard shortcuts. For example:

Open an image and, if necessary, select the view to focus on. If the layout has more than one view, you can move across the views with Tab and Shift + Tab. The view surrounded by an orange line is the focused view.
Navigate through images within a series with Up and Down
Navigate through series within a study with Left and Right
Navigate through studies within a patient with Ctrl + Left and Ctrl + Right
Navigate through patients with Ctrl + Up and Ctrl + Down (follow the order in the patient’s combo box and select the last tab if a patient has several tabs already open). To navigate open tabs, use Ctrl + Tab and Ctrl + Shift + Tab.

Patient Level

Weasis allows multi-patient display. By default, when images are imported a tab with the patient’s name opens in the main area.
A tab containing a multi-view layout can only display images from a single patient.
Changing patients can be done either through the first combobox in the DICOM Explorer (see image above) or by selecting a tab in the main area.
In the combobox the patients are sorted in alphabetical order regardless of case and according to the regional setting.
Studies and Series are displayed within the same patient when the metadata Patient Name and Patient ID are the same. Otherwise, new patients are displayed.

Study Level

A study contains one or more series (thumbnails) belonging to a patient. A line representing the study surrounds its series (see image above).
By default, the studies are sorted by reverse chronology order (since Version4.1.0 “Study data sorting” can be changed in the menu “File > Preferences > DICOM > DICOM Explorer”). If there is no study date then the studies are sorted alphabetically according to the Study Description.
By default, all the studies are displayed, however, you can choose to display only one of them from the study combobox.

Series Level

A series is represented by a thumbnail that contains a certain number of images (number displayed at the bottom left).
According to predefined rules, some series are separated into subseries also represented by a thumbnail with a number preceded by ‘#’ in the upper right corner. Series splitting is necessary for the consistency of some tools such as the MPR, cross-lines and synchronization of series. However, sometimes separation is not desired, and sub-series can be re-merged using the context menu.

4D Series Sub-Series Splitting

When a DICOM series is loaded, Weasis automatically analyzes it to detect multi-phase acquisitions (e.g., cardiac phases, contrast phases, 4D volumes). If multiple phases are detected, the series is split — automatically or with a confirmation step — into separate sub-series, one per phase. Each sub-series can then be used independently in the MPR, MIP, or 3D (VR) viewer.

Splitting behavior by number of detected phases

Phases	Behavior
1	No split — treated as a standard single-phase series.
2 – 7	Automatic split — the series is immediately divided into one sub-series per phase, without any user interaction.
≥ 8	Manual split — Weasis stores the phase count but leaves the series intact. A confirmation dialog is shown before splitting to prevent unintended fragmentation of large datasets.

Manual split confirmation dialog (≥ 8 phases)

When 8 or more phases are detected, a dialog is displayed asking the user to confirm the split. Once confirmed, the series is divided exactly as in the automatic case. Cancelling leaves the series intact as a single entry in the DICOM Explorer.

Sub-series structure after splitting

After splitting, each phase becomes a separate thumbnail in the DICOM Explorer. The first sub-series reuses the original series entry; additional sub-series are created as new entries in the study tree, identified by a # number in the upper-right corner of the thumbnail.

Tip

After splitting, open any individual phase sub-series in the MPR, MIP, or 3D viewer for accurate volumetric analysis. Each sub-series contains only the images of a single phase and can be reconstructed as a coherent 3D volume.

If the split is not needed or was done unintentionally, the sub-series can be merged back together. Select the thumbnails you want to merge (all or a subset of them) and choose Merge Selected Series from the context menu. The selected sub-series are recombined into a single series entry in the DICOM Explorer.

Note

Phase detection is based on the spatial position of each image in the series. If multiple images share the same slice position, they are assumed to belong to different temporal phases. If no such overlap is found, the series is treated as a standard single-phase acquisition and is never split.

Series Display and Opening

The sorting of the series is done by the serial number and if this last one is not present, then in a chronological way by the date of the series or other dates.
To open new series:
- Drag and drop a thumbnail in the main area (if the series is dropped in a view of the same patient, then the series is replaced, otherwise a new tab is created).
- Double click or navigate with the up/down arrow key and press return on a selected thumbnail (if a view of the same patient exists, then the series in the view surrounded by an orange line is replaced)
- Select one or more thumbnails and choose an action from the “2D DICOM Viewer” context menu:
  - Open: Opens the series in the most appropriate layout (replaces the series if the patient’s tab already exists)
  - Open in new tab: Opens the series in the most appropriate layout in a new tab.
  - Open in screen: Opens the series in the most appropriate layout in a specific screen.
  - Add: Adds the series to the current patient’s layout if exists.

Preferences

From the main menu “File > Preferences > DICOM > DICOM Explorer”:

Thumbnail size: defines the width of the thumbnails and adjusts the panel accordingly (Default: 144). It is recommended to restart the application after this change.
Study data sorting: allows sorting the studies by chronological order or inversely chronological (Default: reverse chronology order). Since Version4.1.0.
Open in new tab: behavior to automatically open the images of a patient when using WADO or WADO-RS (Default: All the patients)
Download all series immediately: allows starting the download of the series immediately when using WADO or WADO-RS (Default: true). If unchecked then you must click on the play button on each series or globally at the bottom of the thumbnail list.