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The Images sidebar allows you to simultaneously display multiple image sets that have been uploaded to the patient. This is especially useful while contouring to be able to view information from multiple image modalities (e.g., CT and MR). To view the available images for the selected patient, click the Images tab located in the right sidebar.
Displaying Multiple Image Sets
The Images sidebar contains two sections, the first lists the currently "Active" image sets in the patient. Active image sets include the primary image set (indicated by a green checkmark in the Browse tab) as well as any secondary image sets (indicated by a blue checkmark in the Browse tab). The second section lists the currently "Inactive" image sets in the patient (if available). All inactive image sets are displayed in the "Inactive" section, however, by default, they must be located in the same coordinate system as the primary image set, as indicated by the DICOM 'Frame of Reference UID' (0020,0052) tag, in order to be activated.
To activate a currently inactive image set that shares the same coordinate system as the primary image set, simply click on the checkbox to the left of the inactive image set. Similarly, to deactivate a currently active secondary image set, simply uncheck the checkbox to the left of the active image set. Please note that you can not deactivate the primary image set from the Images sidebar (this can only be done by double clicking on a different item from the Browse tab).
Unlocking Image Sets in Different Coordinate Systems
The DICOM 'Frame of Reference UID' (0020,0052) tag is how DICOM-compliant systems communicate that one or more objects are in the same coordinate space. If ProKnow DS indicates that two images are not in the same coordinate system, it implies that the source images were not transmitted with the same frame of reference. However, in some rare cases, the frame of reference may be set incorrectly in the source DICOM files, and the images may actually be in the same coordinate system. To accommodate this scenario, ProKnow DS allows you to unlock an image set in a different coordinate system, thereby allowing it to be displayed simultaneously with the primary image set. In these situations, it is important to understand that even though two image sets may appear to be in the same coordinate system, there may be subtle differences that are difficult to detect. As such, by unlocking an image set in a different coordinate system, you take full responsibility for ensuring that the objects are in the same coordinate system, despite the fact that the files imported to ProKnow DS indicate otherwise.
To unlock a currently inactive image set that does not share the same coordinate system as the primary image set, you can click the lock icon to the right of the inactive image set. Once unlocked, you can click the checkbox to the left of the unlocked image set to activate. Please note that unlocking an image set in a different coordinate system has the following restrictions:
- It is not possible to view secondary images that are not in the same coordinate system as the primary image set while contouring. Therefore, it is not possible to unlock images while contouring, nor it is possible to start editing a structure set if there are any active patient objects that are not in the same coordinate system.
- The unlocked state of an image set is not saved with the patient state, and any activated secondary image sets that are not in the same coordinate system as the primary image set will be automatically returned to the inactive state upon reloading the patient. This is to ensure that it is not possible for a user to unknowingly view a set of images in different coordinate systems while viewing or analyzing a patient.
In the event that one or more image sets with different frames of reference are indeed in the same coordinate system, it is possible to use the Force Frame of Reference operation from the Patient Browse tab to permanently force the objects to have a consistent frame of reference.
Adjusting Image Set Display Options
Once an image set has been activated, the Images sidebar allows editing the display options for the image set, including:
- Style (e.g., Grayscale, Inverted, Glow)
Please note that the Window/Level dropdown available from the Patient toolbar will always reflect the current display options of the primary image set (and not secondary image sets). In addition, with two image sets enabled, it is possible to synchronize the opacity of the two image sets by clicking on the Synchronize Opacity button located on the right side of the Active section header (this option is only available when there are exactly two active image sets).